Patent Publication Number: US-2023151756-A1

Title: Cover and sensor for diesel exhaust fluid (def) module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This a Continuation of U.S. patent application Ser. No. 17/700,012 which was filed on Mar. 21, 2022 as a Divisional of U.S. patent application Ser. No. 17/206,834 which was filed on Mar. 19, 2021, and the contents of both are incorporated herein by reference as if fully set forth herein. 
    
    
     FIELD OF INVENTION 
     This disclosure generally relates to a diesel exhaust fluid (DEF) module. 
     BACKGROUND 
     Diesel exhaust fluid (DEF) is used in diesel engines in order to reduce pollution generated by the engine. DEF is typically made of a urea solution and is configured to reduce nitrogen oxides (NO x ) into water and nitrogen, which drastically reduces the polluting effect of the engine exhaust. 
     DEF tanks or modules are separate from other engine components due to urea being corrosive to metal. Additionally, DEF has a freezing point around 12° F. and therefore must be heated in order to ensure that DEF remains liquid and can be pumped from the DEF tank to the exhaust pipeline. One method of ensuring that the DEF is maintained at the proper temperature is to provide a heating element within the DEF tank. Sensor assemblies also monitor the DEF temperature and provide alerts or indications when DEF levels in the tank are low. 
     Due to these various requirements, it is critical that components or tubing passing thorough the cover are properly and reliably sealed. 
     SUMMARY 
     The Applicant has addressed the prior art failings with a DEF module cover assembly with a closure that has more a reliable sealing and an improved sensor assembly. 
     The closure has a cover portion that is dimensioned to close the DEF holding tank and includes a variety of openings for passing different components through the cover and into the DEF holding tank. A plurality of sealing devices are provided for sealing the openings according to the combination of an opening and a selected component. Each sealing device is fixed to the cover portion by a sonic weld. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing Summary and the following Detailed Description will be better understood when read in conjunction with the appended drawings, which illustrate a preferred embodiment of the disclosure. In the drawings: 
         FIG.  1    is a perspective view of a DEF assembly. 
         FIG.  2    is a partially assembled view of a module of the DEF assembly. 
         FIG.  3    illustrates a heating assembly attached to a cover of the module. 
         FIG.  4    is a magnified view of a pickup tube of the module. 
         FIG.  5    is a perspective view of the cover of the module taken along a cross-section through an opening defined for passage of electrical wires. 
         FIG.  6    is another view of the cover of  FIG.  5   . 
         FIG.  7    is a magnified cross-sectional view of the cover in a region of the opening for the pickup tube. 
         FIG.  8    is a side cross-sectional view of a sensor assembly in an upper region. 
         FIG.  9    is a side cross-sectional view of the sensor assembly in a lower region. 
         FIG.  10    is a side view of the sensor assembly of  FIGS.  8  and  9   . 
         FIG.  11    is a cross-sectional side view of the sensor assembly in the upper region. 
         FIG.  12    is an additional cross-sectional side view of the sensor assembly in the lower region. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS.  1  and  2   , the DEF assembly  10  generally includes a DEF holding tank  12 , a pump  14 , and a cover module or closure  16 . The closure  16  includes a cover  18  that forms the top of the tank  12 . A pickup tube  20  is arranged within the tank  12  to provide DEF from the tank  12  to the exhaust pipeline via the pump  14 . 
     The DEF closure  16  includes a heating assembly  30  shown in  FIG.  3   . The heating assembly  30  includes a heating element  32  configured to be submerged in DEF within the tank  12 . The heating assembly  30  includes a first set of electrical leads  34   a  and  34   b  that are connected to the heating element  32 . A second set of electrical leads  36   a  and  36   b , shown in  FIGS.  3  and  4   , are helically wrapped around the pickup tube  20 . 
     As shown in  FIGS.  5  and  6   , the cover  18  includes a sealing assembly  40  that retains and seals multiple components passing through the cover  18 . With reference to  FIG.  5   , each sealing assembly includes a plug  42  dimensioned for a press-fit into an opening, such as  19   a  or  19   b , in the cover  18 . The plug  42  has a radially outer surface with a tapered profile that complements the radially inner surface and taper of the opening  19   a . The press-fit engagement between the tapered surfaces of the plug  42  and opening  19   a  secures the plug  42  relative to the cover  18 . The plug  42  may include a plurality of passages  43   a    43   b  that are dimensioned to receive and secure wires, cables, or other components passing through the cover  18 . The plug  42  is preferably formed from a material that is compressible, or capable of deformation. Press-fitting the plug  42  into the opening  19   a  causes the plug  42  to elastically compress or deform to constrict the passages  43   a    43   b  and secure the components within the plug  42 . As a result of this press-fit, the need for separate clamping devises for securing a plug  42  to the cover  18  is eliminated. 
     As shown in  FIG.  5   , the cover  18  has a shoulder or collar  21  surrounding the opening  19   a . In the preferred assembly, the plug  42  is pressed into the opening  19   a  until the top surface of plug  42  is at least flush with the axial or free end of the collar  21 . A sealing cap  44  is positioned over the plug  42  and the collar  21 . The sealing cap  44  has lower portion  45   a  that is dimensioned to surround the collar  21  and an upper portion  45   b  that extends inwardly toward the center opening to extend over the plug  42 . In the preferred embodiment, the sealing cap  44  is fastened to the plug  42  and the cover  18  by sonic welding them together as a unit. 
     With reference to  FIGS.  3  and  5  through  7   , a pickup tube hose  20 ′ is secured to the cover  18  via a barbed hose fitting  47  and a metal clamp  48 . The barbed hose fitting  47  is illustrated in  FIG.  7    without the metal clamp  48 . The barbed hose fitting  47  can be attached to the cover  18  by a press-fit, a sonic weld, or a threaded connection. Alternatively, the hose fitting  47  may be molded as part of the cover  18 . 
     As shown in  FIGS.  8 - 12   , a sensor assembly  50  is provided for the cover assembly  16 . In one aspect, the sensor assembly  50  is configured to both detect a temperature of the DEF and detect a fill level of the DEF within the tank  12 . As shown in  FIGS.  8 - 12   , the housing  52  of sensor assembly  50  includes at least one sensor  76  that passes through collar  53  defined on a proximal or first end of the sensor housing  52 , and extends to base of the tank  12 , shown in  FIG.  1   . A cap  58  closes the distal end  56  of the sensor housing  52 . Preferably, the base cap  58  is sonic welded to the housing  52 . A temperature sensor element  60 , such as a thermistor, is preferably arranged within the sensor housing  52 . At least one electrical lead  61  is connected between a power source and the temperature sensor element  60 . A thermally conductive potting compound  62  is placed in opening  54  of the housing  52  to set the temperature sensor element  60 . The housing  52  includes a shoulder  55  at the end opposite to cap  58  that is dimensioned to protrude through the opening  19   b  when the housing connected to the cover  18 . 
     With reference to  FIGS.  8  and  10   , the junction housing  64  includes a sleeve  65  that is dimensioned to surround and engage the collar  53  of the sensor housing  52 . The sensor housing  52  and the junction housing  64  are preferably fastened to each other by sonic welding. As shown in  FIG.  8   , the cavity  70  inside the junction housing  64  is filled with the thermally conductive potting compound  62 . 
     A second or free end  66  of junction housing  64  is open as a passage for the electrical lead  61  to extend out to a power source. Depending on the information being collected, multiple electrical conductors or other components can be fed out through the free end  66  of housing  64 . The components passing through the free end  66  of the junction housing  64  are typically enclosed in an oil resistant wrapping or tube  74  that passes through a gasket. The free end  66  is closed with a sealing cap  68  that is dimensioned to surround the free end  66 . The cap  68  is preferably sonic welded to the free end  66 .