Abstract:
An assembly includes a first component connectable to a second component by a fastener extending through respective openings in the first component and in the second component. The assembly includes a compression load limiter housed in the opening of the first component and having a passage adapted to allow the fastener to extend therethrough. The compression load limiter is adjustable due to an adjustment feature configured to cause the load limiter to translate within the opening of the first component to span a gap between the first component and the second component. The load limiter bears at least a portion of a compression load of the fastener when the fastener is inserted in the respective openings of the first and the second components to secure the first component to the second component.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a compression load limiter for an assembly, such as for an engine assembly having an oil pan mounted to an engine block. 
       BACKGROUND 
       [0002]    Compression load limiters are generally used to protect components of an assembly from compressive loads generated by bolt tightening. For example, compression load limiters protect plastic from excessive tightening by a bolt used to connect the plastic component to another component. Excessive tightening of the plastic component may exceed the elastic limit of the plastic, leading to deformation, creep and eventual loosening of the assembly at the bolt. 
         [0003]    Many assemblies, such as engine assemblies, have components with a range of build tolerances. Gaps of different sizes between the components may result from the build tolerances. This may lead to distortion of the components when bolted to one another, as the bolts may compress the components to span the gaps. 
         [0004]    An engine assembly typically has an oil pan bolted to an engine block. The oil pan may be a composite oil pan with a steel structural brace supporting the oil pan. 
       SUMMARY 
       [0005]    An assembly includes a first component connectable to a second component by a fastener extending through respective openings in the first component and in the second component. For example, the assembly may be an engine assembly, having an oil pan as the first component, an engine block or an engine block cover as the second component, and a bolt as the fastener. The assembly includes a compression load limiter housed in the opening of the first component and having a passage adapted to allow the fastener to extend therethrough. The compression load limiter has an adjustment feature configured to cause the load limiter to translate within the opening of the first component to span a gap between the first component and the second component. The load limiter bears at least a portion of a compression load of the fastener when the fastener is inserted into the respective openings of the first and the second components to secure the first component to the second component. 
         [0006]    The adjustment feature may be an elastomeric element secured to the inner surface of the compression load limiter in the passage, or secured to the fastener itself. Alternatively, the adjustment feature may be internal threads in the passage of the compression load limiter that mate with threads of the fastener. In these embodiments, the fastener itself drives the load limiter to span the gap. Still further, the adjustment feature could be slots at a chamfered end of the compression load limiter that allow a driving tool to adjust the load limiter to span the gap prior to insertion of the fastener. 
         [0007]    For embodiments in which the assembly is an engine assembly, the oil pan may be a composite oil pan supported by a structural brace. The compression load limiter acts to limit the compressive load by the bolt on the oil pan while allowing the compressive load limiter to span the gap to create a solid joint between the structural brace and the engine block or engine block cover, alleviating potential bending of the oil pan. 
         [0008]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic side view illustration of an engine assembly including an oil pan mounted to an engine block and an engine cover, and a structural brace supporting the oil pan; 
           [0010]      FIG. 2  is a schematic perspective illustration of the oil pan and the structural brace of  FIG. 1 ; 
           [0011]      FIG. 3  is a schematic cross-sectional illustration in fragmentary view of the oil pan and structural brace of  FIG. 2 , taken at lines  3 - 3  in  FIG. 2 , showing bolts and a first embodiment of an adjustable bolt compression limiter; 
           [0012]      FIG. 4  is a schematic perspective illustration of the structural brace of  FIG. 1  and compression limiters supported on the oil pan, which is shown in phantom; 
           [0013]      FIG. 5  is a schematic cross-sectional illustration in fragmentary view of the oil pan and structural brace of  FIG. 3  with the bolt and the first embodiment of the adjustable bolt compression limiter in closer view; 
           [0014]      FIG. 6  is a schematic cross-sectional illustration in fragmentary view of the oil pan and structural brace of  FIG. 3  with the first embodiment of the adjustable bolt compression limiter spanning a gap between the oil pan and the engine cover; 
           [0015]      FIG. 7  is a schematic cross-sectional illustration in fragmentary view of the oil pan and structural brace of  FIG. 3  with a second embodiment of an adjustable bolt compression limiter spanning the gap between the oil pan and the engine cover; and 
           [0016]      FIG. 8  is a schematic cross-sectional illustration in fragmentary view of the oil pan and structural brace of  FIG. 3  with a third embodiment of an adjustable bolt compression limiter spanning the gap between the oil pan and the engine cover. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to the drawings, wherein like reference numbers refer to like components,  FIG. 1  shows an engine assembly  10  that includes an engine block  12  with an engine cover  14 . A transmission  16  is operatively connected to the engine assembly  10 . As further described below, a composite oil pan  18  is mounted to the engine block  12  and the engine cover  14  at a flange  20  of the oil pan  18 , and a structural brace  22  supports the oil pan  18 . The structural brace  22  protects the composite oil pan  18  and improves powertrain bending stiffness. The oil pan  18  is also referred to herein as a first component, and the engine block cover  14  as a second component. 
         [0018]    Referring to  FIG. 2 , the structural brace  22  surrounds a portion of the oil pan  18 . A side  24  of the structural brace  22  interfaces with a housing of the transmission  16  of  FIG. 1 . A plurality of fasteners such as bolts  26 , some of which are shown in  FIG. 3 , extend through openings  28  in the structural brace  22  and aligned openings  30  in the oil pan flange  20 . Each bolt  26  extends through an additional opening on the engine block  12  or in the engine block cover  14 , depending on where the particular bolt  26  is positioned on the oil pan flange  20 .  FIG. 1  shows representative openings  32  in the engine block  12  and a representative opening  34  in the engine block cover  14 . 
         [0019]    Referring to  FIG. 4 , the oil pan  18  is shown in phantom to better view the structural brace  22 . Additionally, bolt compression limiters  40  are shown housed in the openings of the oil pan flange  20 . Two adjustable bolt compression limiters  42 , also referred to herein as load limiters, are positioned in the oil pan flange  20  and partially in the structural brace  22  as further described below. A person of ordinary skill in the art will readily understand the function and operation of the bolt compression limiters  40 . Namely, the bolt compression limiters  40  prevent excessive compression of the composite oil pan flange  20  by bolts  26  inserted through the respective openings  30  in the oil pan flange  20  to attach the oil pan  18  to the engine block  12  or the engine block cover  14  as described with respect to  FIGS. 1-3 . Each bolt  26  is inserted from below the oil pan flange  20  in  FIG. 1 , and is threaded into either opening  32  in the engine block  12  or an opening  34  in the engine block cover  14 . The head of the bolt  26  will rest against the bottom  41  of the bolt compression limiter  40 , as indicated in  FIG. 4 , and the bolt  26  cannot compress the oil pan flange  20  to a thickness less than the thickness  44  of the bolt compression limiter  40 . 
         [0020]    Because the oil pan  18  is connected to both the engine block  12  and the engine block cover  14 , as well as to the transmission  16 , build tolerances of these components affect the alignment of the openings  28 ,  30 ,  32 ,  34 , and may create gaps between the oil pan flange  20 , the engine block  12 , and the engine block cover  14 . For example, if bolts  26  are installed to connect the oil pan  18  to the engine block  12  first (prior to the engine block cover  14 ), there may be a gap  45  between the upper surface  46  of the oil pan flange  20  and the lower surface  48  of the engine block cover  14 , as shown in  FIG. 6 . If only traditional (non-adjustable) bolt compression limiters  40  are used in the oil pan flange  20 , then the oil pan  18  will have to bend along its longitudinal axis  50  (indicated in  FIG. 2 ) in order for the upper surface  46  of the oil pan flange  20  to contact the lower surface  48  of the engine block cover  14  and allow the traditional bolt compression limiter  40  to contact the engine block cover  14  to create a solid joint from the structural brace  22  to the engine block cover  14 . 
         [0021]    To avoid the potential bending and distortion of components due to build tolerances of typical bolt compression limiters, at least one adjustable bolt compression limiter  42 , also referred to as an adjustable load limiter, is used to mount the oil pan  18  to the engine block  12  and the engine block cover  14 . In the embodiment shown in  FIG. 3 , two adjustable bolt compression limiters  42  are used at the rear of the oil pan  18  and structural brace  22  in the vicinity of the transmission  16  of  FIG. 1 . More adjustable bolt compression limiters  42  could be used, and they may alternatively be positioned at the opposite end of the oil pan  18  where it connects to the engine block  12 . 
         [0022]    As shown in  FIGS. 5 and 6 , the adjustable bolt compression limiter  42  has external threads  52  at which it is initially screwed into a threaded outlet portion of the opening  28  in the structural brace  22  at internal threads  54 . The adjustable bolt compression limiter  42  is generally annular with a central passage  56  through which the bolt  26  extends when connecting the structural brace  22  and oil pan flange  20  to the engine block cover  14 . Prior to inserting the bolt  26 , a bottom surface  58  of the bolt compression limiter  42  rests on a shoulder  60  of the opening  28 . In that position, the upper surface  62  of the adjustable bolt compression limiter  42  is substantially level with the upper surface  46  of the oil pan flange  20 . The adjustable bolt compression limiter  42  has an adjustment feature  64  that causes the adjustable bolt compression limiter  42  to move in unison with the bolt  26  when the bolt  26  is inserted into the passage  56  until the upper surface  62  of the adjustable bolt compression limiter  42  contacts the lower surface  48  of the engine block cover  14 . The adjustable bolt compression limiter  42  thus spans the gap  45  and ensures a solid joint between the structural brace  22  and the engine block cover  14  through the adjustable bolt compression limiter  42 . The bolt  26  has external threads shown in phantom. 
         [0023]    In the embodiment of  FIGS. 5 and 6 , the adjustment feature  64  is an elastomeric ring attached to an inner surface of the adjustable bolt compression limiter  42  in the passage  56 . The elastomeric ring adjustment feature  64  is sufficiently sized to grip the outer surface  66  of the bolt  26  as it is inserted into the passage  56 . The bolt  26  acts as a drive feature to drive the adjustable bolt compression limiter  42  upward in the opening  30 . The gripping of the adjustment feature  64  to the bolt  26  causes the adjustable bolt compression limiter  42  to move in unison with the bolt  26  as the bolt  26  translates through the passage  56  to thread to the engine block cover  14  at opening  34 . 
         [0024]    Alternately, the adjustment feature  64  could be an elastomeric ring identical to the ring shown in  FIG. 6  but attached to the outer surface  66  of the bolt  26  and that grips the inner surface of the passage  56  when the bolt  26  is driven in the passage  56  to cause the adjustable bolt compression limiter  42  to move in unison with the bolt  26 . The adjustable bolt limiter  42  moves upward in  FIG. 6  with the bolt  26  until the surface  62  contacts the surface  48 , closing the gap  45 . The bolt  26  continues to move upward until the bolt head  70  (shown in  FIG. 3 ) seats against the brace  22 . 
         [0025]    In other embodiments, the adjustment feature  64  could be a deformable plastic piece, a metallic spring, or another configuration able to cause the adjustable bolt compression limiter  42  to move in unison with the bolt  26 . 
         [0026]    An anti-rotation feature, such as a coating of adhesive  72  shown schematically in  FIG. 6  may be applied to the inner surface of the adjustable bolt compression limiter  42  at the passage  56  to prevent rotation of the adjustable bolt compression limiter  42  relative to the bolt  26 . The adhesive  72  is time curing, and would hold the relative positions of the adjustable bolt compression limiter  42  and the installed bolt  26  after curing. The adhesive  72  could be applied to the thread  52  or  54  as an anti-rotation feature between the adjustable bolt compression limiter  42  and the structural brace  22 . The adjustable bolt limiter  42  prevents the bolt  26  from compressing the flange  20  or distorting or bending the flange  20  and accommodates build tolerances that create gaps, such as gap  45 . 
         [0027]    Referring to  FIG. 7 , an alternate embodiment of an adjustable bolt compression limiter  142  is shown. In this embodiment, the adjustable bolt compression limiter  142  has internal threads  164  at the passage  56  that act as the adjustment feature. The internal threads  164  mate with external threads  166  on the bolt  26 . The mating threads  164 ,  166  allow the bolt  26  to act as a drive feature to drive the adjustable bolt compression limiter  142  upward in the opening  30  until the upper surface  162  of the adjustable bolt compression limiter  142  contacts the surface  48  of the engine block cover  14 , with the adjustable bolt compression limiter  142  spanning the gap  45  to create a solid joint from the brace  22  to the engine block cover  14  through the adjustable bolt compression limiter  142 . 
         [0028]    Referring to  FIG. 8 , another alternate embodiment of an adjustable bolt compression limiter  242  is shown. In this embodiment, the adjustable bolt compression limiter  242  has slots  264  at a chamfered end  266  of the adjustable bolt compression limiter  242  that receive an end of a driving tool  268  (shown in phantom) sized to fit through the opening  28  in the brace  22 . In this embodiment, the diameter of the opening  28  may be slightly larger than the diameter of the passage  56  to accommodate the slots  264  and the tool  268 . The end of the tool  268  engages the adjustable bolt compression limiter  242  at the slots  264  such that the adjustable bolt compression limiter  242  turns as the tool  268  is turned, so that threads  52  move upward along threads  54  and the gap  45  is closed when the upper surface  262  contacts the surface  48  of the engine block cover  14 , creating a solid joint from the brace  22  to the engine block cover  14  through the adjustable bolt compression limiter  242 . 
         [0029]    While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.