Abstract:
An internal combustion engine crankshaft assembly includes a crankshaft having an output device, such as a flywheel or crankshaft damper, fastened to the crankshaft. An electronic engine control device is positioned between the crankshaft and the output device. The electronic engine control device includes a generally planar base which contacts both the output device and the crankshaft. The planar base is coated with a pressure-responsive friction-promoting material which causes the output device be torsionally locked with respect to the crankshaft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The subject matter disclosed herein relates to a crankshaft assembly for a reciprocating internal combustion engine having a crankshaft position encoder which is mounted upon either a crankshaft output flange, or at the front of the crankshaft. 
         [0004]    2. Discussion of Prior Art 
         [0005]    Reciprocating internal combustion engines, particularly those employed in automotive vehicles, utilize a crankshaft having an output flange to which a flywheel or flex plate is fastened. The friction necessary to transmit torque between the engine&#39;s crankshaft and the flywheel is produced at least in part by clamping the flywheel to the output flange by means of threaded fasteners. Unfortunately, as engine output torques have increased, sometimes without a concomitant increase in the engine size, and often through the use power adders such as charge boosters, it has become increasingly difficult to transmit engine torques efficiently. Moreover, if a flywheel or flexplate begins to slip or shift upon a crankshaft, the resulting vibration, while annoying, is only a telltale of far greater problems, because rapid engine destruction may ensue. Although it is known to insert a friction-enhancing washer between a flywheel and a crankshaft output flange, this type of structure is problematic because the washer may be omitted inadvertently during the assembly process, with the result that the engine will likely fail due to slippage of the flywheel with respect to the crankshaft. 
         [0006]    Most automotive engines utilize a crankshaft pulley, mounted at the end of the crankshaft opposite the flywheel or flexplate end. Depending upon the particular application, such crankshaft pulleys usually drive a number of accessories, such as a generator, water pump, air conditioning compressor, power steering pump, and others. This duty necessitates a high torque capacity joint between the crankshaft pulley and the crankshaft. While it is known to handle this torque requirement, at least in part, by a key inserted into a keyway defined by slots formed in the crank damper&#39;s hub and the crankshaft&#39;s pulley mounting surface. This arrangement is not entirely satisfactory, because the majority of the torque load is accommodated by the joint defined by the crankshaft damper bore and the crankshaft&#39;s snout. Unfortunately, higher torque operation requires a concomitant increase in the size of the joint, which is sometimes difficult to provide because there is insufficient space to package the joint. 
         [0007]    It would be desirable to provide a crankshaft assembly with a friction-enhancing component interposed between the crankshaft and the flywheel or crankshaft pulley, wherein the introduced component is essential to the operation of the engine, to the extent that absence of the component will prevent the engine from operating. This will assure that the higher torque capacity provided by the friction enhancing component is always present during operation of the engine. 
       SUMMARY OF THE INVENTION 
       [0008]    According to an aspect of the present invention, an internal combustion engine crankshaft assembly includes a crankshaft having an output flange, a flywheel fastened to the output flange, and a sensor wheel positioned between the output flange and the flywheel, with the sensor wheel including a generally planar base having a first side in contact with the output flange, and a second side in contact with the flywheel. An integral ring-shaped sensor element circumscribes the generally planar base of the sensor wheel. A pressure-responsive friction-promoting material is applied to both of the first side and the second side of the sensor wheel, whereby the flywheel is torsionally locked with respect to the crankshaft flange. 
         [0009]    According to another aspect of the present invention, the generally planar base of the sensor wheel is configured as an annulus having a pilot bore which is engaged with a pilot formed on the crankshaft. 
         [0010]    According to another aspect of the present invention, the friction-promoting material applied to the sensor wheel may include a mineral based particulate, or a crystalline diamond composition. 
         [0011]    According to yet another aspect of the present invention, the sensor wheel may include a toothed encoder wheel which functions as a crankshaft position encoder wheel. 
         [0012]    According to yet another aspect of the present invention, an electronic engine control device may be positioned between the output flange of a crankshaft and a flywheel, with friction promoting material being applied to both the crankshaft and the flywheel sides of the engine control device. 
         [0013]    It is an advantage of the present invention that an engine will have increased torque transmitting capability between the engine&#39;s crankshaft and the flywheel, which is assured because of the use of an engine control device which must be in place for the engine to operate at all. 
         [0014]    It is another advantage of a system according to the present invention that enhanced torque transmitting capability is established between an engine crankshaft and flywheel without the cost of additional components. 
         [0015]    It is another advantage of a system according to the present invention that enhanced torque transmitting capability is achievable without increasing the size of crankshaft, flywheel, and crankshaft damper components. 
         [0016]    It is another advantage of a system according to the present invention that enhanced torque transmitting capability is achievable with spark ignition, compression ignition and homogeneous charge compression ignition internal combustion engines. 
         [0017]    Other advantages, as well as features of the present invention, will become apparent to the reader of this specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of a crankshaft assembly according to the present invention. 
           [0019]      FIG. 2  is perspective view of a crankshaft assembly of  FIG. 1 , showing a rearward portion of a flywheel. 
           [0020]      FIG. 3  is a perspective view of an encoder wheel according to one aspect of the present invention. 
           [0021]      FIG. 4  illustrates the encoder wheel of  FIG. 3  having been put in place upon the output flange of a crankshaft. 
           [0022]      FIG. 5  illustrates an encoder wheel attached to the front end accessory drive portion of a crankshaft according to an aspect of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    As shown in  FIGS. 1 and 2 , crankshaft assembly  10  has a crankshaft  14 , to which a number of pistons,  18 , are connected by means of connecting rods,  22 . Crankshaft  14  has an output flange,  26 , which is configured as a right, circular truncated cylinder. Output flange  26  provides mounting for sensor wheel,  38 , as well as a flywheel  34 . As shown in  FIG. 2 , flywheel  34  and sensor wheel  38  are mounted to output flange  26  by means of a number of cap screws,  36 . Flywheel  34  is centered upon output flange  26  by means of a pilot,  30 , which is shown in  FIG. 2 . 
         [0024]    Details of sensor wheel  38 , which comes from a class of control devices such as rotary position encoder wheels which are mountable upon an engine crankshaft, are shown in specificity in  FIG. 3 . As used herein, the term “control device” means an item of electronic engine control hardware which is essential for operation of the engine. For a spark-ignited engine, a spark coil represents another type of “control device” because such an engine cannot operate without at least one spark coil or other source of high voltage. The illustrated crankshaft encoder is required for operation of the engine&#39;s spark and fuel injection timing; in the absence of proper operation of sensor wheel  38 , the engine will not run. For compression ignition or “diesel” engines, crankshaft position information is needed to operate the fuel injection system. In any event, sensor wheel  38  includes an encoder ring,  46 , with a number of teeth,  48 . Ring  46  functions with a conventional pickup (not shown) as a crankshaft position sensor device. Control device  38  has an annular base,  40 , with a center aperture,  42 , which registers with pilot  30  when sensor wheel  38  has been installed upon crankshaft  14 . Sensor wheel  38  has a first side,  50 A, which is in contact with output flange  26 , and a second side,  50 B, which is in contact with flywheel  34 . In a preferred embodiment, a friction-promoting material, configured as a crystalline diamond composition,  52 , is applied to both sides  50 A and  50 B of sensor wheel  38 . One such material found to be useful for practicing the present invention is a diamond-filled nickel phosphate coating sold by ESK, a Ceradyne Company, under the trade name EKagrip™. 
         [0025]    As shown in  FIG. 4 , sensor wheel  38  is configured to nest upon output flange  26  so as to compactly install toothed encoder ring  46  in a very small diameter package, and with minimal weight and expense. Notice that a portion of pilot  30  protrudes past the face  50 B of sensor wheel  38 , so as to permit piloting of flywheel or flex plate  34  upon crankshaft  14 . When sensor wheel  38 , as specially prepared with friction-promoting material, has been placed between output flange  26 , and flywheel  34 , and fasteners  36  have been torqued to specification, coating  52 , which is described above in a preferred embodiment as a crystalline diamond composition, will cause flywheel  34  to be torsionally locked to crankshaft output flange  26 , and for that matter with a balance of crankshaft  14 . The previously described diamond-bearing coating is thus said to be pressure-responsive because the act of torquing the flywheel&#39;s fasteners creates a clamping force which embeds the freestanding diamond particles into the adjoining metallic surfaces. In turn, this causes the claimed torsional locking of flywheel  34  to crankshaft  14 . 
         [0026]    Those skilled in the art will appreciate in view of this disclosure that other compositions, such as, without limitation, mineral-based particulates, sometimes configured as abrasive compositions, may be used as a pressure-responsive, friction-promoting material in the present system. 
         [0027]      FIG. 5  illustrates an encoder wheel attached to a front end accessory drive portion,  106 , of a crankshaft,  101 . This portion is opposite the end of the crankshaft to which the flywheel or flexplate is attached. In this embodiment, rotary position encoder wheel  100 , which is prepared with friction material as described above, is teamed with a Hall Effect sensor,  105 . Encoder wheel  100  has a central pilot hole which is engaged by pilot  108  extending from damper mounting stub  106  of crankshaft  101 . Encoder wheel  100  and crankshaft torsional damper  102 , including front end accessory drive pulley  104 , are mounted to damper mounting stub  106  with a plurality of fasteners extending into threaded holes  118  through apertures  114  in pulley  104 , as well as apertures  116  in encoder wheel  100 . Dowel  120 , which is carried in crankshaft  101 , engages aperture  122  in encoder wheel  100 , and aperture  124  in pulley  104 , to index encoder wheel  100  and damper  102 . 
         [0028]    The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.