Patent Publication Number: US-9903311-B1

Title: Engine cam cover with integrated wiring and quick-connect electrical components

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to engine covers, and, more specifically, to molded covers receiving electrical engine components such as sensors and coil-on-plug units. 
     An outer surface of an internal combustion engine may include various covers enclosing certain moving and/or lubricated parts such as valves or a camshaft. Depending on the particular type of engine, such a cover may be commonly referred to as a cam cover, valve cover, or rocker cover. All such covers are referred to herein as a cam cover. 
     Modern internal combustion engines utilize multiple ancillary electrical components attached to their cam covers. These components may require large engine harnesses and a variety of electrical connectors. Potential disadvantages associated with engine harnesses and their associated electrical connectors may include problems with “hanking” of the harness on the outside of the cam cover, difficulties in making intermediate splices within the wire harness, incomplete seating of connectors, and missed connections during assembly or servicing of a vehicle. When a problem occurs, correction could require a simple reconnect to a much more expensive diagnosis with multiple component replacements and wire harness repairs of pigtail connectors. 
     In addition to complexity associated with the wiring, electrical components mounted to the cam cover such as a camshaft position sensor, camshaft timing solenoid, coil-on-plug unit, wastegate solenoid, wastegate vacuum sensor, engine temperature and pressure sensors, or a throttle body have required separate mechanical fasteners. The separate fasteners increase the complexity of both assembly and servicing of a vehicle as well as the cost. 
     SUMMARY OF THE INVENTION 
     The invention embeds electrical wires and contacts for the electrical components within a plastic molded cover which also forms integrated mounting features to eliminate separate mechanical fasteners. In one preferred embodiment, a flat ribbon-style wire harness is sealed between two plastic layers which are joined around their periphery by vibration welding. A locking feature is preferably provided for each electrical component which simultaneously obtains electrical contact and mechanical retention. For example, robust metal pin contacts on a component slide inside a helical groove during assembly to the plastic cam cover and are captured in mating metal cup contacts. The metal cups are attached to the wire harness inside the cover. An electrical connector at the opposite end of the embedded wire harness connects to an external harness in order to complete the electrical circuits necessary for the installed electrical components to function. The resulting cam cover is less cluttered with wires and connectors, and the number of electrical connectors that could be missed or improperly installed during production assembly is reduced. 
     In one particular aspect of the invention, a sealed cover for a combustion engine apparatus comprises a shell having molded inner and outer layers attached together and providing a sealing surface around an outer periphery. The shell defines a plurality of sockets providing respective passages through the layers for interfacing respective electrical components to the combustion engine. A wire bundle has a plurality of wires extending from a connector end disposed outside the shell to a terminal end disposed within a space between the inner and outer layers. A plurality of retainers are each disposed in a respective passage and having at least one helical track for rotationally receiving a connector pin extending radially from a respective electrical component. A plurality of metal cups are each installed at an end of a respective helical track and each connected to a respective wire at a respective terminal end. Each socket is configured to provide a latch to hold each respective connector pin at the respective track end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art valve cover. 
         FIG. 2  is a perspective view of the cover of  FIG. 1  with an engine and a wiring harness. 
         FIG. 3  is a side view of a conventional coil-on-plug unit and mechanical fastener. 
         FIG. 4  is a perspective view of one embodiment of a cam cover of the present invention. 
         FIG. 5  is an exploded, perspective view of another embodiment of a cam cover of the present invention. 
         FIG. 6  shows a coil-on-plug unit configured to be attached to the cam cover of  FIG. 5 . 
         FIG. 7  is a cross-sectional view of the cam cover and coil-on-plug unit of  FIGS. 5 and 6 . 
         FIG. 8  is a partial, side view of a groove retainer seen along line A indicated in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 and 2 , a dome-shaped cam cover  10  with a periphery  11  is mounted on an engine  12 . Cover  10  is preferably comprised of a molded plastic body including a plurality of sockets  14 - 18  for receiving respective electrical components of the combustion engine  12 . The electrical components may include a coil-on-plug unit  20  as shown in  FIG. 3  which passes through cover  10  to connect with a spark plug (not shown) on engine  12 . Sockets  14 - 16  are adapted to receive coil on plug units and sockets  17  and  18  are adapted to receive respective sensors. 
     In a prior art architecture shown in  FIG. 2 , a wiring harness  21  includes a thick wire bundle from which various wiring sections and connectors emerge, such as connectors  22 - 24  associated with sockets  14 - 16  and connectors  25  and  26  associated with sockets  17  and  18 . Thus, installation or servicing of cam cover  10  involves the connection and/or disconnection of numerous electrical connectors associated with the electrical components. Moreover, separate electrical and mechanical connectors and/or fasteners are required for servicing each electrical component, and sufficient space must be maintained surrounding cover  10  in order to accommodate all the fasteners and connectors. 
       FIG. 4  shows a sealed cam cover  25  formed as a dome-like shell with a molded inner layer  26  and a molded outer layer  27  providing a sealing surface  28  around an outer periphery. Sealing surface  28  may receive a gasket (not shown) to obtain a hermetic seal with an engine. Cover  25  is attached to the engine (not shown) using fasteners such as threaded bolts passing through a plurality of attachment bores  29 . A plurality of electrical components including coil-on-plug units  30 - 32 , variable camshaft timing solenoid valves  33  and  34 , and a camshaft position sensor  35 , are mounted within (i.e., interfaced with) respective passages defined by sockets  40 - 45  of shell cover  25 . 
     A wire bundle having a plurality of wires for interconnecting with electrical components  30 - 35  is partially contained within shell  25  between the layers  26  and  27 . Alternatively, the wires can be insert molded within shell  25 . The wire bundle has a connector end  36  at an edge of shell  25  adapted to connect with an external wiring harness connector  37 . 
     In order to simultaneously obtain electrical interconnection and mechanical fastening of electrical components  30 - 35 , sockets  40 - 45  and electrical components  30 - 35  include specially cooperating features that achieve a quick connect or quick disconnect in one manual operation without tools. 
     In particular, each electrical component has a plurality of connector pins extending radially from a central body. For example, a pin  39  projecting radially from coil-on-plug unit  30  is connected internally to the constituent circuitry of unit  30 . Together with the central body of unit  30 , pin  39  has structural robustness sufficient to carry a respective portion of the mechanical load that fastens unit  30  in place. The connector pins interact with retainers in each socket, wherein each retainer includes at least one helical track as shown by track  38  within socket  40 . Track  38  is formed as a continuous channel similar to a screw thread. The angular spacing of pins  39  on each type of electrical component and the corresponding tracks  38  within sockets  40  are configured to be unsymmetrical to ensure correct “keyed” installation of the electrical components. When the corresponding electrical component is “screwed into” the respective socket, the connector pin is received into a specific helical track which concludes with a metal cup (not shown). Each metal cup is electrically connected to a respective wire of the wire bundle. 
     Each socket is configured to provide a latch that holds each respective connector pin at the end of the respective track in a manner that simultaneously achieves mechanical fastening and electrical interconnection. For example, a latch mechanism in  FIG. 4  includes a radial notch  48  in a sealing flange  46 . Flange  46  extends laterally from the central body of electrical component  30  and has a lower surface that seals against and bears on a socket surface  47  after component  30  has been rotationally inserted in socket  40  and connector pin  39  has reached the end of helical track  38  to enter a corresponding metal cup. Upon reaching full rotation, a flexible post  49  which extends in an axial direction at a periphery of socket  40  is captured in radial notch  48 . Flange  46  preferably includes a ramp section  50  adjacent to radial notch  48  for gradually deflecting post  49  while component  30  is being inserted and rotationally installed into socket  40 . In order to remove component  30 , post  49  may be manually pulled in an outward radial direction from notch  48  so that counter-clockwise rotation of electrical component  30  can be applied to make the connector pins travel upward along the helical tracks. Preferably, each helical track spans 180° or less of rotation in each respective socket. Most preferably, the tracks span about a quarter turn. 
       FIGS. 5-8  illustrate another embodiment of the invention wherein a cover  55  has an inner layer  56  and an outer layer  57  formed of molded thermoplastic. Layers  56  and  57  are stacked to encapsulate a portion of a wire bundle  60  within an internal space that remains after layers  56  and  57  are vibration welded together along a peripheral welding track  58 . Inner layer  56  has a plurality of raised collars  61 A,  62 A, and  63 A that are aligned with raised collars  61 B,  62 B, and  63 B on outer layer  57 . The raised collars have matching openings corresponding to central passages for each socket. A plurality of retainers are arranged to further define the central passages between each respective pair of collars  61 A- 61 B,  62 A- 62 B, and  63 A- 63 B, such as retainers  61 C and  62 C. The retainers (e.g.,  61 C and  62 C) are attached to inner and outer layers  56  and  57  to complete the socket passageways (e.g., by adhesive bonding). 
     Wire bundle  60  may preferably be comprised of a flat ribbon cable. Wire bundle  60  has individual wires  66  extending from a connector end  64  to terminal ends of wires  66  which are connected to metal cups  67  (e.g., by soldering and/or crimping). Metal cups  67  are fixed in place at the ends of respective helical tracks  68  in the retainers (e.g., retainers  61 C and  62 C). Metal cups  67  can be bonded to the retainers, or captured between a respective retainer and raised collar. 
       FIG. 6  shows a quick-connect mounting for a coil-on-plug unit  70  in a socket  61  in greater detail. Unit  70  has a central body  71  with a sealing flange  72  and metal connector pins  73 - 75  extending radially from central body  71 . A spark plug socket (not shown) within a rubber boot  76  extends downward from unit  70  to pass through socket  61  in order to connect to a spark plug  85  ( FIG. 7 ) within a spark plug tube  86  of an engine. Socket  61  includes helical tracks  77  and  78  in retainer  61 C spiraling downward in socket  61 . A circumferential spacing between helical tracks  77  and  78  matches a circumferential spacing between connector pins  73  and  74 . By inserting pins  73 - 75  into the matching helical tracks and rotating unit  70 , unit  70  is inserted into socket  61  until sealing flange  72  engages an upper surface of socket  61 . Simultaneously, pins  73  and  74  engage metal cups  81  and  80 , respectively, thereby making the electrical connections of unit  70  to the embedded wire bundle. 
     In order to simultaneously latch unit  70  at the fully installed position in socket  61 , the bottom end of the helical tracks and/or the metal cups include a latching feature for acting on the connector pins of the electrical component as shown in FIG.  8 . Thus, helical track  77  in retainer  61 C defines a catch  90  as an indentation that captures a connector pin during assembly of the electrical component to the cam cover. Retainer  61 C may be flexible so that catch  90  can snap into place over the connector pin during insertion of the electrical component. This mechanical retention of the electrical component can be reversed by counter-rotating the electrical component with enough force to bend retainer  61 C to release the connector pin. Alternatively, a resilient sealing gasket can be used between the electrical component and the sealing surface of the socket so that a spring action from compressing the gasket can provide a force that retains the connector pin in catch  90 .