Abstract:
An engine system providing exceptional fuel efficiency is one that has two powerplants coupled by an electrically-actuated clutch. Packaging the two powerplants, the clutch, and the engine accessories presents a challenge. By driving the accessories via a shaft associated with the clutch, the accessories can be mounted between the two engines. Furthermore, this may facilitate providing one of each accessory rather than one per engine. The housing of the clutch is provided with tabs extending outwardly on which the accessories and associated components, such as mounting plates, mounting brackets, shafts, idler pulleys, tensioners, and pulleys, are mounted.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority benefit from U.S. provisional patent application No. 61/543,347 filed 5 Oct. 2011. 
     
    
     FIELD 
       [0002]    The present disclosure relates to an accessory drive for a multiple powertrain system. 
       BACKGROUND 
       [0003]    A powertrain system that provides superior fuel efficiency is one that includes two internal combustion engines that are coupled via a clutch. At most operating conditions, power is provided by one of the engines. When demanded power level exceeds what the operating engine can provide, the second engine is commanded to also operate. In one scenario, one of the two engines is the primary engine which is the engine that provides the driving power with the secondary engine operated only as needed. In another scenario, either of the two engines can serve as the primary engine, i.e., the engine operated at low power requirements. This is advantageous to ensure equal wear on the two engines so that the powertrain system has longer operational life. A simple way of accomplishing this is to motor the non-operating engine. Alternatively, a gear set, such as is common in hybrid electric vehicles, can be arranged to allow the power from either engine to provide the driving power. 
         [0004]    In any of the scenarios, a compact apparatus to drive accessories, such as the alternator, power steering pump, air conditioner, water pump, and brake booster, is desired. Furthermore, it is desirable to provide one of each accessory rather than two, i.e., one coupled to each powerplant. 
       SUMMARY 
       [0005]    An accessory drive for a powertrain system having two powerplants includes a clutch that selectively couples the two powertrains via first and second selectively-coupled portions. The clutch is provided with a plurality of mounting tabs extending outwardly substantially in a radial direction from a housing of the clutch. The housing of the clutch includes a plurality of sections each having a flange with the housing sections coupled at the flanges and at least one of the mounting tabs extends outwardly from one of the flanges. In one embodiment, a first mounting tab defines a journal providing a bearing surface to support a shaft associated with an accessory drive pulley and a second mounting tab defines mounting holes to which an accessory support member is coupled. In another embodiment, at least one mounting tab extends from a first end of the clutch housing proximate the first powerplant and at least one mounting tab extends from a second end of the clutch housing proximate the second powerplant. 
         [0006]    In some embodiments, the first portion of the clutch has a clutch shaft that is coupled with a crankshaft of the first powerplant. An accessory drive shaft has an axis of the accessory drive shaft substantially parallel with the clutch shaft. The clutch shaft and the accessory drive shaft have teeth that engage with a chain linking the shafts in a defined rotational relationship. The system may further include a pulley coupled to the accessory drive shaft, a plate mounted to at least one of the mounting tabs, an accessory mounted to the plate with the accessory having a pulley, and a belt wrapped around the pulley associated with the accessory drive shaft and the pulley associated with the accessory. The accessory may be a steering power pump, an alternator, or a water pump. The system may further include a belt tensioner having a pulley. The belt is further wrapped around the pulley associated with the belt tensioner coupled to the accessory drive shaft wrapped around the first pulley coupled to the accessory drive shaft wrapped around the second pulley mounted to at least one of the mounting tabs mounted to the first plate with the first accessory having a pulley onto which the second belt is further wrapped, and a second accessory having a pulley onto which the second belt is further wrapped. 
         [0007]    Also disclosed is a clutch having a first housing portion with a first flange extending therefrom substantially radially, a second housing portion with a second flange extending therefrom substantially radially, and first and second mounting tabs extending outwardly from one of the first and second flanges. The first mounting tab defines a journal providing a bearing surface adapted to support a rotatable shaft and the second mounting tab defines mounting holes adapted to support an accessory device. At least one additional mounting tab extends outwardly substantially radially proximate an end of the clutch in some embodiments. The clutch is adapted to couple to first and second powertrains and the clutch selectively couples the first powerplant to the second powerplant. Also disclosed is a powertrain system has a first powerplant, a second powerplant, a clutch coupled between the first powerplant and the second powerplant, and a plurality of mounting tabs extending outwardly substantially in a radial direction from a housing of the clutch wherein a first mounting tab defines a journal providing a bearing surface to support a shaft associated with an accessory drive pulley and a second mounting tab has mounting holes to which an accessory support member is coupled. A clutch shaft extends axially from the clutch. An accessory drive shaft with an axis of the accessory drive shaft is substantially parallel with the central axis of the clutch. The accessory drive shaft rotates within the bearing surface in the first mounting tab and a flexible member couples the accessory drive shaft. The system may further include a drive pulley coupled to the accessory drive shaft, a first accessory coupled to the second mounting tab wherein the first accessory has an accessory pulley, and a belt coupling the drive pulley and the accessory pulley. 
         [0008]    In one embodiment, the system includes a clutch shaft extending axially from the clutch and an accessory drive shaft with an axis of the accessory drive shaft substantially parallel with the central axis of the clutch. The system includes a first overrunning clutch coupled to one end of the accessory drive shaft, a second overrunning clutch coupled to the other end of the accessory drive shaft, a first flexible member coupling the accessory drive shaft with the first overrunning clutch, and a second flexible member coupling the accessory drive shaft with the second overrunning clutch. A drive pulley is coupled to the accessory drive shaft. A first accessory is coupled to the second mounting tab. The first accessory has an accessory pulley and a belt couples the drive pulley and the accessory pulley. 
         [0009]    By providing the accessory drive components between the two powerplants, the system can be packaged compactly and the system may be provided with a single accessory that can be used to satisfy both engines and/or a vehicle into which the engine system is provided. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIGS. 1 and 2  are isometric representations of a multiple powerplant system according to an embodiment of the disclosure; and 
           [0011]      FIGS. 3 and 4  are schematic representations of multiple powerplant systems. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. Those of ordinary skill in the art may recognize similar applications or implementations whether or not explicitly described or illustrated. 
         [0013]    A powertrain system according to an embodiment of the disclosure is shown in  FIG. 1 . A primary engine  10  is selectively coupled to a secondary engine  12  via an electronically-controlled clutch (ECC)  14 . Engines  10  and  12  are opposed-piston, opposed-cylinder engines such as disclosed in U.S. Pat. No. 6,170,443. The present disclosure, however, applies to any type of powerplant. Furthermore, the primary and secondary powerplants may be of different types and/or sizes. 
         [0014]    Referring now to  FIGS. 1 and 2 , the housing  19  of clutch  14  includes at least two housing portions  16  and  18 . Housing portion  16  has a flange  20  that is coupled to a flange  22  of housing portion  18 . Flange  22  has a plurality of mounting tabs  30 ,  32 , and  34  extending outwardly (radially) from clutch  14 . Tab  30  has two orifices; to one of which an alternator  40  is mounted. 
         [0015]    Housing portion  16  is extended axially on an end proximate primary powerplant  10 , shown as extension  52  in  FIG. 2 . Such extension  51  is provided to house an extended shaft  51  on clutch  14 . Shaft  52  is extended axially to allow for a sprocket portion on shaft  52  to couple with a chain, discussed further below. In regards to the extension  51  and extended shaft  52 , these are extended in relation to a prior art clutch in which there is no power takeoff to drive ancillaries. 
         [0016]    A tab  36  extends outwardly from the end of clutch  14 . Tabs  34  and  36  each have a journal through which a shaft  50  extends. In  FIG. 2 , a shaft  52  extends axially out of clutch. A belt  54  meshes with sprockets associated with shafts  50  and  52 . Shaft  50  is driven via shaft  52  of clutch  14 . Pulleys  60  and  62  are coupled to shaft  50 . Belts  70  and  72  are wrapped around pulleys  60  and  62 , respectively. 
         [0017]    On the end of clutch  14  proximate secondary powerplant  12  are yet more mounting tabs  37 - 39  (visible in  FIG. 2 ; mostly occluded in the view of  FIG. 1 ). A plate  76  mounts to tabs  37  and  38  as well as to a bracket  78  mounted to alternator  40 . A pulley  64  coupled to a power steering pump  80  also has belt  72  wrapped around. Belt  72  wraps is also wrapped around pulley  65  of alternator  40 , idler pulley  66 , and pulley  67  of belt tensioner  82 . Belt  70  engages with pulleys of other accessories (not shown). 
         [0018]    When primary powerplant  10  rotates, shaft  52  is caused to rotate. Via belt  54 , shaft  50 , along with pulleys  60  and  62 , rotates. Via belt  72 , power steering pump  80 , and alternator  40  also rotate. Similarly, pulley  60 , via belt  70 , may drive additional accessories that are not shown in  FIGS. 1 and 2 . 
         [0019]    Elements  54 ,  70 , and  72  are shown as belts in  FIGS. 1 and 2 , but are not intended to be limiting. These may be chains or belts or any other suitable flexible member to engage with the pulleys. 
         [0020]    In  FIG. 3  a schematic is shown in which primary powerplant  110  is coupled to a first portion  116  of clutch  114  and secondary powerplant  112  is coupled to a second portion  118  of clutch  114 . As shown in  FIG. 3 , first and second portions  116  and  118 , shown as plates, are not touching and thus primary powerplant  110  may be rotating independently of secondary powerplant. When plates  116  and  118  are pressed together, powerplants  110  and  112  rotate together. Output from primary powerplant  110  is transmitted through transmission  120 . When plates  116  and  118  are engaged, output from both powerplants  110  and  112  is transmitted through transmission  120 . Also shown schematically in  FIG. 3 , is a chain  154  coupled to first portion  116 . Chain  154  drives shaft  150  which in turn drives accessories. In such an arrangement, powerplant  110  serves as the primary powerplant. 
         [0021]    In  FIG. 3 , a central axis  196  of clutch  114  is shown. In some embodiments, mounting tabs are described as being extending radially. The radial direction is taken with respect to central axis  196 . 
         [0022]    In  FIG. 4 , a schematic is shown in which either of powerplants  210  or  212  may be the primary powerplant. When clutch  214  is disengaged, as shown in  FIG. 4 , if powerplant  210  is rotating, chain  254  that meshes with shaft  280  associated with clutch portion  216  also moves. Chain  254  engages with overrunning clutch  260  that is coupled to accessory shaft  250 . Analogously, crankshaft  292  of powerplant  212  is coupled to clutch portion  218  via shaft  282 . Chain  252  engages with overrunning clutch  262  that is also coupled to accessory shaft  250 . Accessory shaft  250  has a pulley  258  by which accessories can be driven. 
         [0023]    When powerplant  210  rotates and powerplant  212  is stationary, overrunning clutch  260  is engaged with shaft  250 , but overrunning clutch  262  is disengaged with shaft  250  so that shaft  250  can rotate while chain  252  and powertrain  212  remain stationary. Or, if both powerplants  210 ,  212  are rotating, the powerplant that is rotating at a higher speed actually drives shaft  250  via its respective overrunning clutch with the overrunning not engages with shaft  250 . With such a configuration, shaft  250  rotates when either powerplant rotates. 
         [0024]    While the best mode has been described in detail with respect to particular embodiments, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. While various embodiments may have been described as providing advantages or being preferred over other embodiments with respect to one or more desired characteristics, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. The embodiments described herein that are characterized as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.