Abstract:
A power compounder, for transmitting rotary power from a transmission to a driveline assembly includes a housing adapted to be mounted to the transmission. An input shaft is rotatably supported by the housing and adapted to be driven by the transmission. The compounder further includes an output shaft adapted to drive the driveline assembly and a gearset. The gearset selectively communicates rotational movement between the input and output shafts. A centralized passageway is formed in the input shaft. A separator insert is disposed in the passageway and is adapted to carry fluid at a first pressure to a first predetermined location and carry fluid at a second pressure to a second predetermined location.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of U.S. patent application Ser. No. 10/916,106 filed on Aug. 11, 2004, now U.S. Pat. No. 7,059,987, which claims benefit of U.S. Provisional Application No. 60/496,454 filed on Aug. 20, 2003. 

   FIELD OF THE INVENTION 
   The present invention relates generally to power transmission assemblies for use in motor vehicles and, more specifically, to a compounder assembly that is operable to establish at least one additional speed ratio when used in conjunction with a multi-speed automatic transmission. 
   BACKGROUND OF THE INVENTION 
   Due to the lead time and expense required to design and build new multi-speed automatic transmissions, some motor vehicles are equipped with an auxiliary or “add-on” gearbox to provide one or more additional gear ratios. Some motor vehicles use this auxiliary gearbox to compound the gear ratios provided by the conventional automatic transmission so as to provide the additional gear ratios. Typically, such “compounders” include a planetary gearset and one or more clutches and/or brakes that can be selectively actuated to establish a direct drive mode and either of an underdrive ratio mode or an overdrive ratio mode. As is known, the direct drive mode provides a one-to-one gear ratio. On the other hand, the ratio drive modes provide a gear ratio other than one-to-one which, in conjunction with the multiple speed ratios established by the automatic transmission, provides a simple and relatively inexpensive means for establishing additional drive gears. 
   With reference to  FIG. 8 , a prior art compounder assembly  8  will be described. To manufacture compounder assembly  8 , a first bore B 1  is drilled into an input shaft for carrying fluid at a first pressure. A second bore B 2  is drilled into the input shaft for carrying fluid at a second pressure. Typically, first bore B 1  is adapted to carry fluid for influencing clutch actuation during a gearshift event while the second bore B 2  carries fluid for lubrication. While such compounders have proven to work satisfactorily for their intended purpose, a need exists to minimize complexity while advancing the state of the art. 
   SUMMARY OF THE INVENTION 
   A compounder assembly for transmitting rotary power from a transmission to a driveline includes a housing adapted to be mounted to the transmission. An input shaft is rotatably supported by the housing and adapted to be driven by an output shaft of the transmission. The compounder assembly further includes an output shaft, a planetary gearset between the input and output shafts, and a plurality of torque transfer devices arranged to selectively couple components of the planetary gearset. The planetary gearset selectively transfer rotary power (i.e., drive torque) from the input shaft to the output shaft. In accordance with a unique feature of the present invention, an elongated central passageway is formed in the input shaft. A port separator insert is disposed in the central passageway and is adapted to carry fluid at a first pressure to a first predetermined location and carry fluid at a second pressure to a second predetermined location. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a schematic diagram of a motor vehicle with one or more power transmission devices according to the present invention; 
       FIG. 2  is a sectional view of a compounder assembly according the present invention; 
       FIG. 3  is a sectional view of the separator insert according to a first embodiment of the present invention; 
       FIG. 4  is a sectional view of the separator insert of  FIG. 3  taken along line  4 - 4 ; 
       FIG. 5  is a partial perspective view of a separator insert according to a second embodiment of the present invention; 
       FIG. 6 and 7  are a partial perspective views of a separator insert according to third and fourth embodiments of the present invention; and 
       FIG. 8  is a sectional view illustrating a prior art compounder assembly; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring to  FIG. 1 , a motor vehicle drivetrain  10  is schematically illustrated to include a powertrain  12  for delivery motive power (i.e. drive torque) to wheels  14  of a primary driveline assembly  16 . Powertrain  12  includes an internal combustion engine  18  and an automatic multi-speed transmission  20 . Transmission  20  includes a plurality of torque transfer devices (i.e., clutches, brakes, etc.) under the control of an electro-hydraulic shift control system  22  that can be selectively actuated to establish a distinct number of forward gear ratios and at least one reverse gear ratio. 
   In an effort to promote smoother transmission shifting and greater fuel efficiency, it is known to equip powertrain  12  with an auxiliary or add-on power transmission assembly, hereinafter referred to as compounder assembly  24 , for permitting the establishment of additional forward gear ratios. Compounder assembly  24  is operably installed between the output shaft of transmission  20  and a driveshaft  26  associated with driveline assembly  16 . As will be detailed, compounder assembly  24  also includes torque transfer devices that are controlled by an electro-hydraulic shift control system  28  for establishing either of a direct drive connection or a ratio drive connection between the output shaft of transmission  20  and driveshaft  26 . In order to coordinate shifting of the torque transfer devices in transmission  20  and compounder assembly  24 , a transmission controller  30  is provided which selectively controls actuation of transmission shift control system  22  and compounder shift control system  28  in response to signals from various vehicle sensors  32 . The signals from vehicle sensors  32  are inputted to controller  30  and used to develop control signals that are delivered to the shift system actuators for establishing the desired gear ratio drive connection between engine  18  and driveshaft  26 . 
   With reference to  FIG. 2 , the components associated with compounder assembly  24  will now be described in greater detail. Compounder assembly  24  includes an underdrive unit  34  which is operable to selectively interconnect an input shaft  36  and an output shaft  38  for establishing both of the direct and ratio drive connections therebetween. Input shaft  38  and output shaft  38  are rotatably supported within a housing  40  and are coaxially aligned such that they rotate about a common longitudinal axis “A”. While not shown, it is understood that input shaft  36  is adapted for connection to and rotation with the output shaft of transmission  20 . Likewise, output shaft  38  is adapted for connection to and rotation with driveshaft  26  of driveline assembly  16 . 
   Underdrive unit  34  includes a planetary gearset  42  having an input member driven by input shaft  36 , a reaction member, and an output member driving output shaft  38 . In this regard, the input member of planetary gearset  42  includes a ring gear  44  which is driven by input shaft  36 . In particular, ring gear  44  is rigidly secured to a drive ring  46  which is fixed (i.e., splined) for rotation with input shaft  36 . The output member of planetary gearset  42  includes a planet carrier  48  fixed to a driven ring  50  which, in turn, is fixed for rotation with output shaft  38 . A sun gear  52  acts as the reaction member in planetary gearset  42  and is rotatably supported on input shaft  26  by a bearing assembly  54 . A plurality of planet gears  56  are rotatably supported from planet carrier  48  and meshed with ring gear  44  and sun gear  52 . 
   Underdrive unit  34  is further shown to include a direct clutch  58 , an underdrive clutch  60 , and an overrunning clutch  62 . Direct clutch  58  includes a clutch drum  64  fixed for rotation with sun gear  52 , a clutch hub  66  fixed for rotation with input shaft  36 , and a friction clutch pack  68  having interleaved clutch plates operably installed between drum  64  and hub  66 . Direct clutch  58  also includes a piston  70  supported for sliding movement in a pressure chamber  72  formed within drum  64 , and a spring assembly  74  for biasing piston  70  relative to clutch pack  68 . As seen, a reaction plate  76  also is fixed (i.e., splined) for rotation with drum  64 . Direct clutch  58  is operable in a locked mode when piston  70  exerts a compressive clutch engagement force on clutch pack  68  sufficient to couple drum  64  for rotation with hub  66 , thereby coupling sun gear  52  for common rotation with input shaft  36 . In contrast, direct clutch  58  is operable in a released mode when piston  70  is retracted from clutch pack  68  such that drum  64  and sun gear  52  are permitted to rotate relative to input shaft  36 . 
   Underdrive clutch  60  includes a clutch drum  80  that extends from housing  40 , a clutch hub  82 , and a clutch pack  84  of interleaved clutch plates installed therebetween. As seen, hub  82  also acts as an outer race member of overrunning clutch  62  which further includes an inner race  86  that is fixed to a hub extension  88  of housing  40  and rolling lock members  90  disposed therebetween. In addition, hub  82  is shown to be coupled to reaction plate  76  of direct clutch  58  via a set of interdigitated lugs  92 . Underdrive clutch  60  also includes a piston  94  supported for sliding movement in a pressure chamber  96  formed in housing  40  between drum  80  and hub extension  88 , and a bias spring  98  acting on piston  94 . Underdrive clutch  60  is operable in a released mode when spring  98  biases piston  94  to a retracted position such that hub  66  is permitted to rotate relative to housing  40 . In contrast, underdrive clutch  60  is operable in a locked mode when piston  94  engages clutch pack  84  such that hub  82  is braked against rotation. Such braking of hub  82  also causes reaction plate  76  and drum  64  to be braked against rotation, thereby braking rotation of sun gear  52 . 
   As is conventional, automatic transmission  20  is equipped with a series of control valves for controlling the supply and discharge of high pressure fluid to actuators associated with transmission shift control system  22 . The control valves receive electric control signals from controller  30 . The source of fluid used to supply hydraulic fluid to the actuators is maintained in a sump region within transmission  20 . As is conventional, pump and accumulator arrangements within transmission  20  draw fluid from the sump and provide fluid at high actuation pressures to the control valves. In a like manner, compounder assembly  24  is also equipped with a series of control valves for controlling the fluid pressure delivered to pressure chamber  72  of direct clutch  58  and to pressure chamber  96  of underdrive clutch  60 , as well as for delivering fluid to a lubrication circuit within underdrive unit  34 . In this regard, a first flow path within compounder assembly  24  for providing fluid to pressure chamber  72  of direct clutch  58  is shown to include an inlet passage  100  and a channel  102  formed in housing  40 , a through bore  104  formed in a journal bushing  106  located between housing  40  and input shaft  36 , and a circumferential channel groove  108  formed in input shaft  36 . A radial inlet bore  110  connects groove  108  to an elongated central longitudinal bore  112  formed in input shaft  36 . Preferably, bore  112  is gun-drilled so as to be coaxial with rotary axis “A” of input shaft  36 . As will be detailed, an elongated separator insert  114  is installed in bore  112  to define at least two distinct flow channels therein. A first flow channel  116  in separator insert  114  provides fluid communication between radial inlet bore  110  and a radial outlet bore  118  and a circumferential outlet groove  120  formed in input shaft  36 . To conclude the first flow path, a throughbore  122  in a hub segment of drum  64  permits fluid in outlet groove  120  to communicate with pressure chamber  72 . 
   A second flow path for underdrive clutch  60  is shown to include a port  122  in housing  40  and an inlet passage  124  which communicates with pressure chamber  96 . Likewise, a third flow path is provided to circulate fluid for lubricating and cooling the components of underdrive unit  34 . This third flow path includes an inlet passage  126  and a channel  128  formed in housing  40 , a bore  130  through journal bushing  106 , a circumferential groove  132  and a radial inlet bore  134  formed in input shaft  36 , and a second flow channel  136  established by separator insert  114  within elongated central bore  112 . As seen, a series of radial lubrication bores  140  connect second flow channel  136  to various lubrication bores formed in input shaft  36  which, in turn, supply lubricant to components of underdrive unit  34 . 
   In operation, a first control valve would be selectively actuated to control the delivery of fluid from the pressure source to pressure chamber  72 , thereby controlling shifting of direct clutch  58  between its released and locked modes. Likewise, a second control valve would be selectively actuated to control the delivery of fluid from the pressure source to pressure chamber  96 , thereby controlling shifting of underdrive clutch  60  between its released and locked modes. Delivery of fluid to the third flow path for lubrication and cooling can, if required, be controlled by a third control valve for regulating the flow of fluid from the pressure source. Preferably, the fluid source for compounder assembly  24  is the same as transmission  20 , namely, the hydraulic fluid maintained in the sump of transmission  20 . As such, passages  100 ,  122  and  126  would be connected thereto via suitable hosing or piping. 
   Referring now to  FIGS. 3 and 4 , separator insert  114  is shown to include first and second circular end rings  150  and  152 , respectively, and a planar divider plate  154  therebetween. The end rings are sized to establish an interference fit with bore  112  to prevent leakage of fluid from channels  116  and  136 . As seen, divider plate  154  separates channel  116  and  136 . This arrangement is a significant improvement over known prior art arrangements with separate fluid delivery bores since a single central bore  112  can be easily machined and yet permit establishment of a number of distinct flow channels. In the embodiment shown, the centerline “C” of separator insert  114  is aligned with rotary axis “A” such that channels  116  and  136  have substantially similar volumes. To prevent distortion of separator insert  114  due to introduction of high pressure fluid into one or both of the channels, divider plate  154  is sized to have a sufficient thickness based on the fluid pressure and type of material used to fabricate the separator insert  114 . It is contemplated that separator insert  114  be made of any suitable material to provide a fluid tight seal with bore  112  and the required rigidity. As an option, a rigid metallic core member may be over-molded with plastic or rubber to provide the required strength and rigidity. 
   Referring to  FIG. 5 , a modified version of separator insert  114  is partially shown and identified by reference numeral  114 A. As seen, first channel  116 A is larger than second channel  136 A with the centerline “C 1 ” of divider plate  154 ′ offset from rotary axis “A”. Such an arrangement illustrates the ability to design the size of the flow channels to accommodate the different pressure and flow requirements of compounder assembly  24 . 
   Referring to  FIG. 6 , a further alternative version of separator insert  114  is partially shown and identified by reference numeral  114 B. As seen, flow channels  116 B and  136 B are formed in a side-by-side parallel arrangement with each having a corresponding inlet port  160 A and  160 B adapted to be aligned and communicate with a corresponding inlet bore in input shaft  36 . Finally,  FIG. 7  is a modified version of  FIG. 6  wherein an additional flow channel is provided to define three distinct flow channels. A third flow channel  162  can be used for lubricant delivery while channels  116 B and  136 B provide high pressure fluid to the friction clutches. 
   Those skilled in the art of power transmission devices, particularly of the type used in motor vehicle drivelines, will appreciate that the port separator insert of the present invention can be used in a plethora of applications and is not limited to use in the compounder assembly shown. Rather, it is contemplated that this concept of providing multiple flow channels in a single central bore can be used in transmissions, axle assemblies, transfer cases, torque couplings, power take-offs and all other power transmission devices which require at least two distinct fluid flow pressure paths. 
   The forgoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined in the following claims.