Abstract:
A clutch for a manual or automatic transmission according to the present invention includes an axial fan or turbine disposed on a shaft extending between the clutch and the transmission. Air is supplied to the turbine through one or more radial passageways between the clutch and transmission housings and is provided through an annular passageway around the shaft. Air from the annular passageway is then dispersed generally radially between the clutch plates or disks and other clutch components to absorb and carry away heat generated during clutch operation.

Description:
FIELD 
       [0001]    The present disclosure relates to clutches for motor vehicle transmissions and more particularly to clutches for manual or automatic transmissions having improved cooling. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    Clutches for motor vehicle powertrains provide a frictional, variable torque transmitting coupling between the vehicle prime mover and the transmission. Because of this function, significant heat may be developed in the clutch plates, especially if the vehicle is driven hard or the clutch is operated partially engaged for any period of time. Such worst case operating scenarios, which much be addressed, typically result in a clutch designs that comprehend larger clutch plates, more numerous clutch plates, a larger flywheel, more robust clutch materials (facings) and other design approaches. Such larger clutch components are not solely driven by higher torque requirements but also by operating temperature and heat dissipation considerations. That is, larger clutch plates and faces, while carrying less torque and therefore generating less heat per square unit of measure than smaller clutches, also have the capability of dissipating more heat, more rapidly than smaller clutches, not only because of their larger size but also the larger size of their housings which, in turn, increases the rate at which heat can be transferred to the ambient. 
         [0004]    Increasing the size of a clutch, while thus clearly advantageous from heat generation and dissipation viewpoints, is not an engineering solution without serious consequences. First of all, it clearly adversely affects the weight of the clutch and housing and thus the overall weight of the vehicle. In an age when every ounce of removed vehicle weight is considered a small victory, adding several ounces or pounds to a clutch assembly requires the most sound justification. Second of all, increased clutch and housing size affects not only the size of the overall powertrain but also its packaging. Whereas a smaller clutch and housing will permit enhanced packaging flexibility, a larger clutch may create additional constraints. Last of all, increasing the weight of the rotating powertrain components will have a small but tangible effect on the fuel consumption of the associated vehicle as well as its performance. 
         [0005]    From the foregoing, it is apparent that approaches to clutch heat dissipation other than simply increasing the size of the clutch may provide better solutions with fewer compromises. The present invention addresses this problem. 
       SUMMARY 
       [0006]    The present invention provides a clutch for a manual or automatic transmission motor vehicle powertrain having improved heat dissipating characteristics. The clutch according to the present invention includes an axial fan or turbine disposed on a shaft extending between the clutch and the transmission. Air is supplied to the turbine through one or more radial passageways between the clutch and transmission housings and is provided to the interior of the clutch through an annular passageway disposed about the transmission input shaft. Air from the annular passageway is then dispersed generally radially between the clutch plates or disks and other clutch components to absorb and carry away heat generated during operation of the clutch. 
         [0007]    Thus it is an aspect of the present invention to provide a means for supplying cooling air to the components of a manual or automatic transmission motor vehicle clutch. 
         [0008]    It is a further aspect of the present invention to provide an axial fan or turbine which supplies cooling air to the components of a manual or automatic transmission motor vehicle clutch. 
         [0009]    It is a still further aspect of the present invention to provide an axial fan or turbine having adjacent radial air passageways which supply cooling air to the components of a manual or automatic transmission motor vehicle clutch. 
         [0010]    It is a still further aspect of the present invention to provide an axial fan or turbine which supplies cooling air through an annular passageway to the components of a manual or automatic transmission motor vehicle clutch. 
         [0011]    It is a still further aspect of the present invention to provide an axial fan or turbine which supplies cooling air to the clutch plates of a manual or automatic transmission motor vehicle clutch. 
         [0012]    It is a still further aspect of the present invention to provide an axial fan or turbine which supplies cooling air to the clutch plates of a manual or automatic transmission motor vehicle clutch to carry heat to the ambient. 
         [0013]    Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0014]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0015]      FIG. 1  is a top, full sectional view of a dry transmission clutch incorporating the present invention; 
           [0016]      FIG. 2  is an enlarged sectional view of the turbine according to the present invention; and 
           [0017]      FIG. 3  is a full sectional view of a dry transmission clutch incorporating the present invention taken through the inlet passageways. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0019]    With reference to  FIG. 1 , a portion of a motor vehicle powertrain is illustrated and generally designated by the number  10 . The motor vehicle powertrain  10  includes a clutch assembly  12  which includes a typically cast exterior metal housing  14  which locates, secures and protects the various components of the clutch assembly  12 . The clutch assembly  12  is supplied with drive torque from a prime mover  16  such as a gasoline, Diesel, flex fuel or hybrid power plant by a crankshaft/clutch input member  18  and supplies drive torque to a transmission  20  through a transmission input (clutch output) shaft  22 . It should be understood that the transmission  20  with which the present invention is utilized may be either a manual transmission or an automatic transmission, for example, a dual clutch transmission (DCT). The clutch input member  18  is coupled to and drives a conventional dual mass flywheel  24  and a spring damper assembly  26  which, in turn, drives a dry manual clutch  30 . It should be understood that while the dry clutch  30  is herein characterized as a manual clutch, it may either be a manual (directly operator controlled) clutch or a clutch controlled by a hydraulic, pneumatic or electric actuator. 
         [0020]    The dry manual clutch  30  includes a pair of input side or first clutch plates or disks  32  which are disposed on opposite sides of and in operating, i.e., selective torque transferring, relationship with an output side or second, double sided clutch plate or disk  34 . A plurality of shock absorbing isolator springs  36  are disposed in an isolator plate  38  between the output side clutch plate or disc  34  and the transmission input (clutch output) shaft  22 . The isolator plate  38  is preferably coupled to the transmission input shaft  22  by a set of interengaging splines  42 . 
         [0021]    The dry manual clutch  30  also includes a plurality of first class levers  44  that extend between a clutch release bearing  46  and one of the pair of input side clutch plates or disks  32  and transmit axial clutch engaging and releasing motion therebetween. The clutch release bearing  46  is supported on a collar or hub  50  that is disposed concentrically about the transmission input shaft  22  and secured to the cast metal housing  14  by a plurality of suitable fasteners (not illustrated). The collar or hub  50  defines an annular air inlet passageway  56  between its inside surface and the outside surface of the transmission input shaft  22 . The top of the housing  14  of the clutch assembly  12  includes and defines an air exit or exhaust port or passageway  58  which allows air from the interior of the clutch assembly  12  to flow to the outside of the housing  14  and thereby carry heat from the interior of the clutch assembly  12  to the ambient. 
         [0022]    As illustrated in  FIG. 2 , the transmission input shaft  22  extends into a transmission housing  60  where it is supported for rotation on an anti-friction roller bearing assembly  62 . An oil seal  64  disposed between the transmission input shaft  22  and the transmission housing  60  provides a fluid tight seal therebetween. 
         [0023]    Integrally formed with the transmission input shaft  22  or secured thereto by an interference fit or other mechanical means such as flats, splines, keys and keyways, one or more set screws, or a combination thereof, is a fan or turbine  70 . The fan or turbine  70  includes blades or vanes  72  that are configured to draw air in at its base and deliver it axially under low pressure to the annular passageway  56  when the transmission input shaft  22  rotates in a direction corresponding to forward motion of the associated vehicle. When viewed from behind the clutch assembly  12 , that is, the right in  FIG. 2 , the typical transmission input shaft  22  will rotate counter-clockwise when the associated vehicle is moving forward and thus the blades or vanes  72  are configured as illustrated in  FIG. 2 , drawing air in at the base of the fan or turbine  70  as it rotates counter-clockwise and discharging air axially into the annular passageway  56 . Note the arrows in  FIG. 1  which illustrate such air flow. 
         [0024]    Referring now to  FIG. 3 , the exterior clutch housing  14  defines a center circular chamber  82  that receives the fan or turbine  70  disposed on the transmission input shaft  22 . Communicating with the circular chamber  82  are a plurality of preferably radial passageways  84 . The radial passageways  84  may be two, three, four or more in number and are preferably arranged at and above the horizontal midpoint of the exterior clutch housing  14  as illustrated in  FIG. 3 . The radial passageways  84  merge and communicate with a circumferential passageway  86  having an air inlet port or opening  88  generally disposed at the top (12 o&#39;clock) of the exterior clutch housing  14 . 
         [0025]    The lower portion of the circumferential passageway  86  may be closed off or, optionally, may include a small bleed hole  92  which functions as a drain. The air inlet port or opening  88  is preferably covered by a cap or diverter  94 . It will be appreciated that the radial and circumferential passageways  84  and  86  and the air inlet port  88  may also be formed in the face of the transmission housing  60 . Thus, as the transmission input shaft  22  rotates and the associated motor vehicle moves, ambient air is drawn in through the inlet port or opening  88 , through the circumferential passageway  86  and through the radial passageways  84  to the fan or turbine  70 . Air under low pressure is then forced along the annular passageway  56  and generally into the interior of the dry manual clutch  30 . The air then disperses and flows over and through the dry manual clutch  30  and the associated components such as the flywheel  24 , carrying away heat to the ambient. 
         [0026]    It will be appreciated that the cooling fan or turbine  70  of the present invention reduces the operating temperature of the dry manual clutch  30  and the dual mass flywheel  24 . As noted above, this permits a reduction in the size of the clutch  30  and the flywheel  24  and thus also their weight. Since these are rotating components, weight reduction not only reduces vehicle weight but also rotating inertia and thus improves vehicle performance. Such cooling also reduces the operating temperature of the clutch hydraulic fluid which reduces the friction and hysteresis of the apply system. 
         [0027]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.