Abstract:
A motor applies torque to a ball and ramp actuator element generating thrust that is transferred thru a bearing from the stationary actuator to the rotating clutch pack elements of a marine transmission.

Description:
CONTINUATION-IN-PART APPLICATION 
       [0001]    This application presents improvements on application Ser. No. 11/364,783 Docket New Case Ready for Examination titled Motor driven ball and ramp clutching system for a marine transmission. 
         [0002]    Background of the invention is covered by application Ser. No. 11/364,783. 
     
    
     BRIEF SUMMARY OF THE INVENTION 
       [0003]    A marine transmission may require high level clutch torque for full engine power or lower level varying torque for clutch modulation when trolling to provide constant propeller speed with variation in engine input speed or clutch torque. Application Ser. No. 11/364,783 utilizes a ball ramp thrust actuator to generate clutch engagement pressure. The use of three balls assures equal ball loading distribution. Significant surface stresses and deformations between the ball and ramp spherical and curved surfaces may affect smooth movement and action efficiency during trolling, in particular as minute ramp rotations are required to maintain constant propeller speed. The electric motor operates in a stalled or “torque only” mode. Although the motor may be used continuously energized it is advantageous from a standpoint of motor life and motor heat dissipation to de-energize the motor during high torque operation required at vessel full power and speed. 
         [0004]    One purpose of the improvements is to allow continuous clutch engagement by mechanical overlock for vessel full power, electric motor de-energized. Another purpose is to lower the ball and ramp contact stresses and improve efficiency during the trolling mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 6  shows how two reversible motors may engage or release either clutch when the teeth on the rotatable circular member of the forward clutch mesh with the teeth on the rotatable circular member of the reverse clutch. 
           [0006]      FIG. 7  is a longitudinal section of a means used to allow overlocked engagement of either the forward or reverse clutch and in addition accommodate clutch plate wear. The electric motor may be de-energized.  FIG. 7  uses cylindrical rollers mounted on anti friction bearings to improve sliding action and reduce contact stresses with the ramp surfaces. 
           [0007]      FIG. 8  provides mechanical overlock ramp engagement using balls and a worm pinion instead of a conventional gear pinion. The worm may sustain the position of the rotatable circular member by preventing back drive. The electric motor may be de-energized. Clutch plate wear is accommodated.  FIG. 8  also describes ramp angles required for release, plate engagement, torque load and overlock. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0008]    Referring to  FIG. 7 , electric motor  34  when energized drives pinion  38  meshing with teeth on rotatable circular member  33 . 
         [0009]    Member  33  has a plurality of arcuate recesses each recess having multiple ramp angles allowing clutch release, clutch engagement, clutch torque generation and clutch overlock. Overlock may be a negative angle. Annular support member  53  has splines  60  that mesh slidably with splines on stationary end cover housing  15  to allow axial movement of member  53 . Arms  57  extend from support member  53  to contain and support curved roller assemblies consisting each of a roller  54  anti friction bearing  55  and pin  56 . 
         [0010]    Support member  53  also supports a Belleville spring  58  held in a pre-loaded condition by snap ring  59 . Spring  58  is held in contact with annular protrusion  61  on adjustable element  43 -A by clutch release spring  41  when the clutch is released. 
         [0011]    When the clutch is engaged to maximum torque, the clamping force reacts to further compress the Belleville spring  58  away from snap ring  59 . Spring  58  then compensates for clutch plate wear during ramp overlooked engagement position. The electric motor  34  is then de-energized. Release spring  40  acts together with spring  41  to rotate the circular member  33  to a neutral released position at disengagement. 
         [0012]    Refer to  FIG. 8 . 
         [0013]      FIG. 8  is a longitudinal section of another means to allow overlooked engagement of either the forward or reverse clutch. It acts also to accommodate plate wear. It uses the ball ramp design of application Ser. No. 11/364,783.  FIG. 8  utilizes a self locking worm  13 , one in which the gear  33  cannot backdrive the worm  63 . Very high reduction ratios can be achieved allowing the use of a smaller electric motor. 
         [0014]    The arcuate recesses may be in both the rotatable member  33  and the non-rotatable member  53 A providing a greater axial travel to rotational travel ratio than that of  FIG. 7 . Spline  60  Belleville spring  58  snap ring  59  and adjustable element  43 A act in the same manner as  FIG. 7  to allow overlooked engagement and compensation for clutch plate wear. The electric motor is again de-energized in this mode.  FIG. 8  also shows that ramp angles may be flat for release, steep for clutch plates engagement, low for torque load, and possibly negative for overlock.