Clutch driven plate assembly with a two-part hub
BACKGROUND OF THE INVENTION 
     In a conventional friction clutch for a manual transmission in an automotive vehicle, the vehicle engine produces power and inertia impulses which will drive the engaged clutch with an irregular series of thrusts with the transmission in neutral and the engine at idle rpm. These impulses are transmitted through the clutch and transmission input shaft to the transmission gears which becomes excited, resulting in oscillation through their backlash space to produce objectionable rattle. In U.S. Pat. No. 4,446,955, a driven plate assembly is disclosed utilizing a helical connection between an inner hub and an outer hub to allow relative axial movement between the hubs to dissipate the engine impulses. Also, in copending application Ser. No. 556,517, now U.S. Pat. No. 4,556,136, a cam and ramp arrangement is shown for translation of rotary to axial motion to overcome the engine impulses. The present invention relates to an improved approach to this problem providing simplification of the clutch structure. 
     SUMMARY OF THE INVENTION 
     The present invention comprehends the provision of a clutch driven plate assembly having a novel hub assembly and cooperating cam arrangement to dissipate engine impulses which previously resulted in objectionable transmission gear rattle with the clutch engaged, the transmission in neutral and the engine at idle rpm. The hub assembly includes an inner hub having a barrel in operative engagement with the transmission input shaft and an integral radial flange with external backlash splines formed thereon and an outer hub having a flange with damper spring windows formed therein and internal meshing backlash splines. An inner cam has a splined internal diameter and 45° camming surfaces or ramps interengaging complementary ramps on an outer cam provided with anti-rotation lugs engaging notches formed in the outer hub for simultaneous rotation thereof, and resilient means acting between the inner cam and the inner hub. The interengaging camming surfaces provide for axial movement of the inner cam relative to the outer cam and hub against the force of the resilient means. 
     Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a rear elevational view of a clutch driven plate assembly with a portion broken away embodying the present invention. 
     FIG. 2 is an enlarged cross sectional view of the clutch assembly taken on the irregular line 2--2 of FIG. 1. 
     FIG. 3 is a rear elevational view of the inner hub for the hub assembly. 
     FIG. 4 is a vertical cross sectional view of the inner hub taken on line 4--4 of FIG. 3. 
     FIG. 5 is an enlarged rear elevational view of a spacer in the clutch assembly. 
     FIG. 6 is a vertical cross sectional view of the spacer taken on line 6--6 of FIG. 5. 
     FIG. 7 is a rear elevational view of the outer hub of FIGS. 1 and 2. 
     FIG. 8 is a rear elevational view of an outer cam. 
     FIG. 9 is a vertical cross sectional view taken on line 9--9 of FIG. 8. 
     FIG. 10 is a rear elevational view of an inner cam. 
     FIG. 11 is a side elevational view of the inner cam. 
     FIG. 12 is a vertical cross sectional view taken on line 12--12 of FIG. 10. 
     FIG. 13 is an enlarged partial cross sectional view taken on the arcuate line 13--13 of FIG. 8. 
     FIG. 4 is an enlarged partial cross sectional view of the hub and cam arrangement shown in FIG. 2. 
     FIG. 15 is an enlarged partial cross sectional view taken on line 15--15 of FIG. 14. 
     FIG. 16 is a rear elevational view of a thrust plate for the clutch assembly. 
     FIG. 17 is a cross sectional view taken on the irregular line 17--17 of FIG. 16. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring more particularly to the disclosure in the drawings wherein is shown an illustrative embodiment of the present invention, FIGS. 1 and 2 disclose a clutch driven plate assembly 10 including a hub assembly 11, a clutch plate 25 carrying friction facings 34 mounted on the periphery thereof and adapted to be positioned between friction surfaces of a flywheel and a pressure plate (not shown) for the vehicle clutch, and a spring retainer plate 36. The hub assembly 11 (FIGS. 2, 3, 4 and 7) includes an inner hub 12 having a barrel 13 with a splined central opening 14 receiving the splined end of a transmission input shaft (not shown) and integral radially extending equally spaced tapered splines 15; each spline containing a forwardly opening spring recess 16. An outer hub 17 has a central opening 18 which has recesses 19 generally complementary to but larger than the splines 15 (see FIG. 15) of the inner hub for a purpose to be later described. The outer hub 17 is a generally flat plate with circumferentially equally spaced openings 21 for damper springs 22, each opening having a central notch 23 (FIG. 7). Also, the periphery of the outer hub is provided with elongated notches 24. 
     The clutch driven plate 25 has a central opening 26, a plurality of circumferentially equally spaced spring windows 27, and an inwardly offset outer periphery 28 containing a plurality of openings 29 and 31 arranged on two circles; the openings 31 receiving rivets 32 to secure cushioning plates 33 thereto carrying the opposed friction facings 34 for the clutch. 
     The spring retainer plate 36 has a central opening 37 with four circumferentially equally spaced openings 38 therein adjacent the central opening, a plurality of circumferentially equally spaced arcuate spring windows 39 axially aligned with and of substantially the same dimensions as the windows 21 and 27 of the outer hub and clutch plate, respectively, and a plurality of openings 42 in the inwardly offset periphery 41 axially aligned with openings 29 to receive spacer rivets 43. The rivets 43 extend through the elongated notches 24 in the outer hub periphery to secure the clutch plate 25 and spring retainer plate 36 together. 
     Positioned on the hub barrel 13 is a spacer or bearing 45 (FIGS. 5 and 6) having a radial flange 46 and integral axial sleeve 47. Four axially forwardly extending lugs 48 are formed on the periphery of flange 46 to be partially received in the notches 23 in the outer hub 17 to rotate therewith, so that the inner hub 12 is piloted concentric to the outer hub. The spacer is formed of a suitable plastic material with, as seen in FIG. 6, a friction washer 49 molded in place to provide a friction surface for shims 51 located between the spacer flange 46, thrust plate 52 (FIGS. 16 and 17) and spring retainer plate 36. The thrust plate 52 is a generally annular flat plate with rearwardly extending ears 53 projecting into the openings 38 of the spring retainer plate. 
     An outer cam 55, positioned on the opposite side of the hub assembly from the spacer 45, is located between the clutch 25 and the outer hub 17 and has a friction washer 56 molded in place to cooperate with shims 57. The outer cam (FIGS. 8 and 9) includes a generally rectangular body 58 with rearwardly extending integral lugs 59 partially extending into the notches 23 in the outer hub and four circumferentially equally spaced forwardly and inwardly extending projections 61 having oppositely disposed 45° ramps 62 thereon; the ramps diverging from rear edges 63. 
     Located concentrically within the outer cam 55 is an axially reciprocable inner cam 65 (FIGS. 10 through 12) including a cylindrical body of barrel 66 having a central splined opening 67 receiving the splined end of the transmission input shaft. Extending radially outwardly from the barrel 66 are four circumferentially equally spaced projections 68 having oppositely disposed 45° inclined ramps or camming surfaces 69,69 with the projections being complementarily received between the projections 61 on the outer cam 55; the ramp surfaces 69,69 converging toward the front 71 of the cam. In the rear surface 72 of each cam projection 68 is a spring recess 73 adapted to be axially aligned with the recesses 16 in the inner hub 12 to receive the ends of relatively light compression springs 74. These springs serve the dual function of normally biasing the inner hub and inner cam apart, limited by the coacting projections 61,68 and of aligning the splines in the central openings 14 and 67 of the inner hub 12 and inner cam barrel 66, respectively. 
     One or more concentric damper springs 22 are located in each aligned set of spring windows 27,38 and 21 in the plates and outer hub, with the plate windows 27 and 38 having inclined outer lips 75 to retain the springs in operative position. The spring windows 21 in the outer hub 17 and the windows 27 and 38 in the clutch and spring retainer plates have identical circumferential dimensions so that the plates, damper springs and outer hub can all rotate simultaneously. Also, the springs 74 are 90° out of plane with the normal damper springs 22 to break up harmonic influence and resonance by changing the plane of motion. 
     In the disengaged position of the clutch, the spacer bushing 45 acts to pilot the inner hub 12 central to the outer hub 17, the thrust plate 52 is keyed to the spring retainer plate 36 through the ears 53 received in openings 38, and the damper springs 22 are positioned in the spring windows of the plate and outer hub in an uncompressed state. Also, the springs 74 urge the inner cam 65 forwardly away from the inner hub 12 with the ramps 62 and 69 being fully engaged as seen in FIG. 13. This clutch assembly operates in the same manner as a conventional assembly except for the action of the inner cam 65 and outer cam 55 with the clutch engaged at idle rpm and the transmission in neutral position. With the clutch engaged between the flywheel and pressure plate, the engine impulses during idle act to rotate the clutch plate 25, spring retainer plate 36, outer hub 17 and damper springs 22 relative to the inner hub 12 due to the backlash space between the splines 15 on the inner hub and recesses 19 in the outer hub (see FIG. 15). As the lugs 59 of the outer cam 55 are conformably received in the notches 23 of the outer hub, the outer cam rotates with the outer hub and causes the inner cam to move axially rearwardly towards the inner hub on the input shaft against the force of compression springs 74 due to the interaction of the ramp surfaces 62,69. Movement continues until the splines 15 engage the sides of recesses 19 and compression of the damper springs 22 is initiated. Thus, the energy of the impulses is used to actuate the inner cam in the above manner rather than transmit the undiminished impulses to the vehicle transmission to cause its gears to rattle. 
     In the normal driving mode of the vehicle, the outer hub 17 engages the inner hub 12 and the damper springs 22 are compressed upon torque application to the friction facings. The friction washers 49 and 56 on the spacer 45 and outer cam 55, respectively, act with the shims to provide friction lag for the normal damper operation in the conventional manner.