Abstract:
Torque is transmitted from a drive plate (70) to piston plate (60), components of a bypass clutch for an automatic transmission torque converter, through a piston pin (73) fixed to the piston plate and carrying a detent ball (122) that is forced radially outward from the body (116) of the piston pin into contact with a hole (112) formed in the piston plate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of torque converters for automatic transmissions. The invention pertains particularly to a bypass clutch, which mechanically connects a turbine wheel and impeller wheel, bypassing a hydrokinetic connection between them, and releases the turbine and impeller, thereby reestablishing the hydrokinetic connection. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,209,330, assigned to the assignee of the present invention, describes a torque converter assembly for use in an automatic transmission, a slipping bypass clutch for mechanically connecting the impeller and turbine of a torque converter, and a damper subassembly driven by the bypass clutch for reducing vibrations and noise in the torque converter assembly and to modulate torque oscillations due to operation of the bypass clutch. That patent describes use of a drive plate welded to an impeller cover and extending radially inward toward the axis of the torque converter, a piston plate slidably mounted on the hub of a turbine wheel adjacent the drive plate, a drive ring riveted to the piston plate and defining a system of axially directed spline teeth on the outer periphery of the ring. The radially inner surface of the drive plate is formed with spline teeth that are continually engaged with the splines of the drive ring to produce a drive connection between the piston plate and impeller cover. 
     When the torque converter bypass clutch is released, oscillation in the spline connection between the drive plate and drive ring produces unwanted noise. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a reliable, easy-to-assemble drive connection between a driveplate and piston plate in an automatic transmission torque converter bypass clutch assembly that transmits torque between the components without producing noise, despite engine speed variations. Advantages of the invention include its ease of assembly and installation and its functional reliability. 
     In realizing these objects and advantages, the invention includes a driveplate fixed to the impeller cover and formed with a first hole, a piston plate located near the driveplate, supported for displacement relative to the driveplate, and having a second hole substantially aligned with the first hole. A piston pin, fixed to the piston plate, has a shank extending into the second hole, a body extending from the piston plate into the first hole, and a third hole directed radially from the axis of the piston pin. A compression spring is located in the third hole. A ball located partially in the third hole, and partially extending outward from the third hole, is biased radially outward by the spring, the axis of the third hole being directed substantially parallel to the direction the driveplate drives the piston plate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross section of a torque converter through a vertical plane showing the components of a bypass clutch and damper. 
     FIG. 2 is a front view of a portion of a piston plate. 
     FIG. 3 is a side view of a piston pin. 
     FIG. 4 is a cross section taken at plane 4--4 of FIG. 3. 
     FIG. 5 is a partial cross section of a converter showing an alternate technique for connecting the piston and drive plate. 
     FIG. 6 is an end view of a sleeve spring taken in direction 6 of FIG. 5. 
     FIG. 7 is a perspective view of the wave sleeve spring. 
     FIG. 8 is a partial cross section of a torque converter showing a spring clip located between a drive plate and piston pin. 
     FIG. 9 is a cross section taken at plane 9--9 of FIG. 8. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1, a torque converter 10 includes an impeller cover 12 welded to an impeller shell 14 having recesses 16, which receive tabs 18 formed on the outer surface of impeller blades 20. The impeller blades are retained between shell 14 and an inner shroud 22. 
     Impeller cover 12 supports a circular pattern of threaded studs 24 to which a flywheel, rotatably supported on an engine crankshaft, is bolted, thereby drivably connecting the cover to the engine. 
     Turbine blades 26 are spaced mutually about the axis of rotation and are located with respect to the impeller blades so that the toroidal fluid flow within the torque converter exits the impeller and enters the turbine at the radially outer area and leaves the turbine at the radially inner area. The outer periphery of the turbine blades is fixed mechanically, or by welding or brazing, to a turbine shell 28, which has openings 29 that receive tabs 30 formed on the turbine blades. The inner periphery of the turbine blades is connected to an inner turbine shroud 32 by locating tabs 34 within slots formed in shroud 32 and bending the tabs over on the inner surface of the shroud, thereby fixing the position of blades 26 between shell 28 and shroud 32. Turbine shell 28 is secured by rivets 36 to a turbine hub 38 having an internally splined surface 40 adapted to engage an externally splined surface on a transmission input shaft 41. Disc 42, welded at 45 to the impeller casing, includes a splined surface 44. 
     Located between the flow exit section of the turbine and the flow entrance section of the impeller is a stator assembly comprising stator blades 46, spaced mutually around the axis of rotation, a hub 48 supporting blades 46, an inner shroud 50 connecting the radially inner tips of the blades, and an outer shroud 52 connecting the radially inner ends of the stator blades. An overrunning brake 54, fixed by splines 56 to a stationary sleeve shaft 57, provides one-way braking between the stator blades and the sleeve shaft. 
     A bypass clutch includes a piston assembly, which includes a piston plate 60, slidably mounted in an axially directed surface 62 formed on turbine hub 38 and sealed against the passage of hydraulic fluid by an O-ring 64 located in a recess formed in surface 62. Axial movement of piston 60 is limited by a shoulder formed on turbine hub 38, as FIG. 1 shows. 
     The drive plate 70 is fixed to the inner surface of cover 12 by a spot weld 72, which provides a seal against the passage of hydraulic fluid between the axially outer surface of drive plate 70 and the adjacent inner surface of the cover. Clutch plate 70 and piston 60 are drivably connected through cover 12 and piston pin 73 to the engine. 
     Drive ring 74 includes a radial leg 76 located between the inner face of drive plate 70 and the outer face of piston 60, and six axial legs 78 spaced mutually angularly about the axis of rotation and directed from leg 76 toward the turbine wheel. The surfaces of leg 76 that face plate 70 and piston 60 carry friction material 80, commonly referred to as &#34;paper face&#34; material, which is bonded to axially opposite radial surfaces of drive ring 74 by a bonding technique described by Frosbie, Milek and Smith in SAE Design Practices, Volume 5, (1962). The friction material may be bonded to the surfaces of piston 60 and clutch plate that face leg 76 of the drive ring. 
     The turbine shroud 28 and a torque converter damper support 91 are joined to a radially extending flange of turbine hub 38 at a riveted connection 36. At the radially outer end of support 91, several arcuate flanges 92, spaced angularly about the axis at 60 degree intervals, are formed. A spring retainer ring 94 includes a radially inwardly extending web riveted to support plate 91 at angularly spaced locations 98, and an arcuate flange 100 substantially complimentary to flange 92 of the support plate. Flanges 92 and 100 define between them a substantially circular tubular cavity, in which are located six angularly spaced, helically-coiled damper springs 102. At six equally spaced angular locations spaced mutually about the axis of rotation, flange 100 of the retainer ring is formed with a local bead 104. 
     Drive ring 74 is supported on several arcuate surfaces 105 that coincide with the angularly spaced beads 104 and the radial ends of the support plate. Surfaces 105 guide the drive ring as it moves axially toward clutch plate 70, due to contact with the piston 60, and away from the clutch plate as pressure within control chamber 90 falls in relation to pressure on the axially opposite side of the piston. Contact between the arcuate flanges 92 and the drive ring limits the extent to which the springs are compressed. Contact between the beads and radial ends of the support plate limit the extent to which the springs can expand. 
     Other details of the torque converter bypass clutch damper are described in U.S. Pat. No. 5,209,330, which is assigned to the assignee of this invention. 
     Piston pin 73 is fixed against a shoulder formed on piston plate 60 by inserting the shank of pin 73 through a hole extending through the thickness of piston 60 and then deforming the axial end of the shank to form the head 110 of the pin. The pin is drivably connected to drive plate 90 at a flanged hole 112 formed in plate 70. Preferably, the holes 112 are angularly spaced mutually about the axis of the drive plate at four equal intervals, and piston pin 73 is fixed to piston 60 at four equally angularly spaced holes formed in the piston, which holes align with the holes of the drive plate containing the shank of pin 73. 
     Referring now to FIGS. 3 and 4, the shank 114 of piston pin 73 extends axially from a cylindrical body portion 116, into which a hole 118 has been formed, directed transverse to the axis of the pin and substantially perpendicular to the axis of the torque converter. Located within the hole is a compression spring 120 and a steel ball 122 nested within the coils of the spring. The surface of the cylindrical portion 116 is deformed by staking, as best seen in FIG. 3, after the spring and ball are located within the hole, thereby preventing the ball and spring from exiting the hole after assembly. The shoulder, located where the shank and body meet, is held against the axially outer surface of the piston plate 60 after the head 110 of pin 73 is formed. 
     FIG. 2 shows the piston pins located in the correct angular position in the piston plate so that the spring loaded detent balls 122 are directed in the correct circumferential direction. The piston plate 60 is driven by drive plate 70 through the piston pins that protrude from the piston plate. The diameter of the piston pin body 116 is smaller than the diameter of the drive plate holes 112. The detent balls 122 eliminate rattle between the piston plate and drive plate due to engine speed variations while the torque converter bypass clutch is unlocked. Compression spring 120 forces the detent ball 122 into contact with the drive plate hole and prevents the piston plate from moving relative to the drive plate hole. 
     The center of the detent ball on the surface of the drive plate hole 112 preferably is located diametrically opposite from the line of contact where the piston pin body contacts the surface of the drive plate at hole 112. In FIG. 2, vector A represents the sense of direction of torque transmitted from the drive plate 70 to the piston pins. The cylindrical surface of the piston pin body 116 contacts the cylindrical surface of hole 112. Preferably, the magnitude of the product of each spring force urging a detent ball into contact with the drive plate times the radius from the axis of the torque converter to the center of a piston pin is approximately equal to one-fourth of the inertia load transmitted from the drive plate to the piston plate through each piston pin. Contact between the detent ball and drive plate hole should remain in the drive plate hole during engagement and disengagement of the piston plate. 
     An alternate technique to eliminate noise in a torque converter assembly, as illustrated in FIGS. 5-7, includes a piston pin 124, having a head 110 formed after the shank 126 of the pin is inserted through the hole in the piston plate. A spring sleeve 128, expanded radially to fit over the body portion of pin 124, resiliently contacts the outer surface of the pin. After installation on the pin, sleeve 128 is rotated about the axis of the pill to its correct angular position, shown in FIG. 6, and then the sleeve is fixed in position by staking pin material against the sleeve at 130. 
     FIG. 6 shows an end view of spring sleeve 128 having an elongated circular form located in its correct angular position with respect to the direction of the torsional load, represented by arrow 132, transmitted from drive plate 70 to piston plate 60. 
     FIG. 7 shows axially opposite end faces 134, 136 of the spring sleeve mutually spaced along the axis of pin 124. The outer surface of the pin body is a right circular cylinder. FIG. 7, a top view of the sleeve spring, shows that its contour is C-shaped and located within the annular space between the outer surface of the body of the piston pin 124 and the surface of the flanged hole 112 formed in the drive plate 70. The annular surface of sleeve 128 is circumferentially discontinuous, having two free ends 140, 142. The contour of each sleeve spring is such that the outer surface contacts the surface of hole 112 at a first point of contact 144 and near the open ends at 146, 148. At the angular plane located approximately perpendicular to the plane that contains contact point 144 and passes through the diameter of the sleeve spring, the spring contacts the outer surface of the piston pin at 150, 152. 
     Referring now to FIG. 8, an alternate spring clip 154 is located in the annular space between the surface of piston Fin 156 and the hole 112 of drive plate 70. The spring clip includes radially directed flanges 158, preferably three such flanges spaced mutually at equal intervals about the axis of end 156 and located adjacent the surface of drive plate 70. The spring clip also includes legs 160, preferably three such legs, extending outwardly from web 162 and mutually spaced angularly about the axis of the pin. Web 162 of spring clip 154 contacts the surface of the hole 112 of drive plate 70 at 164, 166, 168, 170. The inner surface of the spring clip web 162 contacts the surface of piston pin 156 at 172, 174, 176. The torsional load transmitted through the piston pin from the drive plate 70 to piston plate 60 is in the direction of arrow 178. 
     While the preferred embodiment of the present invention has been disclosed and described in detail, further modifications, enhancements, and embodiments are contemplated to be within the spirit and scope of the present invention and the following claims.