Driveable connection between drum components for automatic transmission friction disc clutch

The connection for releasably joining two drum components of a hydraulically-actuated double friction disc clutch includes first and second drum components having circular cylindrical surface directed substantially axially, one overlapping the other. The inner component is formed with a catch groove or two catch recesses and the outer drum component includes catch projections, offset mutually 180.degree. and adapted to become locked within the catch groove. The outer drum includes tabs at an axial end adapted to fit within recesses formed on the periphery of the inner drum between catch projections. The drums are driveably connected by applying oppositely directed axial force sufficient to snap the catch projections into the catch groove. The drums are disassembled by elastically deforming the outer drum until the catch projections clear the catch groove and then applying an axial force that separates the drums.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a catch connection joining two drum components 
for a hydraulically actuated friction disc clutch of an automatic 
transmission for motor vehicles. In particular the invention pertains to 
the connection itself and to a technique for establishing and 
disestablishing it. 
2. Description of the Prior Art 
German Patentschrift 16 30 950 describes a technique for joining two drum 
components of a double clutch used to control gear ratio changes in a 
planetary gear system. The two drums are joined by a bayonet-type catch 
connection to form an assembled unit. 
The bayonet-type catch connection makes it necessary to insert the two drum 
components axially into one another and thereafter to rotate one of them 
circumferentially with respect to the other. Furthermore, to prevent 
undesired release of the bayonet-type catch connection while the drum 
components rotate during operation, a push-over locking mechanism is 
provided to prevent relative rotation between the drum components. 
The catch connection of the '950 document is therefore difficult to 
manipulate during assembly and requires additional cost to manufacture the 
locking mechanism. 
A planetary gear transmission for motor vehicles is described in 
Patentschrift 20 13 612. The transmission includes two drum components of 
a hydraulically actuated double friction disc clutch connected mutually by 
interlocking the drum components to form an assembled unit. The 
interlocking is achieved by a snap ring groove provided on one component 
and a snap ring inserted within the groove and partially surrounding the 
other drum component. In this clutch, a carrier that supports one set of 
friction discs is supported by a thrust bearing on a cylindrical extension 
of a central carrier of the transmission. One drum component is rotatably 
mounted on the carrier by a radial needle bearing, from which the 
cylinder/piston unit is supplied with pressure from a source of hydraulic 
pressure. 
Assembly and disassembly of the snap ring connecting the two drum 
components must be accomplished manually. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a catch connection for two drum 
components of a hydraulically actuated double friction disc clutch for an 
automatic transmission. The connection is simple and inexpensive to 
produce and is suitable for automated assembly such that it can be 
released readily for repair or replacement when necessary. 
This object is achieved in that an encircling catch groove or two catch 
recesses are formed on one drum component, and two radially directed catch 
projections, offset mutually by 180.degree., are formed on the other drum 
component. The two drums are driveably connected by axially pressing one 
drum component against the catch projection, expanding it radially to 
clear the lip of the recess and allowing engagement of the projection 
within the recess. 
Because one pot-shaped drum component is connected in a catching manner and 
merely being pressed axially onto the other drum component by radial 
enlargement of the other drum component in the elastic region, reliable 
axial and radial interlocking is achieved simply and at low fabrication 
and assembly cost. 
The radial protruding catch projections, which are offset mutually by 
180.degree., are provided with different catch and release ramps adapted 
to the catch groove or catch recesses.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The gearset of a planetary transmission having a Simpson-type gearset 3 is 
located in a rear chamber of a transmission casing separated from a 
forward chamber by a central carrier 2. Driving torque is introduced into 
the planetary gear transmission by an overdrive planetary gearset through 
a central shaft 4. 
Shaft 4 is driveably connected by a spline to a clutch carrier component 5, 
which supports a first set of friction discs 6 fixed to the carrier on its 
external periphery and a second set of friction discs 7 fixed to the 
carrier on an internal periphery. 
Between each disc of the first set of friction discs 6 there is located 
another set of friction discs 6', whose members are driveably fixed on 
their external peripheries to an internal surface of a first pot-shaped 
drum component 8. Drum component 8 forms a circular cylinder 9, in which 
there is located an annular piston 10 by which friction discs 6 and 6' are 
hydraulically actuated and mutually engaged. Drum component 8 is rotatably 
mounted on a cylindrical extension 11 of central carrier 2 by a needle 
bearing, which runs on an internal race and centers the adjacent needle 
bearing 12. 
Also located in clutch carrier component 5 is an annular cylinder 13, which 
contains an annular piston 14 by which two sets of friction discs 7 and 7' 
are hydraulically actuated and mutually engaged. Located between each 
member of the second set of friction discs 7 there is located an 
additional set of friction discs 7', whose members are driveably connected 
at their internal peripheries to ring gear 15 of a first planetary gearset 
of the Simpson-type set 3. 
Planet carrier 16 of the first planetary gearset is driveably connected to 
the output shaft 17 of the transmission. Planet carrier 18 of the second 
planetary gearset of the Simpson-type set 3, is connected to brake drum 
19. Ring gear 20 of the second planetary gearset of the Simpson-type set 3 
is connected to output shaft 17. 
Sun wheel 21, which is common to both planetary gearsets, is connected 
driveably to the first pot-shaped drum component 8 and to pot-shaped drum 
component 22. 
In the prior art, the connection between component 8 and component 22 
consisted merely of axially, manually overlapping tabs 23 and protrusions 
24 located between tabs 23. This arrangement produced a driving connection 
between drum components 8 and 22 but did not prevent the drum components 
from sliding axially apart. Formerly one drum component 8 had to be 
supported on central carrier 2 by means of an axial run-on disc. 
The connection of this invention includes a catch connection produced 
between the two drum components 8 and 22. The catch connection consists of 
an encircling catch groove 25 formed on the first drum component or two 
catch recesses each aligned angularly with radially inwardly protruding 
catch projections 26, mutually offset by 180.degree., on drum component 
22. 
The radially inward protruding catch projections 26 have a catch ramp 27 
and a release ramp 28, seen best in FIG. 5. The connection process for 
interlocking the two drum components 8, 22 includes axially pressing the 
catch ramp 27 against the lip 24 near catch groove 25 until the drum 
components are displaced elastically in the vicinity of catch projections 
26. Expansion of drum component 22 is such that its circular cylindrical 
shape is distorted elastically to an oval whose major diameter passes 
through the angularly spaced projections 26 and whose minor diameter is 
substantially perpendicular to the major diameter. 
To disassemble the drum components, radially directed clamping forces are 
applied inwardly to the outer surface of the circular cylindrical drum 22 
thereby causing elastic distortion inwardly at the point of the 
application of the clamping force and radially outwardly in the major 
diameter connecting catch projections 26. When the magnitude of the 
applied clamping force is sufficiently great, catch projections 26 move 
radially outward relative to the lip 24 of the drum 8 near the axially 
outermost end of catch grooves 25. When this condition is established and 
while it is maintained, an additional force is applied to drum component 
22 directed axially away component 8. The axial force presses release 
ramps 28 against lip 24 and causes additional outward displacement of 
catch projections 26. This combination of radial and axial forces permits 
drum 22 to be removed from drum component 8. 
Torque is transmitted between the drum components 8, 22 by fitting tabs 23 
into the angularly spaced recesses located between lips 24 on the outer 
rim of drum component 8. Tabs 23 and the recesses between lips 24 must 
have sufficient clearance in the radial direction so that the slight oval 
enlargement of drum component 22 required for the assembly and disassembly 
processes is accommodated.