Method of forming a vehicle transmission clutch housing

A clutch housing for a vehicle transmission assembly and a method of making the same. The housing is generally cup-shaped with an axial hub. The outer wall of the housing is formed with a plurality of longitudinal splines of varying configurations. Select splines are formed at an increased depth. A groove is formed in the exterior surface of the housing at a depth sufficient to intersect the select splines of the inner surface thereby forming apertures through the wall of the housing. The dimensions of the apertures are determined by the configuration of the exterior groove and the interior splines.

BACKGROUND OF THE INVENTION 
I. Field of the Invention 
This invention relates to automatic transmission and transfer case clutch 
housings and, in particular, to a cost effective method of forming oil 
escape apertures and speed sensing slots in such clutch housings. 
II. Description of the Prior Art 
Manufacturers are continually developing more cost effective methods of 
developing automobile and truck components to reduce the manufacturing 
costs of vehicles. Metal components may be stamped flow formed from a 
blank and even formed from powder metal depending upon the configuration 
of the part. 
Clutch housings for automatic transmissions and transfer cases have a 
generally cup-shaped configuration with an axial hub. The outer wall of 
the housing includes an inner surface having a plurality of longitudinal 
splines which determine the operation of the clutch housing in conjunction 
with variations in transmission fluid pressure. Typically, the clutch 
housing is flow formed from a blank to the desired configuration. Several 
machining operations are performed to form the desired configuration 
including punching apertures in the outer wall of the housing to create 
oil escape holes. This extra step requires the purchase and use of hole 
punch machines adding to the cost of manufacturing the clutch housing. In 
addition, such hole punching machines provide little flexibility in 
altering the position of the oil escape holes. 
SUMMARY OF THE PRESENT INVENTION 
This invention overcomes the disadvantages of the prior known methods of 
manufacturing transmission clutch housings by forming oil escape holes 
during machining of the outside diameter of the clutch housing. 
The clutch housing formed using the method of the present invention has a 
generally cup-shaped configuration with an axial hub. The housing is 
preferably flow formed to a near-net configuration from a metal preform or 
blank. The flow forming operation forms a plurality of splines on the 
inner surface of the housing outer wall. The number and configuration of 
the splines is determined by the desired operating characteristics of the 
clutch housing. However, at least one of the splines is formed at an extra 
depth thereby increasing the major inner diameter of the housing at 
predetermined intervals. Accordingly, whereas several if not a majority of 
the splines will be formed at an increased depth forming an increased 
major diameter to the inner surface of the housing. A groove is machined 
into the outside diameter of the housing to a depth which will intersect 
the splines of increased depth thereby forming apertures through the wall 
of the housing. The dimensions of the oil escape apertures is determined 
by the width of the groove (forming the axial length of the aperture) and 
the width of the spline formed in the inner surface (forming the 
circumferential width of the aperture). Thus, the number, spacing and size 
of the apertures will be determined primarily by the inner splines formed 
in the housing and the groove machined on the outer surface of the 
housing. By varying these key features, oil escape holes can be formed 
without the need to punch through the housing or by increasing the 
dimensions, speed sensing slots may be provided in the outer wall of the 
housing. 
Other objects, features and advantages of the invention will be apparent 
from the following detailed description taken in connection with the 
accompanying drawings.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
Referring to the drawings, there is shown a clutch housing 10 adapted to be 
used in automatic transmissions and transfer cases for vehicles. The 
present invention is directed to a clutch housing 10 having a plurality of 
oil escape holes and/or speed sensing slots and the method of 
manufacturing the clutch housing 10. 
The clutch housing 10 has a generally cup-shaped configuration with an end 
wall 12, an inner axial hub 14 and an outer wall 16. The outer wall 16 
includes an interior surface 18 defining an inner diameter and an exterior 
surface 20 defining an outer diameter. In accordance with the operating 
characteristics of the clutch housing 10, a series of longitudinal splines 
22 are formed in the interior surface 18 of the outer wall 16. The splines 
22 may be formed at varying intervals, lengths and depths for operation in 
a predetermined manner. In accordance with the present invention, at least 
one and preferably a plurality of the splines 22 are formed at a depth 
grater than the standard major inner diameter of the splines. The interval 
and number of splines 22 with increased depth is dependent upon the 
desired number of apertures through the outer wall 16 of the finished 
clutch housing 10. Although the selected splines 22 are formed at an 
increased depth, sufficient wall structure remains. 
In order to form the oil escape holes, the exterior surface 20 of the outer 
wall 16 is machined to form a circumferential groove 24 transverse to the 
longitudinal splines 22. The groove 24 is machined to a depth sufficient 
to engage the increased depth splines 22 thereby forming an aperture 26 
through the outer wall 16. The width W of the aperture 26 is determined by 
the width of the spline 22 while the length L of the aperture 26 is 
determined by the width of the circumferential groove 24. Thus, the 
outside diameter can be machined accordingly whether oil escape holes or 
speed sensing slots need to be formed in the clutch housing 10. Since 
these apertures do not need to be punched into the housing and the 
exterior of the housing must be machined anyway, the desired apertures can 
be formed at little or no extra cost in manufacturing. Furthermore, the 
size of the apertures 26 can be more precisely controlled through the 
machining operation as opposed to a punching operation. 
The clutch housing 10 of the present invention is manufactured to form the 
required oil escape holes in the housing wall. In a preferred method of 
manufacture, the housing 10 is flow formed from a solid or preformed blank 
to a near-net configuration. During the flow forming operation, the 
splines 22 are formed in the interior surface 18 of the outer wall 16 
including splines of a greater depth to eventually form the apertures 26. 
Thereafter, the exterior surface 20 is machined to the desired 
configuration including the machining of groove 24 to intersect the select 
splines 22. The dimensions of the groove 24 in conjunction with the 
dimensions of the spline 22 will determine the configuration of the 
apertures 26 formed through the outer wall 16 of the clutch housing 10. 
Accordingly, while the method still requires flow forming and machining 
apparatus, an apparatus for punching the apertures 26 in the housing wall 
16 is no longer needed. 
The foregoing detailed description has been given for clearness of 
understanding only and no unnecessary limitations should be understood 
therefrom as some modifications will be obvious to those skilled in the 
art without departing from the scope and spirit of the appended claims.