Motor vehicle differential gear housing

A compact, light weight and easily maintainable differential gear unit casing is provided which comprises a box-like housing having front, rear, top, bottom and two side panels. Each of the front and rear panels has an aperture; which is at least partially axially aligned with each other; and bearing means cooperating with the aperture and demountably secured to the front and rear panels, the bearing means being coaxially aligned with the aligned portions of the apertures on the front and rear panels. Each of the side panels has an opening which is at least partially aligned axially with the other; and axle supporting bearing aligned coaxially with aligned portion of the opening on the side panels and is adapted to have the driving axles journaled in the bearing.

FIELD OF THE INVENTION 
This invention relates to motor vehicle differential gear unit housings. 
BACKGROUND OF THE INVENTION 
In motor vehicles, the drive axle differential gear system in the power 
train is an essential component. The primary function of the differential 
gear system is to translate the engine power through the drive shaft to 
the wheels for forward and backward propulsion efficiently. At the same 
time, it must allow one drive wheel to turn faster than the other when the 
vehicle rounds turns, yet both wheels must receive the proper engine 
torque. 
The traditional design of a differential gear system is characterized by 
its heavy and rugged construction to absorb the driving force of the 
wheels. For example, the internal gears of the differential are usually 
made of high strength hardened steel. Likewise, its casing is made of cast 
steel. The use of high strength materials provides a large margin of 
safety in the design and construction of the components. This, coupled 
with its small number of internal components, makes the differential gear 
system a relatively reliable piece of equipment in the power train of the 
motor vehicle. In view of such high reliability, however, maintenance, 
versatility of mounting and ability to change gear ratio and direction of 
motion has not always been properly considered and provided for in the 
design and construction of the system. 
A good design should consider not only reliability but also these other 
aspects of the unit's function and use. As the demand for high performance 
in motor vehicles increases, new challenges to the traditional designs in 
equipment and components will also be seen.. For example, the demand for 
fuel efficiency often dictates the replacement of heavily constructed or 
rugged components with lighter components or components having different 
material construction. Likewise, maximizing the power output of the engine 
often places new stress upon the various parts and components, thereby 
affecting the overall reliability of the motor vehicle. Other 
applications, such as racing and off road travel for leisure or military 
applications, are likely to subject the various parts and components to 
significant stress factors because of the operating and environmental 
conditions. 
When equipment fails, it must be repaired or restored in a timely manner so 
as to ensure its availability, i.e., the time that the equipment is 
operable. When applied to equipment or components, maintainability means 
the manner in which such equipment or components can be restored to their 
operable state. As often is the case, a key factor in determining 
maintainability is the accessibility to the failed or malfunctioned 
equipment so as to enable the maintenance personnel to diagnose, repair or 
replace the failed or malfunctioned components. 
The traditional differential housing designs do not permit ready 
accessibility to the gear system or bearings, particularly to change gear 
ratios or when repairs must be made in the field or in time-critical 
situations such as racing. In many designs, the housings are made of 
stamped steel parts welded together. In other designs, the entire housing 
may be made of cast steel. Accessibility to the interior of most 
differential gear units is only through a small rear access plate fastened 
to the housing. However, since all of the bearings and seals are located 
within the housing itself, any repair or service work to these parts must 
involve the dismantling of much of the housing and gear system. If the 
axle is to be repaired or if the gears are to be replaced, the 
differential housing must be fully disassembled. The traditional design of 
the differential gear housing thus makes maintenance and repair of the 
gear system and bearings very difficult. 
The accessibility problem is a factor especially serious in a rear engine 
drive system. In this configuration, the differential gear is usually 
positioned between the transmission and the engine. Thus, for maintaining 
or repairing the internal gears or the bearing for the input and output 
shafts and axles, both the transmission and the engine may have to be 
dismounted from the chassis of the vehicle before any work can be 
performed. 
Further, for a differential to be truly universal (or "omni") it should be 
able to be easily re-configured to be able to change the direction of 
driving motion or to be able to reverse input and output directions. 
Accordingly, it would be desirable to have a differential gear housing that 
is compact, lightweight and easily adaptable to different differential 
drive configurations. It would also be advantageous to have a differential 
gear assembly that is easily maintainable. Particularly, it will be highly 
desirable to have a housing which facilitates repair or replacement of the 
bearings for the drive shafts and axles without requiring entry of the 
internal compartment of the differential gear housing. Further, it will be 
advantageous to have a differential gear housing that is simple to 
manufacture and easy to install. 
SUMMARY OF THE INVENTION 
This invention herein provides a compact, light weight and easily 
maintainable differential gear unit housing comprising a box-like casing 
having front, rear, top, bottom and two side panels. All panels are 
demountable for access to any part of the interior of the casing. The 
front and rear panels each contains an aperture for adapting a bearing 
casing which is externally demountable for supporting the coaxially 
configured power and pinion shafts. The side panels contain axially 
aligned externally demountable bearing housings for the drive axles. The 
bottom panel is removably secured to close the bottom of the casing to 
provide accessibility to the internal parts of the differential gear unit. 
The preferred embodiments of the invention incorporate a number of 
features. Vertical ribs on the side panels are provided to increase the 
structural integrity of and provide cooling to the casing.

PREFERRED EMBODIMENT OF THE INVENTION 
FIG. 1 shows a differential housing of the present invention positioned 
between the torque converter or clutch 3 of an engine and a transmission 
unit 5. In this view the vehicle is a rear drive vehicle with its front to 
the right, the engine is located at the rear-most portion of the vehicle 
and the transmission is in the fore position in front of the differential 
gear unit driving the rear wheels. The configuration would be changed for 
mid- or front drive vehicles, in a manner which will be evident to those 
skilled in the art. The power output of the engine is transmitted by way 
of the torque converter or clutch through the input power shaft of the 
differential gear unit to the transmission unit. The output of the 
transmission unit is then translated back to the differential gear unit to 
engage the drive shaft (which, at times, is also referred to the pinion 
shaft). In the present arrangement, both the power shaft and the pinion 
shaft are coaxial, that is the power shaft is rotatably supported within 
the tubular pinion shaft. Such arrangement of the power train will be 
useful for many types of motor vehicles, including sports or racing cars, 
off-road and military vehicles. 
In the preferred embodiment of the invention the differential gear unit 
housing includes a substantially boxlike casing 10 having a front panel 
16, rear panel 18, top panel 20, bottom panel 22, and two side panels 24 
and 26, respectively. An opening 32 on panel 16 is provided for 
accommodating a bearing housing 34. Appropriate mounting means such as 
bolts may be used for securing the bearing housing 34 onto the front panel 
16 as shown in FIG. 2. Bearing housing 34 is secured to the front panel 16 
by bolts mounted through holes 36. This means of mounting will facilitate 
the removal of the bolts and the bearing housing. Other securing means, 
such as the use of interfitting threads between the front panel opening 32 
and the bearing housing 34 for engaging the panel opening 32, may also be 
used. Thus, as shown in FIG. 2, the installation as well as the removal of 
the bearing housing 34 may be carried out externally of the differential 
gear casing assembly without the necessity of opening the casing itself. 
In the preferred embodiment of the invention, opening 32 is circular in 
shape. At the outward side of the opening, a lip portion 35 is provided 
for the placement of a sealing means, for example, an O-ring 37, for 
isolating the interior of the differential gear casing from the outside 
environment. Contained within bearing housing 34 are recesses for the 
bearing 38 and seal 40. Both the bearing 38 and seal 40 can be secured 
through the bearing housing 34 by any conventional means, for example, 
press fit or by interfitting threads between the bearing housing 34 and 
the bearing 38 and/or seal 40. The choice of the particular mounting means 
can be readily made by the person skilled in the art. Bearing 38 is to 
rotatably support the drive shaft or pinion shaft 14. Seal 40, similar to 
O-ring 37, is intended to provide isolation of the interior of the 
differential gear unit casing from the external environment. 
The end of drive shaft 14 is supported at the rear panel 18. FIG. 2 shows 
two alternative embodiments of the bearing housing configuration. The 
first has been described above with respect to the front panel. As with 
front panel 16, rear panel 18 can have an opening 50 to accommodate a 
bearing housing. The bearing housing mounted on the rear panel 18 can be 
similar to bearing housing 34 of front panel 16 in terms of its 
construction and installation. Also illustrated in FIG. 2 is the alternate 
configuration in which the bearing housing 48 is incorporated as an 
integral part of the rear panel 18. The bearing housing 48 on the rear 
panel 18 has an opening 50 to allow the entrance of the input or power 
shaft into the differential gear unit casing. Along the inside wall of the 
rear panel 18, an upraised portion 52 is provided to circumscribe opening 
50. This upraised portion 52 is to accommodate a shaft bearing 56 for 
supporting the drive shaft 14 at its rear-most end. Bearing 56 may be 
mounted within the upraised portion 52 by any conventional means, such as 
press fit or interfitting threads. The input shaft 12 rotates within shaft 
support 60 which has a flange 58 which serves as a stop when the support 
60 is fitted into housing 48. Seal 57 prevents loss of the fluid within 
the unit. At the outermost or outward portion of bearing housing 56 on 
rear panel 18 is a recess 62 for the mounting of the rear seal 64. Both 
the rear seal 64 and structure 58 have a diameter for accommodating the 
input or power shaft entering the differential gear assembly casing. 
In the preferred embodiment of the invention, opening 32 on the front panel 
16 as well as opening 50 on the rear panel 18 are axially aligned for 
shaft alignment. Further, the bearing housing 34 on the front panel and 
the various openings within opening 50 on the rear panel are axially 
aligned so as to reduce any unwarranted interference with shaft rotation. 
As shown in FIG. 2, both the front panel 16 and the rear panel 18 are 
secured at their respective opposite ends to the two side panels 24 and 
26. Holes 70 are provided along the end portions of the panels whereby 
fastening means such as screws or bolts may be used for joining the panels 
together. 
Side panels 24 and 26 both have openings 78 and 98 respectively fitted with 
axle bearing housings 80 and 100. These axle bearing housings are mounted 
the openings 78 and 98, in the side panels by interfitting screw threads 
82 and 102. Each of the bearing housings 80 and 100 contains a recessed 
area for accommodating a bearing 84 or 104 to support the ring gear 
carrier 110 at its opposite ends. For side panel 24, on the outboard side 
of bearing 84, a second bearing 86, having a smaller diameter than bearing 
84, provides the support to the axle for the drive flange 90. An external 
seal 88 is installed at the outermost portion of the bearing housing 80 to 
isolate the internal parts of the differential gear assembly from the 
external environment. Seal 88 may be mounted upon the bearing housing 80 
by press fit or other conventional means. 
Similarly, on side panel 26 the bearing housing 100 has an outboard bearing 
106 to support the drive axle 107 on the opposite side of the ring gear 
carrier 110. An external seal 108 is also provided to isolate the interior 
of the differential gear casing from any external contaminants. Bearing 
housing 100 has extended depth to allow for support of the ring gear 
carrier 110 closer to the center of the differential gear unit casing. 
This arrangement is necessary since the ring gear is located off-center of 
the longitudinal axis of the drive shaft. 
In the preferred embodiment of the invention, the top panel 20 of the 
differential gear casing 10 is integrated with the side panels 24 and 26. 
Each of the panels may be individually constructed by casting, forging, 
machining or other conventional means, or the entire casing may be cast or 
otherwise formed as a unit. The advantage of such a unit construction is 
that it eliminates the need for separately aligning the side panels during 
the assembly of the differential gear unit. On the other hand, it will in 
many cases be advantageous to have each of the panels separately attached 
and demountable as indicated with bolts 85 in FIG. 2. As seen in FIGS. 1 
and 2, side panels are provided with ribs 112 along the outside of the 
side panels 24 and 26. The ribs add structural strength to the side panels 
so as to assure the structural integrity of the differential gear unit and 
also provide for cooling of the unit. 
FIG. 3 shows a bottom panel 22 removably mounted onto the casing to 
complete the enclosure of the differential gear unit casing and to provide 
additional shear strength to the casing 10, thereby enhancing the 
structural integrity of the differential gear unit. The bottom panel 22 
substantially covers the entire bottom of the casing. Suitable fastening 
means 23, such as shoulder screws or bolts and dowels, are provided to 
secure the closure. These fastening means 23 will be located on the bottom 
panel 22 such that the stress associated with the bolts will be evenly 
distributed, so that the panel 22 will serve as a shear plate. When it is 
necessary to provide service, maintenance or repair to the gears or other 
components within the differential gear casing, the bottom panel 22 can be 
unfastened and removed to allow access for the maintenance personnel to 
the interior components. Since most of the shaft supporting components, 
that is, the bearings and seals as well as their housings, are not located 
within the differential gear casing itself, adequate working space will be 
available to carry out the necessary work. 
The foregoing descriptions and figures are given for illustrative purposes 
only, it being understood that the invention is not limited to the 
embodiments disclosed, but is intended to embrace any and all 
alternatives, equivalents, modifications and rearrangements of elements 
falling within the scope of the inventions defined by the following 
claims. What is claimed is: