Plenum oil seal

An oil seal for a locking differential mechanism. The seal assembly includes a generally flat plate with a first generally circular oil seal adjacent an outer margin of the flat plate, a circular inner margin defining an opening in the flat plate with a second oil seal surrounding the inner margin, an oil outlet opening lying in an otherwise imperforate area between the first and second margins, and a cover for the flat plate with the cover and plate defining between them a passage for oil extending from a point radially outside the first seal to at least a point adjacent the oil outlet. The seal takes in a supply of oil from the differential sump and supplies it through the oil outlet to a multi-plate clutch which is activated only when the two axles undergo rotation relative to each other and thereby actuate a Gerotor type oil pump.

BACKGROUND OF THE INVENTION 
The present invention relates generally to oil seals and more particularly, 
to a combination seal and oil directing device. 
Still further, the invention relates to a device that enables oil, 
including relatively heavy oil, to be picked up from a sump and delivered 
to a pump which operates only intermittently, and serves to supply 
pressure to an annular piston. The piston, in turn, when energized, acts 
through a multi-plate clutch and tends to lock the spider gears of a 
differential against relative rotation and thus lock the drive axles of a 
vehicle together. When there is little or no relative motion between the 
axles, the pump ceases to function transiently and the axles are unlocked. 
The seal also functions to deliver oil sufficient to permit somewhat 
limited slippage of the two axles. 
The invention preferably includes a large stamping, a small circular 
stamping, and a third auxiliary stamping that serves, in cooperation with 
the main stamping, to form a dip tube to deliver the oil from the sump to 
the oil pump, where it performs to above-described functions. In a 
preferred form, the main stamping includes one or more tabs to prevent 
rotation relative to the ring gear with which it is associated in use. 
Normally, the ring gear rotates and the seal directing device does not. 
Herein, although the plenum seal of the invention has the oil directing 
and other functions, it is sometimes referred to herein for convenience 
merely as a "seal". 
According to the invention, a preferred form of the device includes a part 
facing the intake of the oil pump, with a seal band extending around the 
exterior thereof, and an opening of a smaller diameter nearer the center 
thereof, which also features a seal extending in the opposite direction. 
On the side opposite the oil outlet, are preferably several tabs that 
serve to locate the seal in its environment. 
One of the components of the seal includes a cover element preferably 
having associated therewith a cover with an offset area serving to define, 
in combination with the main body unit, an oil passage. This cover is held 
to the main body unit by a series of tabs and preferably, also by adhesive 
surrounding the formation but leaving the oil inlet free. The differential 
housing includes a sump, and hence the oil seal has an opening at the 
bottom, an area of thin, and preferably enlarging, dimension leading to 
the oil outlet opening in the seal, and terminating at the opening. 
The differential housing contains a pinion or driving gear, which serve to 
rotate a ring gear and its associated components, at a reduced speed 
relative to the pinion gear. 
Referring again to the side with the opening, this side faces the opening 
in the ring gear for the inlet of an oil pump. The pump consists of two 
gears or rotors which rotate at different speeds relative to each other 
within a housing. Preferably, the pieces are of a "Gerotor" design that 
takes oil in through openings inside a cover plate that lies partially 
within the ring gear and forces oil out in the opposite axial direction 
against a bonded piston to actuate a multi-plate clutch. 
The gear pump includes an exterior housing, an internal rotor and an 
external rotor. The internal rotor includes teeth on its inner diameter 
for engaging one axle and has outwardly directed formations thereon, and 
the external gear has internal formations thereon. These two, 
collectively, form an oil pump which has an inlet on one axial side and an 
outlet on the opposite axial side, with the inlet and outlet being spaced 
apart by about half a diameter. The oil is then pumped into a cavity in a 
housing containing a bonded piston. Upon sensing oil pressure, the piston 
moves so as to compress the discs of a multi-plate clutch and ultimately 
causes the drive axles to rotate together. 
One drive axle extends through an opening in the ring gear, and this drive 
axle is splined so as to fit into the internal gear of the Gerotor, the 
driven clutch plates, and one of the side gears of the spider set. The 
second axle is internally splined to the other side gear. When the oil 
acts on the bonded piston, it tends to lock the internal splines on the 
first shaft to the second shaft, by locking out the spider carrier, thus 
causing both shafts to rotate as a unit, and doing away with differential 
action. When the bonded piston sees less oil pressure, it releases its 
grip, allowing the clutch plates to release to a greater or less degree, 
and the differential is then free to provide more or less differential 
action. 
Accordingly, it is an object of the present invention to provide a plenum 
seal having certain advantages and characteristics. 
Another object of the invention is to provide a plenum seal that seals on 
two diameters, that includes an oil passage therethrough, extending from 
outside both diameters to a point intermediate the two diameters. 
Yet another object of the invention is to provide an oil seal that is made 
from inexpensive, preferably, stamped parts. 
Still another object of the invention is to provide a seal having three 
components, one of which comprises a cover for a part of the other. 
A further object of the invention is to provide a plenum seal having a flat 
plate with an O.D. seal, an opening in the flat plate, a stamping with an 
I.D. seal, and a cover, preferably of a contoured design, that fits over 
the flat plate to provide an oil supply line or area to a given part of an 
associated pump mechanism. 
A still further object is to provide an oil seal that includes tabs for 
preventing rotation and thus insuring that the seal will remain in place 
relative to a rotating ring gear assembly. 
Another object of the invention is to provide an oil seal of a design which 
may be generally followed in practice in a number of different sizes and 
which will serve to fulfill the requirements for an effective oil seal for 
a locking differential. 
Yet another object of the invention is to provide an oil seal that includes 
a spring loaded lip on the inside sealing surface, and a non-spring loaded 
lip on the outside sealing surface, with the two lips facing in opposite 
axial directions. 
Another object of the invention is to provide an oil seal assembly having 
oppositely directed seals, an oil delivery tube, and an oil outlet, with 
the delivery tube lying on the side opposite the outer diameter seal. 
A further object of the invention is to provide a seal assembly with an oil 
pickup on one side of an outer diameter seal and an oil discharge opening 
on the other side. 
A still further object of the invention is to provide a seal assembly that 
can maintain a volume of oil in the space between two seals for supplying 
the needs of an oil pump from time to time. 
The invention achieves its objects, and other inherent objects and 
advantages by providing a plenum seal for a differential ring gear 
assembly, said seal including a portion sealing on an inside diameter of a 
part associated in use with the ring gear, such as an oil pump housing, 
and a portion sealing on an enlarged diameter of such part to create a 
sealed region between them, an oil outlet in the inter-seal area, and an 
oil inlet lying outside the sealed area, whereby oil may be picked up and 
pumped from a sump into a specially constructed differential, wherein it 
will serve, under proper conditions, to lock the drive axles together and 
enable a substantial torque to be applied to both axles. 
The manner in which the foregoing and other objects are achieved in 
practice will become more clearly apparent when reference is made to the 
following detailed description of the present invention and to the 
accompanying drawings, in which like numbers indicate corresponding parts 
throughout.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
The seal of the present invention has a primary use, and that is with a 
locking differential, particularly of the type described. However, with or 
without modifications, it may provide other uses wherein its features are 
advantageous, namely, filling and maintaining a reservoir of oil between 
inner and outer diameter seals, and between a sealed part and the two 
elastomeric seals of the device of the invention. 
Referring now to the drawings in greater detail, FIG. 1 shows the inventive 
unit to be embodied in a form of plenum seal generally designated 18, 
shown to be associated in use with a differential mechanism generally 
designated 20, and contained within a housing 22 for the differential 
assembly 20. Here, a pinion shaft 24 drives a conventional pinion gear 26, 
which in turn engages and drives a ring gear 28. 
Fasteners, such as cap screws 27 or the like, connect the ring gear 28 to a 
pump housing 30. A Gerotor-type oil pump 31 (FIG. 6) is an 
internal-external rotor type of a type known to those skilled in the art, 
and includes an interior rotor 32 and an exterior rotor 34. These rotors, 
as is known to those skilled in the art, operate by providing a gradually 
increasing space 35 between teeth wherein the oil is taken axially into 
the space between gears, transferred radially, and then expelled axially 
from the diminishing space 37 between the teeth as the rotors converge. 
The pump operates in conjunction with plural inlet passages 36 (FIG. 7) in 
the housing, and in connection with a recess 38 forming a part of an 
associated outlet to be referred to elsewhere herein. 
Referring again to the differential ring gear 28 in FIG. 1, in addition to 
the pump housing 30, the ring gear also has affixed thereto a spider 
carrier 42. This spider carrier includes a spider gear shaft 44 carrying a 
pair of spider gears 46, 48 which in turn mesh with side gears 50, 52. 
Each of the side gears is splined to an axle 54, 56, with the pair of 
axles 54, 56 operating according to generally known principles, i.e., they 
will work together, or, in the case of an unbalanced load, the 
differential will allow one to spin and the other to stand still, to any 
degree necessary. 
However, the present invention differs substantially from the prior art by 
being associated with a novel, modified differential assembly. In this new 
version, in addition to the novel plenum seal 18, and to the known spider 
carrier 42, spider gear shaft 44, spider gears 46, 48 and side gears 50, 
52, the spider carrier 42 includes a large recess 58 which accommodates, 
among other things, a plurality of clutch driving plates 60 keyed to the 
carrier 42, and a plurality of clutch driven plates 62 splined to an 
internally toothed gear 64, which is then splined to one axle 56. 
In addition, the spider carrier 42 contains, near its axially outermost 
end, (the left end as shown in FIG. 1) and inside the recess 58, a bonded 
piston assembly generally designated 66, which comprises a housing 
generally designated 67 including an outer cylindrical stub wall 68, an 
inner cylindrical stub wall 70, an apertured rear wall 72, and a bonded 
piston assembly generally designated 74. The piston assembly includes an 
oil seal at its outer diameter 76, an oil seal at its inner diameter 78, a 
radially inner face 80 and a radially outer face 82 which is slightly 
offset towards the clutch plates 60, 62. An oil bleed opening 84 is 
drilled in the piston 74 and the opening 84 includes a radial passage 86 
therein, to allow an exact amount of oil to be bled therefrom. 
The housing 67 for the bonded piston also contains a plurality of locating 
lugs 88. In addition, the rear wall 72 of the housing 67 contains a 
plurality of openings 90 for oil which, under proper conditions, passes 
from the oil pump 31 and pressurizes the bonded piston 74, urging it to 
the right as shown in FIG. 1. 
Referring now to the first embodiment of the plenum-type oil seal 18 of the 
invention, this unit is shown in varying positions in FIGS. 2-5, as well 
as in the sectional view of FIG. 1. The plenum seal generally designated 
18 is shown to be comprised of a main body plate generally designated 94, 
a plate cover generally designated 96, and a seal insert generally 
designated 98. The main body plate 94 includes tabs 100, 102 to prevent 
rotation of the plenum seal 18 about its own axis. Upon installation, the 
tabs 100, 102 fit over a bearing cap or other fixed part to prevent 
rotation of the seal 18. The main body plate 94 also includes an opening 
104 for the outlet of oil, and a large diameter, axially inwardly 
extending oil seal 106 adjacent its outside diameter. 
A plurality of tabs 108 are also formed on the main body plate 94 for 
holding the cover plate unit 96 in place over the plate 94. The cover unit 
generally designated 96 includes a raised central portion 110, and a 
margin 112 overlying the main body plate 94 in the remainder of the area. 
The cover 96 is preferably also adhesively fastened to the main body plate 
94, and then clinched in place with the tabs 108. 
An oil pickup opening 114, as shown in FIG. 4, is provided at the bottom of 
the plate 94 and cover 96 for the inlet of oil. The raised portion of the 
cover 110 has a gradually increasing depth (from bottom to top as shown in 
FIG. 4) as it extends from the inlet towards the outlet at the middle of 
the seal assembly 18, and also a somewhat diminishing front-to-rear 
dimension as it approaches the middle of the seal assembly 18. The 
cross-sectional area of the oil passage is thus, generally speaking, kept 
approximately constant from the bottom to the top of the oil passage. 
Referring now to the seal insert 98, FIG. 5 shows that this unit is pressed 
into fluid-tight relation in an opening 120 formed in the main body plate 
94. The assembly includes a relatively rigid stamping or other exterior 
casing 122, an elastomeric oil seal body 124, and "air" side and "oil" 
side surfaces 126, 128 meeting along a generally circumferential locus 
defining a seal band 130. "Air" and "oil" side surfaces are conventional 
in the seal art and refer to the surfaces facing the exterior space as 
well as the enclosed space, respectively. In the present case, however, it 
will be understood that oil exists on both sides of the seal. Under some 
conditions, a bath of oil is held between the seal and the housing 30, and 
in this sense, there is more oil in this area. 
The elastomeric seal body 124 also includes an optional spring groove 132 
in which a garter spring 134 is disposed for additional radial load. 
Additional tabs or ears 136 are also provided to allow oil to enter the 
area and lubricate the bearing and the seal. The tabs also provide a 
"stand off" function; that is, they serve as spacers for the installation. 
Referring now to the operation of the inventive plenum seal 18, it will be 
assumed that the ring gear is in place with the oil pump housing 
thereover. The oil pump housing 30 houses the pump 31, and in addition, 
includes the rear surface 140, which has a rearwardly extending outer 
diameter cylindrical formation 142 and an inner diameter cylindrical 
formation 144 as well as a plate extension 146 which is spaced somewhat 
apart by an opening 148 from the axle 54. With the exception of the 
openings which form a part of the inlet passages 36, the rear plate 140 of 
the housing 30 is imperforate. 
The plenum seal 18 fits generally over the plate 30, with the seal 106 
snugly engaging the cylindrical formation 142 in fluid-tight relation. On 
the inner diameter, the elastomeric seal body 124 fits snugly over the 
cylindrical surface 144 so that the seal band 130 engages the cylindrical 
surface 144. As a result, there is an oil tight space 150 between the seal 
18 and the rear surface 140 of the pump housing. 
When the axle rotates relative to the ring gear, as permitted occasionally 
by the spider gears, the interior rotor 32 rotates with respect to the 
outer rotor 34. This creates a vacuum in the space 37 and draws oil up the 
vertical passage 152 from the bottom outlet 114, out the opening 104 in 
the main body plate, thus filling the space 150. From here, the oil 
travels through the opening 37, and ultimately out the space 38, through 
the openings 40 and into the space 66 behind the bonded piston 74. 
Except for the small amount which leaks controllably out the opening 84 and 
through the passage 86, the system is fluid-tight. The oil pressure thus 
forces the plates 60, 62 together, ultimately rotating the spider carrier 
as a whole, and causing the gears 52, 50 to rotate together as a unit. As 
the elements continue to rotate, the oil pump operates and the clutch 
plates remain forced together. 
When the force tending towards driving the gears at different speeds is 
lessened, then pump speed lessens and the hydraulic force is reduced. The 
axles are gradually freed to rotate at about the same speed. As long as 
the axles are rotating at almost (or exactly) the same speed, the pump 
will not operate. However, in this case, it will not be necessary in order 
to insure that the axles both rotate at the same speed. 
It is only when the one axle begins to spin relative to the other that this 
action takes place. If the right-hand axle 54 rotates, relative to the 
left-hand axle 56, the result is still the same, as the pump 31 will be 
driven by the axle in any case. In this instance, the assembly will still 
lock up, and torque will then be transmitted equally to both axles. 
Referring now to FIGS. 8-10, a slightly different embodiment of the 
invention is shown. Here, a main body plate 194 is shown, having a insert 
198 pressed into the opening 220. The oil hole or outlet 204 is the same, 
as are the outer diameter seal 206 and the inside diameter seal body 124. 
The tabs, 200, 202 are in a slightly different location as are the tabs 
236. Nevertheless, these serve the same function as their counterparts in 
the above example. 
Referring to the cover 196, this also includes the raised portion 210, and 
the tabs 208 securing it in place are the same. The depressed margin 212 
is also the same or similar. However, the cross-section is somewhat 
different, with the cover assembly 196 having a contoured, raised portion 
210. The plate 194 of the unit includes an offset portion 195 near the 
bottom, and the cover plate has a gradually increasing depth as it 
approaches the top, thereby keeping the cross-section of the space 252 
generally constant. Other variations may be made to the form of seal shown 
in the drawings. 
In the two forms of seal shown in the drawings, the intake for oil is shown 
as the space between the plate and the cover. Preferably, this places the 
oil intake just outside the diameter of the outer seal. If for some reason 
an oil pickup could be found in another location, i.e., with a substantial 
axial offset, the oil passage could be in the form of a tube or the like 
extending in fluid-tight relation from the oil outlet to a suitable place 
at which pickup would occur. 
The plate 94 is shown as being flat or almost so, but there is no reason, 
other than economy, why it could not contain one or more offsets or 
indentations. The seal is shown with no garter spring on the outer 
diameter; however, this seal element could have a garter spring, just as 
the garter spring for the inside diameter could be omitted. Other 
variations will occur to those skilled in the art. 
It will thus be seen that the present invention provides a combination seal 
and oil directing device, having a number of advantages and 
characteristics including those expressly pointed out here, and others 
which are inherent in the invention. Two illustrative embodiments of the 
product of the invention having been shown and described, it is 
anticipated that variations to the described form of apparatus will occur 
to those skilled in the art and that such modifications and changes may be 
made without departing from the spirit of the invention, or the scope of 
the appended claims.