Machine element or mechanism – Elements – Gear casings
Reexamination Certificate
1998-11-10
2001-08-28
Luong, Vinh T. (Department: 3682)
Machine element or mechanism
Elements
Gear casings
C475S083000, C060S487000
Reexamination Certificate
active
06279422
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an arrangement for adjusting the axial positioning of a pair of colinear shafts in a power transmission apparatus and, more specifically, to an endplay adjuster assembly disposed between the colinear input shaft and mainshaft of a four-wheel drive transfer case.
Many power transmission apparatuses (i.e., transfer cases, transmissions, transaxles, etc.) of the type used in the driveline of motor vehicles are equipped with a pair of colinear and relatively rotatable shafts and a clutch mechanism for transferring drive torque therebetween. For example, a conventional transfer case
10
is shown in
FIG. 1
to include a housing assembly
12
, an input shaft
14
, a planetary gearset
16
driven by input shaft
14
, a mainshaft or rear output shaft
18
, and a range clutch
20
operable for selectively coupling rear output shaft
18
for rotation with one of input shaft
14
and an output
22
of planetary gearset
16
. Transfer case
10
also includes a front output shaft
24
, a drive sprocket
26
fixed to front output shaft
24
, a drive sprocket
28
rotatably mounted on rear output shaft
18
, a chain assembly
30
interconnecting driven sprocket
26
to drive sprocket
28
, and a mode clutch
32
operable for selectively coupling drive sprocket
28
to rear output shaft
18
. A shift mechanism
34
, under the control of the vehicle operator, is connected to range clutch
20
and mode clutch
32
to facilitate coordinated actuation thereof for establishing various drive modes.
Input shaft
14
is shown to be rotatably supported in a front housing section
12
a
by a front bearing assembly
36
. Likewise, rear output shaft
18
has a pilot hub
38
formed on its forward end which is rotatably supported by a needle bearing assembly
40
that is retained in a pilot bore
42
formed in input shaft
14
. The rearward end of rear output shaft
18
is rotatably supported from rear housing section
12
b
by a rear bearing assembly
44
. Thus, input shaft
14
and rear output shaft
18
are colinear and supported for rotation about a common rotary axis “A”. In addition, a cup plug
46
seals pilot hub
38
of rear output shaft
18
relative to input shaft
14
.
During assembly of transfer case
10
, an inner race
36
a
of front bearing assembly
36
is slid onto input shaft
14
until it abuts a radial shoulder surface
48
formed thereon and a snap ring
50
is then mounted in a circumferential groove
51
formed in input shaft
14
, thereby retaining front bearing assembly
36
on input shaft
14
. Input shaft
14
is then installed into housing section
12
a
such that an outer race
36
b
of front bearing assembly
36
engages a radial shoulder surface
52
of housing section
12
a
and then a snap ring
54
is mounted in a circumferential groove
55
formed in housing section
12
a
, thereby axially positioning and restraining input shaft
14
relative thereto. Alternatively, front bearing assembly
36
could be initially mounted to housing section
12
a
with input shaft
14
thereafter installed in front bearing assembly
36
and snap ring
50
mounted in the groove
51
formed in input shaft
14
.
During continuation of the assembly of transfer case
10
, an inner race
44
a
of rear bearing assembly
44
is slid onto rear output shaft
18
and is axially restrained between a pair of snap rings
56
a
and
56
b
mounted in circumferential grooves
57
a
and
57
b
formed in rear output shaft
18
respectively. Thereafter, rear output shaft
18
is installed in housing section
12
b
such that outer race
44
b
of rear bearing assembly
44
abuts a radial shoulder surface
58
of housing section
12
b
and then a snap ring
60
is mounted in a corresponding groove
61
formed in housing section
12
b
. Alternatively, rear bearing assembly
44
could initially be installed in housing section
12
b
with rear output shaft
18
slid into its inner race
44
a
followed by installation of snap ring
56
b
. As seen, a hole
62
in housing section
12
b
provides the requisite access to install snap ring
60
and is then sealed by a rubber housing plug
64
. Once pilot hub
38
of rear output shaft
18
is mounted in pilot bore
42
, housing sections
12
a
and
12
b
are then interconnected in a manner well known in the art.
In such colinear shaft layouts, the machining tolerances for the groove location, groove width, shoulder locations, and the snap ring width, in conjunction with the necessary design assembly clearances, may stack up to permit an excessive amount of axial movement (i.e., “endplay”) between input shaft
14
and rear output shaft
18
Such endplay has been recognized as contributing to driveline noise or clunk and may also cause increased wear of the driveline components.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to overcome the disadvantages associated with prior art colinear shaft assemblies by providing an endplay adjustment assembly which facilitates axial adjustment of the colinear shafts in a power transmission apparatus to accommodate tolerance variations between the various driveline components.
In accordance with the present invention, a preferred embodiment of the endplay adjustment assembly includes an endplay adjuster plug and a thrust bearing operably disposed between a first shaft and a second shaft rotatably supported from a housing. More specifically, the first shaft has a pilot bore for receiving and rotatably supporting one end of the second shaft. The endplay adjustment assembly is operably disposed in the pilot bore between the first shaft and the second shaft. The adjuster plug has external threads which engage internal threads formed in the pilot bore. The thrust bearing is disposed between the adjuster plug and the end of the second shaft. First and second bearing assemblies rotatably support the first shaft and second shaft within the housing. More specifically, bearing seats formed on the shafts and in the housing receive the bearing assemblies. Thereafter, the threaded adjuster plug is tightened to axially displace the first shaft relative to the second shaft, thereby forcing the first bearing assembly against its bearing seats while also forcing the second bearing assembly against its bearing seats. After appropriate tightening of the adjuster plug, the axial positioning of the shafts is optimized in a manner which is independent of machining tolerances, thereby eliminating endplay of the shaft assembly.
The present invention is particularly applicable to eliminate endplay in the shaft assembly of a four-wheel drive transfer case, thereby eliminating driveline clunk caused by such endplay. Furthermore, the present invention eliminates the conventional use of snap rings and the need to machine snap ring grooves in the housing and on the shafts. As such, the present invention greatly reduces the axial tolerance stack ups for allowing more precise positioning of critical components and less misalignment therein. As a further advantage, the present invention allows a press fit rather than a slip fit with the first and second bearing assemblies, thus improving bearing durability and overall alignment. As yet an additional advantage, the present invention provides faster and easier assembly and disassembly of the transfer case by eliminating the snap rings and rubber plugs.
Additional advantages and features of the present invention will become apparent from the following description and appended claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5142940 (1992-09-01), Hasegawa
patent: 5616092 (1997-04-01), Hauser et al.
patent: 5771758 (1998-06-01), Hauser
patent: 5979271 (1999-11-01), Louis et al.
patent: 1810040 (1969-08-01), None
Harness & Dickey & Pierce P.L.C.
Luong Vinh T.
New Venture Gear Inc.
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