U.S. patent application number 09/910143 was filed with the patent office on 2002-01-17 for seal cover for shaft assembly.
Invention is credited to Rapp, Robert J..
Application Number | 20020004975 09/910143 |
Document ID | / |
Family ID | 23488407 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020004975 |
Kind Code |
A1 |
Rapp, Robert J. |
January 17, 2002 |
Seal cover for shaft assembly
Abstract
A tool for driving an annular seal into a cavity defined by a
shaft assembly housing that surrounds a rotatable shaft includes an
elongated body having an interior cavity that opens at a first end
of the body for receiving the shaft. The body defines an annular
surface at the first end. The annular surface has an inner diameter
greater than the outer diameter of the rotatable shaft and forming
a removable frictional seal with the inner diameter of the
cavity.
Inventors: |
Rapp, Robert J.;
(Simpsonville, SC) |
Correspondence
Address: |
Alexander Gerasimow
Allen-Bradley Company
Patent Dept., 704P Floor 8 T29
1201 South Second Street
Milwaukee
WI
53204
US
|
Family ID: |
23488407 |
Appl. No.: |
09/910143 |
Filed: |
July 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09910143 |
Jul 20, 2001 |
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09377260 |
Aug 19, 1999 |
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6282768 |
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Current U.S.
Class: |
29/275 |
Current CPC
Class: |
Y10T 29/53657 20150115;
B25B 27/0028 20130101; Y10T 29/5393 20150115 |
Class at
Publication: |
29/275 |
International
Class: |
B25B 027/14 |
Claims
What is claimed is:
1. A tool for driving an annular seal into a cavity defined by a
shaft assembly housing that surrounds a rotatable shaft, said tool
comprising an elongated body having an interior cavity that opens
at a first end of said body for receiving said shaft, said body
defining an annular surface at said first end to abut said seal,
and said annular surface having an inner diameter greater than an
outer diameter of said shaft and having an outer diameter forming a
removable frictional seal with an inner diameter of said interior
cavity.
2. A tool according to claim 1, wherein an exterior surface of said
body is frusto-conical in shape.
3. A tool according to claim 1, wherein said frusto-conical shape
begins at said first end abutting said seal and tapers to a second
end opposite said first end.
4. A tool according to claim 1, wherein second end extends beyond a
distal end of said shaft when said first end engages said seal so
that said tool is removable from said housing by applying force
perpendicular to the longitudinal axis of said rotatable shaft
proximate said second end.
5. A seal cover for a shaft rotatably disposed in a cavity defined
by a housing surrounding the shaft, said seal cover comprising an
elongated body having an enclosed, generally cup-shaped, interior
cavity that opens at an end of said body for receiving said shaft,
said body defining an annular outer surface at said end to abut
said housing.
6. A tool for driving an annular seal into a cavity defined by a
shaft assembly housing that surrounds a hollow rotatable shaft,
said tool comprising: a body having an interior cavity that opens
at an end of said body for receiving said shaft, wherein said body
defines an annular surface at said end to abut said seal and
wherein said annular surface has an inner diameter greater than an
outer diameter of said shaft and an outer diameter forming a
removable frictional seal with an inner diameter of said cavity;
and a stem approximately centered with respect to said annular
surface of said body that extends axially from said end and has a
diameter smaller than an inner diameter of said hollow shaft so
that stem is slidably receivable within said hollow shaft.
7. A tool according to claim 6, wherein said body and said stem are
integrally formed.
8. A seal cover for a shaft rotatably disposed in a cavity defined
by a housing surrounding the shaft, said seal cover comprising a
cup-shaped body having an interior cavity that opens at an end of
said body for receiving said shaft, said body defining an annular
outer surface at said end to surround and abut a flange attached to
said housing.
9. A seal cover according to claim 8, wherein said end abuts a
seal.
10. A shaft assembly, said assembly comprising: a housing having a
bore formed therein; a shaft disposed rotatably in said housing and
within said bore; a seal extending between said shaft and a
circumferential surface of said bore; and a tool for driving said
seal into said cavity, said tool including an elongated body having
an interior cavity that opens at a first end of said body for
receiving said shaft, wherein said body defines an annular surface
at said first end to abut said seal, and wherein said annular
surface has an inner diameter greater than an outer diameter of
said shaft and an outer diameter forming a removable frictional
seal with an inner diameter of said interior cavity.
11. An assembly as in claim 10, wherein an exterior surface of said
body is frusto-conical in shape.
12. An assembly as in claim 10, wherein said frusto-conical shape
begins at said first end abutting said seal and tapers to a second
end opposite said first end.
Description
BACKGROUND OF THE INVENTION
[0001] Shaft assemblies such as motors and speed reducers generally
include a housing in which a shaft is rotatably disposed. Motors
generally include means for rotationally driving the shaft, which
extends out of the housing through a bore. Speed reducers generally
include a driven input shaft that rotationally drives one or more
output shafts through gearing that controls the rotational speed of
the output shaft(s). The input and output shafts extend into and
out of the housing through respective bores. Shaft assemblies such
as motors and speed reducers sometimes have a double output
shaft.
[0002] Such assemblies often include a lip seal at the housing bore
that extends between the housing and the shaft. The lip seal
typically includes a rigid outer portion secured within the bore by
an interference fit between the seal's outer circumferential
surface and the bore's inner circumference. An elastomeric portion
extends inward from the rigid outer portion to engage the shaft.
This elastomeric lip bends axially inward toward the shaft
assembly's interior, thus preventing the escape of lubricant from
the interior area while providing an effective seal that prevents
entrance of exterior contaminants into the interior area.
SUMMARY OF THE INVENTION
[0003] The present invention recognizes and addresses disadvantages
of prior art construction and methods.
[0004] Accordingly, it is an object of the present invention to
provide a tool for driving an annular seal into a cavity defined by
a shaft assembly housing that surrounds a rotatable shaft.
[0005] It is a further object of the present invention to provide a
seal cover for a shaft rotatably disposed in a cavity defined by a
housing surrounding the shaft.
[0006] One or more of these objects are achieved by a tool for
driving an annular seal into a cavity defined by a shaft assembly
housing that surrounds a rotatable shaft. The tool includes an
elongated body having an interior cavity that opens at a first end
of the body for receiving the shaft. The body defines an annular
surface at the first end to abut the seal. The annular surface has
an inner diameter greater than an outer diameter of the shaft and
an outer diameter forming a removable frictional seal with an inner
diameter of the interior cavity.
[0007] In another embodiment, a seal cover for a shaft that is
rotatably disposed in a cavity defined by a housing surrounding the
shaft includes an elongated body having an enclosed, generally
cup-shaped, interior cavity that opens at an end of the body for
receiving the shaft. The body defines an annular outer surface at
the end to abut the housing.
[0008] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate one or more
embodiments of the invention and, together with the description,
serve to explain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth in the specification, which makes
reference to the appended drawings, in which:
[0010] FIG. 1 is an exploded perspective view of preferred
embodiments of a shaft assembly for use with a tool or cover
according to the present invention;
[0011] FIG. 2 is a partial cross-sectional view of a shaft assembly
for use with a tool or cover according to a preferred embodiment of
the present invention;
[0012] FIG. 3 is a partial cross-sectional view of the shaft
assembly as in FIG. 2;
[0013] FIG. 4 is a partial cross-sectional view of the shaft
assembly as in FIG. 2;
[0014] FIG. 5 is an exploded view of a shaft assembly for use with
a tool or cover according to a preferred embodiment of the present
invention;
[0015] FIG. 6 is a partial cross-sectional view of the shaft
assembly as in FIG. 5;
[0016] FIG. 7 is a partial cross-sectional view of the shaft
assembly as in FIG. 5;
[0017] FIG. 8 is a partial cross-sectional view of a shaft assembly
for use with a tool or cover according to a preferred embodiment of
the present invention;
[0018] FIG. 9 is a partial exploded view of a shaft assembly for
use with a tool or cover according to a preferred embodiment of the
present invention;
[0019] FIG. 10 is a partial perspective view of the shaft assembly
as in FIG. 9;
[0020] FIG. 11 is a partial cross-sectional view of the shaft
assembly as in FIG. 9;
[0021] FIG. 12 is a perspective view of a shaft assembly according
to a preferred embodiment of the invention; and
[0022] FIG. 13 is a partial cross-sectional view of the shaft
assembly as in FIG. 12.
[0023] Repeat use of reference characters in the present
specification and drawings is intended to represent same or
analogous features or elements of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] Reference will now be made in detail to presently preferred
embodiments of the invention, one or more examples of which are
illustrated in the accompanying drawings. Each example is provided
by way of explanation of the invention, not limitation of the
invention. In fact, it will be apparent to those skilled in the art
that modifications and variations can be made in the present
invention without departing from the scope or spirit thereof. For
instance, features illustrated or described as part of one
embodiment may be used on another embodiment to yield a still
further embodiment. Thus, it is intended that the present invention
covers such modifications and variations as come within the scope
of the appended claims and their equivalents.
[0025] Referring to FIG. 1, a speed reducer 10 includes a housing
12 and an output shaft 14 extending through a bore 16 in the
housing. The output shaft is driven by an input shaft surrounded by
a bell portion 17 of housing 12. Although speed reducers are shown
in the illustrated embodiments herein, it should be understood that
this is for exemplary purposes only and that any suitable shaft
assembly may be employed within the present invention.
[0026] An annular seal 18 extends between shaft 14 and the inner
circumference of bore 16. Referring also to FIG. 2, the lip seal
construction of seal 18 should be well understood by those skilled
in this art. Seal 18 includes a rigid outer portion 20 secured to
the inner circumference of bore 16 by an interference fit and an
elastomeric portion 22 extending from rigid portion 20 to shaft 14.
Rigid portion 20 may be formed from any suitable material, for
example steel or hard polymer materials. Elastomeric portion 22 may
be formed from any suitable elastomer material. Elastomeric portion
22 deflects axially inward, with respect to shaft 14, toward an
interior area 24 of speed reducer 10 as portion 22 extends from
rigid portion 20 to engage shaft 14. Thus, seal 18 is able to
retain lubricant in area 24 while effectively preventing entrance
of external contaminants.
[0027] Referring to FIGS. 1 and 3, an auxiliary seal comprised of a
second annular seal member 26 and a third annular seal member 28 is
placed over shaft 14. A hollow tool 30 as described below is then
placed over shaft 14 and hammered axially inward, as indicated by
arrow 32, to drive the second and third members into position as
shown in FIG. 4. This drives seal 18 axially inward within bore 16
from its position shown in FIG. 2 to its position shown in FIG.
4.
[0028] An inner circumferential surface 36 of second member 26
establishes an interference fit with shaft 14, and second member 26
therefore rotates with the shaft. An outer circumferential surface
38, however, sufficiently clears an inner circumferential 40 of
third member 28 to allow relative rotation between the second and
third members. An outer circumferential surface 42 of third member
28 forms an interference fit with the internal circumference of
bore 16. An annular lip portion 44 of third member 28 abuts a
radially extending edge 46 of bore 16.
[0029] Accordingly, referring specifically to FIG. 4, third member
28 and annular seal 18 are rotationally fixed to housing 12, while
second member 26 is rotationally fixed to shaft 14. Third member 28
includes a first annular portion 48 extending between housing 12
and second member 26 and a second annular portion 50 extending from
the housing to the shaft, thereby forming a groove that receives
second member 26. Thus, the interfaces between second annular
portion 50 and shaft 14, between third member 28 and second member
26, and between second member 26 and seal 18 form a labyrinth
between the exterior area and the point at which elastomeric
portion 22 engages the shaft. The labyrinth protects the flexible
lip portion of seal 18 from dust and other debris and from direct
contact with pressurized water used to clean the speed reducer.
[0030] Referring again to FIG. 1, third member 28 in a second
embodiment includes a radially extending flange 52 so that the
third member may be secured to housing 12 by bolts 54 that extend
through holes 56 and threadedly engage tapped holes (not shown) in
housing 12. In this embodiment, therefore, outer circumferential
surface 42 of first annular portion 48 need not form an
interference fit with the inner circumference of bore 16.
[0031] In a preferred embodiment, second member 26 and third member
28 are formed by a hard plastic material such as DELRIN.
[0032] It should be understood that the seal assembly formed by
seal 18 and the auxiliary seal may be constructed in any suitable
manner and that the embodiments illustrated in the Figures are
provided for exemplary purpose only. Thus, for example, an
elastomeric inner portion of seal 18, when present, need not
deflect axially inward. Further, while in each three-part seal
assembly shown herein, the first and third annular members are
rotationally fixed to the housing, and the second member is
rotationally fixed to the shaft, it should be understood that these
arrangements may be reversed.
[0033] Referring to FIGS. 1 and 2, annular seal 18 initially
surrounds rotatable shaft 14 at the edge of bore 16. Referring also
to FIGS. 3 and 4, second member 26 and third member 28 are then
placed over rotatable shaft 14 and seated against annular seal 18.
Tool 30 is placed over the shaft so that the shaft is received by
an interior cavity 106 and so that an annular surface 100 defined
at the tool's open end 102 abuts third member 28. Upon applying
axial force 32 to tool 30, for example by hammer blows, annular
surface 100 impacts third member 28, thereby pushing second member
26 and third member 28 to their positions as shown in FIG. 4.
[0034] In another embodiment of the invention as illustrated in
FIGS. 12 and 13, a tool 31 is used with a speed reducer having a
double extended shaft to cover a shaft 14 not in use and the outlet
of bore 16. As discussed above regarding tool 30, tool 31 may be
used to drive seal 18 back into the bore, as shown in FIG. 13, when
the seal is initially disposed at the bore's edge. The
frusto-conically shaped tool 31 defines an interior diameter 104
larger than diameter 108 of shaft 14 so that the shaft turns freely
within cavity 106. Outer diameter 110 of end 102 measures slightly
greater than the inner diameter of bore 16 so that the tool is held
in place against housing 112 through a removable frictional seal
between the inner circumferential surface of bore 16 and the outer
circumferential surface of tool 31. Thus, the tool may both receive
the shaft and be contained by the bore.
[0035] The removable frictional seal seal holds the tool in place
despite the effects of gravity and normal vibrations but may be
loosened to remove the tool without damage thereto by applying a
force 114 generally perpendicular to the axial direction of the
rotatable shaft 14. The tool's frusto-conical shape facilitates
rotation of end 102 within bore 16 upon application of force 114 so
that the upper edge of end 102 is released from the bore.
[0036] In one preferred embodiment, tool 31 is constructed from a
suitable polymer such as DELRIN or polypropylene. It should be
appreciated, however, that the tool's configuration, including the
shapes of its exterior surface and its interior cavity, may vary.
Additionally, the tool may be used to drive or cover seals of
various configurations. Thus, it should be understood that the
embodiment illustrated in FIGS. 12 and 13 is provided for exemplary
purposes only.
[0037] In certain embodiments, a lip seal such as shown in FIGS.
2-4 is fixed to the housing bore and extends radially inward to
engage the shaft. A second annular member is rotationally fixed to
the shaft axially outward of the elastomeric portion and extends
radially outward from the shaft to cover the elastomeric portion.
That is, in comparison to the embodiment shown in FIG. 4, third
member 28 is omitted, and second member 26 may be extended radially
outward.
[0038] In another preferred embodiment of the present invention
shown in FIG. 5, a speed reducer 10 includes a shaft 14 extending
from a bore 16 of housing 12. As the present invention may be
installed as a retrofit, an originally installed seal 18a is
removed as indicated by arrow 58 and is replaced by a seal assembly
comprising a first seal member 18b, a second seal member 26 and a
third seal member 28. Referring also to FIGS. 6 and 7, lip seal 18b
and second member 26 are placed on shaft 14 and tapped into
position by a first tool 30a as indicated by arrow 60.
[0039] Lip seal 18b includes a rigid outer portion 20 and an
elastomeric inner portion 22 that deflects axially inward as it
extends from the rigid outer portion to engage the shaft. Lubricant
may be maintained in an interior area 24 defined axially inward of
seal 18b.
[0040] Second member 26 includes a first annular portion 66
extending between housing 12 and outer portion 20 of lip seal 18b.
Annular portion 66 defines an outer circumferential surface 68
received by bore 16 in an interference fit to rotationally fix
second member 26 to the housing. The outer portion of the lip seal
is, in turn, received by annular portion 66 in an interference fit.
Thus, the lip seal may be pressed into annular portion 66 prior to
mounting onto shaft 14 so that the lip seal and second member may
be installed together. A second annular portion 70 of second member
26 defines a first inner circumferential surface 72 and a second
inner circumferential surface 74 axially and radially outward of
surface 72.
[0041] Tool 30a has a body 124 with a first end 101 in which is
formed an interior cavity 106. An approximately centered protrusion
or central stem portion 62 extends axially from end 101. Central
stem portion diameter 122 is smaller than hollow rotatable shaft
interior diameter 120 so that stem portion 62 may be slidably
received by hollow rotatable shaft 14. Once the stem portion is
inserted into the shaft so that a cup-shaped outer portion 67 abuts
second member 26, as shown in phantom in FIG. 6, hammer blows
received at end 101 push lip seal 18b and second member 26 into
position about shaft 14.
[0042] Cup-shaped outer portion 67 defines cavity 106, which in
turn defines an interior cavity diameter 104 that is greater than
hollow rotating shaft exterior diameter 108. Thus, if necessary,
hollow shaft 14 may extend into interior cavity 106. Cup-shaped
portion 67 mates with flange 126 on second member 26 so that flange
126 is not deformed as second member 26 is pushed into position
around shaft 14.
[0043] In the particular speed reducer 10 shown in FIGS. 5 and 7, a
machine shaft (not shown) is inserted into the bore of shaft 14 and
is secured by set screws 76. If third annular member 28 were to be
placed on shaft 14 at the same time as seal 18b and second member
26, it would cover the set screws and prevent their tightening onto
the machine shaft. Accordingly, following the placement of seal 18b
and second member 26 on shaft 14, third member 28 is placed over
the machine shaft, which is then inserted into the bore of shaft 14
and secured to shaft 14 by the set screws. An operator may then
slide third member 28 up to second member 26 and drive it into
position by a tool 30b. Tool 30b includes a cut out portion 78
(FIG. 5) to receive the machine shaft and/or shaft 14 so that the
tool may be placed against third member 28 as indicated by arrow
80.
[0044] Third member 28 rotates with shaft 14, while second member
26 and lip seal 18b are fixed to the housing. Third member 28
defines an inner circumference 81 that forms an interference fit
with shaft 14 as member 28 is tapped onto the shaft by hammer blows
to tool 30b. It also includes a first annular portion 82 defining
an outer circumferential surface 84 and a second annular portion 86
defining an outer circumferential surface 88. Referring also to
FIG. 8, as shown at the right hand side of gear reducer 10, first
annular portion 82 is received within inner circumferential surface
72 of second member 26, and second annular portion 86 is received
within surface 74. Thus, the second and third members form
interengaging grooves, and a labyrinth is formed between second
member 26 and third member 28 and between third member 28 and seal
18b from the exterior to the point at which seal 18b engages shaft
14.
[0045] Referring specifically to FIGS. 5 and 8, speed reducer 10
includes a central shaft 14 extending entirely though housing 12 so
that the reducer may be positioned at a desired axial point on a
machine shaft. That is, the speed reducer may be slidably moved on
the machine shaft to properly position the speed reducer with
respect to an input drive shaft (not shown). If, however, the
machine shaft does not extend entirely through shaft 14, an end cap
90 may be used to cover bore 16 and the open end of shaft 14. Cap
90 has a cup-shaped body defining an annular flange portion 92
extending about an open end of the body and surrounding a central
portion 94. Flange 92 includes an inwardly curving edge that is
received within a gap defined between housing 12 and an annular lip
96 of annular portion 86 of second member 26.
[0046] Thus, cap 90 is axially fixed to the housing through the
engagement of opposing lips formed by the cap and the seal
assembly. The opposing lips on the cap and seal need not be
continuous. For example, the cap lip may comprise fingers received
in spaced apart recesses in the housing or seal. The cap is
preferably made from a flexible polymer material so that it may be
removed.
[0047] As shown at the left hand side of FIG. 8, the third annular
member 28 is not installed since the machine shaft is not attached
at this end. Thus, cap 90 protects annular lip portion 22. Of
course, provided there is no interfering machine shaft, cap 90 may
be used to cover bore 16 even where third member 28 is present, as
indicated in phantom at the right hand side of FIG. 8.
[0048] Referring now to FIGS. 9, 10 and 11, a speed reducer 10
includes an output shaft 14 disposed in a housing 12. Depending on
the reducer's design, one or two ends may be connected to a machine
shaft. Speed reducers, such as illustrated in these and other
figures herein, should be well understood in this art and are
therefore not discussed in detail. It should be understood,
however, that any suitable means for attaching the machine shaft to
the output shaft may be used. In the example shown in FIGS. 9-11,
the interior bore of shaft 14 is tapered, with the diameter
expanding outward towards the shaft's end. An attachment collar 98
includes a central section 103 received in the shaft bore and
having an outer circumferential surface 105 defining a taper that
corresponds to the shaft taper. Collar 98 defines a radial cut 109
so that compression of the collar reduces the diameter of the
collar's central bore 111. Thus, when the center portion of collar
98 is pushed axially into the shaft bore, the diameter of bore 111
is reduced as the outer tapered surface 105 of collar 98 slides
down against the inner tapered surface of shaft 14, thus securing a
machine shaft (not shown) to shaft 14. Collar 98 is rotationally
fixed to shaft 14 by friction or other means.
[0049] Collar 98 includes an annular flange 107 having holes
through which three bolts 113 extend. Bolts 113 threadedly engage
holes in a ring 115 axially retained on shaft 14 by a clip 117. As
bolts 113 are tightened into ring 115, collar 98 is pulled axially
inward into shaft 14, thus tightening the collar onto the machine
shaft.
[0050] An annular seal 119, for example made of an elastomeric
material, is rotationally fixed to housing 12 in bore 16 and
retains lubricant within interior area 24 of gear reducer 10. To
provide auxiliary protection, an annular ring 121 is received about
ring 115 and flange 107. Ring 121 is attached to housing 12 by
screws 123 received in threaded holes 125 tapped into housing 12.
Ring 121 may be made, for example, from a metal or a hard polymer
material such as DELRIN. Although ring 121 is attached to the
housing block axially and radially outward of bore 16, it may also
be considered an extension of the bore from the block so that
flange 107 and ring 115 form annular members creating a labyrinth
between the exterior area and seal 119.
[0051] While one or more preferred embodiments of the invention
have been described above, it should be understood that any and all
equivalent realizations of the present invention are included
within the scope and spirit thereof. For example, the present
invention may be embodied in a variety of shaft assemblies in which
a rotatable shaft is disposed in a housing and within a bore in the
housing extending between the exterior area and an interior area.
Thus, the present invention is not limited to motors and speed
reducers, and the embodiments depicted are presented by way of
example only and are not intended as limitations upon the present
invention. Thus, it should be understood by those of ordinary skill
in this art that the present invention is not limited to these
embodiments since modifications can be made. Therefore, it is
contemplated that any and all such embodiments are included in the
present invention as may fall within the literal or equivalent
scope of the appended claims.
* * * * *