U.S. patent application number 10/950489 was filed with the patent office on 2005-04-21 for seal assembly and crawler-track connection structure.
This patent application is currently assigned to KOMATSU LTD.. Invention is credited to Hashimoto, Akira, Nakaishi, Hiroyuki, Yamamoto, Teiji.
Application Number | 20050082767 10/950489 |
Document ID | / |
Family ID | 25222927 |
Filed Date | 2005-04-21 |
United States Patent
Application |
20050082767 |
Kind Code |
A1 |
Yamamoto, Teiji ; et
al. |
April 21, 2005 |
Seal assembly and crawler-track connection structure
Abstract
A seal assembly has simple assembly structures, and provides
secure sealing effects. A crawler-track connection structure allows
the seal assembly to be easily mounted, and securely prevents
overflow of a lubricant and the like to the outside. A pair of seal
rings (1) and (1) individually having lip portions (23) and (23)
are disposed such that each of the lip portions (23) and (23)
protrudes in a direction opposing an axial direction, and a load
seal ring (2) is compressed and inserted between the pair of seal
rings (1) and (1). The load seal ring (2) exerts reaction forces on
the pair of lip portions (23) and (23) outwardly in the axial
direction.
Inventors: |
Yamamoto, Teiji; (Osaka,
JP) ; Hashimoto, Akira; (Osaka, JP) ;
Nakaishi, Hiroyuki; (Osaka, JP) |
Correspondence
Address: |
ARMSTRONG, KRATZ, QUINTOS, HANSON & BROOKS, LLP
1725 K STREET, NW
SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
KOMATSU LTD.
Tokyo
JP
|
Family ID: |
25222927 |
Appl. No.: |
10/950489 |
Filed: |
September 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10950489 |
Sep 28, 2004 |
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10461369 |
Jun 16, 2003 |
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10461369 |
Jun 16, 2003 |
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09817365 |
Mar 22, 2001 |
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Current U.S.
Class: |
277/510 |
Current CPC
Class: |
F16J 15/344 20130101;
F16J 15/3456 20130101 |
Class at
Publication: |
277/510 |
International
Class: |
F16J 015/18 |
Claims
1-3. (canceled).
4. A seal assembly comprising: a pair of seal rings (1) and (1)
individually comprising lip portions (23) and (23) disposed such
that each of said lip portions (23) and (23) protrudes in a
direction opposing an axial direction; and a load seal ring (2)
compressed and inserted between said seal rings (1) and (1), said
load seal ring (2) exerting reaction forces on said lip portions
(23) and (23) outwardly in the axial direction, wherein one of said
seal rings (1) and (1) comprises said outer-diameter controller
body (32) for controlling the displacement of said load seal ring
(2) in the periphery outer direction, and the other one of said
seal rings (1) and (1) comprises said inner-diameter controller
body (32) for controlling the displacement of said load seal ring
(2) in the periphery inner direction.
5. The seal assembly as defined in one of claims 4, wherein said
load seal ring (2) comprises a circumferential groove (27) that
tolerates axial-direction compression.
6. The seal assembly as defined in one of claims 4 to 5, wherein a
cross section of said seal assembly is symmetric with respect to a
radial-direction line passing the center thereof,
7. The crawler-track connection structure comprising: a pin (8) to
be inserted through superposed end portions of links (5) and (5);
and a seal assembly (S) externally fitted on said pin (8) for
preventing overflow of a lubricant to the outside, the lubricant
being supplied to an outer peripheral side of said pin (8), wherein
one of said links (5) and (5) is immobilized on said pin (8); the
other one of said links (5) and (5) is supported on said pin (8) to
be rotatable thereon; and said seal assembly comprises a load seal
ring (2) disposed between radial-direction walls (W) and (W)
opposing each other along an axial direction, a first seal ring (I)
comprising a lip portion (23) press-engaged with one of said
radial-direction walls (W) and (W) according to a pressure exerted
from said load seal ring (2), and a second seal ring (1) comprising
a lip portion (23) press-engaged with the other one of said
radial-direction walls (W) and (W) according to a pressure exerted
from said load seal ring (2).
8. The crawler-track connection structure as defined in claim 7,
further comprising a bushing (12) immobilized in the other one of
said links (5) and (5) to be rotatable on said pin (8), and an end
surface of said bushing functions as the one of said
radial-direction walls (W) and (W).
9. The crawler-track connection structure as defined in claim 7,
further comprising: a bushing (12) immobilized in the other one of
said links (5) and (5) to be rotatable on said pin (8); and a
bushing (13) on the side of a sprocket (18), wherein said seal
assembly (S) is inserted between said bushing (12) and said bushing
(13).
10. The crawler-track connection structure as defined in one of
claims 7 to 9, further comprising a ring body (31) disposed in an
inner-diameter side of said load seal ring (2) for controlling the
displacement of said load seal ring (2) in a periphery inner
direction.
11. The crawler-track connection structure as defined in one of
claims 7 to 9, further comprising a dust seal ring (37) disposed in
an outer peripheral side of said seal assembly (S).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a seal assembly and a
crawler-track connection structure.
[0003] 2. Description of the Related Art
[0004] Generally, as shown in FIG. 6, a crawler vehicle such as a
construction machine, e.g., a bulldozer tractor or a hydraulic
shovel tractor, has an endless link chain 81 and a plurality of
ground-contacting shoe plates (not shown) mounted on the link chain
81. The link chain 81 comprises a plurality of links 82a, . . . and
82b, . . . that are disposed parallel to each other, and a
crawler-track connection Structure 84 for pivotably connecting the
links 82a and 82b opposing each other. Specifically, the links 82a
and 82b comprise an intermediate portion 85 where the shoe plates
(not shown) are mounted, and connecting portions 86 and 87
protruding from the intermediate portion 85. A pin insertion
opening 88 is provided in the connecting portion 86, and a bushing
insertion opening 89 is provided in the connecting portion 87. The
links 82a and 82a and the links 82b and 82b are individually
connected together via the crawler-track connection structure 84
such that the connecting portion 86 and the connecting portion 87
are overlapped with each other.
[0005] The crawler-track connection structure 84 comprises a pin 90
and a bushing 91 externally fitted around the pin 90. End portions
of the pin 90 extend outward from the bushing 91 In the axial
direction, and the pin 90 is press-fitted into the pin insertion
opening 88 of the link 82. End portions of the bushing 91 are
press-fitted into the bushing insertion openings 89. An opening
portion of the pin insertion opening 88 on the side of the bushing
is formed as a large-diameter portion 92. Space portions 94 are
formed by the large-diameter portion 92, an outer end surface of
the bushing 91, and an outer peripheral surface 93 of the pin 90. A
seal assembly 95 is fitted into the space portion 94. In this case,
the bushing 91 is externally fitted to be rotatable around the pin
90, the pin 90 is unitized with the connecting portion 86, and the
bushing 91 is unitized with the connecting portion 87. Thereby, end
portions of the links 82 and 82 to be connected, i.e., the
connecting portions 86 and 87, are pivotably connected together. In
addition, an oil injection opening 96 is provided in the pin 90.
Oil in the oil injection opening 96 flows to the side of the outer
peripheral surface 93 of the pin 90 through a path (not shown) and
serves as a lubricant between the pin 90 and the bushing 91.
[0006] As shown in FIG. 7, the seal assembly 95 comprises a seal
ring 98 having a lip portion 97, a support ring 99 for supporting
the seal ring 98, and a load ring 100 for receiving a pressure from
the lip portion 97 of the seal ring 98. Thereby, the seal assembly
95 prevents overflow of the aforementioned lubricant to the
outside.
[0007] In the above-described conventional crawler-track connection
structure, to cause the lip portion 97 to press-engage with a
corresponding wall (an end surface of the bushing 91 in FIG. 6),
the load ring 100 needs to receive a pressure from an outer
peripheral side thereof. Therefore, In the conventional structure,
housings (space portions 94) need to be formed to insert the seal
assembly 95, thereby complicating the overall structure that makes
the manufacturing processing to be difficult. In addition, since
the seal assembly 95 must be inserted in the space portions 94, the
overall assembly requires complicated steps, thereby reducing the
productivity.
SUMMARY OF THE INVENTION
[0008] The present invention is made to solve the above-described
problems with the conventional case. Accordingly, an object of the
invention is to provide a seal assembly that has a simple assembly
structure and that provides secure sealing effects. Another object
of the invention is to provide a crawler-track connection structure
that allows the seal assembly to be easily mounted, and in
addition, that securely prevents overflow of a lubricant and the
like to the outside.
[0009] To these ends, according to first aspect of the invention, a
seal assembly comprises a pair of seal rings 1 and 1 individually
comprising lip portions 23 and 23 disposed such that each of the
lip portions 23 and 23 protrudes in a direction opposing an axial
direction; and a load seal ring 2 compressed and inserted between
the seal rings 1 and 1, the load seal ring 2 exerting reaction
forces on the lip portions 23 and 23 outwardly in the axial
direction.
[0010] In the seal assembly according to the first aspect of the
invention, with an axial-direction compressive force being exerted
on the load seal ring 2, the load seal ring 2 presses the
respective lip portions 23 and 23 of the seal rings 1 and 1
outwardly in the axial direction. Therefore, when the seal assembly
is mounted between walls that form a gap of which the length is
less than the axial-direction length of the seal assembly in a free
state, the individual lip portions 23 and 23 are press-engaged with
the corresponding walls, thereby allowing an inner-diameter side
and an outer-diameter side of the lip portion 23 and 23 to be
hermetically enclosed. That is, with the seal assembly, assembly
thereof into a crawler-track connection structure and the like can
easily be performed to thereby improving the efficiency in the
assembly work.
[0011] The seal assembly according to the first aspect of the
invention may further comprise an outer-diameter controller body 32
for controlling the displacement of the load seal ring 2 in a
periphery outer direction.
[0012] In this case, the displacement of the load seal ring 2 in
the periphery outer direction can be controlled by the
outer-diameter controller body 32, and reaction forces of the load
seal ring 2 in the axially-outer direction can be securely exerted
on the lip portions 23 and 23. Thereby, conventionally required
outer-peripheral-side controller walls (space portions 94 shown in
FIG. 6) can be avoided. That is, processing for spaces used for
mounting a seal assembly S is not required. This facilitates
manufacturing processing, and concurrently, allows high-precision
sealing effects to be provided.
[0013] The seal assembly according to the first aspect of the
invention may further comprise an inner-diameter controller body 32
for controlling the displacement of the load seal ring 2 in a
periphery inner direction.
[0014] In this case, the displacement of the load seal ring 2 in
the periphery outer direction can be controlled by the
Inner-diameter controller body 32, and reaction forces of the load
seal ring 2 in the axially-outer direction can be securely exerted
on the lip portions 23 and 23. In addition, the inner-diameter
controller body 33 functions as a spacer disposed in an
inner-diameter side of the seal assembly to thereby allow a
mounting portion of the seal assembly to easily be secured.
[0015] In the seal assembly according to the first aspect of the
invention, one of the seal rings 1 and 1 may comprise the
outer-diameter controller body 32 for controlling the displacement
of the load seal ring 2 in the periphery outer direction, and the
other one of the seal rings 1 and 1 comprise the inner-diameter
controller body 32 for controlling the displacement of the load
seal ring 2 in the periphery inner direction.
[0016] In this case, the displacement of the load seal ring 2 in
the periphery outer direction can be controlled by the
outer-diameter controller body 32, and the displacement of the load
seal ring 2 in the in the periphery inner direction can be
controlled by the inner-diameter controller body 33. Reaction
forces in the axial direction according to the load seal ring 2 can
be securely exerted on the lip portions 23 and 23. Therefore, a
higher-precision function can be produced.
[0017] In the seal assembly according to the first aspect of the
invention, the load seal ring may comprise a circumferential groove
27 that tolerates axial-direction compression.
[0018] In this case, according to the provision of the
circumferential groove 27, when the compressive force is exerted on
the load seal ring 2 in the axial direction, the load seal ring 2
is compressed in the axial direction, and reaction forces in the
axially-outer direction according to the load seal ring 2 can be
securely exerted on the lip portions 23 and 23. Thereby, stable
sealing effects can be produced.
[0019] In the above seal assembly according to the first aspect of
the invention, a cross section of the seal assembly may be
symmetric with respect to a radial-direction line passing the
center thereof.
[0020] In this case, since the cross section of the seal assembly
is symmetric with respect to the radial-direction line passing the
center thereof, the obverse side and the reverse side of the seal
assembly are the same. This provides the advantage of facilitating
mounting work of the seal assembly. Furthermore, only one type of
pair of components, such as the seal rings 1 and 1, may be formed,
the manufacturing cost can thereby be reduced.
[0021] According to a second aspect of the present invention, a
crawler-track connection structure comprises a pin 8 to be inserted
through superposed end portions of links 5 and 5; and a seal
assembly S externally fitted on the pin 8 for preventing overflow
of a lubricant to the outside, the lubricant being supplied to an
outer peripheral side of the pin 8. One of the links 5 and 5 is
immobilized on the pin 8, and the other one of the links 5 and 5 is
supported on the pin 8 to be rotatable thereon. The seal assembly
comprises a load seal ring 2 disposed between radial-direction
walls W and W opposing each other along an axial direction, a first
seal ring 1 comprising a lip portion 23 press-engaged with one of
the radial-direction walls W and W according to a pressure exerted
from the load seal ring 2, and a second seal ring 1 comprising a
lip portion 23 press-engaged with the other one of the
radial-direction walls W and W according to a pressure exerted from
the load seal ring 2.
[0022] In the crawler-track connection structure according to the
second aspect of the invention, with the seal assembly S being
mounted between the radial-direction walls W and W opposing each
other along the axial direction, the lip portions 23 and 23 are
press-engaged with the corresponding walls W and W to thereby allow
an inner-diameter side and an outer-diameter side of the lip
portions 23 and 23 to be hermetically enclosed. That is, in the
seal assembly, the conventional space portions 94 shown in FIG. 6
are not required. Therefore, manufacturing processing and mounting
work of the seal assembly S can be easily performed, and
high-precision sealing effects can be produced.
[0023] The crawler-track connection structure according to the
second aspect of the invention may further comprise a bushing 12
immobilized in the other one of the links 5 and 5 to be rotatable
on the pin 8, and an end surface of the bushing 12 functions as the
one of the radial-direction walls W and W.
[0024] In this case, one of the radial-direction walls W and W for
receiving the seal assembly S can be formed using an end surface of
the bushing 12. Thereby, the crawler-track connection structure can
be simplified overall.
[0025] In addition, the crawler-track connection structure
according to the second aspect of the invention may further
comprise a bushing 12 immobilized in the other one of the links 5
and 5 to be rotatable on the pin 8, and a bushing 13 on the side of
a sprocket 18, wherein the seal assembly S is inserted between the
bushing 12 and the bushing 13.
[0026] In this case, the radial-direction walls W for receiving the
seal assembly S can be formed using the bushing 12. Thereby, the
crawler-track connection structure can be simplified overall, and
the assembly work is facilitated, improving the productivity
thereof.
[0027] The crawler-track connection structure according to the
second aspect of the invention may further comprise a ring body 31
disposed in an inner-diameter side of the load seal ring 2 for
controlling the displacement of the load seal ring 2 in a periphery
inner direction.
[0028] In this case, the displacement of the load seal ring 2 in
the periphery inner direction can be controlled by the
inner-diameter controller body 31, and reaction forces of the load
seal ring 2 in the axially-outer direction can be securely exerted
on the lip portions 23 and 23. In addition, the inner-diameter
controller body 31 functions as a spacer disposed in an
inner-diameter side of the seal assembly to thereby allow a
mounting portion of the seal assembly to easily be secured.
[0029] The crawler-track connection structure according to the
second aspect of the invention may further comprise a dust seal
ring 37 disposed in an outer peripheral side of the seal assembly
S.
[0030] In this case, the dust seal ring 37 prevents the entrance of
dust, mud, muddy water, and the like to the seal assembly S from
the outer peripheral side. Thereby, the seal assembly S provides
stable sealing effects, the quality of the crawler track can be
improved, and the durability of the crawler track can be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1A is an essential-portion cross-sectional view of a
seal assembly (premounted) according to an embodiment of the
present invention;
[0032] FIG. 1B is an essential-portion cross-sectional view of the
seal assembly (postmounted);
[0033] FIG. 2 is a cross-directional view of a crawler-track
connection structure according to an embodiment of the present
invention;
[0034] FIG. 3 is an essential-portion cross-sectional view showing
a disposed state of a dust seal ring according to the present
invention;
[0035] FIG. 4A is an essential-portion cross-sectional view of a
seal assembly (premounted) according to another embodiment of the
present invention;
[0036] FIG. 4B is an essential-portion cross-sectional view of the
seal assembly (postmounted);
[0037] FIG. 5A is an essential-portion cross-sectional view of a
seal assembly (premounted) according to still another embodiment of
the present invention;
[0038] FIG. 5B is an essential-portion cross-sectional view of the
seal assembly (postmounted);
[0039] FIG. 6 is a cross-sectional view of a conventional
crawler-track connection structure; and
[0040] FIG. 7 is a cross-sectional view of a conventional seal
assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Hereinbelow, referring to the accompanying drawings,
practical embodiments of the present invention will be described in
detail. FIGS. 1A and 1B are essential-portion cross-sectional views
of an embodiment of a seal assembly according to the present
invention. A seal assembly S is used for, for example, a
crawler-track connection structure. The seal assembly S has a pair
of seal rings 1 and 1 and load seal ring 2 disposed between the
seal rings 1 and 1, and each of the seal rings 1 and 1 is supported
by a support ring 3 that has an L-shaped cross section. In the
cross-sectional view, the seal assembly S is formed symmetric with
respect to a radial line passing the center of the assembly S. The
crawler-track connection structure is intended for use in a
traveling crawler of a crawler vehicle, such as a construction
machine, e.g., a bulldozer tractor or a hydraulic shovel
tractor.
[0042] As shown in FIG. 2, the above-described connection structure
connects links 5 and 5 in a state where a connecting portion 6 at
an end portion of one of the links 5 and 5 is superposed on a
connecting portion 7 at an end portion of the other link 5.
Specifically, the individual link 5 has the connecting portion 6 on
one end side, and the connecting portion 7 on the other end side,
in which the connecting portion 6 and the connecting portion 7 of
the adjacent links 5 and 5 are connected together via the
connection structure. As shown in FIG. 6, in the individual links
5, an intermediate portion (not shown) Is formed between the
connecting portion 6 and the connecting portion 7, and shoe plates
are disposed in the intermediate portion. In addition, although not
shown in FIG. 2, links 5 and 5 are similarly connected together at
the other end portion of a pin 8.
[0043] The connection structure comprises a fallout prevention pin
9 externally fitted around the pin 8. Specifically, a pin insertion
opening 10 is provided in the connecting portion 6 of the link, and
a bushing insertion opening 11 is provided in the connecting
portion 7 of the link 5, in which an and portion of the pin 8 is
press-fitted into the pin insertion opening 10, and a bushing 12 is
press-fitted into the bushing insertion opening 11 of the
connecting portion 7 to be rotatable around the pin 8. In addition,
another bushing 13 externally fitted around the pin 8, that is, a
bushing on the side of a sprocket 18 described below, is provided
between the connecting portions 6 of the links 5 and 5 opposing
each other at a predetermined space (in the drawing, opposing links
5 and 5 on the other side are omitted). The seal assembly S of the
present invention is provided between the bushings 12 and 13. An
end surface of the bushing 12 on the one side and an end surface of
the bushing 13 on the other side function as radial-direction walls
W and W, on which lip portions 23 and 23 are provided,
respectively. A conventional seal assembly Sa is provided between
the bushing 12 and the connecting portion 6 of the link 5 on the
one side.
[0044] A circumferential U-shaped groove 14 is provided at an end
portion of the pin 8, and a tapered face 15 is provided around a
peripheral portion of the pin insertion opening 10 to reduce the
diameter of the opening inwardly in the axial direction. The
tapered face 15 and the circumferential U-shaped groove 14 together
form a circular space 16. The fallout prevention pin 9 is
elastically flexible in diameter, and 1t is fitted in the circular
space 16 to thereby fix the link 5 and the pin 8 together. The
links 5 are thus connected to form a link chain. The link chain is
engaged with a sprocket 18 (refer to FIG. 2) of a crawler vehicle,
such as a construction machine. An oil injection opening (not
shown) is provided in the pin 8. Oil in the oil injection opening
flows to the side of an outer peripheral face 19 and serves as a
lubricant between the pin 8 and the bushing 12,
[0045] As shown in FIGS. 1A and 1B, the seal ring 1 in the seal
assembly S is formed of, for example, a urethane resin having the
hardness of about Hs 95. The seal ring 1 comprises a first portion
20, a second portion 21, and a pendulous peripheral wall 22. The
first portion 20 is provided on an outer peripheral side, and
extends in the axial direction. The second portion 21 inwardly
extends in a radial direction from an axial-direction outer portion
of the first portion 20. The pendulous peripheral wall 22 inwardly
extends in the radial direction to an axial-direction inner portion
of the first portion 20. The lip portion 23 has a triangular cross
section outwardly protruding in the axial direction, and it is
provided in the second portion 21.
[0046] The support ring 3 is formed of metal, and it is disposed on
a reverse-face side of the seal rings 1. The support ring 3
comprises a first portion 24 and a second portion 25. The first
portion 24 engages with the first portion 20 of the seal ring 1,
the second portion 25 engages with the second portion 21 of the
seal ring 1, and an inner surface of the pendulous peripheral wall
22 of the seal ring 1 engages with an end surface of the support
ring 3. Thus, the aforementioned portions are unitized with the
seal ring 1.
[0047] The load seal ring 2 is formed of, for example, NBR having
the hardness of about Hs 90. The load seal ring 2 is formed of a
ring body that has a substantially trapezoidal cross section in
which a circumferential groove 27 is provided on an outer
peripheral surface 26. Specifically, cutout portions 29 and 29 are
provided on two end surfaces 28 and 28, respectively, in which the
axial-direction length of an inner peripheral surface 30 is less
than the axial-direction length of the outer peripheral surface 26.
Therefore, when an axial direction compressive force is exerted on
the load seal ring 2, the axial-direction length of the load seal
ring 2 is reduced. On the other hand, the outer peripheral surface
26 of the load seal ring 2 engages with an inner peripheral surface
of the first portion 24 of the support ring 3, and the end surface
28 of the load seal ring 2 engages with an inner surface of the
second portion 25 of the support ring 3.
[0048] In a free state shown in FIG. 1A, the axial-direction length
of the seal assembly S is larger than the dimension between the
bushings 12 and 13, and a ring body 31 is provided between the
bushings 12 and 13. In this case, the outer diameter of the ring
body 31 is arranged to be substantially the same as the inner
diameter of the aforementioned load seal ring 2. Thereby, the ring
body 31 controls the displacement of the load seal ring 2 in the
periphery inner direction, and controls the reduction in the
dimension between the bushings 12 and 13.
[0049] In the free state, the seal assembly S configured as
described above is greater than the dimension between the bushings
12 and 13. Therefore, as shown in FIG. 1B, when seal assembly S is
disposed between the bushings 12 and 13, it receives an
axial-direction compressive force. When the seal assembly S
receives the axial-direction compressive force, the axial-direction
length of the load seal ring 2 is reduced. In this case, the ring
body 31 functions as an inner-diameter controller body 33 for
controlling the displacement of the load seal ring 2 in the
periphery inner direction. In addition, the first portion 24 of the
load seal ring 2 functions as an outer-diameter controller body 32
for controlling the displacement of load seal ring 2 in the
periphery outer direction. This ensures that reaction forces are
exerted on the lip portions 23 and 23 outwardly in the axial
direction from the load seal ring 2.
[0050] As described above, when the load seal ring 2 is compressed
in the axial direction, the reaction forces can be obtained.
According to the reaction force, the lip portion 23 of the first
seal ring 1 (which hereinbelow will refer to the seal ring 1 on the
side of the bushing 12) is press-engaged with the end surface (that
is, the radial-direction wall W) of the bushing 12. Concurrently,
the lip portion 23 of the second seal ring 1 (which hereinbelow
will refer to the seal ring 1 on the side of the bushing 13) is
press-engaged with the end surface (that is, the radial-direction
wall W) of the bushing 32. Thereby, an inner-diameter side and an
outer-diameter side of the lip portion 23,23 can be hermetically
enclosed to allow a seal function to be implemented. Therefore, use
of the seal assembly S avoids the necessity of the provision of
walls for receiving the outer peripheral side and the space portion
94. In addition, the use of the seal assembly S avoids the
necessity of the conventionally required space portions 94 (shown
in FIG. 6) provided to insert the seal assembly S. Thereby, the
crawler-track connection structure can be simplified and
furthermore, the seal assembly S need not be inserted Into the
housings 94. This allows the efficiency In assembly to be improved.
In addition, the seal assembly S is formed to have the cross
section symmetric with respect to the radial-direction line passing
the center of the assembly. Therefore, the obverse side and the
reverse side of the seal assembly S are the same. This provides an
advantage in that the seal assembly S can be easily inserted.
Furthermore, since only one type of pair of components, such as the
seal rings 1 and 1 or the support rings 3 and 3, may be formed, the
manufacturing cost can thereby be reduced. In the above, there is
still another advantage In that since the load seal ring 2 is also
formed symmetric with respect to the aforementioned
radial-direction line, the manufacture thereof is facilitated.
[0051] As shown in FIG. 2, in the above-described crawler-track
connection structure, the conventional seal assembly Sa is inserted
between the connecting portions 6 and 7 of the links 5 and 5 in the
manner described above. The seal assembly Sa comprises the seal
ring 98 having the lip portion 97, the support ring 99 for
supporting the seal ring 98, and the load ring 100 for receiving a
pressure from the lip portion 97 of the seal ring 98. More
specifically, with the pin insertion opening 10, the opening
portion on the busing side is used as a large-diameter portion, a
space portion (housing) 34 is formed using the large-diameter
portion 35, the end surface of the bushing 12, and the outer
peripheral face 19 of the pin 8. Therefor, the seal assembly Sa
prevents overflow of the lubricant from the side of the outer
peripheral face 19 of the pin 8 to the outside between the links 5
and 5, which are connected together. In addition, a spacer 36 to be
fitted around the pin 8 is disposed on the inner-diameter side of
the load ring 100.
[0052] In the crawler-track connection structure shown in FIG. 2,
since the outer peripheral side of the seal assembly S is in an
open state, mud, muddy water, dust, and the like can enter the seal
assembly S through the outer peripheral side. To prevent the
entrance, as shown in FIG. 3, it is preferable that a dust seal
ring 37 be disposed. The dust seal ring 37 is formed of a ring body
having a cross section substantially shaped as an irregular
rectangle. In addition, the dust seal ring 37 has lip portions 38
and 38 on two end surfaces, and is provided between a connecting
portion 7 of a link 5 and a bushing 13. This configuration securely
prevents the entrance of dust and the like from the outside.
Furthermore, the above configuration prevents overflow of the
lubricant and the like from the interior of the seal assembly S to
the outside.
[0053] FIGS. 4A and 4B show another embodiment of a seal assembly.
This embodiment is different from the above-described embodiment in
that a pair of seal ring 1 and 1 are shaped different from each
other. Specifically, one of the seal rings 1 and 1 (which
hereinbelow will be referred to as a first seal ring 1) is formed
of a ring body having a cross section substantially shaped as a
trapezoid. A first support ring 3 for supporting the first seal
ring 1 comprises a first portion 40 and a second portion 41. The
first portion 40 is disposed in an inner-diameter side and extends
in the axial direction, and the second portion 41 extends outwardly
in the radial direction from an axial-direction outer end portion
of the first portion 40. The second portion 41 is buried in the
first seal ring 1. On the other hand, the other-seal ring 1 (which
hereinbelow will be referred to as a second seal ring 1) comprises
a first portion 42 and a second portion 43. The first portion 42 is
disposed in an outer-diameter side, and extends in the axial
direction. The second portion 43 extends outwardly in the radial
direction from an axial-direction outer end portion of the first
portion 42, and a lip portion 23 is provided in the second portion
43. A second support ring 3 for receiving the second seal ring 1
comprises a first portion 44 and a second portion 45. The first
portion 44 is disposed in an outer-diameter side, and extends in
the axial direction. The second portion 45 extends inwardly in the
radial direction from an axial-direction outer end portion of the
first portion 44. The second portion 45 is buried in the second
portion 43 of the second seal ring 1.
[0054] In a load seal ring 2, a cutout portion 46 is formed on the
side of the first seal ring 1 of an outer peripheral surface 26,
and a cutout portion 47 is formed on the side of the second seal
ring 1 of an inner peripheral surface 30. In addition, when the
load seal ring 2 is provided, the outer peripheral surface 26
engages with an inner peripheral surface of the first portion 44 of
the second support ring 3, an outer end surface 48 (a surface
corresponding to the second seal ring 1) thereof engages with an
inner surface of the second portion 43 of the second seal ring 1,
the inner peripheral surface 30 thereof engages with an outer
peripheral surface of the first portion 40 of the first support
ring 3, and an outer end surface 49 (a surface corresponding to the
first seal ring 1) thereof engages with an inner surface of the
first seal ring 1.
[0055] Also in this case, the axial-direction length in a free
state is larger than the length between the bushings 12 and 13, and
as shown in FIG. 4B, the seal assembly S is disposed between the
bushings 12 and 13. In thin case, the aforementioned cutout
portions 46 and 47 are used as circumferential grooves 27 and 27
each tolerating axial-direction compression of the load seal ring
2, and the axial-direction length of the seal assembly S is thereby
reduced. Concurrently, the first portion 40 of the first support
ring 3 receives the load seal ring 2 from the Inner-diameter side,
and the first portion 44 of the second support ring 3 receives the
load seal ring 2 from the outer-diameter side. Thereby, the outer
end surface 49 functions as an inner-diameter controller body 33
for controlling the displacement of the load seal ring 2 in the
periphery inner direction. In addition, the first portion 44 of the
load seal ring 2 functions as an outer-diameter controller body 32
for controlling the displacement of load seal ring 2 in the
periphery outer direction. Accordingly, the displacement of the
load seal ring 2 in the radial direction is controlled, reaction
forces are exerted on the lip portions 23 and 23 outwardly in the
axial direction, and the lip portions 23 and 23 closely contact the
bushings 12 and 13, respectively. Thereby, a high-precision seal
function can be implemented.
[0056] FIGS. 5A and 5B show a still another embodiment of a seal
assembly. In this case, each of seal rings 1 and 1 is formed of a
ring body having a cross section substantially shaped as a
trapezoid, and a corner portion on an outer side thereof in the
axial direction is used as a lip portion 23. A support ring 3,3 is
formed of a first portion 51 and a second portion 52. In an
inner-diameter side, the first portion 51 extends in the axial
direction, and the second portion 52 extends in the radial
direction from an outer end portion of the first portion 51. In
this case, the second portion 52 expands outwardly in the axial
direction; and it is formed of an inner diameter portion 52a, an
intermediate portion 52b, and an outer diameter portion 52c, and is
buried in the seal ring 1. Specifically, although the intermediate
portion 52b and the outer diameter portion 52c are completely
buried therein, an inner surface of the inner diameter portion 52a
is exposed to the outside. When .theta..sub.1 represents the
expansion angle of the inner diameter portion 52a, .theta..sub.2
represents the expansion angle of the inner diameter portion 52b,
and .theta..sub.3 represents the expansion angle of the inner
diameter portion 52c, the relationship thereof is
.theta..sub.2<.theta..sub.1<.theta..sub.3. However, the
relationship is not restricted thereto.
[0057] In the present embodiment, a load seal ring 2 is formed of a
ring body having a cross section substantially shaped as a letter V
turned upside down. A circumferential groove 27 is formed on an
inner peripheral surface 30. Two end surfaces are each formed of an
inner-diameter-side slanting surface 53 and an outer-diameter-side
slanting surface 54. The diameter of the inner-diameter-side
slanting surface 53 increases along the direction of an
outer-diameter side, whereas the diameter of the
outer-diameter-side slanting surface 54 decreases along the
direction of an outer-diameter side. An inner peripheral surface 30
of the load seal ring 2 engages with an outer peripheral surface of
a first portion 51 of a support ring 3, and the inner-diameter-side
slanting surface 53 engages with the inner diameter portion 52a of
the support ring 3 or an inner surface of the seal ring 1.
[0058] A dust seal ring 37 is disposed on an outer-diameter side of
the load seal ring 2. In this case, a core member 55 is buried in
the dust seal ring 37. Specifically, the dust seal ring 37 is used
to form an outer-diameter controller body 32 for controlling the
displacement of load seal ring 2 in the direction of the
outer-diameter side.
[0059] Also in this case, the axial-direction length in a free
state is larger than the length between the bushings 12 and 13, and
as shown in FIG. 5B, the seal assembly S is disposed between the
bushings 12 and 13. In this case, since the circumferential groove
27 is provided, the load seal ring 2 tolerates compression in the
axial direction of the load seal ring 2, and the axial-direction
length of the seal assembly S is thereby reduced. Concurrently, the
first portion 51 of the first support ring 3 functions as an
inner-diameter controller body 33 for controlling the displacement
of the load seal ring 2 in the direction of the inner-diameter
side. In addition, the dust seal ring 37 functions as an
outer-diameter controller body 32 for controlling the displacement
of the load seal ring 2 in the direction of the outer-diameter
direction. Accordingly, the displacement of the load seal ring 2 in
the radial direction is controlled, reaction forces are exerted on
the lip portions 23 and 23 outwardly in the axial direction, and
the lip portions 23 and 23 closely contact the bushings 12 and 13,
respectively. Thereby, a high-precision seal function can be
implemented. Furthermore, the above-described structure securely
prevents the entrance of dust and the like from the outside.
[0060] As above, while the present invention has been described
with reference to the practical embodiments of the seal assembly,
the invention is not limited thereto. On the contrary, the
invention may be implemented with various modifications within the
spirit and scope of the invention. For example, in the embodiment
of the seal assembly shown in FIGS. 1A and 1B, the cross section of
the circumferential groove 27 is not limited to be semicircular,
but may be modified to have various other shapes, for example, a
semielliptical or semi-lengthen-circular shape, a V shape, and a
rectangular shape. This may also be applied to the shape of the
circumferential groove 27 of the seal assembly shown in FIGS. 5A
and 5B. In addition, in the seal assembly shown in FIGS. 4A and 4B,
the diameter of the seal ring 1 on the side of the bushing 13 is
relatively large, and the seal ring 1 on the side of the bushing 12
is relatively small. However, the relationship of the diameters may
be reverse. That is, the diameter of the seal ring 1 on the side of
the bushing 13 may be relatively small, and the seal ring 1 on the
side of the bushing 12 may be relatively large. Furthermore, in the
crawler-track connection structure shown in FIG. 2, the seal
assembly S may be used instead of the seal assembly Sa disposed in
the housing 34.
* * * * *