U.S. patent application number 13/464666 was filed with the patent office on 2012-08-30 for oil seal.
This patent application is currently assigned to Arai Seisakusho Co., Ltd.. Invention is credited to Tetsuya Ishikawa, Masaki Sohda, Takao Suzuki, Sinichi Tamura, Takashi Umeki.
Application Number | 20120217707 13/464666 |
Document ID | / |
Family ID | 38437360 |
Filed Date | 2012-08-30 |
United States Patent
Application |
20120217707 |
Kind Code |
A1 |
Suzuki; Takao ; et
al. |
August 30, 2012 |
OIL SEAL
Abstract
An oil seal (1A) has an outer member (2) fitted to a crankcase
(100), an inner member (3) integrally rotatably fitted to a
crankshaft (101), and a first movable lip (4) disposed in the gap
(G1) formed by the outer member (2) and the inner member (3). The
first movable lip (4) is disposed such that it is not in contact
with the outer member (2) when rotation of the crankshaft (101) is
stopped and that it is displaced in the direction to approach the
outer member (2), coming into contact with the outer member (2) to
close the gap (G1).
Inventors: |
Suzuki; Takao; (Numazu-shi,
JP) ; Tamura; Sinichi; (Susono-shi, JP) ;
Sohda; Masaki; (Funabashi-shi, JP) ; Ishikawa;
Tetsuya; (Omitama-shi, JP) ; Umeki; Takashi;
(Tokyo-to, JP) |
Assignee: |
Arai Seisakusho Co., Ltd.
Toyota Jidosha Kabushiki Kaisha
|
Family ID: |
38437360 |
Appl. No.: |
13/464666 |
Filed: |
May 4, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12162009 |
Oct 30, 2008 |
8191900 |
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PCT/JP2007/053074 |
Feb 20, 2007 |
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13464666 |
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Current U.S.
Class: |
277/558 ;
277/549 |
Current CPC
Class: |
F16J 15/164 20130101;
F16J 15/3284 20130101; F16J 15/3264 20130101 |
Class at
Publication: |
277/558 ;
277/549 |
International
Class: |
F16J 15/40 20060101
F16J015/40; F16J 15/32 20060101 F16J015/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 21, 2006 |
JP |
2006-044085 |
Claims
1-13. (canceled)
14. An oil seal disposed between a stationary body and a rotation
body which is rotatably attached to the stationary body,
comprising: an outer member fitted to the stationary body; an inner
member which is integrally rotatably fitted to the rotation body
and is assembled together with the outer member such that a
prescribed gap is formed between the inner member and the outer
member; and a movable member which is disposed in the prescribed
gap, wherein the movable member is provided to the inner member
such that it is not in contact with the outer member when rotation
of the rotation body is stopped and that it is displaced in the
direction to approach the outer member, coming into contacts with
the outer member to close the prescribed gap as the rotational
speed of the rotation body increases, wherein the movable member
has a contact part which comes into contact with the outer member,
and is formed of material having lower friction coefficient than
that of other parts of thereof, the contact part has a low friction
region formed of the low friction material and an elastic region
formed of elastic material having lower stiffness than that of the
low friction material, and the low friction region and the elastic
region are disposed respectively on the contact part such that, as
the rotational speed of the rotation body increases, the movable
member changes from the state the low friction region of the
movable member is in contact with the outer member but the elastic
region of the movable member is not in contact with the outer
member to the state both the low friction region and the elastic
region of the movable member are in contact with the outer
member.
15. An oil seal disposed between a stationary body and a rotation
body which is rotatably attached to the stationary body,
comprising: an outer member fitted to the stationary body; an inner
member which is integrally rotatably fitted to the rotation body
and is assembled together with the outer member such that a
prescribed gap is formed between the inner member and the outer
member; and a movable member which is disposed in the prescribed
gap, wherein the movable member is provided to the inner member
such that it is not in contact with the outer member when rotation
of the rotation body is stopped and that it is displaced in the
direction to approach the outer member, coming into contacts with
the outer member to close the prescribed gap as the rotational
speed of the rotation body increases, wherein the movable member
has a contact part which comes into contact with the outer member,
and is formed of material having lower friction coefficient than
that of other parts of thereof, the outer member is provided with
an auxiliary elastic part which opposes to the contact part of the
movable member and is formed of elastic material having lower
stiffness than that of the constituent material of the outer
member, and the movable member is displaced such that the contact
part comes into contact with the auxiliary elastic part as the
rotational speed of the rotation body increases.
16. The oil seal according to claim 14, wherein the movable member
is provided with a pressure receiving part which receives pressure
in the internal space of the stationary body and urges the movable
member in the direction to approach.
17. The oil seal according to claim 16, wherein the pressure
receiving part comprises a skirt which comes into contact with the
outer member when the movable member comes into contact with the
outer member.
18. The oil seal according to claim 14, further comprising another
movable member which is disposed in the prescribed, gap, wherein
the another movable member is provided to the inner member such
that the another member is in contact with the outer member and the
prescribed gap is closed when rotation of the rotation body is
stopped, and the another movable member is disposed in the
direction to be separated from the outer member such that the
prescribed gap gets opened as the rotational speed of the rotation
body increases.
19. The oil seal according to claim 14, wherein a crankcase of an
internal combustion engine is provided as the stationary body, and
a crankshaft, of the internal combustion engine is provided as the
rotation body.
Description
TECHNICAL FIELD
[0001] The present invention relates to an oil seal disposed
between a stationary body and a rotation body which is rotatably
attached to the stationary body.
RELATED ART
[0002] Some oil seal which prevents leakage of fluid such as oil is
provided with a movable floating ring in a prescribed gap between a
rotation body and a stationary body, and is provided with a lip
seal which is in contact with the stationary body to close the
prescribed gap when rotation of the rotation body is stopped
(Patent document 1).
[0003] [Patent document 1] JP2004-A-132524
SUMMARY OF INVENTION
Problems to be Solved by the Invention
[0004] In the oil seal of Patent document 1, the lip seal is
displaced by centrifugal force in the direction to be separated
from the stationary body as the rotational speed of the rotation
body increases, the stationary body and the lip seal change from
the state they are in contact with each other to the state they are
not in contact with each other. Accordingly, frictional resistance
between the stationary body and the lip seal is reduced. However,
when the stationary body and the lip seal get in the state they are
not in contact with each other as the rotational speed of the
rotation body increases, leakage of oil may be provoked since the
gap closed by the lip seal is opened.
[0005] Thus, it is an object of the present invention to provide an
oil seal capable of preventing leakage of oil due to increase of
the rotational speed of a rotation body.
Means of Solving Problems
[0006] In order to solve the above problem, the oil seal according
to the present invention is an oil seal disposed between a
stationary body and a rotation body which is rotatably attached to
the stationary body; and includes an outer member fitted to the
stationary body; an inner member which is integrally rotatably
fitted to the rotation body and is assembled together with the
outer member such that a prescribed gap is formed between the inner
member and the outer member; and a movable member which is disposed
in the prescribed gap, wherein the movable member is provided to
the inner member such that it is not in contact with the outer
member when rotation of the rotation body is stopped and that it is
displaced in the direction to approach the outer member, coming
into contact with the outer member to close the prescribed gap as
the rotational speed of the rotation body increases.
[0007] According to this oil seal, the movable member that is not
in contact with the outer member when rotation of the rotation body
is stopped is displaced in the direction to approach the outer
member, and comes into contact with the outer member as the
rotational speed of the rotation body increases. Accordingly,
frictional resistance is reduced, since the outer member is not in
contact with the movable member until the movable member comes into
contact with the outer member. Since the prescribed gap is closed
after the movable member comes into contact with the outer member,
leakage of oil dues to the increase of the rotational speed of the
rotation body can be prevented reliably.
[0008] In the oil seal of the present invention, the movable member
may be provided with a pressure receiving part which receives
pressure in the internal space of the stationary body and urges the
movable member in the approaching direction. According to this
aspect, since the pressure receiving part receives pressure in the
internal space, the movable member is urged in the direction to
approach the outer member. Thus, sealing effect of the movable
member of closing the prescribed gap is improved, since the movable
member can be pressed against the outer member by using pressure in
the internal space. In this aspect, the pressure receiving part may
have a skirt which comes into contact with the outer member when
the movable member comes into contact with the outer member. In
this case, since the skirt facilitates the pressure receiving part
to receive pressure in the internal space, the movable member can
be pressed more strongly against the outer member. Furthermore, the
skirt also comes into contact with the outer member, when the
movable member comes into contact with the outer member.
Accordingly, the contact between the movable member and the outer
member becomes more tightly, and thus the sealing effect is
improved further.
[0009] In the oil seal of the present invention, the gap between
the movable member and the outer member may be provided such that
labyrinth seal able to suppress leakage of oil is formed between
the movable member and the outer member when the movable member is
not in contact with the outer member. According to this aspect,
even when the movable member is not in contact with the outer
member, leakage of oil is suppressed by the labyrinth seal which is
formed of the outer member and the movable member. Accordingly,
leakage of oil can be prevented effectively over the speed range
from a low rotational speed of the rotation body before the
prescribed gap is closed by the movable member to a high rotational
speed of the rotation body after the prescribed gap is closed by
the movable member, without increasing number of parts.
[0010] In the oil seal of the present invention, the oil seal of
the present invention may further include another movable member
which is disposed in the prescribed gap, wherein the another
movable member is provided to the inner member such that the
another movable member is in contact with the outer member and the
prescribed gap is closed when rotation of the rotation body is
stopped, and the another movable member is displaced in the
direction to be separated from the outer member such that the
prescribed gap gets opened as the rotational speed of the rotation
body increases. According to this aspect, by properly setting the
displacement characteristics of the two movable members,
respectively, the characteristics of the oil seal can be flexibly
adjusted according to required characteristics.
[0011] In the oil seal of the present invention, a floating ring
which is movable in no contact with both the outer member and the
inner member may be disposed in the prescribed gap. According to
this embodiment, labyrinth seal can be formed easily without
setting the narrow width of the prescribed gap. Accordingly,
leakage of oil can be prevented effectively over the speed range
from a low rotational speed of the rotation body before the
prescribed gap is closed by the movable member to a high rotational
speed of the rotation body after the prescribed gap is closed by
the movable member, without increasing the frictional
resistance.
[0012] In the oil seal of the present invention, the movable member
may have a contact part which comes into contact with the outer
member; and the contact part may be formed of low friction material
having lower friction coefficient than that of the other parts
thereof. Furthermore, the outer member may have a contact part
which comes into contact with the movable member; and the contact
part may be formed of low friction material having lower friction
coefficient than that of other parts thereof. In these cases, the
resistance to pressure of the oil seal is improved, since the
movable member can be pressed more strongly against the outer
member while suppressing the increase of the frictional
resistance.
[0013] In a case that the movable member has such a contact part,
the contact part may have a low friction region formed of low
friction material and an elastic region formed of elastic material
having lower stiffness than that of the low friction material. The
low friction region and the elastic region may be disposed
respectively on the contact part such that, as the rotational speed
of the rotation body increases, the movable member changes from the
state the low friction region of the movable member is in contact
with the outer member but the elastic region of the movable member
is not in contact with the outer member to the state that both the
low friction region and the elastic region of the movable member
are in contact with the outer member. According to this aspect, the
frictional resistance between the outer member and the movable
member can be reduced when the outer member is in contact with the
low friction region but the outer member is not in contact with the
elastic region. Then, when the rotational speed of the rotation
body increase further than that state, pressure in the internal
space of the stationary body increases, however; sealing
characteristics is improved since the outer member is in contact
with both the low friction region and the elastic region.
Accordingly, leakage of oil can be reliably prevented, for example,
even when pressure in the internal space 100 becomes
extraordinarily high for any reason. At the same time, intrusion of
foreign matter from outside can be prevented, too.
[0014] Furthermore, the outer member may be provided with an
auxiliary elastic part which opposes to the contact part of the
movable member and may be formed of elastic material having lower
stiffness than that of the constituent material of the outer
member. The movable member may be displaced such that the contact
part comes into contact with the auxiliary elastic part as the
rotational speed of the rotation body increases. In this case,
sealing characteristics is improved when the movable member is in
contact with the outer member with the auxiliary elastic member
interposed therebetween, since the auxiliary elastic part is formed
of elastic material having lower stiffness than that of the
constituent material of the outer member. Furthermore, since the
auxiliary elastic part is provided to the stationary outer member,
the increase of the weight of the movable member can be avoided.
Thus, sealing characteristics can be improved while keeping the
response of the movable member.
[0015] In the oil seal of the present invention, the another
movable member may have a contact part which comes into contact
with the outer member, and the contact part may be formed of low
friction material having lower friction coefficient than that of
the other parts thereof. According to this aspect, the frictional
resistance between the another movable member and the outer member
can be reduced before the another movable member is separated from
the outer member.
[0016] In this aspect, the contact part may have a low friction
region formed of the low friction material and an elastic region
formed of the low friction material having lower stiffness than
that of the low friction material. The another movable member may
be provided to the inner member such that the outer member is in
contact with both the low friction region and the elastic region
when rotation of the rotation body is stopped. When the contact
part of the another movable member is fully formed of low friction
material, the reducing effect of friction is improved, however;
sealing characteristics is easily degraded due to the influence of
axial runout or the like at a low rotational speed before the
another movable member gets separated from the outer member, since
it is hard to be deformed. According to this aspect, since the
outer member is in contact with both the low friction region and
the elastic region before the another movable member gets separated
from the outer member, such degradation of the sealing
characteristics can be compensated, and frictional force can be
reduced further than the case when the contact part is fully formed
of elastic material.
[0017] In the oil seal of the present invention, a crankcase of an
internal combustion engine may be provided as the stationary body,
and a crankshaft of the internal combustion engine may be as the
rotation body. According to this aspect, since the movable member
is in contact with the outer member and the prescribed gap is
closed even when the internal pressure in the crankcase becomes
higher than atmospheric pressure due to the increase of load at a
high speed rotation of the crankshaft, leakage of oil and blow-by
gas in the crankcase can be reliably prevented
EFFECT OF INVENTION
[0018] As described above, according to the present invention, the
movable member, which is not in contact with the outer member when
rotation of the rotation body is stopped, is displaced in the
direction to approach the outer member and comes into contact with
the outer member as the rotational speed of the rotation body
increases. Since the prescribed gap is thus closed, leakage of oil
due to the increase of the rotational speed of the rotation body
can be prevented.
BRIEF DESCRIPTION OF DRAWINGS
[0019] [FIG. 1] FIG. 1 is a schematic cross-sectional view showing
a main part of an internal combustion engine to which an oil seal
according to the first embodiment of the present invention is
applied.
[0020] [FIG. 2] FIG. 2 is a view showing the oil seal of FIG. 1
when the crankshaft is in a rotating state.
[0021] [FIG. 3] FIG. 3 is a view showing the oil seal of FIG. 1
when the rotational speed of the crankshaft is faster than that in
FIG. 2.
[0022] [FIG. 4] FIG. 4 is a schematic cross-sectional view showing
a main part of an internal combustion engine to which an oil seal
according to the second embodiment of the present invention is
applied.
[0023] [FIG. 5] FIG. 5 is a view showing the oil seal of FIG. 4
when the crankshaft is rotating.
[0024] [FIG. 6] FIG. 6 is a schematic cross-sectional view showing
a main part of an internal combustion engine to which an oil seal
according to the third embodiment of the present invention is
applied.
[0025] [FIG. 7] FIG. 7 is a schematic cross-sectional view showing
a main part of an internal combustion engine to which an oil seal
according to the fourth embodiment of the present invention is
applied.
[0026] [FIG. 8] FIG. 8 is a schematic cross-sectional view showing
a main part of an internal combustion engine to which an oil seal
according to the fifth embodiment of the present invention is
applied.
[0027] [FIG. 9] Fig .9 is a view showing the oil seal of FIG. 8
when the crankshaft is rotating.
[0028] [FIG. 10] FIG. 10 is a schematic cross-sectional view
showing a main part of an internal combustion engine to which an
oil seal according to the sixth embodiment of the present invention
is applied.
[0029] [FIG. 11] FIG. 11 is a view showing the oil seal of FIG. 10
when the crankshaft is rotating.
[0030] [FIG. 12] FIG. 12 is a view showing the oil seal of FIG. 10
when the rotational speed of the crankshaft is faster than that in
FIG. 11.
[0031] [FIG. 13] FIG. 13 is a schematic cross-sectional view
showing a main part of an internal combustion engine to which an
oil seal according to the seventh embodiment of the present
invention is applied.
[0032] [FIG. 14] FIG. 14 is a view showing the oil seal of FIG. 13
when the crankshaft is rotating.
[0033] [FIG. 15] FIG. 15 is a schematic cross-sectional view
showing a main part of an internal combustion engine to which an
oil seal according to the eighth embodiment of the present
invention is applied.
[0034] [FIG. 16] FIG. 16 is a view showing the oil seal of FIG. 15
when the crankshaft is rotating.
[0035] [FIG. 17] FIG. 17 is a view showing the oil seal of FIG. 15
when the rotational speed of the crankshaft is faster than that in
FIG. 16.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0036] FIG. 1 is a schematic cross-sectional view showing a main
part of an internal combustion engine in which an oil seal
according to the first embodiment of the present invention is
installed. It is noted that only a half of a cross section will be
shown in FIG. 1 and other figures, since the oil seal according to
the present invention is axially symmetric with respect to the axis
CL. FIG. 1 shows a state of a crankshaft 101 when rotation is
stopped, and the crankshaft 101 is attached to a crankcase 100 in a
rotatable manner around the axis CL. The oil seal 1A is disposed
between the crankcase 100 and the crankshaft 101, wherein the
crankcase 100 serves as a stationary body and the crankshaft 101
serves as a rotation body. Namely, the oil seal 1A is fitted in an
annular gap formed between the crankcase 100 and the crankshaft
101. The oil seal 1A separates an atmospheric side AS outside the
crankcase 100 from a hermetically sealed side OS inside the
crankcase 100, thereby to prevent the leakage of fluid such as oil
and blow-by gas from the hermetically sealed side OS to the
atmospheric side AS and to prevent intrusion of foreign matter such
as dust from the atmospheric side AS to the hermetically sealed
side OS. The oil seal 1A has an annular outer member 2 provided
coaxially with the crankshaft 101 and an annular inner member 3,
respectively. The outer member 2 is fitted to the crankcase 100
with the oil seal retainer 103 interposed therebetween, whereas the
inner member 3 is integrally rotatably fitted to the crankshaft
101. The outer member 2 and the inner member 3 are assembled
together with a separation from each other, such that a gap G is
formed between them.
[0037] The outer member 2 has an outer cylinder 21 which is fixed
to the oil seal retainer 103 and extends in the direction of the
axis CL; and an inward flange 22 which extends radial inwardly from
the end of the outer cylinder 21 at the atmospheric side AS. The
inward flange 22 includes a vertical wall 22a which rises up radial
inwardly and substantial vertically with respect to the outer
cylinder 21; an inclined wall 22b which continues to the vertical
wall 22a and is inclined toward the hermetically sealed side OS;
and a side wall 22c which continues to the inclined wall 22b and
extends in the direction of the axis CL. On the other hand, the
inner member 3 has an internal cylinder 31 which is fixed to the
crankshaft 101 and extends in the direction of the axis CL; and an
outward flange 32 which extends radial outwardly from the end of
the internal cylinder 31 at the hermetically sealed side OS. The
outward flange 32 is disposed so as to oppose to the inward flange
22 of the outer member 2. Namely, the outward flange 32 includes a
vertical wall 32a which rises up radial outwardly and substantially
vertically with respect to the internal cylinder 31 and is
substantially parallel to the vertical wall 22a of the inward
flange 22; a side wall 32c which continues to the vertical wall 32a
and extends in the direction of the axis CL and is substantially
parallel to the side wall 22c of the inward flange 22; and an
inclined wall 32b which continues to the side wall 32c and extends
so as to be inclined toward the atmospheric side AS and is
substantially parallel to the inclined wall 22b of the inward
flange 22.
[0038] Among the gap G's formed between the outer member 2 and the
inner member 3, an annular first movable lip 4 which serves as a
movable member is disposed in the gap G1 formed between the side
wall 22c of the inward flange 22 and the internal cylinder 31 of
the inner member 3. The first movable lip 4 is formed of elastic
material such as rubber, and has a base end 4a attached to the end
of the internal cylinder 31 at the hermetically sealed side OS; a
middle part 4b which extends from the base end 4a toward the
atmospheric side AS; and a tip end 4c which is folded back radial
outwardly from the middle part 4b toward. An annular garter spring
7 which urges the first movable lip 4 radial inwardly is attached
to the tip end 4c. In the state shown in FIG. 1 that rotation is
stopped, the first movable lip 4 is kept in no contact with the
outer member 2, that is, in the state the gap G1 is opened by the
elastic force of the garter spring 7.
[0039] Furthermore, among the gap G's formed between the outer
member 2 and the inner member 3, an annular second movable lip 5
which serves as another movable member is disposed in the gap G2
formed between the side wall 22c of the inward flange 22 and the
side wall 32c of the outward flange 32. The second movable lip 5 is
formed of elastic material such as rubber in the same manner as the
first movable lip 4. The second movable lip 5 has a base end 5a
which is attached to at the boundary between the vertical wall 32a
of the outward flange 32 and the side wall 32c; a middle part 5b
which extends from the base end 5a toward the atmospheric side AS;
and a tip end 5c which is folded back radial inwardly from the
middle part 5b. An annular garter spring 8 for urging the second
movable lip 5 radial inwardly is attached to the tip end 5c. In the
state shown in FIG. 1 that rotation is stopped, the second movable
lip 5 is pressed against the outer member 2 by the elastic force of
the garter spring 8, and is kept in a state the gap G2 is closed by
the second movable lip 5.
[0040] Furthermore, among the gap G's formed between the outer
member 2 and the inner member 3, a floating ring 9 is disposed in
the gap G3 formed between the inclined wall 22b of the inward
flange 22 and the inclined wall 32b of the outward flange 3. The
floating ring 9 can move in the gap G3 in no contact with the outer
member 2 and the inner member 3, respectively, while the crankshaft
101 is rotating. Namely, the floating ring 9 is structured to
rotate concentrically with the inner member 3 at a slower speed
than the circumferential velocity of the inner member 3 while the
oil existing in the gap G3 is interposed between the floating ring
9 and the outer member 2 and between the floating ring 9 and the
inner member 3, respectively. By considering the width of the gap
G3, the thickness of the floating ring 9 is set such that labyrinth
seals are formed between the three members of the floating ring 9,
the outer member 2, and the inner member 3.
[0041] FIG. 2 and FIG. 3 show the oil seal 1A when the crankshaft
101 is in a rotating state; and FIG. 3 shows a state the rotational
speed of the crankshaft 101 is faster than that in the state of
FIG. 2. Since the inner member 3 rotates integrally with the
crankshaft 101 when the crankshaft 101 rotates, radial outwardly
oriented centrifugal force exerts on the first movable lip 4. The
centrifugal force increases in proportion to the rotational speed
of the crankshaft 101. Thus, along with the rotational speed of the
crankshaft 101 increases, the first movable lip 4 is displaced in
the direction to approach the outer member 2, and the first movable
lip 4 comes into contact with the outer member 2 as shown in FIG.
3. Accordingly, the gap G1 is closed by the first movable lip 4.
Such behavior of the first movable lip 4 according to the variation
in the rotational speed of the crankshaft 101 can be controlled
freely, for example, by setting the specification such as an outer
diameter and a spring constant of the garter spring 7 and the
constituent material of the first movable lip 4 properly. For
example, the first movable lip 4 can be structured so as to come
into contact with the outer member 2 at an arbitrary targeted
rotational speed of the crankshaft 101.
[0042] Furthermore, the radial outwardly oriented centrifugal force
exerts also on the second movable lip 5 disposed in the gap G2 due
to the rotation of the crankshaft 101. As a result of the increase
of the centrifugal force as the rotational speed of the crankshaft
101 increases, the force of pressing the second movable lip 5
against the outer member 2 decreases gradually. Then, the second
movable lip 5 is displaced in the direction of leaving from the
outer member 2 as shown in FIG. 2, so that the gap G2 is opened. In
the same manner as the first movable lip 4, the behavior of the
second movable lip 5 can also be structured such that the second
movable lip 5 is separated from the outer member 2 at an arbitrary
targeted rotational speed of the crankshaft 101, by setting the
specification such as an outer diameter and a spring constant of
the garter spring 8 and the constituent material of the second
movable lip 5 properly.
Second Embodiment
[0043] Next, the second embodiment of the present invention will be
described with h reference to FIG. 4 and FIG. 5. The oil seal 1B
according to the embodiment has the same structure as that of the
oil seal 1A of the first embodiment except for the structure of the
first movable lip 204 which serves as a movable member. In FIG. 4
and FIG. 5, the same components as in the first embodiment have the
same reference numbers. In the following, the duplicated
description with the first embodiment will be omitted.
[0044] The oil seal 1B has an annular first movable lip 204 formed
of elastic material such as rubber; and the first movable lip 204
includes a base end 204a attached to the internal cylinder 31 of
the inner member 3, a middle part 204b which extends from the base
end 204a toward the hermetically sealed side OS, and a tip end 204c
which is folded back radial outwardly from the middle part 204b. In
the oil seal 1B, when the first movable lip 204 is displaced in the
direction to approach the outer member 2 as the rotational speed of
the crankshaft 101 increases, the inner circumference surface 210
of the first movable lip 204 turns toward the hermetically sealed
side OS as shown in FIG. 5. When pressure in the internal space
100a of the crankcase 100 (pressure at the hermetically sealed side
OS) is higher than atmospheric pressure, the pressure exerts on the
inner circumference surface 210 of the first movable lip 204, so
that the first movable lip 204 receives the pressure and is urged
in the direction to approach the outer member 2. Thus, the sealing
effect of the first movable lip 204 is improved, since the first
movable lip 204 can be pressed against the outer member 2 by
utilizing the pressure in the internal space 100a. Accordingly, the
inner circumference surface 210 of the first movable lip 204 works
as the pressure receiving part of the present invention.
Third Embodiment
[0045] Next, the third embodiment of the present invention will be
described with reference to FIG. 6. The oil seal 1C according to
this embodiment is that of the second embodiment in which a skirt
11 is provided to the inner circumference surface 210 of the first
movable lip 204, and corresponds to a variation of the oil seal 1B.
In the following and in FIG. 6, the same components as in the
second embodiment have the same reference numbers, and the
duplicated description will be omitted. The skirt 11 of the oil
seal 10 extends from the first movable lip 204 toward the
hermetically sealed side OA. The skirt 11 is structured such that
the tip end thereof comes into contact with the outer member 2 when
the first movable lip 204 comes into contact with the outer member
2 as shown in FIG. 6 with the solid line. It is noted that when the
crankshaft 101 stops rotating, the first movable lip 204 is kept in
no contact with the outer member 2 as shown in FIG. 6 with broken
line. According to this embodiment, since it gets easy to receive
the pressure in the internal space 100a of the crankcase 100 when
the skirt 11 is provided, the first movable lip 204 can be pressed
more strongly against the outer member 2 by using the pressure.
Thus, the sealing effect of the first movable lip 204 is further
improved than in the second embodiment. In the oil seal 10, the
inner circumference surface 210 of the first movable lip 204 and
the skirt 11 work as the pressure receiving part of the present
invention.
Fourth Embodiment
[0046] Next, the fourth embodiment of the present invention will be
described with reference to FIG. 7. The oil seal 1D according to
this embodiment has an annular first movable lip 404 which is
formed of elastic material such as rubber. The first movable lip
404 has a base end 404a attached to the internal cylinder 31 of the
inner member 3, and is structured so as to extend from its base end
404a toward the hermetically sealed side OS. Unlike the
above-mentioned embodiments, no garter spring is attached to the
first movable lip 404 at its tip end. Namely, the first movable lip
404 is kept in no contact with the outer member 2 by its own
elastic force as shown in FIG. 7 with broken line, when the
crankshaft 101 stops rotating. Then, when the rotational speed of
the crankshaft 101 increases, the centrifugal force generated along
with the rotation overcomes the elastic force of the first movable
lip 404, and thus the first movable lip 404 is displaced in the
direction to approach the outer member 2 as shown in FIG. 7 with
the solid line, and comes into contact with the outer member 2.
Since the structure of the first movable lip 404 is more simplified
than those in the above-mentioned embodiments it can contribute to
the reduction of cost. The inner circumference surface 410 of the
first movable lip 404 of this embodiment turns toward the
hermetically sealed side OS, when the first movable lip 404 is
displaced in the direction to approach the outer member 2. Thus, in
the same manner as the second and the third embodiments, the inner
circumference surface 410 can press the first movable lip 404
against the outer member 2 by utilizing the pressure in the
internal space 100a of the crankcase 100; and the inner
circumference surface 410 works as the pressure receiving part of
the present invention. Nevertheless, the orientation along which
the first movable lip 404 extends may be opposite to that in FIG.
7. Namely, in the same manner as the first embodiment, it may be
structured so as to extend from the base end 404a toward the
atmospheric side AS.
Fifth Embodiment
[0047] Next, the fifth embodiment of the present invention will be
described with reference to FIG. 8 and FIG. 9. As shown in FIG. 8,
the oil seal 1E according to this embodiment has an annular outer
member 502 provided coaxially with the crankshaft 101 and an inner
member 503, respectively. The outer member 502 is fitted to the
crankcase 100 via the oil seal retainer 103, whereas the inner
member 503 is integrally rotatably fitted to the crankshaft 101. In
the same manner as the above-mentioned embodiments, the outer
member 502 and the inner member 503 are assembled together with a
separation from each other, such that a gap G is formed between
them.
[0048] The outer member 502 has an outer cylinder 521 which is
fixed to the oil seal retainer 103 and extends in the direction of
the axis CL; and an inward flange 522 which extends radial inwardly
from the end of the outer cylinder 521 at the atmospheric side AS.
The inward flange 522 includes an inclined wall 522a which is
inclined from the end of the outer cylinder 521 at the atmospheric
side AS toward the atmospheric side AS; a horizontal wall 522b
which continues to the inclined wall 522a and extends radial
inwardly; and a side wall 522c which continues to the horizontal
wall 522b and extends in the direction of the axis CL. On the other
hand, the inner member 503 has an internal cylinder 531 which is
fixed to the crankshaft 101 and extends in the direction of the
axis; and an outward flange 532 which extends radial outwardly from
the end of the internal cylinder 31 at the hermetically sealed side
OS. The outward flange 532 has an inclined wall 532a which is
inclined form the end of the internal cylinder 531 at the
hermetically sealed side OS toward the hermetically sealed side OS;
a horizontal wall 532b which continues to the inclined wall 532a
and extends radial outwardly; and a side wall 532c which continues
to the horizontal wall 532b and extends in the axial direction.
[0049] Among the gap G's formed between the outer member 502 and
the inner member 503, an annular first movable lip 504 which serves
as movable member is disposed in the gap G1 formed between the
inclined wall 522a of the inward flange 522 and the side wall 532c
of the outward flange 532. The first movable lip 504 is formed of
elastic material such as rubber, and has a base end 504a attached
to the end of the outward flange 532 of the side wall 532c at the
atmospheric side AS. The first movable lip 504 is structured so as
to extend from the base end 4a in substantially parallel to the
inclined wall 522a of the inward flange 522. In the same manner as
the fourth embodiment, no garter spring is attached to the tip end
of them. Accordingly, the first movable lip 504 is kept in no
contact with the outer member 502 by its own elastic force as shown
in FIG. 8, when the crankshaft 101 stops rotating. Then, when the
rotational speed of the crankshaft 101 increases, the centrifugal
force generated due to the rotation overcomes the elastic force of
the first movable lip 504, and thus the first movable lip 504 is
displaced in the direction to approach the outer member 502 and
comes into contact with the outer member 502 as shown in FIG. 9. In
the same manner as the second to the fourth embodiments, the inner
circumference surface 510 of the first movable lip 504 turns toward
the hermetically sealed side OS when the first movable lip 504 is
displaced in the direction to approach the outer member 502.
Accordingly, the inner circumference surface 510 of the first
movable lip 504 receives the pressure in the internal space 100a of
the crankcase 100, and can urge the first movable lip 504 in the
direction to approach the outer member 502. Thus, the inner
circumference surface 510 of the movable lip 504 works as the
pressure receiving part of the present invention.
[0050] Among the gap G's formed between the outer member 502 and
the inner member 503, an annular second movable lip 505 which
serves as another movable member is disposed in the gap G2 formed
between the side wall 522c of the inward flange 522 and the side
wall 532c of the outward flange 532. The second movable lip 505 has
the same structure as that of the second movable lip of each of the
above-mentioned embodiments. When the crankshaft 101 stops
rotating, the second movable lip 505 is pressed against the outer
member 502 by the elastic force of the garter spring 8 and is kept
in a state the gap G2 is closed by the second movable lip 505 as
shown in FIG. 8. Then, when the rotational speed of the crankshaft
101 increases, the second movable lip 505 is displaced by the
centrifugal force generated due to the rotation in the direction of
leaving from the outer member 502 as shown in FIG. 9, so that the
gap G2 is opened.
[0051] In this embodiment, the contact part 12 on which the first
movable lip 504 comes into contact with the outer member 502 is
formed of low friction material having lower friction coefficient
than that of other parts thereof (the first movable lip 504). As
the low friction material, for example, fluorine resin such as
polytetrafluoroethylene (PTFE) and diamond like carbon (DLC) can be
used. Accordingly, since the frictional resistance due to the
contact is reduced when the outer member 502 is in contact with the
first movable lip 505, leakage of oil can be reliably prevented
while suppressing the increase of loss of torque. The contact part
13 of the second movable lip 505 is also formed of low friction
material in a same way. Furthermore, the outer member 502 which is
in contact with the first movable lip 504 and the second movable
lip 505 can be formed of the above-mentioned low friction material.
Namely, the contact part of the outer member 502 which is contact
with the first movable lip 504 or the second movable lip 505 may be
formed of the low friction material. It is noted that the contact
part of the movable lip according to any of the above-mentioned
embodiments can be formed of the above-mentioned low friction
material.
[0052] Furthermore, in this embodiment, the gap g between the first
movable lip 504 and the outer member 2 is set such that a labyrinth
seal capable of suppressing leakage of oil is formed between the
first movable lip 504 and the outer member 2 when the first movable
lip 504 and outer member 2 are not in contact with each other. The
width of the gap g is set properly according to the pressure which
can be generated in the internal space 100a of the crankcase 100.
Thus, even when the first movable lip 504 is not in contact with
the outer member 502, leakage of oil is suppressed by the labyrinth
seal formed by the outer member 502 and the first movable lip 504.
Accordingly, in the same manner as the above-mentioned embodiments,
leakage of oil can be prevented effectively over the speed range
from a low rotational speed of the crankshaft 101 before the gap G1
is closed by the first movable lip 504 to the high rotational speed
of the crankshaft 101 after the gap G1 is closed by the first
movable lip 504 without providing with a separate part such as a
floating ring and without increasing number of parts.
Sixth Embodiment
[0053] Next, the sixth embodiment of the present invention will be
described with reference to FIG. 10 to FIG. 12. The sixth
embodiment corresponds to a variation of the fifth embodiment. The
common parts between the sixth embodiment and the fifth embodiment
have the same reference numbers in these figures; and the
duplicated description will be omitted. As shown in these figures,
the oil seal 1F includes a first movable lip 604, which serves as a
movable member and has a contact part 14 that comes into contact
with the outer member 502. The contact part 14 of the first movable
lip 604 has a low friction region 14a formed of the above-mentioned
low friction material having lower friction coefficient than that
of the other parts thereof; and an elastic region 14b formed of
elastic material having lower stiffness than that of the low
friction material. The low friction region 14a is disposed at the
tip end side of the first movable lip 604, whereas the elastic
region 14b is disposed at the side of a base end 604a of the first
movable lip 604, these regions are adjacent to each other. The
elastic region 14b has lower stiffness than the low friction region
14a and is deformed easily. Thus, when the elastic region 14b is in
contact with the outer member 502, the sealing characteristics is
better than when the low friction region 14a is in contact with the
outer member 502. It is noted that the rubber made from polyamide
or the like is suited for the elastic material.
[0054] When the rotational speed of the crank shaft 101 increases,
the oil seal 1F changes from the state of FIG. 10 to the state of
FIG. 11. In the state of FIG. 11, the first movable lip 604 is
displaced to a position where the outer member 502 is in contact
with the low friction region 14a of the contact part 14 but the
outer member 502 is not in contact with the elastic region 14b of
the contact part 14. Then, when the rotational speed of the crank
shaft 101 increases further from the state of FIG. 11, the movable
lip 604 is displaced to a position where the outer member 502 is in
contact with both the low friction region 14a and the elastic
region 14b as shown in FIG. 12.
[0055] According to this embodiment, resistance to friction can be
reduced when the low friction region 14a is in contact with the
outer member 502 in the state of FIG. 11. When the rotational speed
of the crank shaft 101 increases further than that of FIG. 11, the
pressure in the internal space 100a of the crankcase 100 increases,
however; sealing characteristics is improved since the outer member
502 is in contact with both the low friction region 14a and the
elastic region 14b as shown in FIG. 12. Thus, leakage of oil can be
reliably prevented, for example, even when the pressure in the
internal space 100a of the crankcase 100 becomes extraordinarily
high for any reason. At the same time, intrusion of foreign matter
from outside can also be prevented. It is noted that the inner
circumference surface 610 of the first movable lip 604 also serves
as the pressure receiving part of the present invention.
Seventh Embodiment
[0056] Next, the seventh embodiment of the present invention will
be described with reference to FIG. 13 and FIG. 14. The seventh
embodiment corresponds to a variation of the fifth embodiment. The
common parts between the seventh embodiment and the fifth
embodiment have the same reference number in these figures; and the
duplicated description will be omitted. As shown in these figures,
the oil seal 1G has a second movable lip 705 which serves as
another movable member having a contact part 15 which comes into
contact with the outer member 502. The contact part 15 of the
second movable lip 705 has a low friction region 15a formed of the
above-mentioned low friction material having lower friction
coefficient than the other parts of the second movable lip 705 and
an elastic region 15b formed of elastic material having lower
stiffness than that of the low friction material. These regions are
placed side-by-side. Before the second movable lip 705 is separated
from the outer member 502 as shown in FIG. 13, for example, when
the crank shaft 101 stops rotating, the second movable lip 705 is
provided to the inner member 503 such that the outer member 502 is
in contact with both the low friction region 15a and the elastic
region 15b. When the rotational speed of the crank shaft 101
increases, the second movable lip 705 gets in a separated state
from the outer member 502 as shown in FIG. 14.
[0057] Since the variation in torque is large and axial runout is
also large at a low rotational speed before the second movable lip
705 is separated from the outer member 502 or when rotation is
stopped, the second movable lip 705 is easily separated from the
outer member 502. When the contact part 15 is fully formed of low
friction material, the reducing effect of friction is improved,
however; their sealing characteristics are easily degraded at a low
rotational speed when axial runout or the like tends to occur. In
this embodiment, since the outer member 502 contacts with both the
low friction region 15a and the elastic region 15b, the degradation
of the sealing characteristics can be compensated and the
frictional force can be reduced further than the case when the
contact part 15 is fully formed of elastic material. It is noted
that this embodiment can be embodied in combination with the sixth
embodiment shown in FIG. 10.
Eighth Embodiment
[0058] Next, the eighth embodiment of the present invention will be
described with reference to FIG. 15 to FIG. 17. The eighth
embodiment corresponds to a variation of the fifth embodiment. The
common parts between the seventh embodiment and the fifth
embodiment have the same reference numbers in these figures; and
the duplicated description will be omitted. As shown in these
figures, the outer member 502 of the oil seal 1H is provided with
an auxiliary elastic part 16 which opposed to the contact part 12
of the first movable lip 504. The auxiliary elastic part 16 is
formed in an annular shape and is formed of elastic material having
lower stiffness than that of the constituent material of the outer
member 502. In order to contact with the first movable lip 504 more
tightly, the elastic member 16 is structured in a form having a
wedge shape cross section such that it becomes gradually thinner
toward radial outwardly. Since the auxiliary elastic part 16 is
formed of elastic material having lower stiffness than that of the
constituent material of the outer member 502, the sealing
characteristics are improved further in a case when it contacts
with the outer member 502 with the auxiliary elastic member 16
interposed than the case when the contact part 12 contacts with the
outer member 502 itself.
[0059] When the rotational speed of the crank shaft 101 increases,
the oil seal 1H changes from the state of FIG. 15 to the state of
FIG. 116. In the state of FIG. 15, the first movable lip 504 is
displaced to a position where the outer member 502 is contact with
the contact part 12 but the outer member 502 is not contact with
the auxiliary elastic part 16. Then, when the rotational speed of
the crank shaft 101 increases further from the state of FIG. 16,
the movable lip 504 is displaced to the position where the contact
part 12 contact with the auxiliary elastic part 16 as shown in FIG.
17.
[0060] In this embodiment, frictional resistance can be reduced,
when the contact part 12 contact with the outer member 502 in the
state of FIG. 16. When the rotational speed of the crank shaft 101
increases further than the state of FIG. 16, the pressure in the
internal space 100a of the crankcase 100 increase, however; since
the contact part 12 is in contact with the auxiliary elastic part
16 as shown in FIG. 17, the sealing characteristics is improved.
Accordingly, even when the pressure in the internal space 100a of
the crankcase 100 becomes extraordinarily high for any reason, for
example, leakage of oil can be reliably prevented. At the same
time, intrusion of foreign matter from outside can be prevented,
too. Furthermore, since the auxiliary elastic part 16 is provided
to the stationary outer member 502, increase of the weight of the
first movable lip 504 can be avoided. Thus, the sealing
characteristics can be improved while keeping the response of the
first movable lip 504. It is noted that this embodiment can be
embodied in combination with the sixth embodiment shown in FIG. 10
or the seventh embodiment shown in FIG. 13. Furthermore in this
embodiment, the auxiliary elastic part 16 may be disposed such that
the contact part 12 comes into contact with the auxiliary elastic
part 16 without going through the state of FIG. 17 when the first
movable lip 504 is displaced as the rotational speed of the crank
shaft 101 increases.
[0061] The present invention is not limited to the above-mentioned
embodiments; and it can be embodied in various forms within the
spirit and scope of the present invention. For example, the oil
seal according to the present invention can be also applied to
various pumps in addition to the internal combustion engine. In a
case that the oil seal according to the present invention is
applied to a pump, the oil seal according to the present invention
may be disposed between a pump housing which serves as the
stationary body and a pump shaft rotatable attached to the pump
housing.
[0062] Furthermore, the second movable lip is not an essential part
in the above embodiments; and the present invention may be embodied
in an embodiment in which the second movable lip is omitted. Even
in this case, the first movable lip comes into contact with the
outer member as the rotational speed of the rotation body
increases, so that the gap is closed, leakage of oil along with the
increase of rotational speed of the rotation body can be
prevented.
* * * * *