U.S. patent application number 14/764858 was filed with the patent office on 2015-12-17 for sealing device.
This patent application is currently assigned to NOK CORPORATION. The applicant listed for this patent is NOK CORPORATION. Invention is credited to Kazunari SEKI, Koji WATANABE.
Application Number | 20150362074 14/764858 |
Document ID | / |
Family ID | 51391291 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150362074 |
Kind Code |
A1 |
SEKI; Kazunari ; et
al. |
December 17, 2015 |
SEALING DEVICE
Abstract
Provided is a sealing device that is capable of exhibiting a
sealing function even in a condition in which a fluid pressure is
low while suppressing its sliding torque. A sealing device 100 is
characterized by including: a seal ring 200 made of resin which is
in close contact with a side wall surface on a low pressure side of
an annular groove 410, and slides against an inner peripheral
surface of a shaft hole in a housing 500 through which a shaft 400
is inserted; and a metal spring 300 which is provided along an
inner peripheral surface of the seal ring 200 in a state in which a
gap is formed between the metal spring 300 and a groove bottom
surface of the annular groove 410, and presses the seal ring 200
toward an outer peripheral surface side, wherein a concave portion
220 is formed on an outer peripheral surface of the seal ring 200
which extends from an end portion on a high pressure side of the
outer peripheral surface to a position which does not reach an end
portion on a low pressure side of the outer peripheral surface, and
introduces a fluid from the high pressure side.
Inventors: |
SEKI; Kazunari;
(Kitaibaraki-shi, JP) ; WATANABE; Koji;
(Kitaibaraki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NOK CORPORATION |
Minato-ku, Tokyo |
|
JP |
|
|
Assignee: |
NOK CORPORATION
Tokyo
JP
|
Family ID: |
51391291 |
Appl. No.: |
14/764858 |
Filed: |
February 19, 2014 |
PCT Filed: |
February 19, 2014 |
PCT NO: |
PCT/JP2014/053938 |
371 Date: |
July 30, 2015 |
Current U.S.
Class: |
277/512 |
Current CPC
Class: |
F16J 15/441 20130101;
F16J 15/164 20130101; F16J 15/24 20130101 |
International
Class: |
F16J 15/24 20060101
F16J015/24; F16J 15/16 20060101 F16J015/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2013 |
JP |
2013-031085 |
Apr 18, 2013 |
JP |
2013-087087 |
Aug 23, 2013 |
JP |
2013-173512 |
Claims
1. A sealing device which is attached to an annular groove provided
on an outer periphery of a shaft and holds a fluid pressure in a
sealing target area by sealing an annular gap between the shaft and
a housing rotating relative to each other, the sealing target area
being configured such that the fluid pressure changes, the sealing
device comprising: a seal ring made of resin which is in close
contact with a side wall surface on a low pressure side of the
annular groove, and slides against an inner peripheral surface of a
shaft hole in the housing through which the shaft is inserted; and
a metal spring which is provided along an inner peripheral surface
of the seal ring in a state in which a gap is formed between the
metal spring and a groove bottom surface of the annular groove, and
presses the seal ring toward an outer peripheral surface side,
wherein a concave portion is formed on an outer peripheral surface
of the seal ring which extends from an end portion on a high
pressure side of the outer peripheral surface to a position which
does not reach an end portion on a low pressure side of the outer
peripheral surface, and introduces a fluid from the high pressure
side.
2. The sealing device according to claim 1, wherein a plurality of
the concave portions are formed at intervals in a circumferential
direction.
3. The sealing device according to claim 1, wherein a guide portion
which positions the metal spring in an axial direction is formed on
the inner peripheral surface of the seal ring.
4. A sealing device which is attached to an annular groove provided
on an outer periphery of a shaft and holds a fluid pressure in a
sealing target area by sealing an annular gap between the shaft and
a housing rotating relative to each other, the sealing target area
being configured such that the fluid pressure changes, the sealing
device comprising: a seal ring made of resin which is in close
contact with a side wall surface on a low pressure side of the
annular groove, and slides against an inner peripheral surface of a
shaft hole in the housing through which the shaft is inserted; and
a metal spring which is provided along an inner peripheral surface
of the seal ring in a state in which a gap is formed between the
metal spring and a groove bottom surface of the annular groove, and
presses the seal ring toward an outer peripheral surface side,
wherein a concave portion is formed on an outer peripheral surface
of the seal ring which extends from an end portion on a high
pressure side of the outer peripheral surface to a position which
does not reach an end portion on a low pressure side of the outer
peripheral surface, and introduces a fluid from the high pressure
side, and a guide portion which positions the metal spring in an
axial direction is formed on the inner peripheral surface of the
seal ring, and a protrusion which prevents the metal spring from
being detached to an inner peripheral surface side is provided at a
tip of the guide portion.
5. A sealing device which is attached to an annular groove provided
on an outer periphery of a shaft and holds a fluid pressure in a
sealing target area by sealing an annular gap between the shaft and
a housing rotating relative to each other, the sealing target area
being configured such that the fluid pressure changes, the sealing
device comprising: a seal ring made of resin which is in close
contact with a side wall surface on a low pressure side of the
annular groove, and slides against an inner peripheral surface of a
shaft hole in the housing through which the shaft is inserted; and
a metal spring which is provided along an inner peripheral surface
of the seal ring in a state in which a gap is formed between the
metal spring and a groove bottom surface of the annular groove, and
presses the seal ring toward an outer peripheral surface side,
wherein a concave portion is formed on an outer peripheral surface
of the seal ring which extends from an end portion on a high
pressure side of the outer peripheral surface to a position which
does not reach an end portion on a low pressure side of the outer
peripheral surface, and introduces a fluid from the high pressure
side, and an abutment portion is provided at one position on the
seal ring in a circumferential direction, and protrusions which
restrict a movement of the metal spring in the circumferential
direction are provided on the inner peripheral surface on both
sides of the abutment portion.
6. A sealing device which is attached to an annular groove provided
on an outer periphery of a shaft and holds a fluid pressure in a
sealing target area by sealing an annular gap between the shaft and
a housing rotating relative to each other, the sealing target area
being configured such that the fluid pressure changes, the sealing
device comprising: a seal ring made of resin which is in close
contact with a side wall surface on a low pressure side of the
annular groove, and slides against an inner peripheral surface of a
shaft hole in the housing through which the shaft is inserted; and
a metal spring which is provided along an inner peripheral surface
of the seal ring in a state in which a gap is formed between the
metal spring and a groove bottom surface of the annular groove, and
presses the seal ring toward an outer peripheral surface side,
wherein a concave portion is formed on an outer peripheral surface
of the seal ring which extends from an end portion on a high
pressure side of the outer peripheral surface to a position which
does not reach an end portion on a low pressure side of the outer
peripheral surface, and introduces a fluid from the high pressure
side, a guide portion which positions the metal spring in an axial
direction is formed on the inner peripheral surface of the seal
ring, and a first protrusion which prevents the metal spring from
being detached to an inner peripheral surface side is provided at a
tip of the guide portion, and an abutment portion is provided at
one position on the seal ring in a circumferential direction, and
second protrusions which restrict a movement of the metal spring in
the circumferential direction are provided on the inner peripheral
surface on both sides of the abutment portion.
7. The sealing device according to claim 4, wherein a convex
portion which extends in the circumferential direction is provided
at a center in a width direction on the outer peripheral surface of
the seal ring, and a portion closer to the high pressure side than
the convex portion is the concave portion.
8. The sealing device according to claim 2, wherein a guide portion
which positions the metal spring in an axial direction is formed on
the inner peripheral surface of the seal ring.
9. The sealing device according to claim 5, wherein a convex
portion which extends in the circumferential direction is provided
at a center in a width direction on the outer peripheral surface of
the seal ring, and a portion closer to the high pressure side than
the convex portion is the concave portion.
10. The sealing device according to claim 6, wherein a convex
portion which extends in the circumferential direction is provided
at a center in a width direction on the outer peripheral surface of
the seal ring, and a portion closer to the high pressure side than
the convex portion is the concave portion.
Description
TECHNICAL FIELD
[0001] The present invention relates to a sealing device which
seals an annular gap between a shaft and a shaft hole of a
housing.
BACKGROUND ART
[0002] In an automatic transmission (AT) and a continuously
variable transmission (CVT) for automobiles, in order to hold a
hydraulic pressure, a seal ring which seals an annular gap between
a shaft and a housing which rotate relative to each other is
provided. With reference to FIGS. 33 and 34, a seal ring according
to a conventional art will be described. FIG. 33 is a schematic
cross-sectional view showing a seal ring according to the
conventional art in a condition in which the hydraulic pressure is
not held. FIG. 34 is a schematic cross-sectional view showing the
seal ring according to the conventional art in a condition in which
the hydraulic pressure is held. In the case of a seal ring 600
according to the conventional art, the seal ring 600 is configured
so as to seal an annular gap between a shaft 400 and a shaft hole
of a housing 500 by being attached to an annular groove 410
provided on an outer periphery of the shaft 400, and being slidably
in contact with an inner peripheral surface of the shaft hole of
the housing 500, through which the shaft 400 is inserted, and a
side wall surface of the annular groove 410.
[0003] In the seal ring 600 which is used for the above described
purpose, it is required to sufficiently reduce a sliding torque.
Accordingly, the circumference of an outer peripheral surface of
the seal ring 600 is configured to be shorter than the
circumference of the inner peripheral surface of the shaft hole of
the housing 500, thus it is configured to have no interference.
Consequently, in a condition in which an engine of an automobile is
operated and the hydraulic pressure is high, the seal ring 600 is
expanded in diameter by the hydraulic pressure and makes close
contact with the inner peripheral surface of the shaft hole and the
side wall surface of the annular groove 410 to thereby exhibit a
function of sufficiently holding the hydraulic pressure (see FIG.
34). In contrast to this, in a condition in which the hydraulic
pressure is not applied due to stoppage of the engine, the seal
ring 600 is configured so as to be apart from the inner peripheral
surface of the shaft hole and the side wall surface of the annular
groove 410 (see FIG. 33).
[0004] However, in the case of the seal ring 600 which is
configured in the above described manner, the seal ring 600 does
not exhibit a sealing function in the condition in which the
hydraulic pressure is not applied. Accordingly, in a configuration
such as AT or CVT, in which gear shifting control is performed by
oil which is pressure-fed by a hydraulic pump, when it is in a
no-load condition in which the hydraulic pump is stopped (e.g.,
during an idling stop), the oil sealed by the seal ring 600 may no
longer be sealed and return to an oil pan, thereby leaving no oil
in the vicinity of the seal ring 600. Consequently, when the engine
is started (re-started) from such a condition, the operation is
started in a condition in which no oil is present in the vicinity
of the seal ring 600; hence, without lubrication, a problem arises
in that responsiveness or operativity may be poor.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: Japanese Patent No. 4665046. Patent
Literature 2: Japanese Patent Application Laid-open No.
2011-144847. Patent Literature 3: Japanese Patent Application
Laid-open No. 2010-265937
SUMMARY OF INVENTION
Technical Problem
[0006] An object of the present invention is to provide a sealing
device that is capable of exhibiting a sealing function even in a
condition in which a fluid pressure is low while suppressing its
sliding torque.
Solution to Problem
[0007] In order to solve the above problem, the present invention
has adopted the following means.
[0008] That is, the sealing device according to the present
invention is a sealing device which is attached to an annular
groove provided on an outer periphery of a shaft and holds a fluid
pressure in a sealing target area by sealing an annular gap between
the shaft and a housing rotating relative to each other, the
sealing target area being configured such that the fluid pressure
changes, the sealing device including: a seal ring made of resin
which is in close contact with a side wall surface on a low
pressure side of the annular groove, and slides against an inner
peripheral surface of a shaft hole in the housing through which the
shaft is inserted; and a metal spring which is provided along an
inner peripheral surface of the seal ring in a state in which a gap
is formed between the metal spring and a groove bottom surface of
the annular groove, and presses the seal ring toward an outer
peripheral surface side, wherein a concave portion is formed on an
outer peripheral surface of the seal ring which extends from an end
portion on a high pressure side of the outer peripheral surface to
a position which does not reach an end portion on a low pressure
side of the outer peripheral surface, and introduces a fluid from
the high pressure side.
[0009] Note that, in the present invention, the "high pressure
side" denotes one side where a pressure is high when a pressure
difference is created between two sides of the sealing device, and
the "low pressure side" denotes another side where the pressure is
low when the pressure difference is created between the two sides
of the sealing device.
[0010] According to the sealing device of the present invention,
the seal ring is pressed towards the outer peripheral surface side
by the metal spring. Accordingly, even in a condition in which the
fluid pressure is not applied (the pressure difference is not
created) or the fluid pressure is almost not applied (the pressure
difference is almost not created), the seal ring is contact with
the inner peripheral surface of the shaft hole of the housing,
thereby exhibiting a sealing function. Consequently, it is possible
to hold the fluid pressure from immediately after the start of
increase of the fluid pressure in the sealing target area. In
addition, the concave portion is formed on the outer peripheral
surface of the seal ring, and the fluid is introduced into the
concave portion from the high pressure side. Accordingly, even when
the fluid pressure is increased, the fluid pressure acts towards
the inner peripheral surface side within an area where the concave
portion is provided. Consequently, it is possible to prevent the
increase of pressure acting towards the outer peripheral surface
side via the seal ring due to the increase of the fluid pressure,
thereby making it possible to suppress a sliding torque.
[0011] Since the metal spring is provided so as to be placed along
the inner peripheral surface of the seal ring in the state in which
the gap is formed between the metal spring and the groove bottom
surface of the annular groove, the metal spring is hardly
influenced by eccentricity of the shaft and the housing. In
addition, the seal ring and the metal spring would not rotate
relative to each other. Consequently, the seal ring and the metal
spring would not slide relative to each other; hence the inner
peripheral surface side of the seal ring would not be abraded due
to sliding.
[0012] In addition, a plurality of the concave portions may
preferably be formed at intervals in a circumferential
direction.
[0013] When such a configuration is adopted, a portion between the
two concave portions maintains a state in which it is in contact
with the inner peripheral surface of the shaft hole of the housing,
and it becomes possible to suppress degrading of the rigidity of
the seal ring. Consequently, it becomes possible to prevent the
seal ring from being tilted within the annular groove, and
stabilize an attachment state of the seal ring.
[0014] Further, a guide portion which positions the metal spring in
an axial direction (a direction of a central axis of the shaft; the
same shall apply hereinafter) may preferably be formed on the inner
peripheral surface of the seal ring.
[0015] Accordingly, it becomes possible to prevent the metal spring
from being displaced in the axial direction. Consequently, the seal
ring can be pressed towards the outer peripheral surface side
stably by the metal spring.
[0016] In addition, another sealing device of the present invention
is a sealing device which is attached to an annular groove provided
on an outer periphery of a shaft and holds a fluid pressure in a
sealing target area by sealing an annular gap between the shaft and
a housing rotating relative to each other, the sealing target area
being configured such that the fluid pressure changes, the sealing
device including: a seal ring made of resin which is in close
contact with a side wall surface on a low pressure side of the
annular groove, and slides against an inner peripheral surface of a
shaft hole in the housing through which the shaft is inserted; and
a metal spring which is provided along an inner peripheral surface
of the seal ring in a state in which a gap is formed between the
metal spring and a groove bottom surface of the annular groove, and
presses the seal ring toward an outer peripheral surface side,
wherein a concave portion is formed on an outer peripheral surface
of the seal ring which extends from an end portion on a high
pressure side of the outer peripheral surface to a position which
does not reach an end portion on a low pressure side of the outer
peripheral surface, and introduces a fluid from the high pressure
side, and a guide portion which positions the metal spring in an
axial direction is formed on the inner peripheral surface of the
seal ring, and a protrusion which prevents the metal spring from
being detached to an inner peripheral surface side is provided at a
tip of the guide portion.
[0017] Still further, yet another sealing device of the present
invention is a sealing device which is attached to an annular
groove provided on an outer periphery of a shaft and holds a fluid
pressure in a sealing target area by sealing an annular gap between
the shaft and a housing rotating relative to each other, the
sealing target area being configured such that the fluid pressure
changes, the sealing device including: a seal ring made of resin
which is in close contact with a side wall surface on a low
pressure side of the annular groove, and slides against an inner
peripheral surface of a shaft hole in the housing through which the
shaft is inserted; and a metal spring which is provided along an
inner peripheral surface of the seal ring in a state in which a gap
is formed between the metal spring and a groove bottom surface of
the annular groove, and presses the seal ring toward an outer
peripheral surface side, wherein a concave portion is formed on an
outer peripheral surface of the seal ring which extends from an end
portion on a high pressure side of the outer peripheral surface to
a position which does not reach an end portion on a low pressure
side of the outer peripheral surface, and introduces a fluid from
the high pressure side, and an abutment portion is provided at one
position on the seal ring in a circumferential direction, and
protrusions which restrict a movement of the metal spring in the
circumferential direction are provided on the inner peripheral
surface on both sides of the abutment portion.
[0018] Still further, yet another sealing device of the present
invention is a sealing device which is attached to an annular
groove provided on an outer periphery of a shaft and holds a fluid
pressure in a sealing target area by sealing an annular gap between
the shaft and a housing rotating relative to each other, the
sealing target area being configured such that the fluid pressure
changes, the sealing device including: a seal ring made of resin
which is in close contact with a side wall surface on a low
pressure side of the annular groove, and slides against an inner
peripheral surface of a shaft hole in the housing through which the
shaft is inserted; and a metal spring which is provided along an
inner peripheral surface of the seal ring in a state in which a gap
is formed between the metal spring and a groove bottom surface of
the annular groove, and presses the seal ring toward an outer
peripheral surface side, wherein a concave portion is formed on the
inner peripheral surface of the seal ring which extends from an end
portion on a high pressure side of the outer peripheral surface to
a position which does not reach an end portion on a low pressure
side of the outer peripheral surface, and introduces a fluid from
the high pressure side, a guide portion which positions the metal
spring in an axial direction, and a first protrusion which prevents
the metal spring from being detached to an inner peripheral surface
side is provided at a tip of the guide portion, and an abutment
portion is provided at one position on the seal ring in a
circumferential direction, and second protrusions which restrict a
movement of the metal spring in the circumferential direction are
provided on the inner peripheral surface on both sides of the
abutment portion.
[0019] In addition, in each of the aspects of the invention
described above, a convex portion which extends in the
circumferential direction may preferably be provided at a center in
a width direction on the outer peripheral surface of the seal ring,
and a portion closer to the high pressure side than the convex
portion may be the concave portion.
[0020] Note that, in each of these aspects of the present
invention, the "high pressure side" denotes one side where a
pressure is high when a pressure difference is created between two
sides of the sealing device, and the "low pressure side" denotes
another side where the pressure is low when the pressure difference
is created between the two sides of the sealing device.
[0021] Also in each of these sealing devices, the seal ring is
pressed towards the outer peripheral surface side by the metal
spring. Accordingly, even in a condition in which the fluid
pressure is not applied (the pressure difference is not created) or
the fluid pressure is almost not applied (the pressure difference
is almost not created), the seal ring is contact with the inner
peripheral surface of the shaft hole of the housing, thereby
exhibiting a sealing function. Consequently, it is possible to hold
the fluid pressure from immediately after the start of increase of
the fluid pressure in the sealing target area. In addition, the
concave portion is formed on the outer peripheral surface of the
seal ring, and the fluid is introduced into the concave portion
from the high pressure side. Accordingly, even when the fluid
pressure is increased, the fluid pressure acts towards the inner
peripheral surface side within an area where the concave portion is
provided. Consequently, it is possible to prevent the increase of
pressure acting towards the outer peripheral surface side via the
seal ring due to the increase of the fluid pressure, thereby making
it possible to suppress a sliding torque.
e.
[0022] Since the metal spring is provided so as to be placed along
the inner peripheral surface of the seal ring in the state in which
the gap is formed between the metal spring and the groove bottom
surface of the annular groove, the metal spring is hardly
influenced by eccentricity of the shaft and the housing. In
addition, the seal ring and the metal spring would not rotate
relative to each other. Consequently, the seal ring and the metal
spring would not slide relative to each other; hence the inner
peripheral surface side of the seal ring would not be abraded due
to sliding.
[0023] In the case where the configuration is adopted in which a
guide portion which positions the metal spring in the axial
direction is formed on the inner peripheral surface of the seal
ring, it becomes possible to prevent the metal spring from being
displaced in the axial direction. Consequently, the seal ring can
be pressed towards the outer peripheral surface side stably by the
metal spring.
[0024] In addition, by providing the protrusion (the first
protrusion) which prevents the metal spring from being detached to
the inner peripheral surface side at the tip of the guide portion,
it becomes possible to prevent the metal spring from being detached
from the seal ring, when the seal ring is attached to the annular
groove or the like.
[0025] In addition, in the case where the configuration is adopted
in which the abutment portion is provided at one position of the
seal ring in the circumferential direction, and the protrusions
(the second protrusions) which restrict the movement of the metal
spring in the circumferential direction are provided on the inner
peripheral surface on both sides of the abutment portion, it is
possible to prevent positional displacement of the metal spring
relative to the seal ring in the circumferential direction.
Accordingly, it becomes possible to exercise a stable sealing
performance.
Advantageous Effects of Invention
[0026] As described thus far, according to the present invention,
it is possible to exercise the sealing function even in a condition
in which the fluid pressure is low while suppressing the sliding
torque.
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 is a partially cutaway cross-sectional view of a
sealing device according to a first example of the present
invention.
[0028] FIG. 2 is a view showing an outer peripheral ring according
to the first example of the present invention when viewed from an
outer peripheral surface side.
[0029] FIG. 3 is a side view of the outer peripheral ring according
to the first example of the present invention.
[0030] FIG. 4 is a partially cutaway perspective view of the outer
peripheral ring according to the first example of the present
invention.
[0031] FIG. 5 is a schematic cross-sectional view showing a sealing
device according to the first example of the present invention in a
no-load condition.
[0032] FIG. 6 is a schematic cross-sectional view showing the
sealing device according to the first example of the present
invention in the no-load condition.
[0033] FIG. 7 is a schematic cross-sectional view showing the
sealing device according to the first example of the present
invention in a high-pressure condition.
[0034] FIG. 8 is a partially cutaway perspective view of an outer
peripheral ring according to a modification of the first example of
the present invention.
[0035] FIG. 9 is a schematic cross-sectional view showing a sealing
device according to the modification of the first example of the
present invention in a no-load condition.
[0036] FIG. 10 is a schematic cross-sectional view showing the
sealing device according to the modification of the first example
of the present invention in the no-load condition.
[0037] FIG. 11 is a partially cutaway cross-sectional view showing
a sealing device according to a second example of the present
invention.
[0038] FIG. 12 is a side view of a seal ring according to the
second example of the present invention.
[0039] FIG. 13 is a side view of the seal ring according to the
second example of the present invention.
[0040] FIG. 14 is a partially cutaway perspective view of the
sealing device according to the second example of the present
invention.
[0041] FIG. 15 is a schematic cross-sectional view of the seal ring
according to the second example of the present invention.
[0042] FIG. 16 is a schematic cross-sectional view of the seal ring
according to the second example of the present invention.
[0043] FIG. 17 is a schematic cross-sectional view showing the
sealing device according to the second example of the present
invention in a no-load condition.
[0044] FIG. 18 is a schematic cross-sectional view showing the
sealing device according to the second example of the present
invention in the no-load condition.
[0045] FIG. 19 is a schematic cross-sectional view showing the
sealing device according to the second example of the present
invention in a high-pressure condition.
[0046] FIG. 20 is a partially cutaway perspective view of a seal
ring according to a first modification of the second example of the
present invention.
[0047] FIG. 21 is a partially cutaway perspective view of a seal
ring according to a second modification of the second example of
the present invention.
[0048] FIG. 22 is a schematic cross-sectional view showing a
sealing device according to a third modification of the second
example of the present invention in a high-pressure condition.
[0049] FIG. 23 is a partially cutaway perspective view of a seal
ring according to a fourth modification of the second example of
the present invention.
[0050] FIG. 24 is a partially cutaway perspective view of a seal
ring according to a fifth modification of the second example of the
present invention.
[0051] FIG. 25 is a schematic cross-sectional view showing a
sealing device according to a sixth modification of the second
example of the present invention.
[0052] FIG. 26 is a partially cutaway cross-sectional view of a
sealing device according to a third example of the present
invention.
[0053] FIG. 27 is a side view of a seal ring according to the third
example of the present invention.
[0054] FIG. 28 is a partially cutaway perspective view of the
sealing device according to the third example of the present
invention.
[0055] FIG. 29 is a schematic cross-sectional view of the seal ring
according to the third example of the present invention.
[0056] FIG. 30 is a schematic cross-sectional view of the seal ring
according to the third example of the present invention.
[0057] FIG. 31 is a schematic cross-sectional view showing the
sealing device according to the third example of the present
invention in a high-pressure condition.
[0058] FIG. 32 is a partially cutaway cross-sectional view of a
sealing device according to a fourth example of the present
invention.
[0059] FIG. 33 is a schematic cross-sectional view showing a seal
ring according to a conventional art in a condition in which a
hydraulic pressure is not held.
[0060] FIG. 34 is a schematic cross-sectional view showing the seal
ring according to the conventional art in a condition in which the
hydraulic pressure is held.
DESCRIPTION OF EMBODIMENTS
[0061] Hereinafter, modes for carrying out the present invention
will be exemplarily described in detail based on examples thereof
with reference to the drawings. However, the dimensions, materials,
shapes, relative arrangements and so on of constituent parts
described in the examples are not intended to limit the scope of
the present invention to these alone in particular unless
specifically described. Note that a sealing device according to
each of the present examples is used for the purpose of sealing an
annular gap between a shaft and a housing which rotate relative to
each other in order to hold a hydraulic pressure in a transmission
for automobiles such as AT and CVT. In addition, in the following
description, a "high pressure side" denotes one side where a
pressure is high when a pressure difference is created between two
sides of the sealing device, and a "low pressure side" denotes
another side where the pressure is low when the pressure difference
is created between the two sides of the sealing device.
First Example
[0062] With reference to FIGS. 1 to 7, a sealing device according
to a first example of the present invention will be described.
[0063] <Configuration of Sealing Device>
[0064] With reference to FIGS. 1 and 5 to 7, in particular, the
configuration of the sealing device according to the first example
of the present invention will be described. A sealing device 100
according to the present example is attached to an annular groove
410 provided on an outer periphery of a shaft 400, and seals an
annular gap between the shaft 400 and a housing 500 (an inner
peripheral surface of a shaft hole in the housing 500 through which
the shaft 400 is inserted) which rotate relative to each other.
With this, the sealing device 100 holds a fluid pressure in a
sealing target area configured such that the fluid pressure (a
hydraulic pressure in the present example) changes. Herein, in the
present example, the fluid pressure in the right area in each of
FIGS. 5 to 7 is configured to change, and the sealing device 100
plays a role in holding the fluid pressure in the sealing target
area on the right in the drawing. Note that, in a condition in
which an engine of an automobile is stopped, the fluid pressure in
the sealing target area is low and a no-load condition is created,
and when the engine is started, the fluid pressure in the sealing
target area increases.
[0065] The sealing device 100 according to the present example is
constituted of a seal ring 200 that is made of resin such as
polyetheretherketone (PEEK), polyphenylene sulfide (PPS), or
polytetrafluoroethylene (PTFE), and a metal spring 300. For the
metal spring 300 in the present example, a C-ring, in which a
cut-out is made at one place on an annular member in a
circumferential direction, is used.
[0066] In a state in which the seal ring 200 is combined with the
metal spring 300, the circumference of an outer peripheral surface
of the seal ring 200 is configured to be longer than the
circumference of the inner peripheral surface of the shaft hole of
the housing 500. Note that the circumference of the outer
peripheral surface of the seal ring 200 itself is configured to be
shorter than the circumference of the inner peripheral surface of
the shaft hole of the housing 500, and thus configured to have no
interference. Consequently, when the metal spring 300 is not
attached and an external force is not applied, the outer peripheral
surface of the seal ring 200 does not make contact with the inner
peripheral surface of the shaft hole of the housing 500.
[0067] <Seal Ring>
[0068] With reference to FIGS. 1 to 4, in particular, the seal ring
200 according to the first example of the present invention will be
described in detail. On the seal ring 200, an abutment portion 210
is provided at one position in a circumferential direction. In
addition, a plurality of concave portions 220 for introducing a
fluid is formed on the outer peripheral surface of the seal ring
200 at intervals in the circumferential direction. Further, on an
inner peripheral surface of the seal ring 200, protrusions 223 and
224 as guide portions which position the metal spring 300 in an
axial direction (a direction of a central axis of the shaft 400;
the same shall apply hereinafter) are provided. The protrusions 223
and 224 are provided on a side of one of two side surfaces of the
seal ring 200 and on a side of another of the two side surfaces
thereof, respectively, so as to be provided on both sides of the
metal spring 300. A plurality of the protrusions 223 and 224 are
provided at intervals in the circumferential direction.
[0069] Note that the seal ring 200 according to the present example
has the configuration in which the abutment portion 210, a
plurality of the concave portions 220, and a plurality of the
protrusions 223 and 224 are formed on an annular member having a
rectangular cross section. However, this is only a description of
the shape, and this does not necessarily mean that an annular
member having the rectangular cross section is used as a material
and a process to form an abutment portion 210, a plurality of
concave portions 220, and a plurality of protrusions 223 and 224 is
applied on this material. As a matter of course, it is also
possible to form an abutment portion 210, a plurality of concave
portions 220, and a plurality of protrusions 223 and 224 by
applying a cutting-work after molding an annular member having a
rectangular cross section. However, for example, a plurality of
concave portions 220 may be formed by applying a cutting-work after
a member having an abutment portion 210 and a plurality of
protrusions 223 and 224 is molded in advance; hence production
method is not particularly limited.
[0070] The abutment portion 210 employs so-called a special step
cut in which the abutment portion 210 is cut to have a step-like
shape when viewed from each of an outer peripheral surface side and
both of side wall surface sides. Accordingly, in the seal ring 200,
a first engagement convex portion 211a and a first engagement
concave portion 212a are provided on an outer peripheral side on
one of two sides separated by a cutoff portion, and a second
engagement concave portion 212b, with which the first engagement
convex portion 211a is engaged, and a second engagement convex
portion 211b, with which the first engagement concave portion 212a
is engaged, are provided on an outer peripheral side on another of
the two sides. Since the special step cut is a well-known
technique, the detailed description thereof will be omitted, but it
should be noted that the special step cut has a characteristic such
that a stable sealing performance can be maintained even when the
circumference of the seal ring 200 changes due to thermal
expansion/contraction. Note that although the case of the special
step cut is described as an example of the abutment portion 210
thus far, the abutment portion 210 is not limited thereto, and it
is also possible to adopt a straight cut or a bias cut. Note that,
in a case where a material having low elasticity (PTFE or the like)
is adopted as a material for the seal ring 200, the seal ring 200
may be made endless without providing an abutment portion 210.
[0071] A plurality of the concave portions 220 are formed at
intervals in the circumferential direction. Note that, in the
present example, a plurality of the concave portions 220 are
provided at regular intervals except in the vicinity of the
abutment portion 210. In addition, the length of the concave
portion 220 in the circumferential direction is configured to be
relatively long, and the length of a portion between the two
concave portions 220 in the circumferential direction is configured
to be shorter than the length of the concave portion 220 in the
circumferential direction except in the vicinity of the abutment
portion 210. Hereinafter, the portion between the two concave
portions 220 is referred to as a rib 221. With the above
configuration, the concave portions 220 are formed over the almost
entire region in the circumferential direction. That is, the
concave portions 220 are formed over the entire region in the
circumferential direction except for the portion where the abutment
portion 210 is formed and the portions where a plurality of the
ribs 221, each having a short length in the circumferential
direction, is formed. In addition, both side surfaces of the rib
221 in the present example are configured to be perpendicular to a
bottom surface of the concave portion 220.
[0072] In addition, the concave portion 220 is formed so as to
extend from one end portion (a high pressure side (H) as will be
described later) to a position which does not reach another end
portion (a low pressure side (L) as will be described later). More
specifically, the concave portion 220 is formed so as to extend to
the position in the vicinity of the other end portion. Hereinafter,
a portion on the other side (the low pressure side (L)) on the
outer peripheral surface side of the seal ring 200 where the
concave portion 220 is not formed is referred to as a low pressure
side convex portion 222. Note that, with regard to the depth of the
concave portion 220, the rigidity of the portions provided with the
rib 221 and the low pressure side convex portion 222 is higher as
the concave portion 220 is shallower. On the other hand, the rib
221 and the low pressure side convex portion 222 become abraded due
to sliding; hence the depth of the concave portion 220 becomes
shallower over time. Accordingly, when the depth of the concave
portion 220 becomes excessively shallow, a fluid may not be
introduced. To cope with this, it is preferable to set the initial
depth of the concave portion 220 in consideration of both of the
rigidity and maintaining the introduction of the fluid even when
the temporal wear progresses. For example, in the case where the
thickness of the seal ring 200 is 1.7 mm, the depth of the concave
portion 220 is preferably set to 0.1 mm or more and 0.3 mm or less,
approximately. With regard to the width of the concave portion 220
(the width in the axial direction), the width of the low pressure
side convex portion 222 becomes narrower as the width of the
concave portion 220 is made wider. Although a torque can be reduced
more as the width is set narrower, sealing performance and
durability may be degraded if the width is set excessively narrow.
To cope with this, it is desirable to reduce the width as much as
possible to the extent that the sealing performance and the
durability can be maintained in accordance with a use environment
or the like. For example, in the case where the overall length of
the width of the seal ring 200 (the width in the axial direction)
is 1.9 mm, the width of the low pressure side convex portion 222 is
preferably set to 0.3 mm or more and 0.7 mm or less, approximately.
In addition, the width of the rib 221 in the circumferential
direction is preferably set to 0.3 mm or more and 0.7 mm or less,
approximately.
[0073] <Mechanism During Use of Sealing Device>
[0074] With reference to FIGS. 5 to 7, in particular, the mechanism
during use of the sealing device 100 according to the present
example will be described. Each of FIGS. 5 and 6 shows a no-load
condition in which there is no pressure difference (or there is
almost no pressure difference) between the left and right areas
separated by the sealing device 100, after the engine has stopped.
Note that FIG. 5 is a schematic cross-sectional view (a
cross-sectional view including the axis of the shaft 400) of a
portion provided with the concave portion 220 on the seal ring 200,
and FIG. 6 is a schematic cross-sectional view (a cross-sectional
view including the axis of the shaft 400) of a portion provided
with the rib 221 on the seal ring 200. The seal ring 200 in FIG. 5
corresponds to an AA cross section in FIG. 3, and the seal ring 200
in FIG. 6 corresponds to a BB cross section in FIG. 3. FIG. 7 shows
a condition in which the engine is started, and the fluid pressure
in the right area is increased and became higher than the fluid
pressure in the left area separated by the sealing device 100. Note
that FIG. 7 is a schematic cross-sectional view (a cross-sectional
view including the axis of the shaft 400) of the portion provided
with the concave portion 220 on the seal ring 200. The seal ring
200 in FIG. 7 corresponds to the AA cross section in FIG. 3.
[0075] In a state in which the sealing device 100 is attached to
the annular groove 410, the metal spring 300 exhibits the function
of pressing the seal ring 200 towards the outer peripheral surface
side by its own expansive force. Consequently, portions of the
outer peripheral surface of the seal ring 200 except for the
concave portions 220, namely portions provided with the rib 221 and
the low pressure side convex portion 222 maintain contact with the
inner peripheral surface of the shaft hole of the housing 500.
[0076] In a condition in which the engine is started and the
pressure difference is created, as shown in FIG. 7, the seal ring
200 is in a state in which it is in close contact with the side
wall surface on the low pressure side (L) of the annular groove 410
by the fluid pressure from the high pressure side (H). Note that it
goes without saying that the seal ring 200 maintains a state in
which it is in contact with (it slides against) the inner
peripheral surface of the shaft hole of the housing 500.
[0077] <Advantages of the Sealing Device According to the
Present Example>
[0078] According to the sealing device 100 of the present example,
the seal ring 200 is pressed towards the outer peripheral surface
side by the metal spring 300. Accordingly, even in a condition in
which the fluid pressure is not applied (the pressure difference is
not created), or the fluid pressure is almost not applied (the
pressure difference is almost not created), the seal ring 200 is in
contact with the inner peripheral surface of the shaft hole of the
housing 500. Note that an annular continuous sealing surface is
formed by the outer peripheral surface of the rib 221, the outer
peripheral surface of the low pressure side convex portion 222, and
the outer peripheral surface of the portion in the vicinity of the
abutment portion 210 where the concave portion 220 is not formed.
Accordingly, as long as the seal ring 200 maintains a state in
which it is in close contact with the side wall surface on the low
pressure side (L) of the annular groove 410, the sealing function
is exhibited. Consequently, it is possible to hold the fluid
pressure from immediately after the start of increase of the fluid
pressure in the sealing target area. That is, as for an engine
having an idling stop function, it is possible to hold the
hydraulic pressure from immediately after the start of increase of
hydraulic pressure on the sealing target area side when the engine
is started by pressing an accelerator pedal from an engine stop
condition.
[0079] Generally speaking, in a case of a seal ring made of resin,
a function of suppressing leakage of a fluid is not exhibited so
well. However, in the present example, because the seal ring 200 is
pressed towards the outer peripheral surface side by the metal
spring 300, the function of suppressing the leakage of the fluid is
exhibited to a certain extent. Accordingly, it becomes possible to
maintain the state in which the pressure difference is present for
a while even after an action of a pump or the like has stopped due
to the stop of the engine. Consequently, in the engine having the
idling stop function, in a case where a period of the engine
stopping state is not too long, it is possible to maintain the
state in which the pressure difference is present; hence, when the
engine is re-started, it is possible to suitably hold the fluid
pressure from immediately after the re-start.
[0080] In a condition in which considerable time has elapsed since
the stop of the engine, the fluid pressure no longer acts (the
pressure difference becomes zero). In this case, the seal ring 200
may move away from the side wall surface of the annular groove 410
(the side wall surface on the low pressure side (L) when the
pressure difference is present). Accordingly, the leakage of the
fluid may occur. However, as described above, in the case where the
period of the engine stop state is not too long, it is possible to
maintain the condition in which the pressure difference is present;
hence it is possible to maintain the state in which the seal ring
200 is in close contact with the side wall surface on the low
pressure side (L) of the annular groove 410. Consequently, even in
a low-load condition, the function of suppressing the leakage of
the fluid is exhibited.
[0081] In addition, a plurality of the concave portions 220 are
formed on the outer peripheral surface of the seal ring 200, and
the fluid is introduced into a plurality of the concave portions
220 from the high pressure side (H). Accordingly, even when the
fluid pressure is increased, the fluid pressure acts towards the
inner peripheral surface side in the region provided with the
concave portions 220. Note that arrows in FIG. 7 show a state in
which the fluid pressure is acting on the seal ring 200. With this,
in the sealing device 100 according to the present example, it is
possible to suppress the increase of the pressure towards the outer
peripheral surface side by the seal ring 200 due to the increase of
the fluid pressure, thereby making it possible to suppress the
sliding torque.
[0082] In addition, since a plurality of the concave portions 220
are formed at intervals in the circumferential direction, the
portion (the rib 221) between two concave portions 220 makes
contact with the inner peripheral surface of the shaft hole of the
housing 500. Further, by providing a plurality of the ribs 221, it
is possible to suppress a degradation in the rigidity of the seal
ring 200 as compared with a case where the ribs 221 are not
provided. Consequently, it is possible to prevent the seal ring 200
from being tilted within the annular groove 410, and stabilize an
attachment state of the seal ring 200. Note that, in a case where a
configuration is adopted in which a plurality of the ribs 221 is
not provided, it is anticipated that the seal ring 200 may be
tilted in counter-clockwise direction in FIGS. 5 and 7.
[0083] In addition, in the present example, the concave portions
220 are formed over the entire periphery except in the vicinity of
the abutment portion 210 and the portions provided with a plurality
of the ribs 221 with a short length in the circumferential
direction, and are formed so as to extend from the end portion on
the high pressure side (H) to the vicinity of the end portion on
the low pressure side (L). As described, in the present example, by
providing the concave portions 220 over a large area of the outer
peripheral surface of the seal ring 200, it is possible to reduce a
sliding area between the seal ring 200 and the inner peripheral
surface of the shaft hole of the housing 500 as much as possible,
thereby significantly reducing the sliding torque. Note that the
sliding area between the seal ring 200 and the inner peripheral
surface of the shaft hole of the housing 500 is sufficiently
smaller than a contact area between the seal ring 200 and the side
wall surface on the low pressure side (L) of the annular groove
410. With this configuration, it is possible to prevent the seal
ring 200 from sliding relative to the side wall surface on the low
pressure side (L) of the annular groove 410. Consequently, in the
seal ring 200 according to the present example, because it is the
outer peripheral surface side that is sliding, a lubricating film
made of a sealing target fluid (an oil film in the present example)
is formed more easily as compared with a case where the sealing
ring slides against the side wall surface of the annular groove;
hence it becomes possible to further reduce the sliding torque.
[0084] As described, since it is possible to realize the reduction
of sliding torque, it becomes possible to suppress the generation
of heat due to sliding; hence it becomes possible to suitably use
the sealing device 100 according to the present example even under
high-speed and high-pressure environmental conditions.
[0085] Further, in the present example, since the metal spring 300
is provided so as to extend along the inner peripheral surface of
the seal ring 200 in a state in which a gap is formed between the
metal spring 300 and the groove bottom surface of the annular
groove 410, the metal spring 300 is hardly influenced by
eccentricity of the shaft 400 and the housing 500. In addition, the
seal ring 200 and the metal spring 300 do not rotate relative to
each other. Consequently, the seal ring 200 and the metal spring
300 do not slide relative to each other; hence the inner peripheral
surface side of the seal ring 200 would not be abraded due to
sliding.
[0086] In addition, the metal spring 300 is positioned in the axial
direction by the protrusions 223 and 224. Consequently, the seal
ring 200 is stably pressed towards the outer peripheral surface
side by the metal spring 300.
[0087] (Modification of Seal Ring)
[0088] In the above example, the case where a plurality of the
protrusions 223 and 224 are formed on the inner peripheral surface
of the seal ring 200 is described as an example of the guide
portion that positions the metal spring 300 in the axial direction.
As described in the above example, by adopting the configuration in
which a plurality of the protrusions 223 and 224 are provided at
intervals in the circumferential direction and the protrusion 223
and the protrusion 224 are disposed at different positions in the
circumferential direction, it becomes possible to easily form the
protrusions 223 and 224 by molding that uses a die. That is, each
of the protrusions 223 and 224 does not have an undercut in the
axial direction.
[0089] However, the configuration of the guide portion that
positions the metal spring 300 in the axial direction is not
limited to the configuration described in the above example. For
example, as shown in FIGS. 8 and 9, a groove 225 may be formed
along the inner peripheral surface of the seal ring 200, and the
metal spring 300 may be fitted in the groove 225. In this case, the
groove 225 may be formed on the inner peripheral surface of the
seal ring 200 by cutting work. In a case where difficulty in
cutting arises, a substantially annular groove 225 may be formed
excluding the vicinity of the abutment portion. In this case, the
metal spring 300, which is a C-ring, may be fitted in the groove
225 such that the cut-out formed at one place in the
circumferential direction is positioned in the vicinity of the
abutment portion. Note that, in FIGS. 8 and 9, the configuration
other than the groove 225 is the same as the configuration
described in the above example; hence the same constituent parts
are designated by the same reference numerals and the description
thereof is omitted.
[0090] In addition, the C-ring has been described as an example of
the metal spring 300, but the metal spring 300 is not limited to
the C-ring. For example, an annular coil spring such as a metal
spring 300a shown in FIG. 10 may also be used. Note that, in FIG.
10, the configuration other than the groove 225 and the metal
spring 300a is the same as the configuration described in the above
example; hence the same constituent parts are designated by the
same reference numerals, and the description thereof is
omitted.
Second Example
[0091] With reference to FIGS. 11 to 19, a sealing device according
to a second example of the present invention will be described.
[0092] <Configuration of Sealing Device>
[0093] With reference to FIGS. 11 and 14 to 19, in particular, the
configuration of the sealing device according to the second example
of the present invention will be described. A sealing device 100
according to the present example is attached to an annular groove
410 provided on an outer periphery of a shaft 400, and seals an
annular gap between the shaft 400 and a housing 500 (an inner
peripheral surface of a shaft hole in the housing 500 through which
the shaft 400 is inserted) which rotate relative to each other.
With this, the sealing device 100 holds a fluid pressure in a
sealing target area configured such that the fluid pressure (a
hydraulic pressure in the present example) changes. Herein, in the
present example, the fluid pressure in the right area in each of
FIGS. 17 to 19 is configured to change, and the sealing device 100
plays a role in holding the fluid pressure in the sealing target
area on the right in the drawing. Note that, in a condition in
which an engine of an automobile is stopped, the fluid pressure in
the sealing target area is low and a no-load condition is created,
and when the engine is started, the fluid pressure in the sealing
target area increases.
[0094] The sealing device 100 according to the present example is
constituted of a seal ring 200 that is made of resin such as
polyetheretherketone (PEEK), polyphenylene sulfide (PPS), or
polytetrafluoroethylene (PTFE), and a metal spring 300. For the
metal spring 300 in the present example, a C-ring, in which a
cut-out is made at one place on an annular member in a
circumferential direction, is used.
[0095] In a state in which the seal ring 200 is combined with the
metal spring 300, the circumference of an outer peripheral surface
of the seal ring 200 is configured to be longer than the
circumference of the inner peripheral surface of the shaft hole of
the housing 500. Note that the circumference of the outer
peripheral surface of the seal ring 200 itself is configured to be
shorter than the circumference of the inner peripheral surface of
the shaft hole of the housing 500, and thus configured to have no
interference. Consequently, when the metal spring 300 is not
attached and an external force is not applied, the outer peripheral
surface of the seal ring 200 does not make contact with the inner
peripheral surface of the shaft hole of the housing 500.
[0096] <Seal Ring>
[0097] With reference to FIGS. 11 to 16, in particular, the seal
ring 200 according to the second example of the present invention
will be described in detail. Note that FIGS. 12 and 13 are side
views of the seal ring 200 according to the present example. FIG.
12 corresponds to a view when the seal ring 200 is seen from the
bottom side of the drawing in FIG. 11, and FIG. 13 corresponds to a
view when the seal ring 200 is seen from the top side of the
drawing in FIG. 11. FIG. 14 is a partially cutaway perspective view
of the vicinity of an abutment portion of the sealing device
according to the present example. FIGS. 15 and 16 are schematic
cross-sectional view of the seal ring 200 according to the present
example. FIG. 15 is an AA cross section in FIG. 13, and FIG. 16 is
a BB cross section in FIG. 13. Note that, in FIGS. 15 and 16, a
position of the metal spring 300 in its attachment state is
depicted in dotted-lines.
[0098] On the seal ring 200, an abutment portion 210 is provided at
one position in a circumferential direction. In addition, a
plurality of concave portions 220 for introducing a fluid is formed
on the outer peripheral surface of the seal ring 200 at intervals
in the circumferential direction.
[0099] In addition, on an inner peripheral surface of the seal ring
200, guide protrusions 231 and 232 as guide portions which position
the metal spring 300 in an axial direction (a direction of a
central axis of the shaft 400) are provided. The guide protrusions
231 and 232 are provided on a side of one of two side surfaces of
the seal ring 200 and on a side of another of the two side surfaces
thereof, respectively, so as to be provided on both sides of the
metal spring 300. A plurality of the guide protrusions 231 and 232
are provided at intervals in the circumferential direction. Note
that the guide protrusions 231 and 232 are provided such that they
protrude towards the inner peripheral surface side.
[0100] In addition, first protrusions 231a and 232a which prevent
the metal spring 300 from being detached to the inner peripheral
surface side are provided at a tip of the guide protrusion 231 and
at a tip of the guide protrusion 232, respectively. The first
protrusions 231a and 232a are provided such that they protrude in
the axial direction and towards the inner peripheral surface
side.
[0101] Further, second protrusions 233 which restrict a movement of
the metal spring 300 in the circumferential direction are provided
on the inner peripheral surface on both sides of the abutment
portion 210 of the seal ring 200. Note that the metal spring 300 is
attached to the inner peripheral surface side of the seal ring 200
so that two ends separated by the cut-out at one place in the
circumferential direction compress a pair of the second protrusions
233 therebetween (see FIG. 14). With this, the ends of the metal
spring 300 abut the second protrusions 233, thereby restricting the
movement of the metal spring in the circumferential direction.
[0102] Note that the seal ring 200 according to the present example
has the configuration in which the abutment portion 210, a
plurality of the concave portions 220, a plurality of the guide
protrusions 231 and 232 provided with the first protrusions 231a
and 232a respectively, and the pair of second protrusions 233 are
formed on an annular member having a rectangular cross section.
However, this is only a description of the shape, and this does not
necessarily mean that an annular member having the rectangular
cross section is used as a material and a process to form an
abutment portion 210, a plurality of concave portions 220, a
plurality of the concave portions 220, a plurality of the guide
protrusions 231 and 232 provided with the first protrusions 231a
and 232a respectively, and the pair of second protrusions 233 is
applied on this material. As a matter of course, it is also
possible to form an abutment portion 210, a plurality of concave
portions 220, a plurality of the concave portions 220, a plurality
of the guide protrusions 231 and 232 provided with the first
protrusions 231a and 232a respectively, and the pair of second
protrusions 233 by applying a cutting-work after molding an annular
member having a rectangular cross section. However, for example, a
plurality of concave portions 220 may be formed by applying a
cutting-work after a member having an abutment portion 210, a
plurality of the guide protrusions 231 and 232 provided with the
first protrusions 231a and 232a respectively, and the pair of
second protrusions 233 is molded in advance; hence production
method is not particularly limited.
[0103] The abutment portion 210 employs so-called a special step
cut in which the abutment portion 210 is cut to have a step-like
shape when viewed from each of an outer peripheral surface side and
both of side wall surface sides. Accordingly, in the seal ring 200,
a first engagement convex portion 211a and a first engagement
concave portion 212a are provided on an outer peripheral side on
one of two sides separated by a cutoff portion, and a second
engagement concave portion 212b, with which the first engagement
convex portion 211a is engaged, and a second engagement convex
portion 211b, with which the first engagement concave portion 212a
is engaged, are provided on an outer peripheral side on another of
the two sides. Since the special step cut is a well-known
technique, the detailed description thereof will be omitted, but it
should be noted that the special step cut has a characteristic such
that a stable sealing performance can be maintained even when the
circumference of the seal ring 200 changes due to thermal
expansion/contraction. Note that although the case of the special
step cut is described as an example of the abutment portion 210
thus far, the abutment portion 210 is not limited thereto, and it
is also possible to adopt a straight cut or a bias cut.
[0104] A plurality of the concave portions 220 are formed at
intervals in the circumferential direction. Note that, in the
present example, a plurality of the concave portions 220 are
provided at regular intervals except in the vicinity of the
abutment portion 210. In addition, the length of the concave
portion 220 in the circumferential direction is configured to be
relatively long, and the length of a portion between the two
concave portions 220 in the circumferential direction is configured
to be shorter than the length of the concave portion 220 in the
circumferential direction except in the vicinity of the abutment
portion 210. Hereinafter, the portion between the two concave
portions 220 is referred to as a rib 221. With the above
configuration, the concave portions 220 are formed over the almost
entire region in the circumferential direction. That is, the
concave portions 220 are formed over the entire region in the
circumferential direction except for the portion where the abutment
portion 210 is formed and the portions where a plurality of the
ribs 221, each having a short length in the circumferential
direction, is formed. In addition, both side surfaces of the rib
221 in the present example are configured to be perpendicular to a
bottom surface of the concave portion 220.
[0105] In addition, the concave portion 220 is formed so as to
extend from one end portion (a high pressure side (H) as will be
described later) to a position which does not reach another end
portion (a low pressure side (L) as will be described later). More
specifically, the concave portion 220 is formed so as to extend to
the position in the vicinity of the other end portion. Hereinafter,
a portion on the other side (the low pressure side (L)) on the
outer peripheral surface side of the seal ring 200 where the
concave portion 220 is not formed is referred to as a low pressure
side convex portion 222. Note that, with regard to the depth of the
concave portion 220, the rigidity of the portions provided with the
rib 221 and the low pressure side convex portion 222 is higher as
the concave portion 220 is shallower. On the other hand, the rib
221 and the low pressure side convex portion 222 become abraded due
to sliding; hence the depth of the concave portion 220 becomes
shallower over time. Accordingly, when the depth of the concave
portion 220 becomes excessively shallow, a fluid may not be
introduced. To cope with this, it is preferable to set the initial
depth of the concave portion 220 in consideration of both of the
rigidity and maintaining the introduction of the fluid even when
the temporal wear progresses. For example, in the case where the
thickness of the seal ring 200 is 1.7 mm, the depth of the concave
portion 220 is preferably set to 0.1 mm or more and 0.3 mm or less,
approximately. With regard to the width of the concave portion 220
(the width in the axial direction), the width of the low pressure
side convex portion 222 becomes narrower as the width of the
concave portion 220 is made wider. Although a torque can be reduced
more as the width is set narrower, sealing performance and
durability may be degraded if the width is set excessively narrow.
To cope with this, it is desirable to reduce the width as much as
possible to the extent that the sealing performance and the
durability can be maintained in accordance with a use environment
or the like. For example, in the case where the overall length of
the width of the seal ring 200 (the width in the axial direction)
is 1.9 mm, the width of the low pressure side convex portion 222 is
preferably set to 0.3 mm or more and 0.7 mm or less, approximately.
In addition, the width of the rib 221 in the circumferential
direction is preferably set to 0.3 mm or more and 0.7 mm or less,
approximately.
[0106] <Mechanism During Use of Sealing Device>
[0107] With reference to FIGS. 17 to 19, in particular, the
mechanism during use of the sealing device 100 according to the
present example will be described. Each of FIGS. 17 and 18 shows a
no-load condition in which there is no pressure difference (or
there is almost no pressure difference) between the left and right
areas separated by the sealing device 100, after the engine has
stopped. Note that FIG. 17 is a schematic cross-sectional view (a
cross-sectional view including the axis of the shaft 400) of a
portion provided with the concave portion 220 on the seal ring 200,
and FIG. 18 is a schematic cross-sectional view (a cross-sectional
view including the axis of the shaft 400) of a portion provided
with the rib 221 on the seal ring 200. The seal ring 200 in FIG. 17
corresponds to a CC cross section in FIG. 13, and the seal ring 200
in FIG. 18 corresponds to a DD cross section in FIG. 13. FIG. 19
shows a condition in which the engine is started, and the fluid
pressure in the right area is increased and became higher than the
fluid pressure in the left area separated by the sealing device
100. Note that FIG. 19 is a schematic cross-sectional view (a
cross-sectional view including the axis of the shaft 400) of the
portion provided with the concave portion 220 on the seal ring 200.
The seal ring 200 in FIG. 19 corresponds to the CC cross section in
FIG. 13.
[0108] In a state in which the sealing device 100 is attached to
the annular groove 410, the metal spring 300 exhibits the function
of pressing the seal ring 200 towards the outer peripheral surface
side by its own expansive force. Consequently, portions of the
outer peripheral surface of the seal ring 200 except for the
concave portions 220, namely portions provided with the rib 221 and
the low pressure side convex portion 222 maintain contact with the
inner peripheral surface of the shaft hole of the housing 500.
[0109] In a condition in which the engine is started and the
pressure difference is created, as shown in FIG. 19, the seal ring
200 is in a state in which it is in close contact with the side
wall surface on the low pressure side (L) of the annular groove 410
by the fluid pressure from the high pressure side (H). Note that it
goes without saying that the seal ring 200 maintains a state in
which it is in contact with (it slides against) the inner
peripheral surface of the shaft hole of the housing 500.
[0110] <Advantages of the Sealing Device According to the
Present Example>
[0111] According to the sealing device 100 of the present example,
the seal ring 200 is pressed towards the outer peripheral surface
side by the metal spring 300. Accordingly, even in a condition in
which the fluid pressure is not applied (the pressure difference is
not created), or the fluid pressure is almost not applied (the
pressure difference is almost not created), the seal ring 200 is in
contact with the inner peripheral surface of the shaft hole of the
housing 500. Note that an annular continuous sealing surface is
formed by the outer peripheral surface of the rib 221, the outer
peripheral surface of the low pressure side convex portion 222, and
the outer peripheral surface of the portion in the vicinity of the
abutment portion 210 where the concave portion 220 is not formed.
Accordingly, as long as the seal ring 200 maintains a state in
which it is in close contact with the side wall surface on the low
pressure side (L) of the annular groove 410, the sealing function
is exhibited. Consequently, it is possible to hold the fluid
pressure from immediately after the start of increase of the fluid
pressure in the sealing target area. That is, as for an engine
having an idling stop function, it is possible to hold the
hydraulic pressure from immediately after the start of increase of
hydraulic pressure on the sealing target area side when the engine
is started by releasing a brake pedal or pressing an accelerator
pedal from an engine stop condition.
[0112] Generally speaking, in a case of a seal ring made of resin,
a function of suppressing leakage of a fluid is not exhibited so
well. However, in the present example, because the seal ring 200 is
pressed towards the outer peripheral surface side by the metal
spring 300, the function of suppressing the leakage of the fluid is
exhibited to a certain extent. Accordingly, it becomes possible to
maintain the state in which the pressure difference is present for
a while even after an action of a pump or the like has stopped due
to the stop of the engine. Consequently, in the engine having the
idling stop function, in a case where a period of the engine
stopping state is not too long, it is possible to maintain the
state in which the pressure difference is present; hence, when the
engine is re-started, it is possible to suitably hold the fluid
pressure from immediately after the re-start.
[0113] In a condition in which considerable time has elapsed since
the stop of the engine, the fluid pressure no longer acts (the
pressure difference becomes zero). In this case, the seal ring 200
may move away from the side wall surface of the annular groove 410
(the side wall surface on the low pressure side (L) when the
pressure difference is present). Accordingly, the leakage of the
fluid may occur. However, as described above, in the case where the
period of the engine stop state is not too long, it is possible to
maintain the condition in which the pressure difference is present;
hence it is possible to maintain the state in which the seal ring
200 is in close contact with the side wall surface on the low
pressure side (L) of the annular groove 410. Consequently, even in
a low-load condition, the function of suppressing the leakage of
the fluid is exhibited.
[0114] In addition, a plurality of the concave portions 220 are
formed on the outer peripheral surface of the seal ring 200, and
the fluid is introduced into a plurality of the concave portions
220 from the high pressure side (H). Accordingly, even when the
fluid pressure is increased, the fluid pressure acts towards the
inner peripheral surface side in the region provided with the
concave portions 220. Note that arrows in FIG. 19 show a state in
which the fluid pressure is acting on the seal ring 200. With this,
in the sealing device 100 according to the present example, it is
possible to suppress the increase of the pressure towards the outer
peripheral surface side by the seal ring 200 due to the increase of
the fluid pressure, thereby making it possible to suppress the
sliding torque.
[0115] In addition, since a plurality of the concave portions 220
are formed at intervals in the circumferential direction, the
portion (the rib 221) between two concave portions 220 makes
contact with the inner peripheral surface of the shaft hole of the
housing 500. Further, by providing a plurality of the ribs 221, it
is possible to suppress a degradation in the rigidity of the seal
ring 200 as compared with a case where the ribs 221 are not
provided. Consequently, it is possible to prevent the seal ring 200
from being tilted within the annular groove 410, and stabilize an
attachment state of the seal ring 200. Note that, in a case where a
configuration is adopted in which a plurality of the ribs 221 is
not provided, it is anticipated that the seal ring 200 may be
tilted in counter-clockwise direction in FIGS. 17 to 19.
[0116] In addition, in the present example, the concave portions
220 are formed over the entire periphery except in the vicinity of
the abutment portion 210 and the portions provided with a plurality
of the ribs 221 with a short length in the circumferential
direction, and are formed so as to extend from the end portion on
the high pressure side (H) to the vicinity of the end portion on
the low pressure side (L). As described, in the present example, by
providing the concave portions 220 over a large area of the outer
peripheral surface of the seal ring 200, it is possible to reduce a
sliding area between the seal ring 200 and the inner peripheral
surface of the shaft hole of the housing 500 as much as possible,
thereby significantly reducing the sliding torque. Note that the
sliding area between the seal ring 200 and the inner peripheral
surface of the shaft hole of the housing 500 is sufficiently
smaller than a contact area between the seal ring 200 and the side
wall surface on the low pressure side (L) of the annular groove
410. With this configuration, it is possible to prevent the seal
ring 200 from sliding relative to the side wall surface on the low
pressure side (L) of the annular groove 410. Consequently, in the
seal ring 200 according to the present example, because it is the
outer peripheral surface side that is sliding, a lubricating film
made of a sealing target fluid (an oil film in the present example)
is formed more easily as compared with a case where the sealing
ring slides against the side wall surface of the annular groove;
hence it becomes possible to further reduce the sliding torque.
[0117] As described, since it is possible to realize the reduction
of sliding torque, it becomes possible to suppress the generation
of heat due to sliding; hence it becomes possible to suitably use
the sealing device 100 according to the present example even under
high-speed and high-pressure environmental conditions.
[0118] Further, in the present example, since the metal spring 300
is provided so as to extend along the inner peripheral surface of
the seal ring 200 in a state in which a gap is formed between the
metal spring 300 and the groove bottom surface of the annular
groove 410, the metal spring 300 is hardly influenced by
eccentricity of the shaft 400 and the housing 500. In addition, the
seal ring 200 and the metal spring 300 do not rotate relative to
each other. Consequently, the seal ring 200 and the metal spring
300 do not slide relative to each other; hence the inner peripheral
surface side of the seal ring 200 would not be abraded due to
sliding.
[0119] In the present example, the guide protrusions 231 and 232
are provided on the inner peripheral surface of the seal ring 200
as the guide portions that position the metal spring 300 in the
axial direction. Consequently, the seal ring 200 is stably pressed
towards the outer peripheral surface side by the metal spring
300.
[0120] In addition, in the present example, a configuration is
adopted in which the first protrusions 231a and 232a which prevent
the metal spring 300 from being detached to the inner peripheral
surface side are provided at the tips of the guide protrusion 231
and 232. Consequently, it becomes possible to prevent the metal
spring 300 from being detached from the seal ring 200 at a time
when the seal ring 200 with the metal ring 300 attached thereto is
being fitted into the annular groove 410 or in a case where
disturbances or the like due to a pressure fluctuation occurred
during transportation or usage.
[0121] In addition, in the present example, a configuration is
adopted in which the second protrusions 233 which restrict a
movement of the metal spring 300 in the circumferential direction
are provided on the inner peripheral surface on both sides of the
abutment portion 210 of the seal ring 200. Consequently, it becomes
possible to prevent positional displacement of the metal spring 300
relative to the seal ring 200 in the circumferential direction.
Accordingly, it becomes possible to exercise a stable sealing
performance.
[0122] (Modification of Seal Ring)
[0123] In the above example, the case has been described where a
plurality of the concave portions 220 are provided at intervals in
the circumferential direction on the outer peripheral surface of
the seal ring 200 and the rib 221s between the neighboring concave
portions 220 are configured to extend in the axial direction.
However, the arrangement configuration of the concave portions 220
and the ribs 221 is not limited to such configuration.
[0124] For example, as shown by a first modification in FIG. 20, a
plurality of ribs 221a may be provided such that they extend form
the low pressure side (L) to the high pressure side (H) as they
advance in a sliding direction of the seal ring 200 with respect to
the housing 500 (a direction of arrow R in FIG. 20). In this case,
the fluid introduced into concave portions 220a due to the relative
rotation of the housing 500 and the seal ring 200 flows from the
high pressure side (H) to the low pressure side (L) and in a
sliding direction of the housing 500 with respect to the seal ring
200 aggressively (the fluid flows in a direction of arrow X in FIG.
20).
[0125] Accordingly, within the concave portion 220a, the flow of
the fluid converges in the vicinity of a wedge-shaped apex formed
by the low pressure side convex portion 222 and the rib 221a. As
dynamic pressure is created by the convergence of the flow of the
fluid, the seal ring 200 is pressed towards the inner peripheral
surface side. Consequently, with the help of the dynamic pressure
as well, it becomes possible to suppress the increase of the
pressure towards the outer peripheral surface side by the seal ring
200, thereby making it possible to suppress the sliding torque.
Note that the first modification can be applied to any of the above
described first and second examples, and the modification of the
first example.
[0126] In addition, as shown by a second modification in FIG. 21, a
plurality of ribs 221b may be provided such that they extend form
the high pressure side (H) to the low pressure side (L) as they
advance in a sliding direction of the seal ring 200 with respect to
the housing 500 (a direction of arrow R in FIG. 21). In this case,
the fluid introduced into concave portions 220b due to the relative
rotation of the housing 500 and the seal ring 200 flows from the
low pressure side (L) to the high pressure side (H) and in a
sliding direction of the housing 500 with respect to the seal ring
200 aggressively (the fluid flows in a direction of arrow X in FIG.
21).
[0127] As described, the relative rotation of the housing 500 and
the seal ring 200 forces the fluid introduced into the concave
portions 220b to return to the high pressure side (H).
Consequently, a leakage of the fluid can be suppressed. Note that
the second modification can be applied to any of the above
described first and second examples, and the modification of the
first example.
[0128] In addition, as shown by a third modification in FIG. 22, a
convex portion 222b may be provided on the outer peripheral surface
of the seal ring 200 such that the convex portion 222b extends in a
circumferential direction, while it also extends to the high
pressure side (H) and the low pressure side (L) alternately such
that it extends to positions that reach one end face in a width
direction and positions that reach another end face in the width
direction. More specifically, the convex portion 222b is configured
such that it serpentines in the circumferential direction to form a
wave shape.
[0129] With the provision of the convex portion 222b, a plurality
of concave portions 220c and 220d are formed at intervals in the
circumferential direction on both of the high pressure side (H) and
the low pressure side (L) of the outer peripheral surface of the
seal ring 200, respectively. The concave portions 220c on the high
pressure side (H) are configured so as to extend from an end
portion on the high pressure side (H) to a position which does not
reach an end portion on the low pressure side (L), and exhibit a
function to introduce the fluid from the high pressure side
(H).
[0130] The convex portion 222b formed on the outer peripheral
surface of the seal ring 200 according to the present modification
is formed such that it extends in the circumferential direction
while switching the positions on the high pressure side (H) and the
low pressure side (L) alternately. Accordingly, a position on the
outer peripheral surface of the seal ring 200 that slides against
the shaft hole of the housing 500 would not be biased on the high
pressure side (H) or the low pressure side (L). Consequently, it
becomes possible to prevent the seal ring 200 from being tilted
within the annular groove 410, and stabilize the attachment state
of the seal ring 200.
[0131] In addition, the plurality of concave portions 220c are
formed on the outer peripheral surface of the seal ring 200, and
the fluid is introduced into the plurality of concave portions 220c
from the high pressure side (H). Accordingly, even when the fluid
pressure is increased, the fluid pressure acts towards the inner
peripheral surface side in the region provided with the concave
portions 220c. With this, in the present modification as well, it
is possible to suppress the increase of the pressure towards the
outer peripheral surface side by the seal ring 200 due to the
increase of the fluid pressure, thereby making it possible to
suppress the sliding torque.
[0132] Furthermore, the seal ring 200 according to the present
modification has a structure that is symmetrical with respect to a
central plane in the width direction (axial direction).
Consequently, it is not necessary to check an attachment direction
when attaching the seal ring 200, hence superior in attachability.
In addition, it can be applied under a condition in which the high
pressure side (H) and the low pressure side (L) alternate. Note
that the third modification can be applied to any of the above
described first and second examples, and the modification of the
first example.
[0133] In addition, as shown by a fourth modification in FIG. 23, a
convex portion 222c may be provided on the outer peripheral surface
of the seal ring 200 such that the convex portion 222c extends in a
circumferential direction, while it also extends to the high
pressure side (H) and the low pressure side (L) alternately such
that it reaches positions that reach one end face in a width
direction and positions that reach another end face in the width
direction. However, in the fourth modification, unlike with the
above described third modification, the convex portion 222c is
configured so as to form a rectangular wave shape in the
circumferential direction.
[0134] With the provision of the convex portion 222c, a plurality
of concave portions 220e and 220f are formed at intervals in the
circumferential direction on both of the high pressure side (H) and
the low pressure side (L) of the outer peripheral surface of the
seal ring 200, respectively. The concave portions 220e on the high
pressure side (H) are configured so as to extend from an end
portion on the high pressure side (H) to a position which does not
reach an end portion on the low pressure side (L), and exhibit a
function to introduce the fluid from the high pressure side
(H).
[0135] It goes without saying that, also in the fourth
modification, the same effects as those in the case of the third
modification can be achieved. Note that the fourth modification can
be applied to any of the above described first and second examples,
and the modification of the first example.
[0136] In addition, as shown by a fifth modification in FIG. 24, a
convex portion 222d may be provided on the outer peripheral surface
of the seal ring 200 such that the convex portion 222d extends in a
circumferential direction, while it also extends to the high
pressure side (H) and the low pressure side (L) alternately such
that it reaches positions that reach one end face in a width
direction and positions that reach another end face in the width
direction. However, in the fifth modification, unlike with the
above described third modification, the convex portion 222d is
configured so as to form a triangular wave shape in the
circumferential direction.
[0137] With the provision of the convex portion 222d, a plurality
of concave portions 220g and 220h are formed at intervals in the
circumferential direction on both of the high pressure side (H) and
the low pressure side (L) of the outer peripheral surface of the
seal ring 200, respectively. The concave portions 220g on the high
pressure side (H) are configured so as to extend from an end
portion on the high pressure side (H) to a position which does not
reach an end portion on the low pressure side (L), and exhibit a
function to introduce the fluid from the high pressure side
(H).
[0138] It goes without saying that, also in the fifth modification,
the same effects as those in the case of the third modification can
be achieved. Note that the fifth modification can be applied to any
of the above described first and second examples, and the
modification of the first example.
[0139] In addition, as described in the above examples, the reason
for providing the plurality of concave portions 220 in the
circumferential direction to provide the rib 221 between the two
concave portions 220 is to prevent the seal ring from being tilted
within the annular groove 410.
[0140] However, as shown by a sixth modification in FIG. 25, the
tilting of the seal ring 200 may be prevented by providing, on the
outer peripheral surface of the seal ring 200, one concave portion
220 over the entire periphery except in the vicinity of the
abutment portion 210, and not only the low pressure side convex
portion 222 but also a high pressure side convex portion 222a on
the high pressure side. However, as for the high pressure side
convex portion 222a, it is necessary to ensure a gap S between the
high pressure side convex portion 222a and the inner peripheral
surface of the shaft hole of the housing 500 by making the
protrusion amount thereof smaller than that of the low pressure
side convex portion 222. By securing the gap S in this manner, it
becomes possible to introduce the fluid into the concave portion
220. Note that, similar to the low pressure side convex portion
222, the high pressure side convex portion 222a may be provided
over the entire periphery except in the vicinity of the abutment
portion 210 of the seal ring 200, or a plurality of the convex
portions 222a may be provided at intervals in the circumferential
direction. Note that the sixth modification can be applied to any
of the above described first and second examples, and the
modification of the first example.
[0141] (Others)
[0142] In the above second example, the case is shown in which the
guide protrusions 231 and 232 provided with the first protrusions
231a and 232a respectively, and the second protrusions are all
provided on the inner peripheral surface of the seal ring 200.
[0143] However, following configurations may be adopted depending
on the usage environments. That is, one configuration may be
adopted in which the guide protrusions 231 and 232 provided with
the first protrusions 231a and 232a respectively are formed on the
inner periphery of the seal ring 200, whereas the second
protrusions 233 are not. In addition, another configuration may be
adopted in which the second protrusions 233 are formed on the inner
periphery of the seal ring 200, whereas the guide protrusions 231
and 232 are not. Furthermore, yet another configuration may be
adopted in which the guide protrusions 231 and 232 without the
first protrusions 231a and 232a, and the second protrusions 233 are
formed on the inner periphery of the seal ring 200.
Third Example
[0144] In FIGS. 26 to 31, a third example according to the present
invention is shown. In the present example, basic configuration and
operations thereof are the same as those in the second example;
hence the same constituent parts are designated by the same
reference numerals, and the description thereof is omitted as
appropriate.
[0145] <Configuration of Sealing Device>
[0146] With reference to FIGS. 26 and 18 to 31, in particular, the
configuration of the sealing device according to the third example
of the present invention will be described. A sealing device 100
according to the present example is attached to an annular groove
410 provided on an outer periphery of a shaft 400, and seals an
annular gap between the shaft 400 and a housing 500 (an inner
peripheral surface of a shaft hole in the housing 500 through which
the shaft 400 is inserted) which rotate relative to each other.
With this, the sealing device 100 holds a fluid pressure in a
sealing target area configured such that the fluid pressure (a
hydraulic pressure in the present example) changes. Herein, in the
present example, the fluid pressure in the right area in FIG. 31 is
configured to change, and the sealing device 100 plays a role in
holding the fluid pressure in the sealing target area on the right
in the drawing. Note that, in a condition in which an engine of an
automobile is stopped, the fluid pressure in the sealing target
area is low and a no-load condition is created, and when the engine
is started, the fluid pressure in the sealing target area
increases.
[0147] The sealing device 100 according to the present example is
constituted of a seal ring 200 that is made of resin such as
polyetheretherketone (PEEK), polyphenylene sulfide (PPS), or
polytetrafluoroethylene (PTFE), and a metal spring 300. For the
metal spring 300 in the present example, a C-ring, in which a
cut-out is made at one place on an annular member in a
circumferential direction, is used.
[0148] In a state in which the seal ring 200 is combined with the
metal spring 300, the circumference of an outer peripheral surface
of the seal ring 200 is configured to be longer than the
circumference of the inner peripheral surface of the shaft hole of
the housing 500. Note that the circumference of the outer
peripheral surface of the seal ring 200 itself is configured to be
shorter than the circumference of the inner peripheral surface of
the shaft hole of the housing 500, and thus configured to have no
interference. Consequently, when the metal spring 300 is not
attached and an external force is not applied, the outer peripheral
surface of the seal ring 200 does not make contact with the inner
peripheral surface of the shaft hole of the housing 500.
[0149] <Seal Ring>
[0150] With reference to FIGS. 26 to 30, in particular, the seal
ring 200 according to the third example of the present invention
will be described in detail. Note that FIG. 28 is a partially
cutaway perspective view of the vicinity of an abutment portion of
the sealing device according to the present example. FIGS. 29 and
30 are schematic cross-sectional view of the seal ring 200
according to the present example. FIG. 29 is an AA cross section in
FIG. 27, and FIG. 30 is a BB cross section in FIG. 27. Note that,
in FIGS. 29 and 30, a position of the metal spring 300 in its
attachment state is depicted in dotted-lines.
[0151] On the seal ring 200, an abutment portion 210 is provided at
one position in a circumferential direction. In addition, a convex
portion 250 which extends in the circumferential direction is
provided at a center in a width direction on the outer peripheral
surface of the seal ring 200. A pair of concave portions 260 is
provided at both sides of the convex portion 250 in an axial
direction (a direction of a central axis of the shaft 400).
[0152] In addition, on an inner peripheral surface of the seal ring
200, guide protrusions 271 and 272 as guide portions which position
the metal spring 300 in the axial direction are provided. The guide
protrusions 271 and 272 are provided on a side of one of two side
surfaces of the seal ring 200 and on a side of another of the two
side surfaces thereof, respectively, so as to be provided on both
sides of the metal spring 300. A plurality of the guide protrusions
271 and 272 are provided at intervals in the circumferential
direction. Note that the guide protrusions 271 and 272 are provided
such that they protrude towards the inner peripheral surface
side.
[0153] In addition, first protrusions 271a and 272a which prevent
the metal spring 300 from being detached to the inner peripheral
surface side are provided at a tip of the guide protrusion 271 and
at a tip of the guide protrusion 272, respectively. The first
protrusions 231a and 232a are provided such that they protrude in
the axial direction and towards the inner peripheral surface
side.
[0154] Further, second protrusions 273 which restrict a movement of
the metal spring 300 in the circumferential direction are provided
on the inner peripheral surface on both sides of the abutment
portion 210 of the seal ring 200. Herein, the second protrusion 233
in the above described second example is configured so as to extend
in the axial direction, whereas the second protrusion 273 in the
present example is configured so as to have an engagement concave
portion 273a with which an end portion of the metal spring 300 is
engaged. However, also in the present example, a configuration that
is similar to the second protrusion 233 described in the second
example can be adopted.
[0155] Note that the seal ring 200 according to the present example
has the configuration in which the abutment portion 210, the convex
portion 250, the pair of concave portions 260, a plurality of the
guide protrusions 271 and 272 provided with the first protrusions
271a and 272a respectively, and the pair of second protrusions 273
are formed on an annular member having a rectangular cross section.
However, this is only a description of the shape, and this does not
necessarily mean that an annular member having the rectangular
cross section is used as a material and a process to form an
abutment portion 210, a convex portion 250, a pair of concave
portions 260, a plurality of guide protrusions 271 and 272 provided
with first protrusions 271a and 272a respectively, and a pair of
second protrusions 273 is applied on this material. As a matter of
course, it is also possible to form an abutment portion 210, a
convex portion 250, a pair of concave portions 260, a plurality of
guide protrusions 271 and 272 provided with first protrusions 271a
and 272a respectively, and a pair of second protrusions 273 by
applying a cutting-work after molding an annular member having a
rectangular cross section. However, for example, a convex portion
250 and a pair of concave portions 260 may be formed by applying a
cutting-work after a member having an abutment portion 210, a
plurality of guide protrusions 271 and 272 provided with first
protrusions 271a and 272a respectively, and a pair of second
protrusions 273 is molded in advance; hence production method is
not particularly limited.
[0156] As for the abutment portion 210, similar to the above
described first and second examples, so-called a special step cut
is employed in the present example as well in which the abutment
portion 210 is cut to have a step-like shape when viewed from each
of an outer peripheral surface side and both of side wall surface
sides. With respect to the abutment portion 210, since the
configuration thereof is similar to that in the first or second
example, the description thereof is omitted.
[0157] The pair of concave portions 260 is formed over the entire
periphery except in the vicinity of the abutment portion 210. A
portion in the vicinity of the abutment portion 260 where the
concave portion 260 is not formed, and an outer peripheral surface
of the convex portion 250 are in plane with each other.
Accordingly, an annular continuous sealing surface is formed on an
outer peripheral surface side of the seal ring 200. That is, on the
outer peripheral surface of the seal ring 200 and in a region
except for the vicinity of the abutment portion 210, only an outer
peripheral surface of the convex portion 250 slides against the
inner peripheral surface of the shaft hole.
[0158] As for a width of the convex portion 250, although a torque
can be reduced more as the width is set narrower, sealing
performance and durability may be degraded if the width is set
excessively narrow. To cope with this, it is desirable to reduce
the width as much as possible to the extent that the sealing
performance and the durability can be maintained in accordance with
a use environment or the like. For example, in the case where the
overall length of the width of the seal ring 200 (the width in the
axial direction) is 1.9 mm, the width of the convex portion 250 is
preferably set to 0.3 mm or more and 0.7 mm or less,
approximately.
[0159] <Mechanism During Use of Sealing Device>
[0160] With reference to FIG. 31, in particular, the mechanism
during use of the sealing device 100 according to the present
example will be described. FIG. 31 shows a condition in which the
engine is started, and the fluid pressure in the right area is
increased and became higher than the fluid pressure in the left
area separated by the sealing device 100. Note that the seal ring
200 in FIG. 31 corresponds to the CC cross section in FIG. 27.
[0161] In a state in which the sealing device 100 is attached to
the annular groove 410, the metal spring 300 exhibits the function
of pressing the seal ring 200 towards the outer peripheral surface
side by its own expansive force. Consequently, a portion of the
outer peripheral surface of the seal ring 200 except for the
concave portions 260, namely a portion provided with the convex
portion 250 maintains contact with the inner peripheral surface of
the shaft hole of the housing 500.
[0162] In a condition in which the engine is started and the
pressure difference is created, as shown in FIG. 31, the seal ring
200 is in a state in which it is in close contact with the side
wall surface on the low pressure side (L) of the annular groove 410
by the fluid pressure from the high pressure side (H). Note that it
goes without saying that the seal ring 200 maintains a state in
which it is in contact with (it slides against) the inner
peripheral surface of the shaft hole of the housing 500.
[0163] <Advantages of the Sealing Device According to the
Present Example>
[0164] Also in the sealing device 100 according to the present
example configured as described above, the same effects as those in
the case of the second example can be achieved.
[0165] Note that in the case of the sealing device 100 according to
the present example, among the pair of concave portions 260
provided on the seal ring 200, the fluid is introduced into the
concave portion 260 on the high pressure side (H) from the high
pressure side (H). Consequently, although a function of suppressing
the increase of the pressure towards the outer peripheral surface
side by the seal ring 200 due to the increase of the fluid pressure
may be inferior compared to the second example, the same effect as
that in the case of the second example can be achieved. Note that
arrows in FIG. 31 show a state in which the fluid pressure is
acting on the seal ring 200.
[0166] In addition, in the case of the seal ring 200 according to
the present example, since the shape thereof is symmetrical with
respect to a central plane in the width direction, it is not
necessary to check an attachment direction when attaching the seal
ring 200 to the annular groove 410. In addition, even under a
condition in which the high pressure side (H) and the low pressure
side (L) alternate, the advantageous effects as described above can
be exhibited.
Fourth Example
[0167] In FIG. 32, a fourth example according to the present
invention is shown. In the present example, a configuration is
described in which a plurality of ribs is further provided within
the pair of concave portions in the configuration of the above
described third example. Other configuration and operations thereof
are the same as those in the third example; hence the same
constituent parts are designated by the same reference numerals,
and the description thereof is omitted as appropriate.
[0168] The sealing device 100 according to the present example is
also constituted of a seal ring 200 that is made of resin and a
metal spring 300. The seal ring 200 according to the present
example also has an abutment portion 210, a convex portion 250, a
pair of concave portions 260, a plurality of guide protrusions 271
and 272 provided with first protrusions 271a and 272a respectively,
and a pair of second protrusions 273. Configurations of these are
the same as those of the seal ring in the third example; hence the
description thereof is omitted. Note that, although the guide
protrusion 272 and the second protrusion 273 described in the third
example are not depicted in FIG. 32, the seal ring 200 according to
the present example is also provided with them. In addition, as for
the abutment portion 210, although the case is described where the
special step cut is adopted in the present example as well, the
abutment portion 210 is not limited thereto as described in the
first and second examples.
[0169] In the present example, a plurality of ribs 251 that are
formed so as to be connected with the convex portion 250 are
provided within the pair of concave portions 260. The point that
the ribs 251 are further provided is the only difference from the
third example.
[0170] Also in the sealing device 100 according to the present
example configured as described above, the same effects as those in
the case of the sealing device 100 according to the third example
can be achieved. In addition, in the present example, since the
ribs 251 are provided, the rigidity of the sealing ring is high,
especially the strength in a torsion direction. Consequently, even
under a condition in which the pressure difference becomes large,
the deformation of the seal ring 200 is suppressed; hence the
sealing performance can be exhibited stably.
REFERENCE SIGNS LIST
[0171] 100: sealing device [0172] 200: seal ring [0173] 210:
abutment portion [0174] 211a: first engagement convex portion
[0175] 211b: second engagement convex portion [0176] 212a: first
engagement concave portion [0177] 212b: second engagement concave
portion [0178] 220, 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h:
concave portion [0179] 221, 221a, 221b: rib [0180] 222: low
pressure side convex portion [0181] 222a: high pressure side convex
portion [0182] 222b, 222c, 222d: convex portion [0183] 223, 224:
protrusion [0184] 225: groove [0185] 231, 232, 271, 272: guide
protrusion [0186] 231a, 232a, 271a, 272a: first protrusion [0187]
233, 273: second protrusion [0188] 250: convex portion [0189] 251:
rib [0190] 260: concave portion [0191] 273a: engagement concave
portion [0192] 400: shaft [0193] 410: annular groove [0194] 500:
housing
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