U.S. patent application number 14/407372 was filed with the patent office on 2015-07-30 for mechanical seal.
The applicant listed for this patent is EAGLE INDUSTRY CO., LTD.. Invention is credited to Masatoshi Itadani, Yoshihiro Ogawa, Takashi Shinomiya.
Application Number | 20150211638 14/407372 |
Document ID | / |
Family ID | 50435064 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150211638 |
Kind Code |
A1 |
Itadani; Masatoshi ; et
al. |
July 30, 2015 |
MECHANICAL SEAL
Abstract
To provide a mechanical seal in which degradation or tearing of
a bellows does not occur, the spring constant of the bellows is
reduced, and the fluctuation in the load due to stretching and
contracting of the bellows is reduced. An inside-type mechanical
seal includes a sleeve fixed to a rotating shaft, and a cartridge
fixed to a housing. A rotation-side sealing ring is provided to the
sleeve. A fixed-side sealing ring, which slides against the
rotation-side sealing ring, and a bellows for axially urging the
fixed-side sealing ring is provided to the cartridge. The bellows
is made from a metal; and the metal bellows has one end fixed to a
case for holding the fixed-side sealing ring and another end fixed
to the cartridge. The plate thickness of the metal bellows is set
so as to be smaller than the plate thickness of the case or the
cartridge.
Inventors: |
Itadani; Masatoshi; (Tokyo,
JP) ; Shinomiya; Takashi; (Tokyo, JP) ; Ogawa;
Yoshihiro; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EAGLE INDUSTRY CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
50435064 |
Appl. No.: |
14/407372 |
Filed: |
October 3, 2013 |
PCT Filed: |
October 3, 2013 |
PCT NO: |
PCT/JP2013/076968 |
371 Date: |
December 11, 2014 |
Current U.S.
Class: |
277/367 |
Current CPC
Class: |
F16J 15/348 20130101;
F16J 15/34 20130101; F16J 15/38 20130101; F16J 15/3452 20130101;
F16J 15/363 20130101; F16J 15/3448 20130101 |
International
Class: |
F16J 15/34 20060101
F16J015/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 4, 2012 |
JP |
2012-222233 |
Claims
1. An inside-type mechanical seal comprising a sleeve fixed to a
rotating shaft, and a cartridge fixed to a housing; a rotation-side
sealing ring being provided to said sleeve; and a fixed-side
sealing ring, which slides against said rotation-side sealing ring,
and a bellows for axially urging the fixed-side sealing ring, being
provided to said cartridge; wherein: said bellows is made from a
metal; and said metal bellows has one end fixed to a case for
holding said fixed-side sealing ring and another end fixed to said
cartridge, the plate thickness of said metal bellows being set so
as to be smaller than the plate thickness of said case or said
cartridge.
2. The mechanical seal according to claim 1, wherein: said metal
bellows comprises a bellows part in which crest parts and trough
parts are alternately formed, and a disc-shaped flange part
extending radially outwards from said trough part at each end of
the bellows part; and said bellows part is formed by molding or
welding so that the outer diameter of said flange parts is greater
than the diameter of said crest parts, and the inner diameter of
said flange parts is substantially the same as or slightly larger
than the diameter of said trough parts.
3. The mechanical seal according to claim 1, wherein the fixing of
said metal bellows to the metal case and the metal cartridge is
performed by welding or fusing at each position located slightly
further towards the inner diameter side relative to the outer
diameter of said flange part of said metal bellows.
4. The mechanical seal according to claim 1, wherein said
rotation-side sealing ring is fixed to said sleeve via a cup
gasket, and said cup gasket is provided across an outer
circumferential surface and a side opposite the sealing face of
said rotation-side sealing ring.
5. An inside-type mechanical seal comprising a sleeve fixed to a
rotating shaft, and a cartridge fixed to a housing; a rotation-side
sealing ring being provided to said sleeve; and a fixed-side
sealing ring, which slides against said rotation-side sealing ring,
and a bellows for axially urging the fixed-side sealing ring, being
provided to said cartridge; wherein: said bellows is made from a
metal; and said metal bellows has one end fixed to a gasket for
holding said fixed-side sealing ring and another end fixed to said
cartridge, the plate thickness of the metal bellows being set so as
to be smaller than the plate thickness of said cartridge.
6. The mechanical seal according to claim 5, wherein a band is
attached on an outer circumference of an outer cylinder part of
said metal bellows fitting into said gasket holding said fixed-side
sealing ring.
7. An inside-type mechanical seal comprising a sleeve fixed to a
rotating shaft, and a cartridge fixed to a housing; a rotation-side
sealing ring being provided to said sleeve; and a fixed-side
sealing ring, which slides against said rotation-side sealing ring,
and a bellows for axially urging the fixed-side sealing ring, being
provided to said cartridge; wherein: said bellows is made from a
metal; and said metal bellows has one end directly fixed to said
fixed-side sealing ring and another end fixed to said cartridge,
the plate thickness of the metal bellows being set so as to be
smaller than the plate thickness of said cartridge.
8. The mechanical seal according to claim 1, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
9. The mechanical seal according to claim 2, wherein the fixing of
said metal bellows to the metal case and the metal cartridge is
performed by welding or fusing at each position located slightly
further towards the inner diameter side relative to the outer
diameter of said flange part of said metal bellows.
10. The mechanical seal according to claim 2, wherein said
rotation-side sealing ring is fixed to said sleeve via a cup
gasket, and said cup gasket is provided across an outer
circumferential surface and a side opposite the sealing face of
said rotation-side sealing ring.
11. The mechanical seal according to claim 3, wherein said
rotation-side sealing ring is fixed to said sleeve via a cup
gasket, and said cup gasket is provided across an outer
circumferential surface and a side opposite the sealing face of
said rotation-side sealing ring.
12. The mechanical seal according to claim 2, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
13. The mechanical seal according to claim 3, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
14. The mechanical seal according to claim 4, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
15. The mechanical seal according to claim 5, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
16. The mechanical seal according to claim 6, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
17. The mechanical seal according to claim 7, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
18. The mechanical seal according to claim 9, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
19. The mechanical seal according to claim 10, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
20. The mechanical seal according to claim 11, being of a type in
which a distal end of an inner cylinder part of said sleeve is
expanded in diameter by crimping and caused to engage with an inner
cylinder part of said cartridge, thereby preventing said cartridge
and said sleeve from axial detachment, wherein: a portion of the
inner cylinder part of said cartridge located on the opposite
axial-direction side relative to said fixed-side sealing ring side
is expanded in diameter and provided with a stepped part; and said
bellows is formed so that the inner diameter of a portion
positioned on the fixed-side sealing ring side relative to the
stepped part of the inner cylinder part of said cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of said cartridge.
Description
TECHNICAL FIELD
[0001] The present invention relates to a mechanical seal used,
e.g., as a shaft-sealing device in a pump or the like.
BACKGROUND ART
[0002] One conventionally known type of a mechanical seal is, as
shown in FIG. 7, an inside-format mechanical seal in which a sealed
fluid that may leak from the outer circumference of a sealing face
to the inner circumference direction is sealed, wherein: an annular
rotation-side sealing ring 53 provided, via a sleeve 51 and a cup
gasket 52, on the side of a rotating shaft 50 for driving a pump
impeller (not shown) on the high-pressure fluid-side, so as to be
capable of rotating integrally with the rotating shaft 50; and an
annular fixed-side sealing ring 55 provided, via a bellows 57 in a
cartridge 56, to a housing 54 Document of the pump in a
non-rotating state so as to be capable of axial movement, are
caused by the bellows 57 and a coiled wave spring 58 axially urging
the fixed-side sealing ring 55 to slide against each other in
intimate contact at respective sealing faces S which have been
mirror-surface-finished by lapping or the like (hereafter referred
to as "prior art 1"; see, e.g., Patent Document 1). The bellows 57
in the mechanical seal in this prior art is made from rubber, and
has one end attached to the fixed ring 55 via a case 59 and the
other end attached to a cartridge inner cylinder part 56 via a
driving band 60.
[0003] Patent Document 2 discloses an invention of a mechanical
seal in which, as shown in FIG. 8, a fixed-side sealing ring 62 is
attached to a housing 61, a rotation-side sealing ring 63 is
provided to a shaft which is rotatably supported by the housing 61,
and the fixed-side sealing ring 62 and the rotation-side sealing
ring 63 are in elastic contact with each other so as to be capable
of sliding, wherein a fixing claw 64a is formed on the right end of
a metal bellows 64 so that the metal bellows 64 supports the
fixed-side sealing ring 62 so as to be capable of axial movement,
the fixing claw 64a is bent and the fixed-side sealing ring 62 is
supported at the right-end interior of the metal bellows 64, and
the left end of the metal bellows 64 is directly fixed to the
housing 61 (hereafter referred to as "prior art 2"; see Patent
Citation 2).
[0004] However, in prior art 1, the bellows 57 being made from
rubber presents problems such as degradation or tearing of the bent
part. Problems are also presented in that an urging member such as
the coiled wave spring 58 and an attaching member such as the
driving band 60 are required, increasing the number of
components.
[0005] In prior art 2, since the structure is one in which the
fixed ring 62 is directly supported by the metal bellows 64 and the
metal bellows 64 is directly fixed to the housing 61 such that the
metal bellows 64 functions also as a cartridge, a problem is
presented in that the metal bellows 64 must have the same thickness
as that of a cartridge or a case, resulting in an increase in the
spring constant of the metal bellows 64.
PRIOR ART DOCUMENTS
Patent Documents
[0006] Patent Document 1: Japanese Laid-Open Patent Application No.
2000-74226 (page 3, FIG. 2) [0007] Patent Document 2: Japanese
Patent No. 2956862 (page 5, FIG. 5)
SUMMARY OF INVENTION
Problems to be Solved by the Invention
[0008] The present invention was devised in order to resolve the
problems presented by the prior art, it being an object thereof to
provide a mechanical seal in which degradation or tearing of a
bellows does not occur, the spring constant of the bellows is
reduced, and the fluctuation in the load due to stretching and
contracting of the bellows is reduced. In addition, assembly of [a
mechanical seal] through integrating the rotation-side and the
fixed-side normally necessitates increasing the inside diameter of
the bellows in order to secure sufficient space, which changes the
pressure-receiving area of the bellows and results in a fluctuation
in the balance value; an object of the present invention is to
provide a mechanical seal in which the fluctuation in the balance
value in such an instance is minimized.
Means for Solving the Problem
[0009] In order to achieve the following objects, first, a
mechanical seal according to the present invention is an
inside-type mechanical seal comprising a sleeve fixed to a rotating
shaft, and a cartridge fixed to a housing; a rotation-side sealing
ring being provided to said sleeve; and a fixed-side sealing ring,
which slides against the rotation-side sealing ring, and a bellows
for axially urging the fixed-side sealing ring, being provided to
the cartridge; the mechanical seal being characterized in that: the
bellows is made from a metal; and the metal bellows has one end
fixed to a case for holding the fixed-side sealing ring and another
end fixed to the cartridge, the plate thickness of the metal
bellows being set so as to be smaller than the plate thickness of
the case or the cartridge. According to this characteristic, the
metal bellows exclusively plays a role of axially urging the
fixed-side sealing ring, and is formed as a separate body with
respect to the case, the cartridge, or the like. Therefore, the
plate thickness of the metal bellows can be reduced, the spring
constant of the metal bellows can be reduced, and a change in load
with respect to the amount of stretching and contracting of the
metal bellows can be reduced. Therefore, even when the
rotation-side sealing ring is axially displaced, the axial urging
force on the fixed-side sealing ring can be kept stable, and the
pressure at the sealing face can be maintained at an optimum value.
In addition, the tolerance of the length of attachment of the metal
bellows can be relaxed. In addition, using a metal bellows instead
of a conventional rubber bellows prevents degradation or tearing of
the bellows and makes it possible to increase the lifespan. Also,
the number of components for attachment can be reduced compared to
instances in which a rubber bellows is used. Furthermore, the
spring constant of the bellows can be freely set by the material,
the plate thickness, or the number of crests. Also, the balance
value can be set to an optimum value.
[0010] Second, a mechanical seal according to the first aspect of
the present invention is characterized in that: the metal bellows
comprises a bellows part in which crest parts and trough parts are
alternately formed, and a disc-shaped flange part extending
radially outwards from the trough part at each end of the bellows
part; and the bellows part is formed by molding or welding so that
the outer diameter of the flange parts is greater than the diameter
of the crest parts, and the inner diameter of the flange parts is
substantially the same as or slightly larger than the diameter of
the trough parts. According to this characteristic, it is possible
to easily fix the metal bellows to the case and the cartridge and
to prevent the sealed fluid from leaking.
[0011] Third, a mechanical seal according to the first or second
aspect of the present invention is characterized in that: fixing of
the metal bellows to the metal case and the metal cartridge is
performed by welding or fusing at each position located slightly
further towards the inner diameter side relative to the outer
diameter of the flange part of the metal bellows. According to this
characteristic, it is possible for the inner circumferential part
of the flange part of the metal bellows to separate from the case
and the cartridge, and it is possible to obtain a stable sealing
performance and excellent tracking performance with respect to the
eccentricity of the rotating shaft. In addition, the metal bellows
can be fixed in a reliable manner without using a special
attachment member.
[0012] Fourth, a mechanical seal according to any of the first
through third aspects of the present invention is characterized in
that the rotation-side sealing ring is fixed to the sleeve via a
cup gasket, and the cup gasket is provided across an outer
circumferential surface and a side opposite the sealing face of the
rotation-side sealing ring. According to this characteristic, it is
possible to prevent the cup gasket from detaching, even when the
pressure of a high-pressure fluid acts on the outer circumferential
surface of the cup gasket.
[0013] Fifth, a mechanical seal of the present invention is an
inside-type mechanical seal comprising a sleeve fixed to a rotating
shaft, and a cartridge fixed to a housing; a rotation-side sealing
ring being provided to the sleeve; and a fixed-side sealing ring,
which slides against the rotation-side sealing ring, and a bellows
for axially urging the fixed-side sealing ring, being provided to
the cartridge; the mechanical seal being characterized in that:
[0014] the bellows is made from a metal; and
[0015] the metal bellows has one end fixed to a gasket for holding
the fixed-side sealing ring and another end fixed to the cartridge,
the plate thickness of the metal bellows being set so as to be
smaller than the plate thickness of the cartridge.
[0016] According to this characteristic, the metal bellows is
formed so as to also function as a case, making it possible to
reduce the number of components and reduce the number of welded
locations.
[0017] Sixth, a mechanical seal according to the fifth aspect of
the present invention is characterized in that a band is attached
on an outer circumference of an outer cylinder part of the metal
bellows fitting into the gasket holding the fixed-side sealing
ring. This characteristic makes it possible for the fitting between
the metal bellows and the cup gasket to be made more reliable.
[0018] Seventh, a mechanical seal of the present invention is an
inside-type mechanical seal comprising a sleeve fixed to a rotating
shaft, and a cartridge fixed to a housing; a rotation-side sealing
ring being provided to the sleeve; and a fixed-side sealing ring,
which slides against the rotation-side sealing ring, and a bellows
for axially urging the fixed-side sealing ring, being provided to
the cartridge; the mechanical seal being characterized in that: the
bellows is made from a metal; and the metal bellows has one end
directly fixed to the fixed-side sealing ring and another end fixed
to the cartridge, the plate thickness of the metal bellows being
set so as to be smaller than the plate thickness of the cartridge.
According to this characteristic, it is possible to reduce the
number of components and reduce the axial length of the mechanical
seal. Alternatively, instead of reducing the axial length of the
mechanical seal, it is also possible to increase the number of
crests of the metal bellows.
[0019] Eighth, a mechanical seal according to any of first through
seventh aspects of the present invention is characterized in being
of a type in which a distal end of an inner cylinder part of the
sleeve is expanded in diameter by crimping and caused to engage
with an inner cylinder part of the cartridge, thereby preventing
the cartridge and the sleeve from axial detachment, wherein:
[0020] a portion of the inner cylinder part of the cartridge
located on the opposite axial-direction side relative to the
fixed-side sealing ring side is expanded in diameter and provided
with a stepped part; and
[0021] the bellows is formed so that the inner diameter of a
portion positioned on the fixed-side sealing ring side relative to
the stepped part of the inner cylinder part of the cartridge is
smaller than the inner diameter of a portion positioned on the
opposite side from the fixed-side sealing ring relative to the
stepped part of the inner cylinder part of the cartridge.
[0022] According to this characteristic, it is possible to suppress
a decrease in the balance value, reduce the amount of leakage at
the sealing face, and suppress an increase in the spring constant
of the bellows, without increasing the outer diameter of the
bellows. In addition, it is possible to suppress an increase in the
diameters of the rotation-side sealing ring and the fixed-side
sealing ring and avoid an increase in size of the mechanical seal,
even when the balance value is set so as to exceed 100%.
Effect of the Invention
[0023] The present invention has the following beneficial
effects.
[0024] (1) Having the bellows be made from a metal, the metal
bellows having one end fixed to a case for holding the fixed-side
sealing ring and another end fixed to the cartridge, the plate
thickness of the metal bellows being set so as to be smaller than
the plate thickness of the case or the cartridge, result in the
metal bellows exclusively playing a role of axially urging the
fixed-side sealing ring, and being formed separately from the case,
the cartridge, or the like. Therefore, the plate thickness of the
metal bellows can be reduced, the spring constant of the metal
bellows can be reduced, and a change in load with respect to the
amount of stretching and contracting of the metal bellows can be
reduced. Therefore, even when the rotation-side sealing ring is
axially displaced, the axial urging force on the fixed-side sealing
ring can be kept stable, and the pressure at the sealing face can
be maintained at an optimum value. In addition, the tolerance of
the length of attachment of the metal bellows can be relaxed. In
addition, using a metal bellows instead of a conventional rubber
bellows prevents degradation or tearing of the bellows and makes it
possible to increase the lifespan. Also, the number of components
for attachment can be reduced compared to instances in which a
rubber bellows is used. Furthermore, the spring constant of the
bellows can be freely set by the material, the plate thickness, or
the number of crests. Also, the balance value can be set to an
optimum value.
[0025] (2) The metal bellows comprising a bellows part in which
crest parts and trough parts are alternately formed, and a
disc-shaped flange part extending radially outwards from the trough
part at each end of the bellows part; and the bellows part being
formed by molding or welding so that the outer diameter of the
flange parts is greater than the diameter of the crest parts, and
the inner diameter of the flange parts is substantially the same as
or slightly larger than the diameter of the trough parts, result in
it being possible to easily fix the metal bellows to the case and
the cartridge and to prevent the sealed fluid from leaking.
[0026] (3) Fixing of the metal bellows to the metal case and the
metal cartridge being performed by welding or fusing at each
position located slightly further towards the inner diameter side
relative to the outer diameter of the flange part of the metal
bellows results in it being possible for the inner circumferential
part of the flange part of the metal bellows to separate from the
case and the cartridge, and it being possible to obtain a stable
sealing performance and excellent tracking performance with respect
to the eccentricity of the rotating shaft. In addition, the metal
bellows can be fixed in a reliable manner without using a special
attachment member.
[0027] (4) The rotation-side sealing ring being fixed to the sleeve
via a cup gasket, and the cup gasket being provided across an outer
circumferential surface and a side opposite the sealing face of the
rotation-side sealing ring, result in it being possible to prevent
the cup gasket from detaching, even when the pressure of a
high-pressure fluid acts on the outer circumferential surface of
the cup gasket.
[0028] (5) The metal bellows having one end fixed to a gasket for
holding the fixed-side sealing ring and another end fixed to the
cartridge, whereby the metal bellows is formed so as to also
function as a case, making it possible to reduce the number of
components and reduce the number of welded locations.
[0029] (6) A band being attached on an outer circumference of an
outer cylinder part of the metal bellows fitting into the gasket
holding the fixed-side sealing ring makes it possible for the
fitting between the metal bellows and the cup gasket to be made
more reliable.
[0030] (7) The metal bellows having one end directly fixed to the
fixed-side sealing ring and another end fixed to the cartridge
results in it being possible to reduce the number of components and
reduce the axial length of the mechanical seal. Alternatively,
instead of reducing the axial length of the mechanical seal, it is
also possible to increase the number of crests of the metal
bellows.
[0031] (8) {The mechanical seal} being of a type in which a distal
end of an inner cylinder part of the sleeve is expanded in diameter
by crimping and caused to engage with an inner cylinder part of the
cartridge, thereby preventing the cartridge and the sleeve from
axial detachment, wherein: a portion of the inner cylinder part of
the cartridge located on the opposite axial-direction side relative
to the fixed-side sealing ring side is expanded in diameter and
provided with a stepped part; and the bellows is formed so that the
inner diameter of a portion positioned on the fixed-side sealing
ring side relative to the stepped part of the inner cylinder part
of the cartridge is smaller than the inner diameter of a portion
positioned on the opposite side from the fixed-side sealing ring
relative to the stepped part of the inner cylinder part of the
cartridge, results in it being possible to suppress a decrease in
the balance value, reduce the amount of leakage at the sealing
face, and suppress an increase in the spring constant of the
bellows, without increasing the outer diameter of the bellows. In
addition, it is possible to suppress an increase in the diameters
of the rotation-side sealing ring and the fixed-side sealing ring
and avoid an increase in size of the mechanical seal, even if the
balance value is set so as to exceed 100%.
BRIEF DESCRIPTION OF DRAWINGS
[0032] FIG. 1 is a vertical cross-section view showing a principal
part of a mechanical seal according to a first example of the
present invention;
[0033] FIG. 2 is a vertical cross-section view showing a principal
part of a mechanical seal according to a second example of the
present invention;
[0034] FIG. 3 is a vertical cross-section view showing a principal
part of a mechanical seal according to a third example of the
present invention;
[0035] FIG. 4 is a vertical cross-section view showing a principal
part of a mechanical seal according to a fourth example of the
present invention;
[0036] FIG. 5 is a vertical cross-section view showing a principal
part of a mechanical seal according to a fifth example of the
present invention;
[0037] FIG. 6 is a vertical cross-section view showing a principal
part of a mechanical seal according to a sixth example of the
present invention;
[0038] FIG. 7 is a vertical cross-section view showing a principal
part of a mechanical seal according to prior art 1;
[0039] FIG. 8 is a vertical cross-section view showing a principal
part of a mechanical seal according to prior art 2; and
[0040] FIG. 9 is a vertical cross-section view showing a principal
part of a reference example for illustrating the mechanical seal
according to the fifth and sixth examples of the present
invention.
DESCRIPTION OF EMBODIMENTS
[0041] Embodiments for carrying out this invention will now be
described by way of example with reference to the accompanying
drawings. The examples are not intended to limit the dimensions,
material, shape, relative arrangement, and other attributes of
constituent components to those set forth in the examples unless
expressly specified otherwise.
First Example
[0042] A description will now be given for a mechanical seal
according to a first example of the present invention. The present
invention is applied to an inside-type mechanical seal of a format
in which a fluid trying to leak from the outer circumference of the
sealing face to the inner circumference direction is sealed. In
FIG. 1, the left side corresponds to the high-pressure fluid side
(sealed fluid side) and the right side corresponds to the
low-pressure fluid side (atmosphere side).
[0043] The mechanical seal according to the present invention is a
mechanical seal comprising a sleeve 2 fixed to a rotating shaft 1,
and a cartridge 4 fixed to a housing 3; a rotation-side sealing
ring 5 being provided to the sleeve 2; and a fixed-side sealing
ring 6, which slides against the rotation-side sealing ring 5, and
a bellows 7 for axially urging the fixed-side sealing ring 6 being
provided to the cartridge 4; the mechanical seal being mainly
characterized in that: the bellows 7 is made from a metal;
[0044] and the metal bellows 7 has one end fixed to a case 8 for
holding the fixed-side sealing ring 6 and another end fixed to the
cartridge 4, and has a plate thickness set so as to be smaller than
the plate thickness of the case 8 or the cartridge 4.
[0045] For example, a pump impeller (not shown) is fixed to the
high-pressure-fluid side of the rotating shaft 1, and the
shaft-sealing part between the inner diameter side of the housing 3
and the outer diameter side of the rotating shaft 1 of the pump has
the mechanical seal of the present invention installed thereto and
sealed.
[0046] The sleeve 2 has: an inner cylinder part 2a fitted to the
rotating shaft 1; a disc part 2b extending in the outer diameter
direction from the high-pressure-fluid side of the inner cylinder
part 2a; and an outer cylinder part 2c extending from the outer
diameter side of the disc part 2b to the low-pressure-fluid side.
The sleeve 2 supports the rotation-side sealing ring 5 to the
low-pressure-fluid side having a substantially C-shaped
cross-section via a cup gasket 9. The cup gasket 9 is provided
across the outer circumferential surface and the side opposite the
sealing face of the rotation-side sealing ring 5. Therefore, even
when the pressure of the high-pressure fluid acts on the outer
circumferential surface of the cup gasket 9, the cup gasket 9 will
not detach.
[0047] The cartridge 4 is made from, e.g., a metal, and has: an
outer cylinder part 4a fitting into the inner circumference of the
housing 3; a disc part 4b extending radially inwards from the
low-pressure-fluid side of the outer cylinder part 4a; and an inner
cylinder part 4c extending to the high-pressure-fluid side along
the rotating shaft from the inner diameter part of the 4b. The
cartridge 4 supports, via the metal bellows 7, the fixed-side
sealing ring 6 to the high-pressure-fluid side having a
substantially C-shaped cross-section so as to be capable of axially
moving. The cartridge 4 is formed as a cartridge format capable of
being attached to and detached from the housing 3. The plate
thickness of the cartridge 4 is, e.g., in the instance of a metal
cartridge, approximately 0.4 mm.
[0048] The outer circumferential surface and the side opposite the
sealing face of the fixed-side sealing ring 6 are held by the case
8 via a cup gasket 10. The case 8 is made, e.g., from a metal, has
a substantially inverse L-shaped cross-section having an outer
cylinder part 8a and a disc part 8b, holds the fixed-side sealing
ring 6 to the high-pressure-fluid side via the cup gasket 10, and
is fixed, at the low-pressure-fluid side of the disc part 8b, to
one end of the metal bellows 7. The plate thickness of the case 8
is, in the instance of a metal case, approximately 0.4 mm. The cup
gaskets 9 and 10 are capable of elastically deforming, and is [made
from a material] selected from, e.g., rubber, a resin, or a
metal.
[0049] The metal bellows 7 has one end fixed to the disc part 8b of
the metal case 8 for holding the fixed-side sealing ring 6 and
another end fixed to the disc part 4b of the metal cartridge 4 by
welding or other means. In other words, the metal bellows 7 is
formed as a separate body with respect to the case 8 and the
cartridge 4.
[0050] In a bellows 7 comprising a stretchable bellows part in
which crest parts 7a and trough parts 7b are alternately formed, a
disc-shaped flange part 7c extending from a trough part 7b of the
bellows 7 is provided at each axial end part of the bellows 7, the
inner diameter of the flange parts 7c, 7c is formed so as to be
substantially the same as or slightly larger than the trough parts
7b of the bellows 7, and the outer diameter of the flange parts 7c
is formed so as to be larger than the crest parts 7a of the bellows
7. The flange parts 7c, 7c at both ends of the bellows 7 are fixed
to the disc part 8b of the case 8 and the disc part 4b of the
cartridge 4, [respectively]. When the fixing is performed, [the
flange parts 7c] are welded or fused to the case 8 and the
cartridge 4 at each position 11 located slightly further towards
the inner diameter side relative to the outer diameter of the
flange part 7c formed so as to be greater than the outer diameter
of the crest parts 7a of the bellows 7. It thereby becomes possible
to easily fix the bellows 7 to the case 8 and the cartridge 4 and
prevent the sealed fluid from leaking. The disc part 8b of the case
8 extends slightly further towards the inner diameter side than the
flange part 7c of the bellows 7, and supports the entire flange
part 7c of the bellows 7, whereby the action and the spring
constant of the bellows 7 are made more stable, and sealing
performance is maintained. Since welding is only performed [at a
position located] slightly further towards the inner diameter side
relative to the outer diameter of the flange part 7c of the bellows
7, it is possible for the inner circumferential parts of the flange
parts 7c of the bellows 7 to separate from the disc part 8b of the
case 8 and the disc part 4b of the cartridge 4, and it is possible
to obtain a stable sealing performance and excellent tracking
performance with respect to the eccentricity of the rotating shaft
1.
[0051] Typical examples of the material constituting the metal
bellows 7 include SUS304, SUS316L, AM350, and Inconel 625. The
metal bellows 7 is made from a molded bellows formed by molding or
a welded bellows formed by welding. The plate thickness of the
metal bellows 7 is set so as to be smaller than the plate thickness
of the metal case 8 or the metal cartridge 4. For example, the
plate thickness of the metal bellows 7 is set to approximately 0.1
mm, and formed so as to be significantly less than the plate
thickness of the case 8 or the cartridge 4.
[0052] Reducing the plate thickness of the metal bellows 7 reduces
the spring constant of the bellows 7 and reduces the change in load
in relation to the amount of stretching and contacting of the
bellows 7. Thus, reducing the change in load in relation to the
amount of stretching and contracting of the bellows 7 stabilizes
the axial urging force on the fixed-side sealing ring 6, even when
the rotation-side sealing ring 5 is axially displaced, making it
possible to maintain the pressure at the sealing face at an optimum
value. There is also a benefit in that the tolerance of the length
of attachment of the bellows 7 can be relaxed. In FIG. 1, the metal
bellows 7 has two crests; however, the number of crests can be
changed as required, e.g., to three crests if the load in relation
to the amount of stretching and contacting of the bellows 7 is
reduced, or to one crest if the axial length is reduced.
[0053] The effective diameter of the metal bellows 7 (i.e., the
diameter midway between the inner and outer diameters) and the
positional relationship of the sealing face S in the radial
direction are set so that a force F1 pressing the fixed-side
sealing ring 6 towards the side of the sealing face and a force F2
pressing the fixed-side sealing ring 6 towards the side opposite
the sealing face are balanced at a given relationship. In the
instance of the example shown in FIG. 1, if A1 represents the
pressure-receiving area of the metal bellows 7 at which pressure
from the sealed fluid is received (i.e., the pressure-receiving
area at which the pressure from the sealed fluid is received by the
bellows 7 for pressing the fixed-side sealing ring 6 towards the
side of the sealing face, represented by the area between the
effective diameter of the bellows 7 and the outer diameter of the
sealing face S; the same definition applies hereafter) and A2
represents the sliding area between the rotation-side sealing ring
5 and the fixed-side sealing ring 6, the balance value represented
by the ratio A1/A2 is set to a range of 50%.ltoreq.balance
value.ltoreq.100%. The balance value can be changed through setting
the balance diameter (effective diameter) and the sliding area, and
is normally set so as to be larger if the pressure of the sealed
fluid is higher and smaller if the pressure of the sealed fluid is
lower.
[0054] Using a metal bellows instead of a conventional rubber
bellows prevents degradation or tearing of the bellows and makes it
possible to increase the lifespan. Also, the number of components
for attachment can be reduced compared to instances in which a
rubber bellows is used. Furthermore, the spring constant of the
bellows can be freely set by the material, the plate thickness, or
the number of crests. Also, the balance value can be set to an
optimum value.
Second Example
[0055] Next, a description will be given for a mechanical seal
according to a second example of the present invention with
reference to FIG. 2. The second example, shown in FIG. 2, differs
from the first example shown in FIG. 1 in having the metal bellows
formed so as to also function as the case. However, other
configurations are the same as those in the first example, and
descriptions that overlap will not be provided.
[0056] In FIG. 2, a bellows 15 comprises a stretchable bellows part
in which crest parts 15a and trough parts 15b are alternately
formed, a disc-shaped flange part 15c extending from a trough part
15b of the bellows 15 is provided at each axial end part of the
bellows 15, the inner diameter of the flange parts 15c, 15c is
formed so as to be substantially the same as or slightly larger
than the trough parts 15b of the bellows 15, and the outer diameter
of the flange parts 15c is formed so as to be larger than the crest
parts 15a of the bellows 15. The flange part 15c of the bellows 15
on the side towards the cartridge 4 is fixed to the disc part 4b of
the cartridge 4. An outer cylinder part 15d is formed continuously
on the flange part 15c on the side towards the fixed-side sealing
ring 6 so as to fit with the outer circumferential surface of the
cup gasket 10 for holding the fixed-side sealing ring 6, and the
outer cylinder part 15d and the outer circumferential surface of
the cup gasket 10 fit to each other elastically. When the flange
part 15c on the side towards the cartridge 4 is fixed to the disc
part 4b of the cartridge 4, [the flange part 15c] is welded or
fused to the cartridge 4 at a position 11 located slightly further
towards the inner diameter side relative to the outer diameter of
the flange part 15c formed so as to be greater than the outer
diameter of the crest parts 15a of the bellows 15. It thereby
becomes possible to easily fix the bellows 15 to the cartridge 4
and the cup gasket 10 and prevent the sealed fluid from leaking.
Since the flange part 7c of the bellows 15 on the side towards the
cartridge 4 is welded only [at a position located] slightly further
towards the inner diameter side relative to the outer diameter, and
the flange part 15c on the side towards the fixed-side sealing ring
6 is elastically joined to the side surface of the cup gasket 10,
it is possible for the inner circumferential parts of the flange
parts 15c of the bellows 15 to separate from the disc part 4b of
the cartridge 4 and the side surface of the cup gasket 10, and it
is possible to obtain a stable sealing performance and excellent
tracking performance with respect to the eccentricity of the
rotating shaft 1.
[0057] The material constituting the metal bellows 15 and the
method for forming the bellows 15 are the same as those for the
metal bellows 7 in the first example. The plate thickness of the
metal bellows 15 is set so as to be smaller than the plate
thickness of the metal cartridge 4.
[0058] In the present second example, the metal bellows 15 is
formed so as to also function as a case, making it possible to
reduce the number of components and reduce the number of welded
locations.
Third Example
[0059] Next, a description will be given for a mechanical seal
according to a third example of the present invention with
reference to FIG. 3. The third example, shown in FIG. 3, differs
from the second example shown in FIG. 2 in that a band is attached
on an outer circumference of an outer cylinder part of the metal
bellows. However, other configurations are the same as those in the
second example, and descriptions that overlap will not be
provided.
[0060] In FIG. 3, a band 16 is attached on the outer circumference
of the outer cylinder part 15d of the metal bellows 15. The band 16
squeezes the outer cylinder part 15d radially inwards so as to act
against the radially outward elastic force of the cup gasket 10.
The band 16 comprises, e.g.: a hose-band-type [element] made from a
ring-shaped flat plate capable of elastically deforming and
configured so that the diameter is decreased by tightening, by
screwing, the circumferential-direction bonding part; a
plate-clip-type [element] (one-touch hose clamp) similarly made
from a ring-shaped flat plate capable of elastically deforming and
configured so as to be capable of being operated in the
diameter-expanding direction at one touch against the elastic force
acting in the contracting direction; or a C-ring-type [element] in
which a ring-shaped flat plate capable of elastically deforming is
cut at one location.
[0061] In the present third example, the band 16 squeezes the outer
cylinder part 15d radially inwards against the radially outward
elastic force of the cup gasket 10, therefore making the fitting
between the outer cylinder part 15d of the bellows 15 and the cup
gasket 10 more reliable.
Fourth Example
[0062] Next, a mechanical seal according to a fourth example of the
present invention will be described with reference to FIG. 4. The
fourth example, shown in FIG. 4, differs from the first example
shown in FIG. 1 in that the flange part of the metal bellows and
the fixed-side sealing ring are directly fixed; however, other
configurations are the same as those in the first example, and
descriptions that overlap will not be provided.
[0063] If the fixed-side sealing ring 6 is made from a material
that can be metal-welded, the metal bellows 7 can be directly
welded to the fixed-side sealing ring 6 without using the case 8
and the cup gasket 10 shown in FIG. 1. In FIG. 4, the flange parts
7c, 7c at both ends of the bellows 7 are fixed to the disc part 4b
of the cartridge 4 and side 6a opposite the sealing face of the
fixed-side sealing ring 6. When the fixing is performed, [the
bellows] is directly welded or fused to the fixed-side sealing ring
6 and the cartridge 4 at each position 11 located slightly further
towards the inner diameter side relative to the outer diameter of
the flange part 7c formed so as to be greater than the outer
diameter of the crest parts 7a of the bellows 7.
[0064] Examples of materials constituting the fixed-side sealing
ring 6 include stainless steel (SUS304), a sintered metal, a
superhard alloy, or silicon carbide (SiC). Fixing can be performed
by welding if the material constituting the fixed-side sealing ring
6 is stainless steel (SUS304) or a sintered metal, or by brazing if
the material is a superhard alloy or silicon carbide (SiC).
[0065] In the present fourth example, the case 8 and the cup gasket
10 as shown in FIG. 1 are not used; therefore, it is possible to
reduce the number of components and reduce the axial length of the
mechanical seal. Alternatively, instead of reducing the axial
length of the mechanical seal, it is also possible to increase the
number of crests of the metal bellows 7.
Fifth Example
[0066] Next, a description will be given for a mechanical seal
according to a fifth example of the present invention with
reference to FIGS. 5 and 9. The fifth example, shown in FIG. 5,
differs from the first through fourth examples shown in FIG. 1
through 4 in being a "fixed-side/rotation-side-crimped" integrated
type in which the cartridge and the sleeve can be prevented from
axial detachment. Other configurations, such as the balance value
being set to a range of 50%.ltoreq.balance value 100%.ltoreq., are
the same as those in the aforementioned examples, and descriptions
that overlap will not be provided.
[0067] FIG. 9 is a reference example for illustrating the
mechanical seal according to the firth example of the present
invention. {The mechanical seal} is of a type in which a distal end
2d of the inner cylinder part 2a of the sleeve 2 is expanded in
diameter by crimping and caused to engage with the inner cylinder
part 4c of the cartridge 4, thereby preventing the cartridge 4 and
the sleeve 2 from axial detachment, wherein:
[0068] the inner cylinder part 4c of the cartridge 4 is provided
with a stepped part 4d which engages with the distal end 2d of the
inner cylinder part 2a of the sleeve 2. The stepped part 4d is
formed by a portion of the inner cylinder part 4c on the side
towards the disc part 4b being shaped so as to expand in diameter.
The distal end 2d, having a diameter expanded by crimping, of the
inner cylinder part 2a is fitted into the expanded-diameter portion
of the inner cylinder part 4c, and the distal end 2d and the
stepped part 4d engage with each other.
[0069] As shown in FIG. 9, in order to provide a stepped part 4d to
the inner cylinder part 4c of the cartridge 4, it is necessary to
have the inner diameter of the bellows 7 be larger than the inner
diameter of the bellows in first through fourth examples and
provide a given gap with respect to the inner cylinder part 4c. If
the inner diameter of the bellows 7 is increased, assuming the
outer diameter to be uniform, the effective diameter will increase,
and the pressure-receiving area A1 on which the bellows 7 receives
pressure from the sealed fluid will decrease; therefore, a problem
is presented in that the balance value=A1/A2 (where A2 is the area
of the sealing face) will decrease and the amount of leakage will
increase. Increasing the outer diameter of the bellows 7 would
increase the pressure-receiving area A1 and also increases the
balance value. However, increasing the outer diameter of the
bellows 7 would present problems of impeding the task of welding
the bellows 7 to the cartridge 4 or other metal components and
increasing the outer diameter of the mechanical seal, and is
therefore not practical.
[0070] The mechanical seal according to the fifth embodiment of the
present invention resolves the problems presented by the reference
example, and FIG. 5 is a vertical cross-section view showing the
principal part of the mechanical seal. The dashed lines in FIG. 5
indicate the cross-section of a rotation locking part provided to a
part of the circumferential direction of the fixed-side sealing
ring 6, and solid lines indicate the cross-section of a portion
other than the rotation locking part. In the first through fourth
examples in FIG. 1 through 4, the solid lines indicate a rotation
locking part and the dashed lines indicate a portion other than the
rotation locking part, in contrast to FIG. 5.
[0071] In FIG. 5, in order to prevent a cartridge 40 and a sleeve
20 from axial detachment by expanding the diameter of a distal end
20d of an inner cylinder part 20a of the sleeve 20 and causing the
distal end 20d to engage with an inner cylinder part 40c of the
cartridge 40, a portion of the inner cylinder part 40c of the
cartridge 40 on the side towards a disc part 40b is expanded in
diameter, an expanded diameter part 40e is formed, and a stepped
part 40d is provided. The stepped part 40d, which engages with the
distal end 20d of the inner cylinder part 20a of the sleeve 20, is
provided. The distal end 20d, having a diameter expanded by
crimping, of the inner cylinder part 20a of the sleeve 20 engages
with the stepped part 40d of the inner cylinder part 40c, whereby
the cartridge 40 and the sleeve 20 are prevented from axial
detachment, and the fixed side and the rotation side are
integrated.
[0072] The metal bellows 30 has an outer diameter identical to that
in the above reference example, and has an inner diameter, at a
portion located on the side of the fixed-side sealing ring 6
relative to the stepped part 40d of the inner cylinder part 40c of
the cartridge 40, formed so as to be smaller than the inner
diameter of the portion located on the opposite side to the
fixed-side sealing ring 6 relative to the stepped part 40d of the
inner cylinder part 40c of the cartridge 40. In other words, the
metal bellows 30 is shaped so that the inner diameter side is
stepped in cross-section.
[0073] In order to facilitate description, the portion of the
bellows 30 having a larger inner diameter may be hereafter referred
to as a large inner diameter part 30-1 and the portion having a
smaller inner diameter may be hereafter referred to as a small
inner diameter part 30-2.
[0074] The large inner diameter part 30-1 of the bellows 30 has the
same effective diameter as that in the above reference example;
therefore, the pressure-receiving area A1-1 represented by the area
between the effective diameter and the outer diameter of the
sealing face S is smaller, and the balance value is also smaller.
In contrast, the small inner diameter part 30-2 of the bellows 30
has a smaller effective diameter than that of the large inner
diameter part 30-1; therefore, the pressure-receiving area A1-2
represented by the area between the effective diameter and the
outer diameter of the sealing face S is larger, and the balance
value is also larger. Therefore, the overall balance value of the
bellows 30 is larger than that of the bellows shown in FIG. 9 in
which the outer diameter is the same and a step is not present
(reference example), and it is possible to suppress a decrease in
the balance value and reduce the amount of leakage at the sealing
face S. In addition, it is also possible to suppress an increase in
the spring constant of the bellows 30.
[0075] In the present example, {the mechanical seal} is of a type
in which the distal end 20d of the inner cylinder part 20 of the
sleeve 20 is expanded in diameter by crimping and caused to engage
with the inner cylinder part 40c of the cartridge 40, thereby
preventing the cartridge 40 and the sleeve 20 from axial
detachment, wherein:
[0076] a portion of the inner cylinder part 40c of the cartridge 40
located on the opposite axial-direction side relative to the
fixed-side sealing ring side 6 is expanded in diameter and provided
with the stepped part 40d; and
[0077] the bellows 30 is formed so that the inner diameter of a
portion positioned on the fixed-side sealing ring 6 side relative
to the stepped part 40d of the inner cylinder part 40c of the
cartridge 40 is smaller than the inner diameter of a portion
positioned on the opposite side from the fixed-side sealing ring 6
relative to the stepped part 40d. Therefore, compared to an
instance in which the outer diameter of the bellows is the same and
the inner diameter is increased in a uniform manner, the balance
value is greater, a decrease in the balance value can be
suppressed, and the amount of leakage at the sealing face S can be
reduced. It is also possible to suppress an increase in the spring
constant of the bellows 30. In other words, [the present example]
has a beneficial effect of it being possible to suppress a decrease
in the balance value, reduce the amount of leakage at the sealing
face, and suppress an increase in the spring constant of the
bellows 30, without increasing the outer diameter of the
bellows.
Sixth Example
[0078] Next, a description will be given for a mechanical seal
according to a sixth example of the present invention with
reference to FIG. 6. The sixth example shown in FIG. 6 is similar
to the fifth example shown in FIG. 5 in being a
"fixed-side/rotation-side-crimped" integrated type in which the
cartridge and the sleeve can be prevented from axial detachment,
but differs from the fifth example shown in FIG. 5 in having the
balance value set so as to exceed 100%. In the following
description, descriptions that overlap with those for the fifth
example will not be provided.
[0079] In the sixth example shown in FIG. 6, if A1 represents the
pressure-receiving area of the metal bellows 30 at which pressure
from the sealed fluid is received (i.e., the average value between
the pressure-receiving area A1-1 and the pressure-receiving area
A1-1) and A2 represents the sliding area between the rotation-side
sealing ring 5 and the fixed-side sealing ring 6, the balance value
represented by the ratio A1/A2 is set so as to exceed 100%.
[0080] In order to set the balance value so as to exceed 100%, it
is necessary to have the inner diameter of the sealing face between
the rotation-side sealing ring 5 and the fixed-side sealing ring 6
be larger than the balance diameter (effective diameter) of the
bellows 30. Therefore, a problem is presented in that if the
balance diameter of the bellows 30 is uniform, the diameters of the
rotation-side sealing ring 5 and the fixed-side sealing ring 6 will
increase, and the size of the mechanical seal will increase.
According to the present example 6, the small inner diameter part
30-2 of the bellows 30 has a smaller effective diameter than that
of the large inner diameter part 30-1, therefore making it possible
to suppress an increase in size of the sealing face between the
rotation-side sealing ring 5 and the fixed-side sealing ring 6.
[0081] In the present example, {the mechanical seal} is of a type
in which the distal end 20d of the inner cylinder part 20 of the
sleeve 20 is expanded in diameter by crimping and caused to engage
with the inner cylinder part 40c of the cartridge 40, thereby
preventing the cartridge 40 and the sleeve 20 from axial
detachment, wherein: a portion of the inner cylinder part 40c of
the cartridge 40 located on the opposite axial-direction side from
the fixed-side sealing ring 6 side is expanded in diameter and
provided with a stepped part 40d; and the bellows 30 is formed so
that the inner diameter of a portion positioned on the fixed-side
sealing ring 6 side relative to the stepped part 40d of the inner
cylinder part 40c of the cartridge 40 is smaller than the inner
diameter of a portion positioned on the opposite side from the
fixed-side sealing ring 6 relative to the stepped part 40d.
Therefore, compared to an instance in which the outer diameter of
the bellows is the same and the inner diameter is increased in a
uniform manner, even if the balance value is set so as to exceed
100%, it is possible to suppress an increase in the inner diameter
of the sealing face between the rotation-side sealing ring 5 and
the fixed-side sealing ring 6. In other words, [the present
example] has a prominent effect of enabling the balance value to be
set so as to exceed 100% and avoid an increase in size of the
mechanical seal without significantly increasing the diameters of
the rotation-side sealing ring 5 and the fixed-side sealing ring
6.
[0082] While embodiments of the present invention have been
described above on the basis of examples, the specific
configurations are not limited to those according to the examples,
and the present invention includes instances in which a variety of
modifications and additions have been made without departing from
the scope of the present invention.
[0083] For example, in the aforementioned examples, descriptions
have been given with regards to instances in which the mechanical
seal of the present invention is applied to a pump. However, this
is not provided by way of limitation; [the mechanical seal of the
present invention] can be applied, e.g., to a compressor, a
submersible motor, or other industrial machinery.
[0084] In the aforementioned examples, descriptions have been given
with regards to instances in which the cartridge 4 and the case 8
are formed from a metal. However, [the material] is not limited to
a metal, and any material having a high corrosion resistance can be
used, e.g., a plastic. In such an instance, the fixing with the
metal bellows may be performed, e.g., by adhesion using an adhesive
or bonding using laser.
[0085] As can be seen by the fact that, e.g., descriptions were
given for instances in which the balance value is set to a range of
50%.ltoreq.balance value.ltoreq.100% in the first through fifth
examples and a description was given for an instance in which the
balance value exceeds 100% in the sixth example, the present
invention can be applied to any balance value. The balance value is
set as appropriate according to factors such as the pressure and
the type of the sealed fluid.
[0086] For example, in the fifth and sixth examples, the effect of
the present invention was described using examples of instances in
which the outer diameter of the bellows is the same in order to
facilitate comprehension, this is not provided by way of
limitation. Even when there is a fluctuation in the outer diameter
of the bellows 30, the effect of the present invention can be
obtained. In short, the technical significance is in reducing the
inner diameter of a portion of the bellows 30 and thereby
preventing the balance value from decreasing and suppressing an
increase in the size of the rotating ring and the fixed ring in a
type [of mechanical seal] in which the fixed side and the rotation
side are integrated.
[0087] In other words, when, as in the fifth example, [the balance
value] is within the range of 50%.ltoreq.balance value.ltoreq.100%,
the balance value is prevented form decreasing, and when, as in the
sixth example, the balance value exceeds 100%, an increase in the
diameters of the rotation-side sealing ring and the fixed-side
sealing ring is suppressed and an increase in size of the
mechanical seal is avoided.
REFERENCE SIGNS LIST
[0088] 1 Rotating shaft [0089] 2 Sleeve [0090] 3 Housing [0091] 4
Cartridge [0092] 5 Rotation-side sealing ring [0093] 6 Fixed-side
sealing ring [0094] 7 Metal bellows [0095] 8 Case [0096] 9 Cup
gasket [0097] 10 Cup gasket [0098] 15 Metal bellows [0099] 16 Band
[0100] 20 Sleeve [0101] 30 Metal bellows [0102] 40 Cartridge
* * * * *