U.S. patent application number 11/043134 was filed with the patent office on 2005-09-01 for dual reciprocating bellows pump with interlock shaft means.
This patent application is currently assigned to Iwaki Co., Ltd.. Invention is credited to Oniduka, Toshiki, Sawada, Tsutomu, Watanabe, Tsuyoshi.
Application Number | 20050191195 11/043134 |
Document ID | / |
Family ID | 34879041 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050191195 |
Kind Code |
A1 |
Oniduka, Toshiki ; et
al. |
September 1, 2005 |
Dual reciprocating bellows pump with interlock shaft means
Abstract
It is sought to provide a dual reciprocating bellows pump having
two, i.e., left and right, bellows interlocked by interlock shafts
to each other, which is free of wear powder or wear dust generated
by the frictional movement of the interlock shafts and bearings
relative to one another from pump feed fluid in pumping chambers,
permits ready use of synthetic resin as pump element material, is
excellent in function and cost and readily permits size reduction
design. Paired interlock shafts coupled to end members 6 of the
pair of, i.e., left and right, bellows, are disposed in paired
working air chambers 8, and are movably inserted in through bores
provided in a pump head. Between each interlock shaft and each
through elastic seal members are disposed, thus sealing the left
and right working air chambers 8 from each other. No particular
bearing is used for the interlock shafts. Lip seals are desirably
used as the elastic seal members.
Inventors: |
Oniduka, Toshiki;
(Saitama-ken, JP) ; Watanabe, Tsuyoshi;
(Saitama-ken, JP) ; Sawada, Tsutomu; (Saitama-ken,
JP) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
|
Assignee: |
Iwaki Co., Ltd.
Tokyo
JP
|
Family ID: |
34879041 |
Appl. No.: |
11/043134 |
Filed: |
January 27, 2005 |
Current U.S.
Class: |
417/473 ;
417/390; 417/472 |
Current CPC
Class: |
F04B 43/084 20130101;
F04B 43/1136 20130101 |
Class at
Publication: |
417/473 ;
417/472; 417/390 |
International
Class: |
F04B 009/08; F04B
017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 2004 |
JP |
2004-18038 |
Claims
What is claimed is:
1. A dual reciprocating bellows pump with interlock shaft means
comprising; a pump housing; a pump head assembled in the pump
housing at the center along a longitudinal axis thereof and capable
of withdrawing and discharging pump feed liquid; a pair of left and
right cylindrical bellows having respective end parts sealedly
mounted on the pump head and capable of expansively and
contractably reciprocating with a predetermined stroke in the pump
housing in longitudinal directions thereof; paired end members each
sealedly coupled to the free end of each bellows and capable of
cooperating with the pump head defining pumping chambers inside the
bellows and also defining working air chambers between the bellows
and the housing; paired interlock shafts as said interlock shaft
means, each having the two ends coupled to the pair of end members
such as to cause reciprocation of each bellows in an interlocked
relation to the reciprocation of the other bellows, inserted
through through bores formed in the pump head and capable of being
displaced in the longitudinal directions of the pump housing;
working air feed means for selectively feeding working air to the
pair of left and right working air chambers, and paired valve means
mounted on the pump head in correspondence to the pumping chambers,
respectively, in the pair of left and right bellows reciprocated in
response to pressure changes of working air fed by the working air
feed means, for controlling the flow of the pump feed fluid into
and out of the pumping chambers; wherein: said through bores formed
in the pump head are open in the pair of left and right working air
chambers; said interlock shafts extend through said through bores
into the pair of left and right working air chambers; and seal
means is provided between said interlock shaft and the
corresponding through bore so as to isolate said left and right
working air chambers.
2. The dual reciprocating bellows pump with interlock shaft means
according to claim 1, wherein: said seal means includes a
cylindrical guide member open at the two ends, inserted and secured
in said through bore of the pump head and extending into the left
and right working air chamber, and an elastic seal member mounted
in said open ends of the guide member; said interlock shaft is
movably inserted in said corresponding cylindrical guide member,
the inner diameter of the cylindrical guide member being greater
than the outer diameter of said interlock shaft; and said elastic
seal member effects isolation of the left and right working air
chambers in sealed contact with said corresponding interlock
shaft.
3. The dual reciprocating bellows pump with interlock shaft means
according to claim 1, wherein: said inner diameter of said through
bore of the pump head is greater than the outer diameter of said
interlock shaft; and an elastic seal member is disposed in said
corresponding through bores such as to be able to be in sealed
contact with said interlock shaft, thereby effecting the isolation
of the left and right working air chambers.
4. The two-ganged interlock bellows pump with interlock shaft means
according to claim 3, wherein; said elastic seal member is
constituted by a lip seal.
5. The dual reciprocating bellows pump with interlock shaft means
according to claim 4, wherein: said pump constituent elements are
all made of synthetic resin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to dual reciprocating bellows pumps
with interlock shaft means, in which a pair of expansible and
contractable cylindrical bellows, with a pump head interposed
therebetween, are interlocked by paired interlock shafts as the
interlock shaft means to each other, with the inside of the
cylindrical bellows made to be pumping chambers for pump fed fluid
such as semiconductor processing liquid and with the outside of the
cylindrical bellows provided with working air chambers defined by a
pump housing.
[0003] 2. Description of the Prior Art
[0004] In this type of dual reciprocating bellows pump, interlock
shaft means is provided to couple together a pair of, i.e., left
and right, bellows, so as to interlock these bellows to each other.
An arrangement of this type with the interlock shaft means disposed
outside a pump housing and also another one with interlock shaft
means disposed inside pumping chambers are well known in Japanese
Patent disclosure No. 2003-314458. In the former arrangement, the
interlock shaft means is coupled to the extended ends of a member,
which is movable in unison with the bellows and is extended to the
outside of the pump housing. In the latter arrangement, a pump head
disposed at the center of a pump housing has through bores open in
pumping chambers, and interlock shafts are inserted through the
through bores to be in frictional contact with the bore inner
periphery. The interlock shafts have their ends extending into the
pumping chambers and operatively coupled to end members provided on
the free ends of the bellows.
[0005] In the above prior art dual reciprocating bellows pump
arrangement, in which the interlock shafts are disposed outside the
pump housing, the coupling mechanism for transferring the bellows
operation to the interlock shafts is complicated, and also the pump
size and cost of manufacture are increased. In the case of the
arrangement with the interlock shafts disposed inside the pumping
chambers, the interlock shafts are in close frictional contact with
the through bores of the pump head for isolating fluid in the
pumping chambers. Therefore, wear powder or wear dust is generated
in the frictional parts and introduced as undesired impurity in the
pump feed fluid in the pumping chambers. Particularly, this poses
very serious problems in the case, in which the pump feed liquid is
semiconductor processing liquid with high purity required
thereto.
[0006] In the pump, in which semiconductor processing liquids or
chemicals are dealt with as shown in the above, richly
corrosion-resistant synthetic resin is used in lieu of metal as the
material the contact-with-liquid materials in the pumping chambers,
and up to date pumps, in which all the pump constituents are all
made of synthetic resin, are spread because they are desired in
view of function and cost. As shown, even in the case of adopting a
pump arrangement using synthetic resin for the contact-with-liquid
parts, so long as the interlock shafts are disposed in the pump
chambers, no grease or like lubricant can be used for the
frictional parts between the pump head and the through bores. Also,
the carbon-containing resin excellent in the frictional property
can not be used due to the occurrence of corrosion resistance and
wear particles. Accordingly, it is inevitable to adopt an
arrangement, in which synthetic resin interlock shafts are in close
frictional contact with through bores of a synthetic resin pump
head via synthetic resin bearings. Thus, even slight distortion at
the time of assembling applies great load on the frictional parts
to give rise to a "scratch" phenomenon and disturb smooth movement
of the interlock shafts and, in an extreme case, results in the
stop of the pumping operation.
[0007] This invention is made in view of the above various
problems, and its object is to provide a dual reciprocating bellows
pump with interlock shaft means, which can prevent intrusion of
undesired impurities in the pump feed liquid, is excellent in
function and cost and permits ready size reduction design.
SUMMARY OF THE INVENTION
[0008] To attain the above object of the invention, according to
the invention it is sought to provide a dual reciprocating bellows
pump with interlock shaft means comprising a pump housing, a pump
head assembled in the pump housing at the center along the
longitudinal axis thereof and capable of withdrawing and
discharging pump feed liquid, a pair of, i.e., left and right,
bellows having respective end parts sealedly mounted on the pump
head and capable of expansively and contractably, reciprocating
with a predetermined stroke in the pump housing in longitudinal
directions thereof, paired end members each sealedly coupled to the
free end of each bellows and capable of cooperating with the pump
head defining pumping chambers inside the bellows and also defining
working air chambers between the bellows and the housing, paired
interlock shafts each having the two ends coupled to the pair of
end members such as to cause reciprocation of each bellows in an
interlocked relation to the reciprocation of the other bellows,
inserted through through bores formed in the pump head and capable
of being displaced in the longitudinal directions of the pump
housing, working air feed means for selectively feeding working air
to the part of, i.e., left and right, working air chamber, and
paired valve means mounted on the pump head in correspondence to
the pumping chambers, respectively, in the pair of, i.e., left and
right, bellows reciprocated in response to pressure changes of
working air fed by the working air feed means, for controlling the
flow of the pump feed fluid into and out of the pumping chamber,
wherein : said through bores formed in the pump head are open in
the pair of, i.e., left and right, working air chambers; said
interlock shafts extend through said through bores into the pair
of, i.e., left and right, working air chambers; and seal means is
provided between said interlock shaft and the corresponding through
bore of the pump head so as to isolate said pair of, i.e., left and
right, working air chambers.
[0009] In the above arrangement according to the invention, the
interlock shafts extend, in their state open to the left and right
working air chambers, through through bores provided in the pump
head into the working air chambers, and are not disposed in the
pumping chambers. Seal means are provided between each through
bores and each working air chamber, whereby the left and right
working air chambers are isolated. Here, no bearing means for
supporting any interlock shaft is needed.
[0010] According to the invention, it is also sought to provide a
dual reciprocating bellows pump with interlock shaft means, wherein
the seal means each include a cylindrical guide member open at the
two ends, inserted and secured in each through bore of the pump
head extending into the left and right working air chambers, and
paired elastic seal members each mounted in each open end of the
guide member, the interlock shafts are each movably inserted in
each cylindrical guide member, the inner diameter of the
cylindrical guide members being greater than the outer diameter of
the interlock shafts, and the elastic seal members effect isolation
of the left and right working air chambers in sealed contact with
the interlock shafts.
[0011] In the above specific arrangement of said seal means
according to the invention, said cylindrical guide members are
inserted through and secured in the through bores, and said elastic
seal members are mounted on the two open ends of the guide members
to be in sealed contact with the interlock shaft movable in said
guide members. In the contact parts, a seal action of isolating the
left and right working air chambers is executed. The inner diameter
of the cylindrical guide members is set to be greater than the
outer diameter of the interlock shafts, and thus there is no
possibility that the movement of the interlock shafts is interfered
in contact with the cylindrical guide members.
[0012] According to the invention it is further sought to provide a
dual reciprocating bellows pump with interlock shaft means, wherein
the inner diameter of the through bores of the pump head is greater
than the outer diameter of the interlock shafts, and paired elastic
seal members are disposed in the through bores such as to be able
to be in sealed contact with the interlock shafts, thereby
effecting the isolation of the left and right working air
chambers.
[0013] In the above specific arrangement according to the
invention, the interlock shafts are directly inserted through the
through bores of the pump head, and a pair of elastic seal members
are disposed in each through bore between the interlock shaft and
the through bore. Again in this case, no bearing for supporting any
interlock shaft is provided.
[0014] According to the invention, it is further sought to provide
a dual reciprocating bellows pump with interlock shaft means,
wherein said elastic seal members are constituted by lip seals.
[0015] In the above specific arrangement according to the
invention, the elastic seal members are each constituted by a
so-called lip seal having a thin tong-like seal contact part. The
lip seals are richly flexible, and can thus absorb even a slight
distortion at the time of the pump assembling. During the pump
operation, the left and right bellows are held in a pressurized
state by working air. With this pressure balance, the bellows are
thought to be horizontally reciprocating without great distortion.
Thus, no greater load than on the interlock shaft in sealed contact
with the lip seals is applied to the lip seals.
[0016] According to the invention, it is further sought to provide
a dual reciprocating bellows pump with interlock shaft means,
wherein the pump constituent elements are all made of synthetic
resin.
[0017] In the above specific arrangement according to the
invention, synthetic resin is used as the material of the pump
constituent members inclusive of contact-with-liquid members of the
pumping chambers accommodating pump feed fluid, that is, all resin
pump design is made.
[0018] According to the invention, since the interlock shafts are
disposed in the working air chambers outside the bellows, there is
no possibility that wear powder and wear dust are introduced into
fluid in the pumping chambers defined in the bellows. Also, since
the interlock shafts are disposed inside the pump housing, the
coupling structure with respect to the bellows is simple, and size
reduction design of the entire pump can be readily made.
[0019] Furthermore, the left and right bellows are held in a state
pressurized by working air with the pumping operation. With this
pressure balance, seal means for isolating the working air chambers
between interlock shafts and through bores of the pump head
penetrated by the interlock shafts, undergo reciprocation
substantially horizontally without generation of great distortion,
and thus it may be of a relatively simple arrangement. Besides,
since no particular bearing is necessary between each interlock
shaft and each through bore, the load on the interlock shafts is
reduced, and it is possible to obtain smooth pumping operation.
[0020] Thus, in the case of adopting the arrangement that
cylindrical guide members for guiding the interlock shafts in the
movement therefore inserted through and secured to the through
bores, the interlock shafts will not be in direct frictional
contact with the guide members in their movement by setting the
inner diameter of the guide members to be greater than the outer
diameter of the interlock shafts. As the seal, the elastic seal
members mounted on the open ends of the guide members can
sufficiently effect isolation of the working air chambers.
[0021] In the case of the arrangement without provision of any
cylindrical guide member, by setting the inner diameter of the
through bores to be greater than the outer diameter of the
interlock shafts, a pair of elastic seal members is disposed
between each through bore and each interlock shaft. Thus, it is not
only possible to avoid the frictional contact of the interlock
shafts with the corresponding through bores during movement, but
also effect sufficient isolation of the working air chambers with
the pair of elastic seal members.
[0022] Moreover, by using lip seals as the elastic seal members, it
is possible to obtain soft contact with the interlock shafts and
absorb even slight distortion at the time of the pump assembling in
the contact parts. The load on the interlock shafts thus can be
further reduced.
[0023] With the arrangement as shown above, according to the
invention, by using synthetic resin as the material of various pump
constituent members such as contact-with-liquid parts of the
pumping chambers accommodating pump feed fluid, all resin pump
design can be readily made, and it is possible to provide a pump,
which is suited for dealing with semiconductor processing liquids
or chemicals as the pump feed fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will become more apparent upon a reading of
the following detailed specification with reference to the
accompanying drawings, in which:
[0025] FIG. 1 is a schematic sectional view showing a first
embodiment of the dual reciprocating bellows pump with interlock
shaft means according to the invention;
[0026] FIG. 2 is a fragmentary enlarged-scale view showing the pump
shown in FIG. 1;
[0027] FIG. 3 is a fragmentary sectional schematic view showing a
second embodiment of the dual reciprocating bellows pump with
interlock shaft means according to the invention;
[0028] FIG. 4 is a fragmentary enlarged-scale view showing the pump
shown in FIG. 3; and
[0029] FIG. 5 is a fragmentary view showing a modification of the
lip seal shown in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Embodiments of the present invention will now be described
with reference to the drawings. FIGS. 1 and 2 show the first
embodiment of the dual reciprocating bellows pump with interlock
shafts as interlock shaft means. Reference numeral 1 designates a
pump housing. Reference numeral 2 designates a pump head disposed
in the pump housing 1 at the center thereof in the longitudinal
axis X-X. The pump housing 1 comprises a pair of, i.e., left and
right, parts with the pump head 2 as a border. These parts are
assembled to be integral with the pump head 2 by a pair of
assembling frames in a stage positioned by pins 3.
[0031] Reference numeral 5 designates a pair of, i.e., left and
right, cylindrical bellows, which have their stem parts 5a mounted
in a sealed stage on the central pump head 2 and expansively and
contractably reciprocal with a predetermined stroke along the
longitudinal axis X-X of the pump housing 1. Reference numeral 6
designates end members, which are each coupled in a sealed state to
the free end of each bellows 5, each define a pumping chamber 7 in
each bellows 5 in cooperation with the pump head 2 and define a
working air chamber 8 between each bellows 5 and the pump housing
1. In this embodiment, the end members 6 are formed to be integral
with the bellows 5, respectively.
[0032] Reference numeral 10 designates interlock shafts constituted
as the interlock shaft means, which are inserted through through
bores 11 open to a pair of, i.e., working air chambers 8, and
extend into the working air chambers 8, respectively. Each free
bellows end part is coupled by bolts 14 to each end member 6 via
two coupling members 12 and 13. The two coupling members 12 and 13
are mounted by the bolts 14 to the corresponding end member 6 such
as to sandwich the end member 6. The pair interlock shafts 10 are
provided face to face in the working air chambers 8 in concentric
positions in radial direction centered on the longitudinal axis
X-X. These interlock shafts 10 are movable along and parallel with
the axis X-X such that one of the bellows 5 is interlocked with
good balance to the reciprocation of the other bellows 5 along the
axis X-X.
[0033] Reference numeral 15 designates paired cylindrical guide
members, which are each inserted in and secured to each through
bore 11. Each interlock shaft 10 is movably inserted in each guide
member 15. As shown in FIG. 2, the inner diameter ID of the guide
members 15 is set to be greater than the outer diameter OD of the
interlock shafts 10. When each interlock shaft 10 is moved in the
longitudinal direction, it is not in frictional contact with the
inner periphery of the guide member 15 owing to a gap G held
between it and an elastic seal member 16 to be described later.
[0034] The elastic seal members 16 have a ring-like shape, and are
mounted on the open end parts 15a of each cylindrical guide member
15 to be in elastic contact with the outer periphery of the
interlock shaft 10, thus effecting the sealed contact. As the
elastic seal members 16, it is particularly desired to use thin
tong-like lip seals as in this embodiment.
[0035] Each elastic seal member 16 constituted by a lip seal is
secured in its state that it is pushed against the open end part
15a of the associated cylindrical guide member 15 and with its stem
part 16a clamped from the back side by a back-up member 17, and its
tong part 16b extending radially inwardly is elastically held in
sealed contact with the entire outer periphery of the associated
interlock shaft 10. Thus, the pair of, i.e., left and right,
elastic seal members 16 isolate the flow of working air in the left
and right working air chambers 8.
[0036] Working air feed switching mechanisms 18 mounted on the
opposite end parts of the pump housing 1 selectively feed working
air from an air source 19 via a control valve 20 to the part of,
i.e., working air chambers 8. When working air is thus fed to one
of the working air chambers 8, the associated bellows 5 undergoes
contracting movement, which is transmitted via the interlock shafts
10 to the other bellows 5, while causing release of the working air
from the other bellows 5 to cause expansion movement thereof. This
operation is repeated.
[0037] The working air feed switching mechanisms 18 each include an
air inlet port 21, an air discharge port 22, a piston 23 and a
cylinder 24, and they constitute an operating air feed means
together with the control valve 20 and the air source 19 connected
via ducts 25 to 28 to them. This means may be the same as what is
disclosed in Japanese Patent Disclosure No. 2003-314458, and its
detailed arrangement is not described.
[0038] The left and right bellows 5 repeatedly undergo expansion
and contracting movement in response to the working air feed
switching operation to cause pumping operation of withdrawing and
discharging pump feed fluid such as semiconductor processing liquid
or a chemical liquid accommodated in the pumping chambers 7 in the
bellows 5. The in-flow and out-flow of the pump feed liquid to and
from the pumping chambers 7 are effected via valves 30 provided on
the pump head 2. Each pumping chamber 7 has a withdrawal guide and
a discharge guide valve 30 provided as a pair. In FIG. 1, these
paired valves 30 are shown side by side in the direction of the
paper surface, and only one set of the paired valves 30 is seen.
These valves are communicated with withdrawal and discharge ports
(not shown) provided on the pump head 2. The arrangement in this
part is the same as what is disclosed in the above Japanese Patent
Disclosure No. 2003-314458, and its detailed description is not
given.
[0039] In the dual reciprocating bellows pump having the above
arrangement, as described above the pumping operation is executed
in such a manner that the pair of, i.e., left and right, bellows 5
undergoes reciprocation along the longitudinal axis X-X in a state
that they are interlocked to each other by the interlock shafts 10
in response to the selective feed of working air. In this
operation, the left and right working air chambers 8 are always in
a state pressurized by working air and held balanced. The bellows 5
thus are not excessively deviated from the direction of the axis
X-X and distorted or do not bring about vibrations. Thus, the
interlock shafts 10 are likewise moved substantially along the
direction of the axis X-X, and they do not to come to be in
excessive contact with the cylindrical guide members 10 and can be
moved smoothly. With this arrangement, the interlock shafts 10 do
not require any special bearing, but require only the elastic seal
members 16, which isolate the left and right working air chambers 8
and are solely in contact at the time of the usual movement. The
load on the interlock shafts 10 is thus extremely reduced, and the
generation of wear powder, wear particles and wear dust from the
contact parts are suppressed as much as possible.
[0040] The pump constituents may all be readily manufactured from
synthetic resin. Particularly, it is desirable to use richly
corrosion-resistant synthetic resin for the contact-with-liquid
parts of the pumping members 7 accommodating the pump feed liquid,
such as the bellows 5, the pump head 2 and the valve 30. The
interlock shafts 10 and cylindrical guide members 15 are desirably
made of such synthetic resin as PEEK (polyeterethylketone) resin.
The lip seals constituting the elastic seal members 16 are
desirably filler-containing PTFE (polytetrafluoroethylene)
resin.
[0041] When the lip seals made of the filler-containing PTFE resin
is in contact with the interlock shafts 10 made of PEEK, PTFE is
transferred as initial wear to the frictional surfaces of the shaft
10. As a result, the lip seals of the filer-containing PTFE come to
be in frictional contact with the filler-containing PTFE having
been transferred to the surfaces of the PEEK resin. Thus, the wear
does not proceed greatly. It is thus an advantage that the sole lip
seals permit sufficient seal, so that no particular bearing is
necessary.
[0042] FIGS. 3 and 4 show a second embodiment of the dual
reciprocating bellows pump according to the invention. In the
figures, elements like those in the preceding first embodiment are
designated by like reference numerals, and their description is not
given in detail. In this embodiment, the inner diameter of the
through bores 11 formed on the central pump head 2 is set to be
greater than the outer diameter of the interlock shafts 10. In each
through bore 11, a pair of, i.e., left and right, ring-like elastic
seal members 16 are disposed in a spaced-apart relation to each
other and held in contact with the interlock shaft 10 inserted
through the through bore 11, thus blocking the flow of working air
in the left and right operating air chambers 8 to effect isolation
of the two chambers 8.
[0043] The second embodiment of the pump is simpler in arrangement
than the first embodiment with omission of the cylindrical guide
members 15. Here, the elastic seal members 16, like the first
embodiment, are constituted by thin tong-like lip seals. As shown
in an enlarged scale in FIG. 4, each elastic seal member 16
constituted by a lip seal has an L-shaped sectional profile, and
its stem part 16a is secured in a threaded annular recess 31 formed
on each side of the pump head 2 by screwing a threaded ring-like
seal retainer 32 in the recess 31. Reference numeral 33 designates
a tool insertion bore formed in the seal retainer 32. The seal
retainer 32 is fitted in the annular recess 31 by inserting a
suitable tool. A tong part 16b of the lip seal 16, extending from
the stem part 16a and bent radially inwardly, is in elastic
frictional contact in a ring-like form on the entire outer
periphery of the interlock shaft 10, thus effecting a seal contact
therein. Thus, during their moving operation the interlock shafts
10 are in contact only with these elastic seal members 16 and not
in direct contact with the inner surfaces of the through bores 11
of the pump head 2. Thus, again in this embodiment no particular
bearing for the interlock shafts 10 is necessary.
[0044] FIGS. 3 and 4 are provided for describing one interlock
shaft 10 and relative arrangement thereto. However, like the first
embodiment a pair of interlock shafts 10 are disposed in the
working air chambers 8. Also, as the material of these constituent
members, like the first embodiment all the elements can be readily
made from appropriate resin.
[0045] FIG. 5 shows a modification of the lip seal constituting the
elastic seal member in corresponding to the part shown in FIG. 4.
As in the seal retainer 32 in the second embodiment, the stem part
16a is formed to have an enlarged shape so that it also serves as
the seal retainer 16 shown in the second embodiment. Here, the stem
part 16a of the lip seal 16 is held in an annular recess 31 without
thread such that it is pushed from the outside by the end face 1a
of the housing 1, and the thin tong part 16b extends such that it
is bent radially inwardly to be in sealed contact with the outer
periphery of the interlock shaft 10.
[0046] As shown, the elastic seal member 16 may be of various
shapes, but its part in contact with the interlock shaft 10 is
desirably of a thin tong-like shape.
[0047] While preferred embodiments and modifications of the
arrangement according to the invention have even described with
reference to the drawings, the interlock shafts 10 are shown to be
of rod-like shape. However, it is possible to use any other shape
such as angular shapes as well, and the illustrated arrangement is
by no means limitative.
* * * * *