U.S. patent application number 15/712564 was filed with the patent office on 2018-03-29 for pump system.
This patent application is currently assigned to AISIN SEIKI KABUSHIKI KAISHA. The applicant listed for this patent is AISIN SEIKI KABUSHIKI KAISHA. Invention is credited to Kensuke Miyazaki, Hiroto Ogawa.
Application Number | 20180087514 15/712564 |
Document ID | / |
Family ID | 61564043 |
Filed Date | 2018-03-29 |
United States Patent
Application |
20180087514 |
Kind Code |
A1 |
Miyazaki; Kensuke ; et
al. |
March 29, 2018 |
Pump System
Abstract
A pump system includes: a metallic flow path housing including a
suction portion configured to suction a fluid and a discharge
portion configured to deliver the suctioned fluid; and a resin
motor housing configured to drive a pump rotor existing inside the
flow path housing in a state of being fitted and connected to the
flow path housing, in which the flow path housing includes a first
fitting portion having a cylindrical inner circumferential surface,
and a first flange portion in an attitude perpendicular to a center
axis that becomes a center of the inner circumferential surface,
and the motor housing includes a second fitting portion having a
columnar outer circumferential surface and a second flange portion,
and on an outer circumferential surface of the second fitting
portion, protrusions are formed.
Inventors: |
Miyazaki; Kensuke;
(Nagoya-shi, JP) ; Ogawa; Hiroto; (Takahama-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AISIN SEIKI KABUSHIKI KAISHA |
Kariya-shi |
|
JP |
|
|
Assignee: |
AISIN SEIKI KABUSHIKI
KAISHA
Kariya-shi
JP
|
Family ID: |
61564043 |
Appl. No.: |
15/712564 |
Filed: |
September 22, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/40 20130101;
F04D 25/0606 20130101; F04D 13/06 20130101; F04D 29/086 20130101;
F04D 29/426 20130101; F04D 29/08 20130101 |
International
Class: |
F04D 25/06 20060101
F04D025/06; F04D 29/40 20060101 F04D029/40; F04D 29/08 20060101
F04D029/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2016 |
JP |
2016-185301 |
Claims
1. A pump system comprising: a metallic flow path housing including
a suction portion configured to suction a fluid and a discharge
portion configured to deliver the suctioned fluid; and a resin
motor housing configured to drive a pump rotor existing inside the
flow path housing in a state of being fitted and connected to the
flow path housing, wherein the flow path housing includes a first
fitting portion having a cylindrical inner circumferential surface,
and a first flange portion in an attitude perpendicular to a center
axis that becomes a center of the inner circumferential surface,
the motor housing includes a second fitting portion having a
columnar outer circumferential surface fitted into the first
fitting portion and a second flange portion connected to the first
flange portion, and on an outer circumferential surface of the
second fitting portion, a plurality of protrusions are formed to
protrude to a position at which the protrusions have a diameter
larger than an inner diameter of the inner circumferential surface
of the first fitting portion, and the first fitting portion and the
second fitting portion are connected to each other in a state where
a gasket is sandwiched between the first flange portion and the
second flange portion.
2. The pump system according to claim 1, wherein the plurality of
protrusions are pressed on an inner surface of the first fitting
portion in a state where the first fitting portion and the second
fitting portion are fitted to each other.
3. The pump system according to claim 1, wherein the second flange
portion has a recessed portion formed in a concave shape in a
region of a connecting surface thereof that surrounds the
protrusion when viewed in a direction along the center axis.
4. The pump system according to claim 1, wherein the protrusions
are disposed near a plurality of fastening portions in which the
first flange portion and the second flange portion are fastened to
each other by a bolt.
5. A pump system comprising: a metallic flow path housing including
a suction portion configured to suction a fluid and a discharge
portion configured to deliver the suctioned fluid; and a resin
motor housing configured to drive a pump rotor existing inside the
flow path housing in a state of being fitted and connected to the
flow path housing, wherein the flow path housing includes a first
fitting portion having a cylindrical inner circumferential surface,
and a first flange portion in an attitude perpendicular to a center
axis that becomes a center of the inner circumferential surface,
the motor housing includes a second fitting portion having a
columnar outer circumferential surface fitted into the first
fitting portion and a second flange portion connected to the first
flange portion, and on an outer circumferential surface of the
second fitting portion, a plurality of protrusions are formed to
protrude to a position at which the protrusions have a diameter
larger than an inner diameter of the inner circumferential surface
of the first fitting portion, the first fitting portion and the
second fitting portion are connected to each other in a state where
a gasket is sandwiched between the first flange portion and the
second flange portion, the plurality of protrusions are pressed on
an inner surface of the first fitting portion in a state where the
first fitting portion and the second fitting portion are fitted to
each other, and the second flange portion has a recessed portion
formed in a concave shape in a region of a connecting surface
thereof that surrounds the protrusion when viewed in a direction
along the center axis.
6. A pump system comprising: a metallic flow path housing including
a suction portion configured to suction a fluid and a discharge
portion configured to deliver the suctioned fluid; and a resin
motor housing configured to drive a pump rotor existing inside the
flow path housing in a state of being fitted and connected to the
flow path housing, wherein the flow path housing includes a first
fitting portion having a cylindrical inner circumferential surface,
and a first flange portion in an attitude perpendicular to a center
axis that becomes a center of the inner circumferential surface,
the motor housing includes a second fitting portion having a
columnar outer circumferential surface fitted into the first
fitting portion and a second flange portion connected to the first
flange portion, and on an outer circumferential surface of the
second fitting portion, a plurality of protrusions are formed to
protrude to a position at which the protrusions have a diameter
larger than an inner diameter of the inner circumferential surface
of the first fitting portion, the first fitting portion and the
second fitting portion are connected to each other in a state where
a gasket is sandwiched between the first flange portion and the
second flange portion, the plurality of protrusions are pressed on
an inner surface of the first fitting portion in a state where the
first fitting portion and the second fitting portion are fitted to
each other, the second flange portion has a recessed portion formed
in a concave shape in a region of a connecting surface thereof that
surrounds the protrusion when viewed in a direction along the
center axis, and the protrusions are disposed near a plurality of
fastening portions in which the first flange portion and the second
flange portion are fastened to each other by a bolt.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
U.S.C. .sctn. 119 to Japanese Patent Application 2016-185301, filed
on Sep. 23, 2016, the entire contents of which are incorporated
herein by reference.
TECHNICAL FIELD
[0002] This disclosure relates to a pump system in which a flow
path housing, through which a fluid flows, and a motor housing,
which drives a pump rotor inside the flow path housing, are
connected to each other.
BACKGROUND DISCUSSION
[0003] As an example of a pump system that supplies cooling water
to an engine of a vehicle, JP 2008-025538 A (Reference 1) discloses
a technique in which a flow path housing (referred to as a pump
case in Reference 1) is attached to a motor housing (referred to as
a motor case in Reference 1) that constitutes a motor unit, and a
pump rotor having a plurality of impellers is accommodated in the
flow path housing.
[0004] In Reference 1, a shaft is provided of which one end is
supported by the motor housing and the other end supported by the
flow path housing, and a rotor unit is rotatably fitted on the
shaft. The pump rotor is configured by providing a permanent magnet
to the rotor unit and providing a plurality of impellers at the end
position of the rotor unit.
[0005] In addition, in Reference 1, in view of the drawings
thereof, the motor housing and the flow path housing are connected
to each other by making flange portions formed on the motor housing
and the flow path housing abut on each other and fitting the
fitting portions formed on the outer circumferences of the flange
portions to each other.
[0006] In the water pump described in Reference 1, the flow path
housing is formed of a resin, and the portion of the motor housing,
which is fitted to the flow path housing, is formed of a resin.
Even in the configuration provided with such fitting structures, it
is difficult to maintain high fitting accuracy since the fitting
structures are both formed of a resin material.
[0007] Therefore, in the configuration in which one end of the
shaft is supported by the motor housing and the other end is
supported by the flow path housing, it is also considered that
axial centering accuracy may be deteriorated.
[0008] In order to solve the problems, a configuration in which the
flow path housing and the motor housing are formed of a metal
material and are fitted to each other in the same manner as in
Reference 1 is effective. However, when considering insulation
performance or manufacturing costs, it is required to use a resin
material for the motor housing.
[0009] Thus, a need exists for a pump system which is not
susceptible to the drawback mentioned above.
SUMMARY
[0010] A feature of a pump system according to an aspect of this
disclosure resides in that the pump system includes: a metallic
flow path housing including a suction portion configured to suction
a fluid and a discharge portion configured to deliver the suctioned
fluid; and a resin motor housing configured to drive a pump rotor
existing inside the flow path housing in a state of being fitted
and connected to the flow path housing, in which the flow path
housing includes a first fitting portion having a cylindrical inner
circumferential surface and a first flange portion in an attitude
perpendicular to a center axis that becomes a center of the inner
circumferential surface, the motor housing includes a second
fitting portion having a columnar outer circumferential surface
fitted into the first fitting portion and a second flange portion
connected to the first flange portion, and on an outer
circumferential surface of the second fitting portion, a plurality
of protrusions are formed to protrude to a position at which the
protrusions have a diameter larger than an inner diameter of the
inner circumferential surface of the first fitting portion, and the
first fitting portion and the second fitting portion are connected
to each other in a state where a gasket is sandwiched between the
first flange portion and the second flange portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing and additional features and characteristics of
this disclosure will become more apparent from the following
detailed description considered with the reference to the
accompanying drawings, wherein:
[0012] FIG. 1 is a partially cut-away side view of a pump
system;
[0013] FIG. 2 is an exploded side view of the pump system, a
portion of which is illustrated in a cross section;
[0014] FIG. 3 is a view illustrating the arrangement of a second
flange portion, a second fitting portion, protruding pieces, and so
on;
[0015] FIG. 4 is a view illustrating the arrangement of a first
flange portion, a first fitting portion, and so on;
[0016] FIG. 5 is a perspective view illustrating the shapes of a
protruding piece and a recessed portion; and
[0017] FIG. 6 is a cross-sectional view illustrating the state of a
protrusion in a state where the first fitting portion and the
second fitting portion are fitted to each other.
DETAILED DESCRIPTION
[0018] Hereinafter, embodiments disclosed here will be described
based on the drawings.
[Basic Configuration]
[0019] As illustrated in FIG. 1, a pump system 100 is configured by
fitting and connecting a metallic flow path housing 10, which is
connected to the bottom wall of an engine 1 so as to return, to the
engine 1, cooling water (an example of the fluid) returned from a
radiator and so on via a hose 2, and a resin motor housing 20
configured to drive a pump unit P inside the flow path housing 10
and accommodate an electric motor M therein.
[0020] In the pump system 100, when the engine 1 is operated, a
pump rotor 22 of the pump unit P is driven by driving force of the
electric motor M accommodated in the motor housing 20, so that
circulation of the cooling water is implemented in the form of
suctioning the cooling water from the radiator and so on into the
flow path housing 10 and returning the cooling water to a water
jacket of the engine 1.
[Flow Path Housing]
[0021] As illustrated in FIGS. 1 and 2, the flow path housing 10
includes a flow path housing body 11 in which a flow path space is
formed to deliver the cooling water. The flow path housing body 11
is integrally formed, on the base end side thereof, with a
discharge portion 12, which is connected to the bottom portion of
the engine 1, and is provided, on the outer end side thereof, with
a suction portion 13, to which the hose 2 is connected.
[0022] In the pump system 100, since the pump unit P is formed in a
centrifugal type, a circular pump chamber 11a centered on the
center axis X is formed in the flow path housing body 11, and a
discharge flow path 11b is formed to extend from the outer
circumference of the pump chamber 11a toward the discharge portion
12.
[0023] A connecting portion 14 is formed in a flange shape on the
discharging portion 12 to connect the flow path housing body 11 to
the engine 1. When the connecting portion 14 is connected to the
engine 1 by connecting bolts 3, the discharge flow path 11b of the
discharge portion 12 communicates with the water jacket of the
engine 1.
[0024] In addition, the suction portion 13 is formed in a
cylindrical shape and fixed to the flow path housing body 11 by
fixing bolts 4 in a direction along the center axis X. As a result,
the suction portion 13 and the pump chamber 11a communicate with
each other. In addition, a support portion 15 is formed coaxially
with the center axis X inside the flow path housing body 11 to
support the axial end of a rotor shaft 21 of the pump rotor 22. In
addition, the suction portion 13 may be integrally formed with the
flow path housing 10.
[0025] In the pump system 100, the rotor shaft 21 is fixedly
installed in the motor housing 20, and a motor rotor (not
illustrated) and the pump rotor 22, which is integrally formed with
the motor rotor, are rotatably supported with respect to the rotor
shaft 21. In addition, instead of this configuration, the pump
system 100 may be configured such that the rotor shaft 21 is
provided to be driven by the electric motor M and the pump rotor 22
rotates integrally with the rotor shaft 21.
[0026] In particular, as illustrated in FIG. 4, the flow path
housing body 11 includes a first fitting portion 16, which has a
cylindrical inner circumferential surface having a circular
cross-sectional shape centered on the center axis X, and a first
flange portion 17, which has a first connecting surface 17S in the
attitude perpendicular to the center axis X of the inner
circumferential surface. A plurality of (four in this embodiment)
screw-hole portions 17a are formed in the first flange portion
17.
[0027] The four screw-hole portions 17a are formed at positions at
which the circumference centered on the center axis X is equally
divided into four portions (positions at which 360 degrees are
divided by 90 degrees around the center axis X).
[0028] In addition, a seal groove 17G, which has a circular shape
centered on the center axis X, is formed in the first connecting
surface 17S of the first flange portion 17, and an annular gasket 6
formed of a flexible material such as rubber or resin, is fitted
therein. The gasket 6 used here is sized to slightly protrude from
the first connecting surface 17S.
[Motor Housing]
[0029] As illustrated in FIGS. 1 to 3, the motor housing 20
accommodates the electric motor M therein, and includes the rotor
shaft 21 coaxially disposed with the center axis X. The pump rotor
22 is supported by the rotor shaft 21, and a plurality of impellers
22a are formed on the pump rotor 22.
[0030] The motor housing 20 is provided with a second fitting
portion 23, which has a columnar shape centered on the center axis
X and has a columnar outer circumferential surface centered on the
center axis X so as to be fittable into the first fitting portion
16, and a second flange portion 24, which has a second connecting
surface 24S in the attitude perpendicular to the center axis X. A
plurality of bolt insertion holes 24a (four in this embodiment) are
formed in the second flange portion 24.
[0031] In addition, the four bolt insertion holes 24a are formed at
positions at which the circumference around the rotor shaft 21 is
equally divided into four portions so as to correspond to the four
screw-hole portions 17a.
[0032] As illustrated in FIG. 3, a plurality of (four) protruding
pieces 25 (e.g., protrusions) each having a thin plate shape are
formed on the outer circumferential surface of the second fitting
portion 23 on imaginary straight lines that interconnect the center
axis X and the respective bolt insertion holes 24a. The protruding
pieces 25 are formed to protrude to a position at which the
protruding pieces 25 have a diameter larger than the inner diameter
of the inner circumferential surface of the first fitting portion
16. That is, the protruding distance D to the protruding end of
each protruding piece 25 based on the center axis X is set to a
value that is larger than the radius R of the inner circumferential
surface of the first fitting portion 16, as illustrated in FIG.
4.
[0033] As illustrated in FIG. 2, compared with the fitting distance
L (fitting margin) of the second fitting portion 23 in the
direction along the center axis X, the region length N of the
protruding piece 25 from the second connecting surface 24S is set
to a value that is smaller than the fitting distance L. In
addition, as illustrated in FIG. 4, the protruding distance D to
the protruding end of the protruding piece 25 based on the center
axis X is set to a value that is sufficiently smaller than the
groove radius E to the inner position of the seal groove 17G, which
has a circular shape centered on the center axis X, in the first
connecting surface 17S. In particular, the offset distance Q from
the first fitting portion 16 to the inner position of the seal
groove 17G is longer than the region length N.
[0034] In addition, as illustrated in FIGS. 3 and 5, in the second
connecting surface 24S of the second flange portion 24, a recessed
portion 26 is formed in a region surrounding the protruding piece
25 when viewed in the direction along the center axis X. In
particular, since the protruding piece 25 is integrally formed with
the motor housing 20, the protruding piece 25 is also formed of a
resin material.
[0035] As illustrated in FIG. 1, in the state where the second
fitting portion 23 is fitted to the first fitting portion 16 and
connected by fastening bolts 5, the pump unit P is constituted by
the pump rotor 22 and the pump chamber 11a in which the pump rotor
22 is disposed. Details of this fitting connection will be
described later.
[0036] The motor housing 20 includes a connector portion 27
provided on the outer end of the second flange portion 24. In
addition, a cover body 28 is provided to cover the motor housing
20, and a flange-shaped connecting body 28a is integrally formed on
the cover body 28 to overlap the outer surface side of the second
flange portion 24. The connecting body 28a has hole portions 28b
formed at positions at which the hole portions 28b overlap the bolt
insertion holes 24a in the second flange portion 24.
[Fitting Connection]
[0037] When the first fitting portion 16 and the second fitting
portion 23 are fitted and connected to each other, the operations
of setting the pump rotor 22 in the motor housing 20, disposing the
cover body 28 at the position at which it covers the motor housing
20, and inserting the outer circumferential surface of the second
fitting portion 23 into the inner circumferential surface of the
first fitting portion 16 are performed.
[0038] During the operations, a fastening operation is performed by
inserting the fastening bolt 5 from the hole portion 28b of the
connecting body 28a through the bolt insertion hole 24a in the
second flange portion 24, and screwing the fastening bolt 5 into
the screw-hole portion 17a of the first flange portion 17.
[0039] When the fastening operation is performed, the motor housing
20 is displaced relative to the first fitting portion 16 in the
direction in which the second fitting portion 23 is inserted in the
direction along the center axis X. With this displacement, a
portion of the plurality (four) of the protruding pieces 25, which
protrudes outward from the opening of the first fitting portion 16,
comes into contact with the opening edge of the first fitting
portion 16, thereby being scraped and, at the same time, pressed
(crushed). Thereby, as illustrated in FIG. 6, the gap between the
inner circumferential surface of the first fitting portion 16 and
the outer circumferential surface of the second fitting portion 23
is filled with the protruding pieces 25.
[0040] In this fastening operation, by equally operating the four
fastening bolts 5, for example, the trouble of causing the rotor
shaft 21 to be tilted with respect to the center axis X or the
trouble of causing the rotor shaft 21 to have a positional
relationship in which the rotor shaft 21 deviates from the center
axis X may be eliminated even in a state where a gap is present
between the inner circumferential surface of the first fitting
portion 16 and the outer circumferential surface of the second
fitting portion 23. Thus, the axial end of the rotor shaft 21 on
the protruding side is accurately fitted into the supporting
portion 15 of the flow path housing 10.
[0041] In addition, when the shape of the protruding pieces 25 is
changed as described above, the protruding pieces 25 may be
partially scraped by the opening edge of the first fitting portion
16 to form fine resin pieces, and the fine resin pieces may be
accommodated in the recessed portions 26. As a result, it is
possible to eliminate the trouble of causing the fine resin pieces
to be sandwiched between the first connecting surface 17S and the
second connecting surface 24S.
[0042] As described above, since the offset distance Q is longer
than the region length N, for example, even if the resin of the
protruding pieces 25, which are scraped by the opening edge of the
first fitting portion 16, falls in a long piece state in the
direction of the gasket 6 without being cut, the resin in the long
piece state does not come into contact with the gasket 6 and the
sealing property is not impaired since the maximum length of the
resin in the long piece state is the region length N.
[0043] By continuing the fastening operation, the second connecting
surface 24S is brought into the state in which the second
connecting surface 24S abuts on the first connecting surface 17S,
and the gasket 6 is sandwiched therebetween, thereby implementing
the sealed state. In addition, the connecting body 28a of the cover
body 28 is pressed against the outer surface side of the second
flange portion 24 by the fastening operation, so that the cover
body 28 covers the motor housing 20.
[0044] As described above, in the state where the second fitting
portion 23 is fitted to the first fitting portion 16, even if a gap
is present between the inner circumferential surface of the first
fitting portion 16 and the outer circumferential surface of the
second fitting portion 23, the deformed protruding pieces 25
reliably come into contact with the inner circumferential surface
of the first fitting portion 16 so as to maintain the flow path
housing 10 and the motor housing 20 in a predetermined proper
positional relationship.
OTHER EMBODIMENTS
[0045] This disclosure may adopt other configurations as follows,
in addition to the above embodiment (the same reference numerals as
those in the embodiment are given to components having functions
similar to those in the embodiment).
[0046] (a) The number of the protruding pieces 25 (e.g.
protrusions) is set to 3 or 4 or more. Although it is ideal that,
with the configuration in which the above-mentioned number is set,
all of the protruding pieces 25 are disposed at the positions
corresponding to the fastening portions of the fastening bolts 5
that connect the first flange portion 17 and the second flange
portion 24 to each other, some of the protruding pieces 25 may be
disposed at positions spaced apart from the fastening
positions.
[0047] (b) The plate thickness of the protruding pieces 25 (e.g.
protrusions) may be set to be thicker toward the second connecting
surface 24S or the protrusion amount of the protruding pieces 25
based on the outer circumferential surface of the second fitting
portion 23 may be set to be larger toward the second connecting
surface 24S. When the protruding pieces 25 are formed in this way,
it is possible to create a better fitting state.
[0048] This disclosure may be used in a pump system in which a
motor housing is connected to a flow path housing.
[0049] A feature of a pump system according to an aspect of this
disclosure resides in that the pump system includes: a metallic
flow path housing including a suction portion configured to suction
a fluid and a discharge portion configured to deliver the suctioned
fluid; and a resin motor housing configured to drive a pump rotor
existing inside the flow path housing in a state of being fitted
and connected to the flow path housing, in which the flow path
housing includes a first fitting portion having a cylindrical inner
circumferential surface and a first flange portion in an attitude
perpendicular to a center axis that becomes a center of the inner
circumferential surface, the motor housing includes a second
fitting portion having a columnar outer circumferential surface
fitted into the first fitting portion and a second flange portion
connected to the first flange portion, and on an outer
circumferential surface of the second fitting portion, a plurality
of protrusions are formed to protrude to a position at which the
protrusions have a diameter larger than an inner diameter of the
inner circumferential surface of the first fitting portion, and the
first fitting portion and the second fitting portion are connected
to each other in a state where a gasket is sandwiched between the
first flange portion and the second flange portion.
[0050] With this configuration, in a case where an operation of
fitting the second fitting portion of the motor housing into the
first fitting portion of the flow path housing is performed, since
the first fitting portion is formed of a metal and the second
fitting portion is formed of a resin, in the plurality of
protrusions protruding from the outer circumferential surface of
the second fitting portion, a portion thereof that has a diameter
larger than that of the inner circumferential surface of the first
fitting portion is scraped or crushed, so that the protrusions are
brought into close contact with the inner circumferential surface
of the first fitting portion. That is, even if a gap is present
between the inner circumferential surface of the first fitting
portion and the outer circumferential surface of the second fitting
portion, the gap may be filled with some of the plurality of
protrusions. As a result, even if the first flange portion and the
second flange portion are connected to each other in a state where
the gasket is sandwiched therebetween, the connection is
implemented in a state where rattling is suppressed between the
first fitting portion and the second fitting portion.
[0051] Therefore, the pump system is configured in which the motor
housing and the flow path housing are fitted and connected to each
other with high accuracy while the motor housing is formed of a
resin material.
[0052] In the aspect of this disclosure, the plurality of
protrusions may be pressed on an inner surface of the first fitting
portion in a state where the first fitting portion and the second
fitting portion are fitted to each other.
[0053] With this configuration, in a state where the first fitting
portion and the second fitting portion are fitted to each other,
the plurality of protrusions are present in a pressed state between
the inner circumferential surface of the first fitting portion and
the outer circumferential surface of the second fitting portion.
Thus, since the gap is filled with the pressed protrusions, a good
connection state is implemented without rattling.
[0054] In the aspect of this disclosure, the second flange portion
may have a recessed portion formed in a concave shape in a region
of a connecting surface thereof that surrounds the protrusion when
viewed in a direction along the center axis.
[0055] With this configuration, when performing an operation of
fitting the second fitting portion of the motor housing into the
first fitting portion of the flow path housing, even if a portion
of the protrusion is scraped by the first fitting portion to form
fine resin pieces, the resin pieces are accommodated in the
recessed portion, thereby suppressing the trouble of causing the
resin pieces to be interposed between the abutment surfaces of the
first flange portion and the second flange portion.
[0056] In the aspect of this disclosure, the protrusions may be
disposed near a plurality of fastening portions in which the first
flange portion and the second flange portion are fastened to each
other by a bolt.
[0057] With this configuration, when the first flange portion and
the second flange portion are fastened to each other by a plurality
of bolts, strong force is applied to the protrusions by fastening
force of the bolts, thereby enabling transition to the connection
state.
[0058] The principles, preferred embodiment and mode of operation
of the present invention have been described in the foregoing
specification. However, the invention which is intended to be
protected is not to be construed as limited to the particular
embodiments disclosed. Further, the embodiments described herein
are to be regarded as illustrative rather than restrictive.
Variations and changes may be made by others, and equivalents
employed, without departing from the spirit of the present
invention. Accordingly, it is expressly intended that all such
variations, changes and equivalents which fall within the spirit
and scope of the present invention as defined in the claims, be
embraced thereby.
* * * * *