U.S. patent application number 10/546422 was filed with the patent office on 2006-12-07 for reciprocating compressor.
Invention is credited to Yasunori Fujita, Ryosuke Izawa, Minoru Kanaizuka, Toshiaki Kuribara, Satoshi Watanabe.
Application Number | 20060275148 10/546422 |
Document ID | / |
Family ID | 32905461 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060275148 |
Kind Code |
A1 |
Watanabe; Satoshi ; et
al. |
December 7, 2006 |
Reciprocating compressor
Abstract
A reciprocating compressor comprising a cylinder block (3)
having formed therein a plurality of cylinders (11), a shaft
rotatably passing through the cylinder block and pistons engaged in
reciprocating movement inside the cylinders (11) as the shaft
rotates, which is installed by fastening mounting leg parts (31)
disposed at the cylinder block (3) at mounting positions, is
characterized in that the mounting leg parts are each constituted
with a connecting portion (31a) extending from the cylinder block 3
and a projected portion (31b) formed continuously to the connecting
portion to project on one side or both sides of the connecting
portion along the tightening direction and that the projected
portion (31b) has a lower level of rigidity compared to the
connecting portion (31a). The reciprocating compressor eliminates
the need for rigorous management of the piston clearance by
assuring firm installation via the mounting leg parts and also
assuring smooth movement of the pistons with the extent of cylinder
deformation kept within the allowable range.
Inventors: |
Watanabe; Satoshi; (Saitama,
JP) ; Kanaizuka; Minoru; (Saitama, JP) ;
Fujita; Yasunori; (Saitama, JP) ; Izawa; Ryosuke;
(Saitama, JP) ; Kuribara; Toshiaki; (Saitama,
JP) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING
1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Family ID: |
32905461 |
Appl. No.: |
10/546422 |
Filed: |
November 17, 2003 |
PCT Filed: |
November 17, 2003 |
PCT NO: |
PCT/JP03/14564 |
371 Date: |
July 6, 2006 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F04B 27/0891 20130101;
F04B 27/1045 20130101; F04B 27/1081 20130101 |
Class at
Publication: |
417/269 |
International
Class: |
F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 21, 2003 |
JP |
2003-044680 |
Claims
1. A reciprocating compressor comprising: a cylinder block having
formed therein a plurality of cylinders, a shaft rotatably passing
through said cylinder block and pistons engaged in reciprocating
movement inside said cylinders as said shaft rotates, which is
installed by fastening mounting leg parts disposed at said cylinder
block at mounting positions, wherein said mounting leg parts are
each constituted with a connecting portion extending from said
cylinder block and a projected portion formed continuously to said
connecting portion to project on one side or both sides of said
connecting portion along the tightening direction; and wherein said
projected portion has a lower level of rigidity compared to said
connecting portion so as to concentrate deformation occurring
during installation into said projected portion.
2. A reciprocating compressor comprising: a cylinder block having
formed therein a plurality of cylinders, a shaft rotatably passing
through said cylinder block and pistons engaged in reciprocating
movement inside said cylinders as said shaft rotates, which is
installed by fastening mounting leg parts disposed at said cylinder
block at mounting positions, wherein said mounting leg parts are
each constituted with a connecting portion extending from said
cylinder block and a projected portion formed continuously to said
connecting portion to project on one side or both sides of said
connecting portion along the tightening direction; and wherein the
sectional area of said projected portion is set smaller than the
sectional area of said connecting portion so as to concentrate
deformation occurring during installation into said projected
portion.
3. A reciprocating compressor according to claim 1, wherein a bolt
insertion hole at which a mounting bolt is inserted is formed at
the center of each projected portion and the wall thickness of said
connecting portion is not thinned out along a direction running
perpendicular to said bolt insertion hole.
4. (canceled)
5. (canceled)
6. A reciprocating compressor according to claim 2, wherein a bolt
insertion hole at which a mounting bolt is inserted is formed at
the center of each projected portion and the wall thickness of said
connecting portion is not thinned out along a direction running
perpendicular to said bolt insertion hole.
7. A reciprocating compressor according to claim 1, wherein the
external shape of said projected portion is cylindrical.
8. A reciprocating compressor according to claim 2, wherein the
external shape of said projected portion is cylindrical.
9. A reciprocating compressor according to claim 3, wherein the
external shape of said projected portion is cylindrical.
10. A reciprocating compressor according to claim 1, wherein a bolt
insertion hole at which a mounting bolt is inserted is formed at
the center of each projected portion, with at least one projected
portion disposed on one side or both sides of said connecting
portion having a length along the axial direction set approximately
equal to or greater than the internal diameter of said bolt
insertion hole.
11. A reciprocating compressor according to claim 2, wherein a bolt
insertion hole at which a mounting bolt is inserted is formed at
the center of each projected portion, with at least one projected
portion disposed on one side or both sides of said connecting
portion having a length along the axial direction set approximately
equal to or greater than the internal diameter of said bolt
insertion hole.
12. A reciprocating compressor according to claim 3, wherein a bolt
insertion hole at which a mounting bolt is inserted is formed at
the center of each projected portion, with at least one projected
portion disposed on one side or both sides of said connecting
portion having a length along the axial direction set approximately
equal to or greater than the internal diameter of said bolt
insertion hole.
13. A reciprocating compressor according to claim 4, wherein a bolt
insertion hole at which a mounting bolt is inserted is formed at
the center of each projected portion, with at least one projected
portion disposed on one side or both sides of said connecting
portion having a length along the axial direction set approximately
equal to or greater than the internal diameter of said bolt
insertion hole.
Description
TECHNICAL FIELD
[0001] The present invention relates to a reciprocating compressor
which is installed by fastening mounting leg parts of the cylinder
block at specific positions with mounting bolts or the like.
BACKGROUND ART
[0002] A reciprocating compressor includes a cylinder block having
a plurality of cylinders formed therein, a shaft rotatably disposed
so as to pass through the cylinder block and pistons engaged in
reciprocating movement inside the cylinders as the shaft rotates.
It is installed at a specific location such as an engine
compartment by fastening and locking mounting leg parts formed at
the external circumferential surface of the cylinder block or the
like at specific positions with mounting bolts or the like.
[0003] While the mounting leg parts formed at the cylinder block or
the like may assume any of various structures, it is essential that
they be firmly locked at the mounting positions. For this reason,
in the structure disclosed in Japanese Unexamined Utility Model
Publication No. H2-43478, having mounting leg parts with
cylindrical front ends formed at the external circumference of the
compressor main unit as an integrated part thereof and bolt
insertion holes formed at the cylindrical front ends so as to
extend along a direction or perpendicular to the axis of the
compressor main unit, the mounting bolts passing through the bolt
insertion holes are fastened to mounting brackets locked onto
mounting eyes.
[0004] Another compressor mounting structure that is widely known
in the related art (see Japanese Unexamined Patent Publication No.
2001-182650) is adopted in conjunction with a compressor having a
bore housing having a plurality of cylinders formed therein and a
side housing having housed therein a piston drive means. Two main
mounting portions, each having a mounting hole or a mounting groove
at which a main locking bolt means is mounted, are disposed at the
external circumferential surface of the side housing and at least
one sub-mounting portion having a mounting hole or a mounting
groove at which a sub locking bolt means is mounted is disposed at
the external circumferential surface of the bore housing so as to
allow the compressor to be locked at the main mounting portions
while it is held at the sub-mounting portion. This structure allows
the compressor to be installed without having to mount the
sub-mounting portion with an excessive level of firmness which may
cause deformation of the bore housing.
[0005] However, the cylinder block of the compressor is often
constituted of an aluminum alloy in order to keep down the weight,
and there is a problem in that as the mounting leg parts are
fastened by tightening mounting bolts as in the structure described
above, the tightening pressure occurring while the mounting leg
parts are fastened deforms the mounting leg parts and the
deformation propagated to the cylinders compromises the shape of
the cylinders, which, in turn, prevents smooth movement of the
pistons. While the piston clearance may be set to a large value by
taking into consideration such cylinder deformation, the quantity
of working fluid leaking along the side surfaces of the pistons is
bound to increase when the piston clearance is large, which will
require more rigorous allowance management. If the management is
not rigorous enough, the performance of the compressor will become
poorer due to the leakage.
[0006] While the problem described above may be solved to some
extent by adopting the structure disclosed in the second
publication described above, the structure in which the level of
the tightening force with which the sub-mounting portion at the
cylinder block is fastened is relatively low is not necessarily
suited for an application in a compressor installed in a vehicle or
the like subjected to a great deal of vibration.
[0007] Accordingly, an object of the present invention is to
provide a reciprocating compressor that does not require rigorous
management of the piston clearance while assuring secure
installation via the mounting leg parts and also assuring smooth
movement of the pistons by keeping the extent of cylinder
deformation occurring during the installation within an allowable
range.
DISCLOSURE OF THE INVENTION
[0008] In order to achieve the object described above, a
reciprocating compressor according to the present invention
comprising a cylinder block having formed therein a plurality of
cylinders, a shaft rotatably passing through the cylinder block and
pistons engaged in reciprocating movement inside the cylinders as
the shaft rotates, which is installed by fastening mounting leg
parts disposed at the cylinder block at mounting positions, is
characterized in that the mounting leg parts are each constituted
with a connecting portion extending from the cylinder block and a
projected portion formed continuously to the connecting portion to
project on one side or both sides of the connecting portion along
the tightening direction and that the projected portion has a lower
level of rigidity compared to the connecting portion.
[0009] Accordingly, as the mounting leg parts disposed at the
cylinder block are fastened onto the mounting positions with
mounting bolts or the like to install the compressor at the
installation location, the tightening pressure occurring as the
mounting bolts are tightened causes deformation of the mounting leg
parts, but since the projected portions formed at the mounting leg
parts are formed to have a relatively low level of rigidity
compared to the connecting portions, the deformation occurring
during the tightening process manifests in a concentrated manner at
the projected portions. Thus, the deformation of the mounting leg
parts occurring during the tightening process can be absorbed at
the projected portions, reducing the extent to which the tightening
pressure is transmitted to the cylinders via the connecting
portions, which makes it possible to ensure that the extent of the
cylinder deformation is kept within the allowable range.
[0010] Alternatively, a reciprocating compressor according to the
present invention comprising a cylinder block having formed therein
a plurality of cylinders, a shaft rotatably passing through the
cylinder block and pistons engaged in reciprocating movement inside
the cylinders as the shaft rotates, which is installed by fastening
mounting leg parts disposed at the cylinder block at mounting
positions, is characterized in that the mounting leg parts are each
constituted with a connecting portion extending from the cylinder
block and a projected portion formed continuously to the connecting
portion to project on one side or both sides of the connecting
portion along the tightening direction and that the sectional area
of the projected portions is set smaller than the sectional area of
the connecting portions.
[0011] In this structure, while the mounting leg parts are caused
to become deformed by the tightening pressure occurring as the
mounting bolts are tightened when the mounting leg parts disposed
at the cylinder block are fastened at the mounting positions with
the mounting bolts to lock the compressor at the installation
location, the deformation occurring during the tightening process
manifests first and foremost at the projected portions since the
sectional area of the projected portions formed at the mounting leg
parts is set smaller than the sectional area of the connecting
portions. Thus, the deformation of the mounting leg parts occurring
during the tightening process can be absorbed at the projected
portions, reducing the extent to which the tightening pressure is
transmitted to the cylinders via the connecting portions, which
makes it possible to ensure that the extent of the cylinder
deformation is kept within the allowable range.
[0012] In either of the structures described above, a bolt
insertion hole at which a mounting bolt is inserted may be formed
at the center of each projected portion and thinning out the wall
thickness of the connecting portion along the direction running
perpendicular to the bolt insertion hole is not required. In such a
case, sufficient rigidity of the connecting portions can be assured
with an even higher level of reliability.
[0013] By forming the projected portions so that they assume a
cylindrical shape externally, uniform deformation may be induced at
the projected portions around the axes thereof during the
tightening process (claim 4). As a further alternative, a bolt
insertion hole at which a mounting bolt is inserted may be formed
at the center of each projected portion with at least one projected
portion disposed on one side or both sides of the corresponding
connecting portion along the tightening direction having a length
along the axial direction set approximately equal to or greater
than the internal diameter of the bolt insertion hole, so as to or
allow the deformation manifesting as the bolt is tightened to
concentrate at the projected portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side elevation of an external view of a
reciprocating compressor according to the present invention;
[0015] FIG. 2 is a sectional view of the reciprocating compressor
according to the present invention taken along line X-X in FIG.
3(b);
[0016] FIG. 3 shows the rear-side cylinder block in the compressor
shown in FIG. 1, with FIG. 3(a) presenting a side elevation and
FIG. 3(b) showing an end surface of the cylinder block, viewed from
the side where the rear-side cylinder head is located;
[0017] FIG. 4 presents an example of another structure that may be
adopted in the mounting leg parts;
[0018] FIG. 5 shows a cylinder block that does not include crush
zones at the mounting leg parts, with FIG. 5(a) presenting a side
elevation and FIG. 5(b) showing an end surface viewed from the
cylinder head side; and
[0019] FIG. 6 is a graph provided to facilitate the comparison of
the extent of cylinder deformation occurring as the mounting leg
portions are fastened in the structure shown in FIG. 5 which does
not include crush zones at the mounting leg parts and the extent of
deformation occurring as the mounting leg portions are fastened in
the structure according to the present invention, which does
include crush zones.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] The following is an explanation of embodiments of the
present invention, given in reference to the drawings. A
reciprocating compressor 1 shown in FIGS. 1 through 3, which is
used in a refrigerating cycle with a coolant used as a working
fluid, comprises a front-side cylinder block 2, a rear-side
cylinder block 3 mounted at the front-side cylinder block 2, a
front-side cylinder head 5 mounted at the front side (the left side
in FIGS. 1 and 2) of the front-side cylinder block 2 via a valve
plate 4 and a rear-side cylinder head 7 mounted at the rear side
(the right side in FIGS. 1 and 2) of the rear-side cylinder block 3
via a valve plate 6. The front-side cylinder head 5, the front-side
cylinder block 2, the rear-side cylinder block 3, and the rear-side
cylinder head 7 are fastened together along the axial direction
with a tightening bolt (not shown) and constitute the housing for
the whole compressor.
[0021] At the cylinder blocks 2 and 3 a shaft support hole 10 that
rotatably supports a shaft 9 to be detailed later, a plurality of
(5) cylinders 11 extending parallel to the shaft support hole 10
and disposed over equal intervals on a circumference of a circle
centered on the shaft 9, two discharge passages 12 extending
parallel to the cylinders 11 and intake passages 13 through which a
low pressure working fluid flows, are formed. The discharge
passages 12 communicate with each other via a guide passage 12a,
and individually communicating with a discharge chamber 14 formed
at the front-side cylinder head 5 to be detailed later and the
other discharge passage communicating with a discharge chamber 14
formed at the rear-side cylinder head 7. In addition, one of the
discharge passages 12 is connected to a discharge port 16 through
which the working fluid is let out to an external cycle via a
passing hole 15 formed at the valve plate 6 or the like. The intake
passages 13 are connected to a swashplate housing chamber 21 to be
detailed below and they are further connected with a low-pressure
passage 18 communicating with intake chambers 17 at the cylinder
heads 5 and 7 via the swashplate housing chamber 21. A double-ended
piston 19 is slidably inserted at each cylinder 11. It is to be
noted that reference numeral 20 in FIG. 3 indicates a bolt
insertion hole formed between adjacent cylinders 11, at which a
tightening bolt is inserted.
[0022] The swashplate housing chamber 21 formed by assembling the
front-side cylinder block 2 and the rear-side cylinder block 3 is
present inside the cylinder blocks, and the shaft 9 inserted at the
shaft support hole 10 formed at the front-side cylinder block 2 and
the rear-side cylinder block 3 with one end projecting out through
the front-side cylinder head 5 and fixed to the armature of an
electromagnetic clutch (not shown) is disposed in the swashplate
housing chamber 21.
[0023] A swashplate 22, which rotates as one with the shaft 9
inside the swashplate housing chamber 21, is fixed to the shaft 9.
The swashplate 22 is rotatably supported at the front-side cylinder
block 2 and the rear-side cylinder block 3 via thrust bearings 23,
with the circumferential edge thereof held at shoe pockets 25
formed at the center of the double ended pistons 19 via
semispherical shoes 24 disposed along the front/rear direction.
Thus, as the shaft 9 rotates causing the swashplate 22 to rotate,
the rotating movement is converted to reciprocal linear motion of
the double ended pistons 19 via the shoes 24, and then as the
double ended pistons 19 engage in the reciprocal motion, the
volumetric capacity of the compression space 26 formed inside each
cylinder 11 between the piston 19 and the valve plates 4 and 6 is
varied.
[0024] An intake hole 27 and a discharge hole 28 are formed at each
valve plate 4 and 6, in correspondence to each of the cylinders 11.
In addition, the intake chambers 17, in which the working fluid to
be supplied to the compression spaces 26 is stored, and the
discharge chambers 14 in which the working fluid discharged from
the compression spaces 26 is stored, are defined. The intake
chambers 17 are allowed to communicate with the compression spaces
26 via the intake holes 27 formed at the valve plates 4 and 6,
whereas the discharge chambers 14 formed continuously around the
intake chambers 17 are allowed to communicate with the compression
spaces 26 via the discharge holes 28 formed at the valve plates 4
and 6.
[0025] The intake holes 27 are opened/closed with intake valves 29
disposed at the end surfaces of the valve plates 4 and 6 toward the
cylinder blocks, whereas the discharge holes 28 are opened/closed
with discharge valves 30 disposed at the end surfaces of the valve
plates 4 and 6 toward the cylinder heads.
[0026] Thus, during an intake stroke in which the volumetric
capacity of the compression space 26 increases as the piston 19
moves reciprocally, the working fluid is taken into the compression
spaces 26 from the intake chamber 17 via the intake hole 27 and the
intake valve 29, whereas during a compression stroke in which the
volumetric capacity of the compression space 26 decreases, the
working fluid having been compressed in the compression space 26 is
discharged via the discharge hole 28 and the discharge valve 30 to
the discharge chamber 14 and is forced to the outside of the
compressor from the discharge port 16 via the discharge passage
12.
[0027] At the external circumferential surfaces of the cylinder
blocks 2 and 3 described above, mounting leg parts 31 used when
installing the compressor at a specific mounting location in an
engine room or the like are formed at positions symmetrical to each
other relative to the axis (upper and lower positions in the
figure).
[0028] The mounting leg parts 31 each include a connecting portion
31a extending from the cylinder block 2 or 3 along a substantially
radial direction and a projected portion 31b formed continuous to
the connecting portion 31a so as to project on one side of the
connecting portion along the tightening direction running
perpendicular to the shaft 9. At the center of the projected
portion 31b, a bolt insertion hole 32 at which a mounting bolt (not
shown) to interlock with a mounting hole formed at the mounting
area is inserted, is formed to range over to the connecting portion
31a. In addition, the wall thickness of the connecting portion 31a
at the mounting leg part 31 is not thinned out from the direction
running perpendicular to the bolt insertion hole 32.
[0029] The mounting leg parts 31 are formed as an integrated part
of the cylinder blocks 2 and 3 by using an aluminum alloy, with the
projected portions 31b formed to have a lower level of rigidity
compared to the connecting portions 31a to form more deformable
crush zones. More specifically, the rigidity at each projected
portion 31b is set lower than the rigidity at the corresponding
connecting portion by setting the area of a section of the
projected portion 31b perpendicular to the axial line of the bolt
insertion hole 32 smaller than the area of a section of the
connecting portion 31a. In this example, the sectional area of the
projected portion is reduced by forming the bolt insertion hole 32
to have a uniform internal diameter over the full range and setting
the external diameter of the projected portion 31b to a relatively
small value so as to form a stage at the surface over which the
connecting portion 31a turns into the projected portion 31b.
[0030] In addition, the projected portion 31b in the structure
described above is formed in a cylindrical shape with a uniform
thickness, with the length of the projected portion 31b along the
axial direction set approximately equal to or greater than the
internal diameter of the bolt insertion hole 32.
[0031] In the structure described above, as a mounting bolt is
inserted at the bolt insertion hole 32 from the side on which the
projected portion 31b is formed (from the direction indicated with
the arrow in FIG. 3(b)) and the corresponding mounting leg part 31
is fastened by interlocking the mounting bolt at a screw hole
formed at a specific mounting position, the mounting leg part 31
becomes deformed due to the tightening pressure. However, since the
level of rigidity of the projected portion 31b formed at the
mounting leg part 31 is set lower than the rigidity of the
connecting portion 31a and the wall of the connecting portion 31a
is not thinned out, the deformation occurring during the tightening
process manifests at the projected portion 31b in a concentrated
manner. Thus, the deformation of the mounting leg part 31 occurring
during the tightening process can be absorbed at the projected
portion 31b, which disallows ready transmission of the tightening
pressure to the cylinder 11 via the connecting portion 31a.
Consequently, the extent of deformation of the cylinder 11 is kept
within the allowable range and the circularity of the cylinder can
be maintained at a high degree of accuracy, assuring smooth
movement of the piston 19. In addition, since the extent of
deformation of the cylinder 11 is reduced, a large piston clearance
for assuring a comfortable margin for the deformation of the
cylinder 11 is not necessary. Moreover, rigorous allowance
management for purposes of managing the working fluid leaking past
the side surface of the piston 19 is not required.
[0032] Furthermore, since the projected portion 31b of the mounting
leg part 31 is formed in a cylindrical shape, the projected portion
31b becomes deformed with uniformity around the axis during the
tightening process. Thus, with the projected portion 31b allowed to
become deformed evenly, the extent to which the cylinder 11 becomes
deformed can be reduced. In addition, since the length of the
projected portion 31b along the axial direction is set
approximately equal to or greater than the diameter of the bolt
insertion hole 32, the deformation occurring as the mounting bolt
is tightened can be concentrated at the projected portion 31b with
an even higher degree of reliability, which also makes it possible
to reduce the extent of deformation of the cylinder 11.
[0033] While the projected portion 31b is formed only on one side
of the connecting portion along the tightening direction in the
example described above, the projected portion 31b may be disposed
on each side along the tightening direction, as shown in FIG. 4(a).
Namely, the mounting leg portion 31 may include projected portions
31b projecting on the two sides along the tightening direction at
the connecting portion 31a extending from the cylinder block 2 or 3
substantially along the radial direction with the bolt insertion
hole 32 formed to have a uniform diameter ranging from one of the
projected portions 31b through the other projected portion 31b and
the sectional area of the projected portions set smaller by setting
the external diameter of the projected portions 31b smaller than
the diameter of the connecting portion 31a so as to form a crush
zone with lower rigidity at each end of the bolt insertion hole
32.
[0034] In addition to advantages similar to the previous structural
example, this structure, which allows the deformation occurring
during the tightening process to be dispersed onto the two sides of
the connecting portion 31a, makes it possible to reduce the extent
to which the tightening force is communicated to the cylinder 11
via the connecting portion 31a with an even higher degree of
reliability.
[0035] While the rigidity at the projected portions 31b is set
smaller relative to the rigidity at the connecting portions by
setting the external diameter of the projected portions 31b to a
smaller value in the structures described above, the rigidity of
the projected portions may be set smaller by adopting structures
other than those explained above.
[0036] For instance, in a structure having a projected portion 31c
formed on each side a long the tightening direction at each
mounting leg part 31, the projected portions 31c may be formed so
that their exteriors range uniformly to the external contour of the
connecting portions 31a without creating stages between the
projected portions and the connecting portion 31a, and the internal
diameter of the bolt insertion hole 32 may be set larger than the
areas where the projected portions 31c are present relative to the
internal diameter in the area over which the connecting portion 31a
is present. In this case, with the sectional area of the projected
portions 31c set smaller than the sectional area of the connecting
portion 31a, a crush zone with lower rigidity is formed at each end
of the bolt insertion hole 32. It is to be noted that since other
structural features such as the projected portions 31c each formed
in a cylindrical shape with a uniform thickness and the length of
the projected portions 31b along the axial direction set
substantially equal to or greater than the internal diameter of the
bolt insertion hole 32 are identical to those of the previous
structural examples, their explanation is omitted.
[0037] This structure, too, makes it possible to concentrate the
deformation occurring during the tightening process at the
projected portions 31c, which, in turn, reduces the extent to which
the mounting bolt tightening force is transmitted to the cylinder
11 via the connecting portion 31a, thereby achieving advantages
similar to those of the previous structural examples.
[0038] Alternatively, crush zones with lower rigidity than the
connecting portion may be formed by using a different material to
constitute the projected portions, as shown in FIG. 4(c). Namely,
in a structure having a projected portion on each side along the
tightening direction at the connecting portion 31a of the mounting
leg part 31, which extends from the cylinder block 2 or 3
substantially along the radial direction, the connecting portion
31a may be constituted of an aluminum alloy, as are the cylinder
blocks 2 and 3, the projected portions 31d may be formed by using a
synthetic resin with a lower level of rigidity compared to the
aluminum alloy, and the connecting portion and the projected
portions may be coupled by an appropriate means such as press
fitting or bonding so as to form low-rigidity crush zones at the
two ends of the bolt insertion hole 32. It is to be noted that
since other structural features such as the projected portions 31d
each formed in a cylindrical shape with a uniform thickness and the
length of the projected portions 31d along the axial direction set
substantially equal to or greater than the internal diameter of the
bolt insertion hole 32 are identical to those of the previous
structural examples, their explanation is omitted.
[0039] This structure, too, makes it possible to concentrate the
deformation occurring during the tightening process at the
projected portions 31d constituted of a synthetic resin, which, in
turn, reduces the extent to which the mounting bolt tightening
force is transmitted to the cylinder 11 via the connecting portion
31a, thereby achieving advantages similar to those of the previous
structural examples. In addition, in this structure, the projected
portions 31d may be formed with their exteriors ranging uniformly
and continuously to the external contour of the connecting portion
31a without creating stages between the projected portions 31d and
the connecting portion 31a with the bolt insertion hole 32 formed
to have a uniform internal diameter ranging from one of the
projected portions 31d through the other projected portion 31d, and
since the connecting portion 31a and the projected portions 31d can
be machined separately, the mounting leg part 31 can be formed with
greater ease.
[0040] A comparison of the extent of deformation occurring at
cylinders 11 when the mounting leg parts 31 are fastened with
mounting bolts by using the cylinder blocks 2 and 3 having the
projected portions 31b, 31c or 31d forming crush zones at the
mounting leg parts 31 as described above and by using a cylinder
block 36 shown in FIG. 5 with no projected portions to form crush
zones included at the mounting leg parts 31 and the wall thickness
reduced over an area 35 from the direction running perpendicular to
the bolt insertion holes 32 provided the results presented in FIG.
6. The bore numbers in FIG. 6 were assigned to identify the
individual cylinders, with "No. V" assigned to the cylinder 11
located closest to the bottom where the mounting leg parts 31 are
present in FIGS. 3 and 5, and "No. IV", "No. III", "No. II" and
"No. I" sequentially assigned to the remaining cylinders 11 by
moving clockwise from the cylinder No. V. The extents of
deformation occurring as the mounting bolts inserted at the bolt
insertion holes 32 from the left side in FIGS. 3 and 5 were
tightened were compared.
[0041] As the results of the comparison clearly indicate, the
extent of deformation of the cylinders 11 that occurred as the
mounting bolts were tightened in either of the structures, was
lessened when crush zones were formed at the mounting leg parts 31,
compared to the extent of deformation at the cylinders 11 in the
structure that did not include any crush zones. The greatest
difference in the extent of deformation manifested at the cylinders
(V) closest to the mounting leg parts 31.
[0042] It is to be noted that while the rigidity of the projected
portions is lessened relative to the rigidity of the connecting
portions by setting the sectional area of the projected portions
smaller than the sectional area of the connecting portions or by
forming the projected portions with a material different from the
material used to form the connecting portions in the structural
examples described above, the features of the structural examples
described above may be adopted in combination as appropriate. In
addition, as an alternative to or as an additional feature to the
structural examples described above, different levels of rigidity
may be achieved chemically through a heat treatment or the
like.
INDUSTRIAL APPLICABILITY
[0043] As described above, the reciprocating compressor according
to the present invention comprising a cylinder block having a
plurality of cylinders formed therein, a shaft rotatably passing
through the cylinder block and pistons engaged in reciprocal motion
in the cylinders as the shaft rotates, which is installed by
fastening mounting leg parts disposed at the cylinder block at
mounting positions, is characterized in that the mounting leg parts
each include a connecting portion extending from the cylinder block
and a projected portion formed continuous to the connecting portion
and projecting on one side or both sides of the connecting portion
along the tightening direction. Since the projected portions are
formed so as to have a lower level of rigidity compared to the
connecting portions, the deformation occurring as the mounting
bolts are tightened can be concentrated at the projected portions,
which makes it possible to assure smooth movement of the pistons by
keeping down the extent of cylinder deformation within the
allowable range while assuring firm installation of the compressor
via the mounting leg parts. As a result, rigorous management of the
piston clearance is no longer required and a greater tolerance can
be assumed for the piston clearance.
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