U.S. patent application number 10/914644 was filed with the patent office on 2005-03-10 for scroll compressor.
Invention is credited to Takeuchi, Makoto, Tokuda, Masaaki, Ukai, Tetsuzo.
Application Number | 20050053507 10/914644 |
Document ID | / |
Family ID | 33566836 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050053507 |
Kind Code |
A1 |
Takeuchi, Makoto ; et
al. |
March 10, 2005 |
Scroll compressor
Abstract
A scroll compressor includes a first scroll and a second scroll.
The first scroll has a step portion that separates an elevated
portion and a recessed portion of a surface of the first scroll. A
spiral wall of the second scroll has a step that separates an
elevated portion and a recessed portion of the wall. A first bypass
hole is provided in the elevated portion of the surface of the
first scroll. A second bypass hole is provided in the recessed
portion of the surface of the first scroll. The second bypass hole
is within 360 degrees toward a center of the spiral of the first
scroll from an outer end of the spiral. The first bypass hole is
within 360 degrees from the second bypass hole toward the center of
the spiral.
Inventors: |
Takeuchi, Makoto; (Aichi,
JP) ; Ukai, Tetsuzo; (Aichi, JP) ; Tokuda,
Masaaki; (Aichi, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Family ID: |
33566836 |
Appl. No.: |
10/914644 |
Filed: |
August 10, 2004 |
Current U.S.
Class: |
418/55.1 ;
418/55.2 |
Current CPC
Class: |
F04C 18/0261 20130101;
F04C 18/0215 20130101; F04C 18/088 20130101; F04C 28/26 20130101;
F04C 18/0276 20130101 |
Class at
Publication: |
418/055.1 ;
418/055.2 |
International
Class: |
F01C 001/02; F04C
018/00; F01C 001/063 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 11, 2003 |
JP |
2003-291296 |
Aug 11, 2003 |
JP |
2003-291297 |
Claims
What is claimed is:
1. A scroll compressor comprising: a first scroll that includes a
first plate having a surface and a first wall fixed in a spiral
manner on the surface of the first plate; a second scroll that
includes a second plate having a surface and a second wall fixed in
a spiral manner on the surface of the second plate, wherein the
first wall of the first scroll and the second wall of the second
scroll engage with each other thereby forming a plurality of
compression chambers, and the first scroll and the second scroll
rotate relative to each other; the surface of the first plate
having a first bottom portion and a second bottom portion and the
first bottom portion and the second bottom portion are separated by
a first bottom step, wherein the first bottom portion is positioned
inside a first spiral formed by the first wall and near a center of
the first spiral, the first bottom portion is elevated in a
direction of height of the first wall, the second bottom portion is
positioned inside the first spiral and on an outer end of the first
spiral, and the second bottom portion is recessed in the direction
of the height of the first wall; the second wall of the second
scroll having a first wall portion and a second wall portion and
the first wall portion and the second wall portion are separated by
a first wall step, wherein the first wall portion is positioned on
a free end of the second wall and near a center of a second spiral
formed by the second wall, the first wall portion is recessed in a
direction of height of the second wall, the second wall portion is
positioned on the free end of the second wall and on an outer end
of the second spiral, and the second wall portion is elevated in
the direction of the height of the second wall, and at one
particular point the first bottom step abutting with the first wall
step when the first scroll and the second scroll rotate relative to
each other; and a bypass hole in the first bottom portion and that
lets a compression chamber among the compression chambers to
communicate with outside.
2. The scroll compressor according to claim 1, wherein the surface
of the second plate having a third bottom portion and a fourth
bottom portion and the third bottom portion and the fourth bottom
portion are separated by a second bottom step, wherein the third
bottom portion is positioned inside the second spiral and near a
center of the second spiral, the third bottom portion is elevated
in a direction of height of the second wall, the fourth bottom
portion is positioned inside the second spiral and on an outer end
of the second spiral, and the fourth bottom portion is recessed in
the direction of the height of the second wall; the first wall of
the first scroll having a third wall portion and a fourth wall
portion and the third wall portion and the fourth wall portion are
separated by a second wall step, wherein the third wall portion is
positioned on a free end of the first wall and near a center of the
first spiral, the first wall portion is recessed in a direction of
height of the first wall, the fourth wall portion is positioned on
the free end of the first wall and on an outer end of the first
spiral, and the fourth wall portion is elevated in the direction of
the height of the first wall, and at one particular point the
second bottom step abutting with the second wall step when the
first scroll and the second scroll rotate relative to each other;
and the first bottom portion having a second bypass hole at
substantially 180 degrees from the bypass hole toward the center of
the first spiral or toward the outer end of the first spiral, and
that lets a different compression chamber among the compression
chambers to communicate with outside.
3. The scroll compressor according to claim 1, wherein the second
bottom portion having a third bypass hole that lets a different
compression chamber among the compression chambers to communicate
with outside.
4. The scroll compressor according to claim 3, wherein the third
bypass hole is within 360 degrees from the outer end of the first
spiral toward the center of the first spiral, and the bypass hole
is within 360 degrees from the third bypass hole toward the center
of the first spiral.
5. The scroll compressor according to claim 4, wherein the third
bypass holes are provided in plurality.
6. The scroll compressor according to claim 3, wherein the second
bottom portion having a fourth bypass hole at substantially 180
degrees from the third bypass hole toward the center of the first
spiral, and that lets a different compression chamber among the
compression chambers to communicate with outside.
7. The scroll compressor according to claim 4, wherein the fourth
bypass holes are provided in plurality.
8. The scroll compressor according to claim 4, wherein the bypass
hole, the second bypass hole, the third bypass hole, and the fourth
bypass hope are substantially circular.
9. The scroll compressor according to claim 4, wherein a portion of
the bypass hole, the second bypass hole, the third bypass hole, and
the fourth bypass, hope is covered with the first wall.
Description
BACKGROUND OF THE INVENTION
[0001] 1) Field of the Invention
[0002] The present invention relates to a scroll compressor in an
air conditioning apparatus, a refrigerating apparatus, and the
like.
[0003] 2) Description of the Related Art
[0004] A scroll compressor includes a fixed scroll and a revolving
scroll. The fixed scroll includes a spiral wall that is vertically
fixed to an end plate. The revolving scroll also includes a spiral
wall, which has substantially the same shape as the wall of the
fixed scroll, that is vertically fixed to another end plate. The
scroll compressor is assembled in such a manner that the walls of
the fixed scroll and the revolving scroll engage with each other.
In this state, the revolving scroll is revolved with respect to the
fixed scroll, whereby a volume of a compression chamber formed
between the walls is gradually reduced to compress fluid in the
compression chamber.
[0005] Some conventional scroll compressors are provided with a
step portion between the spiral walls. The step portion is formed
with surfaces at different levels. The surface that is closer to an
inner end of the spiral (closer to a center of the spiral) is more
distant from a surface of the end plate than the surface that is
closer to an outer end of the spiral (closer to a fluid drawing
port). An edge of the wall is formed in a shape engaging with a
corresponding step portion. With such a structure, a fluid drawing
capacity of a chamber on the outer end side of the spiral is
increased, and pressure in a chamber on the inner end side is
increased. Thus, an improved compression ratio is obtained without
increasing an outer diameter of a scroll (e.g., Japanese Patent
Publication No. S60-17956).
[0006] In other conventional scroll compressors, a fluid through
hole (bypass hole) is provided in an end plate in a portion between
a spiral wall of a fixed scroll. The fluid through hole is openable
and closable. With this structure, by opening the fluid through
hole as required, a compression volume in a compression chamber is
reduced to lower a load on a drive source (e.g., Japanese Patent
Publication No. H1-33675).
[0007] However, when the bypass hole is provided in a portion that
is closer to the outer end of the spiral than the step portion,
there is a problem in that a compression loss occurs due to leakage
of fluid from an engaging part of the step portion and the wall. On
the other hand, when the bypass hole is provided in a portion that
is closer to the center of the spiral than the step portion, since
compression is performed on the outer end side of the spiral, there
is a problem in that excessive compression occurs before reducing a
compression volume with the bypass hole. A load is applied to a
drive source in an area where the excessive compression occurs.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a scroll
compressor that makes it possible to reduce the compression
loss.
[0009] A scroll compressor according to an aspect of the present
invention includes a first scroll that includes a first plate
having a surface and a first wall fixed in a spiral manner on the
surface of the first plate; a second scroll that includes a second
plate having a surface and a second wall fixed in a spiral manner
on the surface of the second plate, wherein the first wall of the
first scroll and the second wall of the second scroll engage with
each other thereby forming a plurality of compression chambers, and
the first scroll and the second scroll rotate relative to each
other; the surface of the first plate having a first bottom portion
and a second bottom portion and the first bottom portion and the
second bottom portion are separated by a first bottom step, wherein
the first bottom portion is positioned inside a first spiral formed
by the first wall and near a center of the first spiral, the first
bottom portion is elevated in a direction of height of the first
wall, the second bottom portion is positioned inside the first
spiral and on an outer end of the first spiral, and the second
bottom portion is recessed in the direction of the height of the
first wall; the second wall of the second scroll having a first
wall portion and a second wall portion and the first wall portion
and the second wall portion are separated by a first wall step,
wherein the first wall portion is positioned on a free end of the
second wall and near a center of a second spiral formed by the
second wall, the first wall portion is recessed in a direction of
height of the second wall, the second wall portion is positioned on
the free end of the second wall and on an outer end of the second
spiral, and the second wall portion is elevated in the direction of
the height of the second wall, and at one particular point the
first bottom step abutting with the first wall step when the first
scroll and the second scroll rotate relative to each other; and a
bypass hole in the first bottom portion and that lets a compression
chamber among the compression chambers to communicate with
outside.
[0010] The other objects, features, and advantages of the present
invention are specifically set forth in or will become apparent
from the following detailed description of the invention when read
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a sectional view of a scroll compressor in a first
embodiment according to the present invention;
[0012] FIG. 2 is a perspective view of a fixed scroll and a
revolving scroll in the first embodiment;
[0013] FIG. 3 is a sectional view of the fixed scroll (or the
revolving scroll) in the first embodiment;
[0014] FIG. 4 is a plan view of the fixed scroll in the first
embodiment;
[0015] FIGS. 5 to 9 are schematics for explaining an operation of
the scroll compressor of the first embodiment;
[0016] FIG. 10 is a plan view of a conventional scroll compressor
corresponding to the scroll compressor of the first embodiment;
[0017] FIG. 11 is a sectional view of a scroll compressor in a
second embodiment according to the present invention;
[0018] FIG. 12 is a perspective view showing a fixed scroll and a
revolving scroll in the second embodiment;
[0019] FIG. 13 is a sectional view of the fixed scroll (or the
revolving scroll) in the second embodiment;
[0020] FIG. 14 is a plan view of the fixed scroll in the second
embodiment;
[0021] FIGS. 15 to 20 are schematics for explaining an operation of
the scroll compressor of the second embodiment;
[0022] FIG. 21 is a plan view of a conventional scroll compressor
corresponding to the scroll compressor of the second
embodiment;
[0023] FIG. 22 is a PV graph of the scroll compressor in the second
embodiment; and
[0024] FIG. 23 is a PV graph of the conventional scroll compressor
shown in FIG. 21.
DETAILED DESCRIPTION
[0025] Exemplary embodiments of a scroll compressor according to
the present invention will be hereinafter explained with reference
to the accompanying drawings.
[0026] FIG. 1 is a sectional view of a scroll compressor according
to a first embodiment of the present invention. This scroll
compressor is provided with a scroll compression mechanism that
includes a fixed scroll 12 that serves as a first scroll, and a
revolving scroll 13 that serves as a second scroll. The fixed
scroll 12 and the revolving scroll 13 are housed in a housing
11.
[0027] The housing 11 includes a housing body 11a that is formed in
a cup shape, which has an opening, and a lid plate 11b that is
fixed to the housing body 11a at the opening.
[0028] The fixed scroll 12 includes a spiral wall 12b on a surface
of an end plate 12a. The spiral wall 12a is arranged vertically to
the end plate 12a. The revolving scroll 13 has substantially a same
structure as the fixed scroll 12, and includes a spiral wall 13b on
a surface of an end plate 13a. The spiral wall 13a is arranged
vertically to the end plate 13a. The wall 12b and the wall 13b are
formed in substantially an identical shape.
[0029] The fixed scroll 12 is fastened to a bottom inside the cup
shape of the housing body 11a with a bolt 14. The revolving scroll
13 is eccentric by a revolution radius and phase-shifted by 180
degrees with respect to the fixed scroll 12, and is combined with
the fixed scroll 12 with the wall 13b thereof engaged with the wall
12b of the fixed scroll 12. Further, the revolving scroll 13 is
supported to be capable of revolving, but not to be capable of
rotating. A rotation preventing mechanism 15 that is provided
between the lid plate 11b and the end plate 13a prevents the
revolving scroll 13 from rotating.
[0030] Concerning the revolution of the revolving scroll 13, a
rotation shaft 16 with a crank 16a is pierced through the lid plate
11b. This rotation shaft 16 is rotatably supported on the lid plate
11b via bearings 17a and 17b. A boss 18 is protrudingly provided in
the center of the end plate 13a on a surface that is on an opposite
side to the surface on which the wall 13b is arranged. An eccentric
portion 16b of the crank 16a is rotatably housed in the boss 18 via
a bearing 19 and a drive bush 20. Consequently, the revolving
scroll 13 revolves according to the rotation of the rotation shaft
16. A balance weight 21, which cancels an unbalance amount given to
the revolving scroll 13, is attached to the rotation shaft 16.
[0031] An intake chamber 22 is formed in a position around the
fixed scroll 12 inside the housing body 11a. With respect to this
intake chamber 22, an intake port 23, which guides low-pressure
fluid toward the intake chamber 22, is provided in the housing body
11a. A discharge cavity 24 is arranged inside the housing body 11a.
The discharge cavity 24 is sectioned by an inner surface at the
bottom of the cup-shaped body of the housing body 11a and a surface
of the end plate 12a that is on the opposite side to the surface on
which the wall 12 b is arranged. With respect to this discharge
cavity 24, a discharge port 25, which guides high-pressure fluid
toward the discharge cavity 24, is arranged at the center of the
end plate 12a on the surface on which the fixed scroll 12 is
arranged. This discharge port 25 is provided in communication with
a compression chamber C, which moves to the center of the spirals
of the walls 12b and 13b while gradually reducing a volume thereof,
in the scroll compression mechanism consisting of the fixed scroll
12 and the revolving scroll 13. A discharge valve 26, which opens
the discharge port 25 only when a predetermined or higher pressure
acts thereon, is provided in the center of the end plate 12a on the
surface that sections the discharge cavity 24.
[0032] As shown in FIG. 2, the end plate 12a of the fixed scroll 12
includes a step portion 42. At this step portion 42, the surface of
the end plate 12a that is toward the center of the spiral, which is
formed by the wall 12b, is elevated than the surface of the end
plate 12a that is toward the outer end of the spiral. Similarly,
the end plate 13a of the revolving scroll 13 includes a step
portion 43. At this step portion 43, the surface of the end plate
13a that is toward the center of the spiral, which is formed by the
wall 13b, is elevated than the surface of the end plate 13a that is
toward the outer end of the spiral. The step portions 42 and 43 are
provided at positions that are substantially equidistance from the
centers of the respective spirals.
[0033] Since the step portion 42 is formed on the surface of the
end plate 12a, the flow path formed in the wall 12b can be divided
into two portions, that is, a flow path having a shallower bottom
surface 12f, which is closer to the center of the spiral, and a
flow path having a deeper bottom surface 129, which is closer to
the outer end of the spiral. A coupling wall surface 12h, which is
formed in the step portion 42 and stands vertically to the bottom
surfaces 12f and 12g, is present between the adjacent bottom
surfaces 12f and 12g. Similarly, since the step portion 43 is
formed on the surface of the end plate 13a, a spiral flow path
formed in the wall 13b is divided into two portions, that is, a
shallow bottom surface 13f provided closer to the center and a deep
bottom surface 13g provided closer to the outer end. A coupling
wall surface 13h, which forms the step portion 43 and stands
vertically connecting the bottom surfaces 13f ad 13g, is present
between the adjacent bottom surfaces 13f and 13g.
[0034] In addition, the wall 12b of the fixed scroll 12 includes a
stepped portion 44 that corresponds to the step portion 43 of the
revolving scroll 13. The wall 12b includes two portions of which
edge is arranged at each different level. The edge of the portion
that is closer to the center of the spiral is at a lower level than
the edge of the portion that is closer to the outer end of the
spiral relative to the level of the surface of the end plate 12a.
Similarly, the wall 13b of the revolving scroll 13 includes a
stepped portion 45 that corresponds to the step portion 42 of the
fixed scroll 12. The wall 13b includes two portions of which edge
is arranged at each different level. The edge of the portion that
is closer to the center of the spiral is at a lower level than the
edge of the portion that is closer to the outer end of the spiral
relative to the level of the surface of the end plate 13a.
[0035] Since the stepped portion 44 is formed, the edge of the wall
12b is divided into two portions, that is, a low edge 12c provided
closer to the center and a high edge 12d provided closer to the
outer end. A coupling edge 12e, which forms the stepped portion 44
and connects the edges 12c and 12d to be vertical to a revolving
surface, is present between the adjacent edges 12c and 12d.
Similarly, since the stepped portion 45 is formed, the edge of the
wall 13b is divided into two portions, that is, a low edge 13c
provided closer to the center and a high edge 13d provided closer
to the outer end. A coupling edge 13e, which forms the stepped
portion 45 and connects the edges 13c and 13d to be vertical to the
revolving surface, is present between the adjacent edges 13c and
13d.
[0036] The coupling edge 12e is formed in such a manner that a
surface of the coupling edge 12e that is vertical to the end plate
12a continues smoothly curving between the wall 12b. A curved line
formed with the surface is semicircle when viewed from a direction
perpendicular to the end plate 12a. A diameter of the semicircle
equals to a thickness of the wall 12b. Similarly, the coupling edge
13e is formed in such a manner that a surface of the coupling edge
13e that is vertical to the end plate 13a continues smoothly
curving between the wall 13b. A curved line formed with the surface
is semicircle when viewed from a direction perpendicular to the end
plate 13a. In addition, the coupling wall surface 12h forms an arc
that is identical with an envelope drawn by the coupling edge 13e
in accordance with revolution of the revolving scroll 13 when the
end plate 12a is viewed from a revolving shaft direction.
Similarly, the coupling wall surface 13h forms an arc that is
identical with an envelope drawn by the coupling edge 12e in
accordance with revolution of the revolving scroll 13.
[0037] As shown in FIG. 3, a rib 12i is provided in a part where
the edge 12c and the coupling edge 12e meet in the wall 12b as if
the rib 12i is built up. The rib 12i is formed integrally with the
wall 12b forming a recessed curved surface that continues smoothly
to the edge 12d and the coupling edge 12e to avoid concentration of
stresses. For the same reason, a rib 13i that has a same shape as
the rib 12i is provided in a part where the edge 13c and the
coupling edge 13e meet in the wall 13b.
[0038] A rib 12j is provided in a part where the bottom surface 12g
and the coupling wall surface 12h meet in the end plate 12a as if
the rib 12j is built up. The rib 12j is formed integrally with the
wall 12b forming a recessed curved surface that continues smoothly
to the bottom surface 12g and the coupling wall surface 12h to
avoid concentration of stresses. Due to the same reason, a rib 13j
of the same shape is provided in a part where the bottom surface
13g and the coupling wall surface 13h meet in the end plate
13a.
[0039] A part where the edges 12d and 12e meet in the wall 12b is
chamfered to avoid interference with the rib 13j at the time of
assembling. A part where the edges 13d and 13e meet in the wall 13b
is chamfered to avoid interference with the rib 12j at the time of
assembling.
[0040] As shown in FIG. 2, chip seals 27c, 27d, and 27e are
disposed in the edges 12c and 12d and the coupling edge 12e of the
wall 12b, respectively. Similarly, chip seals 28c, 28d, and 28e are
disposed in the edges 13c and 13d and the coupling edge 13e of the
wall 13, respectively.
[0041] On the other hand, as shown in FIGS. 2 and 4, bypass holes
46a and 46b that pair off with each other are provided on a bottom
surface 12f. The bottom surface 12f is a surface of a portion in
the end plate 12a of the fixed scroll 12 that is positioned closer
to the center of the spiral than the position of the step portion
42. The bypass hole 46a is arranged on the bottom surface 12f at a
position near the outer end of the spiral, and is arranged along
the surface of the wall 12b that faces opposite to the center of
the spiral. The bypass hole 46b is in a symmetrical position with
respect to the bypass hole 46a and is arranged on the bottom
surface 12f in a position near the center of the spiral, and is
arranged along the surface of the wall 12b that faces toward the
center of the spiral.
[0042] In a state in which the revolving scroll 13 is combined with
the fixed scroll 12, openings of the bypass holes 46a and 46b
facing the end plate 12a are made openable and closable by the low
edge 13c of the wall 13b of the revolving scroll 13. In addition,
the bypass holes 46a and 46b are pierced through the end plate 12a
and open at the surface opposite to the surface on which the wall
12b is arranged. Although not clearly shown in the figures, opening
of the bypass holes 46a and 46b communicate with the intake chamber
22. For example, a part of the housing body 11a, where the opening
of the bypass holes 46a and 46b are located, is divided from the
discharge cavity 24 by a partition wall or the like and
communicates with the intake chamber 22. In addition, although not
clearly shown in the figures, valves are provided at the opening of
the bypass holes 46a and 46b. The valves open and close the opening
as required.
[0043] As shown in FIG. 5, when the revolving scroll 13 is combined
with the fixed scroll 12, the low edge 13d comes into abutment
against the shallow bottom surface 12f, and the high edge 13c comes
into abutment against the deep bottom surface 12g. At the same
time, the low edge 12d comes into abutment against the shallow
bottom surface 13f, and the high edge 12c comes into abutment
against the deep bottom surface 13g. Consequently, a pair of
compression chambers C1 and C2, which are sectioned by the end
plates 12a and 13a and the walls 12b and 13b opposed to each other,
respectively, are formed between both the scrolls. In these
compression chambers Cl and C2, since the deep bottom surfaces 12g
and 13g face each other on the side closer to the outer end of the
spiral than the step portions 42 and 43, the wide compression
chambers C1 and C2 are obtained on the side. Since the shallow
bottom surfaces 12f and 13f face each other on side closer to the
center of the spiral than the step portions 42 and 43, the narrow
compression chambers C1 and C2 are obtained on the side closer to
the center of the spiral than the step portions 42 and 43. As a
result, compression with a volume gradually reduced from the
compression chambers C1 and C2 formed wide to the compression
chambers C1 and C2 formed narrow is performed in the middle of
movement of the compression chambers C1 and C2 from the outer end
to the center in accordance with revolution of the revolving scroll
13. Thus, a compression ratio can be improved.
[0044] In the middle of movement of the compression chambers C1 and
C2 from the outer end to the center in accordance with the
revolution of the revolving scroll 13, when the edge 13c of the
wall 13b comes off the opening of each of the bypass holes 46a and
46b facing toward the end plate 13a, and the valve at the opening
of each of the bypass holes 46a and 46b that opens at the other
side of the end plate 12a is opened, the bypass holes 46a and 46b
cause the compression chambers C1 and C2 and the intake chamber 22
to communicate with each other. In addition, the bypass holes 46a
and 46b separate the compression chambers C1 and C2 and the intake
chamber 22 when the valve is closed. As a result, if the valves are
opened as required, since compression is not performed in the
compression chambers C1 and C2 of which compression is released
through the opening of the bypass holes 46a and 46b, it becomes
possible to reduce a compression volume to reduce load on the drive
source driving the rotation shaft 16. In this way, the bypass holes
46a and 46b performs volume control for the compression chambers C1
and C2.
[0045] How the scroll compressor the compresses a fluid will be
explained with reference to FIGS. 5 to 9. Note that, in the
following explanation, the valves are performing an opening
operation in the opening of the bypass holes 46a and 46b.
[0046] In the state shown in FIG. 5, the outer end of the wall 12b
comes into abutment against the surface of the wall 13b that faces
opposite to the center of the spiral, and the outer end of the wall
13b comes into abutment against the surface of the wall 12b that
face opposite to the center of the spiral. Fluid is encapsulated
between the end plates 12a and 13a and between the walls 12b and
13b. The compression chambers C1 and C2 with a maximum volume are
formed in positions opposed to each other across the center of the
scroll compression mechanism. At this point, the bypass holes 46a
and 46b do not communicate with the compression chambers C1 and
C2.
[0047] In a step in which the revolving scroll 13 revolves
.pi./2(rad) from the state of FIG. 5 to reach a state shown in FIG.
6, the compression chambers C1 and C2 move to the center. In the
state shown in FIG. 6, the bypass holes 46a and 46b communicate
with the compression chambers C1 and C2. Consequently, although
volumes of the compression chambers C1 and C2 are gradually
reduced, compression is not performed.
[0048] In a step in which the revolving scroll 13 revolves
.pi.(rad) from the state of FIG. 6 to reach a state shown in FIG.
7, the compression chambers C1 and C2 move to the center. In this
step, since the bypass holes 46a and 46b do not communicate with
the compression chambers C1 and C2, although a volume of the
compression chambers C1 and C2 are gradually reduced, compression
is not performed. In addition, in the state shown in FIG. 7, a
portion in the outer end of the wall 12b is spaced apart from the
surface of the wall 13b that faces opposite to the center of the
spiral, and a portion in the outer end of the wall 13b is spaced
apart from the surface of the wall 12b that faces opposite to the
center of the spiral. In this case, leakage of fluid from the step
portions 42 and 43 is assumed. However, since the bypass holes 46a
and 46b communicate with the compression chambers C1 and C2 as
described above, compression is not performed in the compression
chambers C1 and C2. Thus, there is no influence of the leakage of
fluid.
[0049] In a step in which the revolving scroll 13 revolves
.pi./2(rad) from the state of FIG. 7 to reach a state shown in FIG.
8, the compression chambers C1 and C2 move to the center. In this
step, since the bypass holes 46a and 46b communicate with the
compression chambers C1 and C2, although a volume of the
compression chambers C1 and C2 are gradually reduced, compression
is not performed. In the state shown in FIG. 8, the opening of the
bypass holes 46a and 46b are blocked by the edge 13c of the wall
13b. Consequently, the compression chambers C1 and C2 are brought
into a closed state.
[0050] In a step in which the revolving scroll 13 revolves
.pi.(rad) from the state of FIG. 8 to reach a state shown in FIG.
9, the compression chambers C1 and C2 move to the center while
keeping the closed state and a volume of the compression chambers
C1 and C2 are gradually reduced to compress fluid. Thereafter, by
continuing the compression, the compression chambers C1 and C2
merge to have a minimum volume, and fluid is discharged from the
scroll compressor via the discharge port 25. Note that, in steps
after FIG. 8, since the compression chambers C1 and C2 are in
positions not involved in the step portions 42 and 43, the fluid in
the compression chambers C1 and C2 never leak from the step
portions 42 and 43.
[0051] Therefore, the scroll compressor according to the first
embodiment includes the structure in which the step portions 42 and
43 and the bypass holes 46a and 46b are provided, and the bypass
holes 46a and 46b are provided in the positions that is closer to
the center of the spiral than the positions of the step portions 42
and 43. Consequently, when leakage of the fluid is assumed from a
contact part of the step portions 42 and 43 and the stepped
portions 44 and 45, since the bypass holes 46a and 46b communicate
with the compression chambers C1 and C2 and compression is not
performed, there is no influence of the leakage of the fluid. In
addition, when the opening of the bypass holes 46a and 46b are
blocked to bring the compression chambers C1 and C2 into the closed
state, since the compression chambers C1 and C2 are in positions
not involved in the step portions 42 and 43, the fluid in the
compression chambers C1 and C2 never leaks from the step portions
42 and 43, and compression can be performed.
[0052] When bypass holes 50 are provided further on the outer end
side of the spiral than the step portions 42 and 43 as shown in
FIG. 10, even if opening of the bypass holes 50 are blocked and in
a state of compression, a state occurs in which the step portions
42 and 43 are placed astride the compression chambers C1 and C2
that should perform compression. As a result, when volume control
is performed in the bypass holes 50, a compression loss occurs
because there is compression leakage in the step portions 42 and
43. On the other hand, the scroll compressor in the first
embodiment can obtain the advantages of the step portions 42 and 43
and the bypass holes 46a and 46b without causing the compression
loss.
[0053] FIG. 11 is a sectional view of a scroll compressor in a
second embodiment according to the present invention. This scroll
compressor is provided with a scroll compression mechanism
consisting of a fixed scroll 112 serving as a first scroll and a
revolving scroll 113 serving as a second scroll in the inside of a
housing 111.
[0054] The housing 111 includes a housing body 111a that is formed
in a cup shape, which has an opening, and a lid plate 111b that is
fixed to the housing body 111a at the opening.
[0055] The fixed scroll 112 includes vertically provided with a
spiral wall 112b on a surface of an end plate 112a. The spiral wall
12a is arranged vertically to the end plate 112a. The revolving
scroll 113 has substantially a same structure as the fixed scroll
112, and includes a spiral wall 113b on a surface of an end plate
113a. The wall 112b and the wall 113b are formed in substantially
an identical shape.
[0056] The fixed scroll 112 is fastened to a bottom inside the cup
shape of the housing body 111a with a bolt 114. The revolving
scroll 113 is eccentric by a revolution radius and phase-shifted by
180 degrees with respect to the fixed scroll 112, and is combined
with the fixed scroll 112 with the wall 113b thereof engaged with
the wall 112b of the fixed scroll 112. Further, the revolving
scroll 113 is supported to be capable of revolving, but not to be
capable of rotating. A rotation preventing mechanism 115 that is
provided between the lid plate 111b and the end plate 113a prevents
the revolving scroll 113 from rotating.
[0057] Concerning the revolution of the revolving scroll 113, a
rotation shaft 116 with a crank 116a is pierced through the lid
plate 111b. This rotation shaft 116 is rotatably supported on the
lid plate 111b via bearings 117a and 117b. A boss 118 is
protrudingly provided in the center of the end plate 113a on a
surface that is on an opposite side to the surface on which the
wall 113b is arranged. An eccentric portion 116b of the crank 116a
is rotatably housed in the boss 118 via a bearing 119 and a drive
bush 120. Consequently, the revolving scroll 113 revolves according
to the rotation of the rotation shaft 116. A balance weight 121,
which cancels an unbalance amount given to the revolving scroll
113, is attached to the rotation shaft 116.
[0058] An intake chamber 122 is formed in a position around the
fixed scroll 112 inside the housing body 111a. With respect to this
intake chamber 122, an intake port 123, which guides low-pressure
fluid toward the intake chamber 122, is provided in the housing
body 111a. A discharge cavity 124 is arranged inside the housing
body 111a. The discharge cavity 124 is sectioned by an inner
surface of the housing body 111a and a surface of the end plate
112a that is on the opposite side to the surface on which the wall
112b is arranged. With respect to this discharge cavity 124, a
discharge port 125, which guides high-pressure fluid toward the
discharge cavity 124, is arrange at the center of the end plate
112a on the surface on which the fixed scroll 112 is arranged. This
discharge port 125 is provided in communication with a compression
chamber CC, which moves to the center of the spirals of the walls
112b and 113b while gradually reducing a volume thereof, in the
scroll compression mechanism consisting of the fixed scroll 112 and
the revolving scroll 113. A discharge valve 126, which opens the
discharge port 125 only when a predetermined or higher pressure
acts thereon, is provided in the center of the end plate 12a on the
surface that sections the discharge cavity 124.
[0059] As shown in FIG. 12, the end plate 112a of the fixed scroll
112 includes a step portion 142. At this step portion 142, the
surface of the end plate 112a that is toward the center of the
spiral, which is formed by the wall 112b, is elevated than the
surface of the end plate 112a that is toward the outer end of the
spiral. Similarly, the end plate 113a of the revolving scroll 113
includes a step portion 143. At this step portion 143, the surface
of the end plate 113a that is toward the center of the spiral,
which is formed by the wall 113b, is elevated than the surface of
the end plate 13a that is toward the outer end of the spiral. The
step portions 142 and 143 are provided at positions that are
substantially equidistance from the centers of the respective
spirals.
[0060] Since the step portion 142 is formed on the surface of the
end plate 112a, the flow path formed in the wall 112b can be
divided into two portions, that is, a flow path having a shallower
bottom surface 112f, which is closer to the center of the spiral,
and a flow path having a deep bottom surface 112g, which is closer
to the outer end of the spiral. A coupling wall surface 112h, which
is formed in the step portion 142 and stands vertically to the
adjacent bottom surfaces 112f and 112g, is present between the
bottom surfaces 112f and 112g. Similarly, since the step portion
143 is formed on the surface of the end plate 113a, a spiral flow
path formed in the wall 113b is divided into two portions, that is,
a shallow bottom surface 113f provided closer to the center and a
deep bottom surface 113g provided closer to the outer end. A
coupling wall surface 113h, which forms the step portion 143 and
stands vertically connecting the adjacent bottom surfaces 13f ad
113g, is present between the bottom surfaces 113f and 113g.
[0061] In addition, the wall 112b of the fixed scroll 112 includes
a stepped portion 144 that corresponds to the step portion 143 of
the revolving scroll 113. The wall 112b includes two portions of
which edge is arranged at each different level. The edge of the
portion that is closer to the center of the spiral is at a lower
level than the edge of the portion that is closer to f the outer
end of the spiral relative to the level of the surface of the end
plate 112a. Similarly, the wall 113b on the revolving scroll 113
includes a stepped portion 145 that corresponds to the step portion
142 of the fixed scroll 112. The wall 13b includes two portions of
which edge is arranged at each different level. The edge of the
portion that is closer to the center of the spiral is at a lower
level than the edge of the portion that is closer to the outer end
of the spiral relative to the level of the surface of the end plate
113a.
[0062] Since the stepped portion 144 is formed, the edge of the
wall 112b is divided into two portions, that is, a low edge 112c
provided closer to the center and a high edge 112d provided closer
to the outer end. A coupling edge 112e, which forms the stepped
portion 144 and connects the edges 112c and 112d to be vertical to
a revolving surface, is present between the adjacent edges 112c and
112d. Similarly, since the stepped portion 145 is formed, the edge
of the wall 113b is divided into two portions, that is, a low edge
113c provided closer to the center and a high edge 113d provided
closer to the outer end. A coupling edge 113e, which forms the
stepped portion 145 and connects the edges 113c and 113d to be
vertical to the revolving surface, is present between the adjacent
edges 113c and 113d.
[0063] The coupling edge 112e is formed in such a manner that a
surface of the coupling edge 112e that is vertical to the end plate
12a continues smoothly curving between the wall 112b. A curved line
formed with the surface is semicircle when viewed from a direction
perpendicular to the end plate 112a. Similarly, the coupling edge
113e is formed in such a manner that a surface of the coupling edge
113e that is vertical to the end plate 113a continues smoothly
curving between the wall 113b. A curved line formed with the
surface is semicircle when viewed from a direction perpendicular to
the end plate 113a. In addition, the coupling wall surface 112h
forms an arc that is identical with an envelope drawn by the
coupling edge 113e in accordance with revolution of the revolving
scroll 113 when the end plate 112a is viewed from a revolving shaft
direction. Similarly, the coupling wall surface 113h forms an arc
that is identical with an envelope drawn by the coupling edge 112e
in accordance with revolution of the revolving scroll 113.
[0064] As shown in FIG. 13, a rib 112i is provided in a part where
the edge 112c and the coupling edge 112e meet in the wall 112b as
if the rib 112i is built up. The rib 112i is formed integrally with
the wall 112b forming a recessed curved surface that continues
smoothly to the edge 112d and the coupling edge 112e to avoid
concentration of stresses. For the same reason, a rib 113i that has
a same shape as the rib 112i is provided in a part where the edge
113c and the coupling edge 113e meet in the wall 113b.
[0065] A rib 112j is provided in a part where the bottom surface
112g and the coupling wall surface 112h meet in the end plate 112a
as if the rib 112j is built up. The rib 112j is formed integrally
with the wall 112b forming a recessed curved surface that continues
smoothly to the bottom surface 112g and the coupling wall surface
112h to avoid concentration of stresses. Due to the same reason, a
rib 113j of the same shape is provided in a part where the bottom
surface 113g and the coupling wall surface 113h meet in the end
plate 113a.
[0066] A part where the edges 112d and 112e meet in the wall 112b
is chamfered to avoid interference with the rib 113j at the time of
assembling. A part where the edges 113d and 113e meet in the wall
113b is chamfered to avoid interference with the rib 112j at the
time of assembling.
[0067] As shown in FIG. 12, chip seals 127c, 127d, and 127e are
disposed in the edges 112c and 112d and the coupling edge 112e of
the wall 112b, respectively. Similarly, chip seals 128c, 128d, and
128e are disposed in the edges 113c and 113d and the coupling edge
113e of the wall 113, respectively.
[0068] On the other hand, as shown in FIGS. 12 and 14, first bypass
holes 146a and 146b that pair off with each other are provided on a
bottom surface 112f. The bottom surface 112f is a surface of a
portion in the end plate 112a of the fixed scroll 112 that is
positioned closer to the center of the spiral than the position of
the step portion 142. In addition, the first bypass holes 146a and
146b are provided in positions within 360 degrees (2.pi.(rad)) to
the center from positions of second bypass holes 147a and 147b,
which will be described later, in a state in which the revolving
scroll 113 is combined with the fixed scroll 112. The first bypass
hole 146a is arranged on the bottom surface 112f at a position near
the outer end of the spiral, and is arranged along the surface of
the wall 112b that faces opposite to the center of the spiral. The
first bypass hole 146b is in a symmetrical position with respect to
the first bypass hole 146a and is arranged on the bottom surface
112f in a position near the center of the spiral, and is arranged
along the surface of the wall 112b that faces toward the center of
the spiral.
[0069] In a state in which the revolving scroll 113 is combined
with the fixed scroll 112, openings of the first bypass holes 146a
and 146b facing the end plate 112a are made openable and closable
by the low edge 113c of the wall 113b of the revolving scroll 113.
In addition, the first bypass holes 146a and 146b are pierced
through the end plate 112a and open at the surface opposite to the
surface on which the wall 112b is arranged. Although not clearly
shown in the figures, opening of the first bypass holes 146a and
146b communicate with the intake chamber 122. For example, a part
of the housing body 111a, where the opening of the first bypass
holes 146a and 146b are located, is divided from the discharge
cavity 124 by a partition wall or the like and communicates with
the intake chamber 122. In addition, although not clearly shown in
the figures, valves are provided in the opening of the first bypass
holes 146a and 146b. The valves open and close the opening as
required.
[0070] Second bypass holes 147a and 147b that pair off with each
other are provided on the bottom surfaces 112g. The bottom surface
112g is a surface of a portion in the end plate 112a of the fixed
scroll 112 that is positioned closer to the outer end of the spiral
than the positions of the first bypass holes 146a and 146b. The
second bypass holes 147a and 147b are provided in positions within
360 degrees (2.pi.(rad)) to the center from the outer end of the
spiral in a state in which the revolving scroll 113 is combined
with the fixed scroll 112. The second bypass hole 147a is arranged
on the bottom surface 112g at a position near the outer end of the
spiral, and is arranged along the surface of the wall 112b that
faces opposite to the center of the spiral. The second bypass hole
147b is in a symmetrical position with respect to the second bypass
hole 147a and is arranged on the bottom surface 112f in a position
near the center of the spiral, and is along the surface of the wall
112b that faces toward the center of the spiral. Note that the
second bypass holes 147a and 147b in this embodiment are provided
in parallel in two places, respectively.
[0071] In a state in which the revolving scroll 113 is combined
with the fixed scroll 112, an opening of the second bypass hole
147a facing the end plate 112a is made openable and closable by the
high edge 113d of the wall 113b of the revolving scroll 113. In
addition, in a state in which the revolving scroll 113 is combined
with the fixed scroll 112, an opening of the second bypass hole
147b that faces to the surface on which the wall 112b is arranged
made openable and closable by the low edge 113c of the wall 113b of
the revolving scroll 113. The second bypass holes 147a and 147b are
pierced through the end plate 112a and open at the surface opposite
to the surface on which the wall 112b is arranged. Although not
clearly shown in the figures, opening of the second bypass holes
147a and 147b communicate with the intake chamber 122. For example,
a part of the housing body 111a, where the opening of the second
bypass holes 147a and 147b are located, is divided from the
discharge cavity 124 by a partition wall or the like and
communicates with the intake chamber 122. In addition, although not
clearly shown in the figures, valves are provided in the opening of
the second bypass holes 147a and 147b. The valves open and close
the opening of the second bypass holes 147a and 147b as
required.
[0072] As shown in FIG. 15, when the revolving scroll 113 is
combined with the fixed scroll 112, the low edge 113d comes into
abutment against the shallow bottom surface 112f, and the high edge
13c comes into abutment against the deep bottom surface 112g. At
the same time, the low edge 112d comes into abutment against the
shallow bottom surface 113f, and the high edge 112c comes into
abutment against the deep bottom surface 113g. Consequently, a pair
of compression chambers CC1 and CC2, which are sectioned by the end
plates 112a and 113a and the walls 112b and 113b opposed to each
other, respectively, are formed between both the scrolls. In these
compression chambers CC1 and CC2, since the deep bottom surfaces
112g and 113g face each other on the side closer to the outer end
of the spiral than the step portions 142 and 143, the wide
compression chambers CC1 and CC2 are obtained further on the outer
end side of the spiral than the step portions 142 and 143. Since
the shallow bottom surfaces 112g and 113g face each other on the
side closer to the center of the spiral than the step portions 142
and 143,, the narrow compression chambers CC1 and CC2 are obtained
on side closer to the center of the spiral than the step portions
142 and 143. As a result, compression with a volume gradually
reduced from the compression chambers CC1 and CC2 formed wide to
the compression chambers CC1 and CC2 formed narrow is performed in
the middle of movement of the compression chambers CC1 and CC2 from
the outer end to the center in accordance with revolution of the
revolving scroll 113. Thus, a compression ratio can be
improved.
[0073] In the middle of movement of the compression chambers CC1
and CC2 from the outer end to the center in accordance with the
revolution of the revolving scroll 113, when the edge 113c of the
wall 113b comes off the opening of each of the bypass holes 46a and
46b facing toward the end plate 113a, and the valve in the opening
is opened, the first bypass holes 146a and 146b and the second
bypass holes 147a and 147b cause the compression chambers CC1 and
CC2 and the intake chamber 122 to communicate with each other. In
addition, the first bypass holes 146a and 146b separate the
compression chambers CC1 and CC2 and the intake chamber 122 when
the valves are closed. As a result, if the valves are opened as
required, since compression is not performed in the compression
chambers CC1 and CC2 of which compression is released through the
opening of the first bypass holes 146a and 146b. The second bypass
holes 147a and 147b are open, it becomes possible to reduce a
compression volume to reduce load on the drive source driving the
rotation shaft 116. In this way, the first bypass holes 146a and
146b and the second bypass holes 147a and 147b perform volume
control for the compression chambers CC1 and CC2.
[0074] How the scroll compressor the compresses fluid will be
explained with reference to FIGS. 15 to 20. Note that, in the
following explanation, the valves are performing an opening
operation in the opening the first bypass holes 146a and 146b and
the second bypass holes 147a and 147b.
[0075] In the state shown in FIG. 15, an outermost end of the wall
112b comes into abutment against the surface of the wall 113b 13b
that faces opposite to the center of the spiral, and an outermost
end of the wall 113b comes into abutment against the surface of the
wall 112b that face opposite to the center of the spiral. Fluid is
encapsulated between the end plates 112a and 113a and between the
walls 112b and 113b. The compression chambers CC1 and CC2 with a
maximum volume are formed in positions opposed to each other across
the center of the scroll compression mechanism. At this point, the
second bypass holes 147a and 147b communicate with the compression
chambers CC1 and CC2, and the first bypass holes 146a and 146b do
not communicate with the compression chambers CC1 and CC2.
[0076] In a step in which the revolving scroll 113 revolves
.pi.(rad) from the state of FIG. 15 to reach a state shown in FIG.
16, the compression chambers CC1 and CC2 move to the center. In the
state shown in FIG. 16, the first bypass holes 146a and 146b and
the second bypass holes 147a and 147b communicate with the
compression chambers CC1 and CC2. Consequently, although a volume
of the compression chambers CC1 and CC2 are gradually reduced,
compression is not performed.
[0077] In a step in which the revolving scroll 113 revolves
.pi./2(rad) from the state of FIG. 16 to reach a state shown in
FIG. 17, the compression chambers CC1 and CC2 moves to the center.
In the state shown in FIG. 17, the first bypass holes 146a and 146b
and the second bypass holes 147a and 147b communicate with the
compression chambers CC1 and CC2. Consequently, although a volume
of the compression chamber CC1 and CC2 are gradually reduced,
compression is not performed. In addition, in the state shown in
FIG. 17, the outer end of the wall 112b is spaced apart from the
surface of the wall 113b that faces opposite to the center of the
spiral, and a portion in the outer end of the wall 113b is spaced
apart from the surface of the wall 112b that faces opposite to the
center of the spiral. In this case, leakage of fluid from the step
portions 142 and 143 is assumed. However, since the first bypass
holes 146a and 146b and the second bypass holes 147a and 147b
communicate with the compression chambers CC1 and CC2 as described
above, compression is not performed in the compression chambers CC1
and CC2. Thus, there is no influence of the leakage of fluid.
[0078] In a step in which the revolving scroll 113 revolves
.pi./2(rad) from the state of FIG. 17 to reach a state shown in
FIG. 18, the compression chambers CC1 and CC2 moves to the center.
In this step, since the bypass holes 146a and 146b communicate with
the compression chambers CC1 and CC2, although a volume of the
compression chambers CC1 and CC2 are gradually reduced, compression
is not performed. In the state shown in FIG. 18, the opening parts
of the second bypass holes 147a and 147b are blocked by the edge
113c of the wall 113b.
[0079] In a step in which the revolving scroll 113 revolves
.pi./2(rad) from the state of FIG. 18 to reach a state shown in
FIG. 19, the compression chambers CC1 and CC2 move to the center.
In the state shown in FIG. 19, the opening parts of the first
bypass holes 146a and 146b are blocked by the edge 113c of the wall
113b. Consequently, the compression chambers CC1 and CC2 are
brought into a closed state.
[0080] In a step in which the revolving scroll 113 revolves
.pi.(rad) from the state of FIG. 19 to reach a state shown in FIG.
20, the compression chambers CC1 and CC2 move to the center while
keeping the closed state and a volume of the compression chambers
CC1 and CC2 are gradually reduced to compress fluid. Thereafter, by
continuing the compression, the compression chambers CC1 and CC2
merge to have a minimum volume, and the fluid is discharged from
the scroll compressor via the discharge port 125. Note that, in
steps after FIG. 18, since the compression chambers CC1 and CC2 are
in positions not involved in the step portions 142 and 143, the
fluid in the compression chambers CC1 and CC2 never leak from the
step portions 142 and 143.
[0081] Therefore, the scroll compressor according to the second
embodiment includes the structure in which the step portions 142
and 143 and the first bypass holes 146a and 146b are provided, and
the first bypass holes 146a and 146b are provided in the positions
that is closer to the center of the spiral than the positions of
the step portions 142 and 143. Consequently, when leakage of the
fluid is assumed from a contact part of the step portions 142 and
143 and the stepped portions 144 and 145, since the bypass holes
146a and 146b communicate with the compression chambers CC1 and CC2
and compression is not performed, there is no influence of the
leakage of the fluid. In addition, when the opening of the first
bypass holes 146a and 146b are blocked to bring the compression
chambers CC1 and CC2 into a closed state, since the compression
chambers CC1 and CC2 are in positions not involved in the step
portions 142 and 143, the fluid in the compression chambers CC1 and
CC2 never leaks from the step portions 142 and 143, and compression
can be performed.
[0082] When bypass holes 150, which are equivalent to the first
bypass holes 146a and 146b, are provided further on the outer end
side of the spiral than the step portions 142 and 143 as shown in
FIG. 21, even if opening of the bypass holes 50 are blocked and in
a state of compression, a state occurs in which the step portions
142 and 143 are placed astride the compression chambers CC1 and CC2
that should perform compression. As a result, a compression loss
occurs because there is compression leakage in the step portions
142 and 143 despite the fact that a compression volume of the
bypass holes 150 is reduced. On the other hand, the scroll
compressor in the first embodiment can obtain the advantages of the
step portions 142 and 143 and the first bypass holes 146a and 146b
without causing the compression loss.
[0083] In the scroll compressor in the second embodiment, the
second bypass holes 147a and 147b are provided in positions closer
to the outer end of the spiral than the positions of the first
bypass holes 146a and 146b and within 360 degrees (2.pi.(rad)) to
the center from the outer end of the spiral. In addition, the first
bypass holes 146a and 146b are provided in positions within 360
degrees (2.pi.(rad)) to the center from the positions of the second
bypass holes 147a and 147b. Consequently, as shown in FIG. 22,
volume control is applied to the compression chambers CC1 and CC2,
which move according to revolution of the revolving scroll 113,
with only the second bypass holes 147a and 147b present in the
compression chambers CC1 and CC2 formed on the outermost end by
closing up intake of the fluid (3). Volume control is applied to
the compression chambers CC1 and CC2, which have moved to the
center of the spiral from there with both the first bypass holes
146a and 146b and the second bypass holes 147a and 147b present
(3).fwdarw.(4). Then, the volume control is applied to the
compression chambers CC1 and CC2, which have moved further to the
center side of the spiral, with only the first bypass holes 146a
and 146b present (4). This makes it possible to prevent excessive
compression after the compression chambers CC1 and CC2 are formed
on the side near the outermost end of the spiral before volume
control is performed by the first bypass holes 146a and 146b. Note
that, in FIG. 22.fwdarw.(1) (2) indicates a case in which the
valves of the first bypass holes 146a and 146b and the second
bypass holes 147a and 147b are closed, and the volume control is
not performed.
[0084] As shown in FIG. 23, when the second bypass holes 147a and
147b are not provided as shown in FIG. 23, after the excessive
compression occurs (3).fwdarw.(4), the volume control is performed
by the first bypass holes 146a and 146b (5). In this way, the
compression of the compression chambers CC1 and CC2 occurs 360
degrees or more before performing the volume control with the first
bypass holes 146a and 146b. On the other hand, the scroll
compressor in the second embodiment can obtain advantages of the
step portions 142 and 143 and the first bypass holes 146a and 146b
without causing the excess compression. Note that, in FIG. 23,
(3).fwdarw.(1) indicates a case in which the valves of the first
bypass holes 146a and 146b are closed, and the volume control is
not performed.
[0085] As described above, the scroll compressor according to the
present invention makes it possible to reduce a compression loss.
In particular, the scroll compressor is suitable for eliminating
compression leakage in the step portions when volume control is
performed by the bypass holes. In addition, in particular, the
scroll compressor is suitable for preventing excessive
compression.
[0086] Moreover, the bypass holes are provided in positions closer
to the center of the spiral than positions of the step portions.
Consequently, when leakage of fluid from the step portions is
assumed, since compression is not performed through the bypass
holes, there is no influence of the leakage of fluid. In addition,
when the bypass holes are closed to bring the compression chambers
into a closed state, since the compression chambers are in a
positional relation in which the compression chambers are not
involved in the step portions, compression in the compression
chambers is performed without regard to the leakage of fluid from
the step portions. As a result, advantages of the step portions and
the bypass holes can be obtained without causing a compression loss
due to the leakage of fluid from the step portions.
[0087] Moreover, the second bypass holes are provided in positions
closer to the outer end of the spiral than positions of the first
bypass holes and within 360 degrees to the center from the outer
end of the spiral, and the first bypass holes are provided in
positions closer to the center of the spiral than positions of the
step portions and within 360 degrees to the center from the
positions of the second bypass holes. Consequently, the second
bypass holes can prevent excessive compression after the
compression chambers are formed on a side near the outermost end of
the spiral and before volume control is performed by the first
bypass holes. In addition, since the first bypass holes are
provided in the positions closer to the center of the spiral than
the positions of the step portions, advantages of the step portions
and the first bypass holes can be obtained without causing a
compression loss due to leakage of fluid from the step
portions.
[0088] Although the invention has been described with respect to a
specific embodiment for a complete and clear disclosure, the
appended claims are not to be thus limited but are to be construed
as embodying all modifications and alternative constructions that
may occur to one skilled in the art which fairly fall within the
basic teaching herein set forth.
* * * * *