U.S. patent application number 12/374868 was filed with the patent office on 2010-01-28 for compressor.
This patent application is currently assigned to Calsonic Kansei Corporation. Invention is credited to Nobuyuki Kobayashi, Hiroyuki Makishima.
Application Number | 20100021318 12/374868 |
Document ID | / |
Family ID | 38981501 |
Filed Date | 2010-01-28 |
United States Patent
Application |
20100021318 |
Kind Code |
A1 |
Makishima; Hiroyuki ; et
al. |
January 28, 2010 |
COMPRESSOR
Abstract
A rotary valve (71) of a compressor is formed with a release
path (71e) configured to release a high pressure residual
refrigerant which have not been discharged in a compression and
discharge stroke from one cylinder bores (B.sub.1) which is in an
initial stage of its suction stroke to other cylinder bores
(B.sub.3, B.sub.4) having a lower pressure than the one cylinder
bores (B.sub.1). The release path (71e) is formed with an inlet
(71f), a first outlet (71g), a second outlet (71h), and a
communication part (71k) connecting the inlet and the outlets.
During a time period when the inlet (71f) of the release path (71e)
is connected to the cylinder bore (B.sub.1) which is in a initial
state of its suction stroke, the first outlet (71g) is connected to
the cylinder bore (B.sub.3) next to, in an opposite direction to
the rotational direction, the cylinder bore (B.sub.4) which is 180
degree opposite to the cylinder bore (B.sub.1), and then, the
second outlet (71h) is connected to the cylinder bore (B.sub.4)
which is 180 degree opposite to the cylinder bore (B.sub.1).
Inventors: |
Makishima; Hiroyuki;
(Saitama, JP) ; Kobayashi; Nobuyuki; (Saitama,
JP) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
Calsonic Kansei Corporation
|
Family ID: |
38981501 |
Appl. No.: |
12/374868 |
Filed: |
July 25, 2007 |
PCT Filed: |
July 25, 2007 |
PCT NO: |
PCT/JP2007/064555 |
371 Date: |
March 10, 2009 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F04B 27/1009 20130101;
F04B 27/1018 20130101 |
Class at
Publication: |
417/269 |
International
Class: |
F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2006 |
JP |
2006 203653 |
Claims
1. A compressor (1) comprising: an even number of at least four of
cylinder bores (Bj) evenly spaced from each other in a
circumferential direction thereof around a drive shaft (10); a
suction chamber (7) separated from the cylinder bores (Bj) by a
first partition wall (9, 85) provided with suction holes (11j) and
configured to communicate with the cylinder bores (Bj) through the
suction holes; a discharge chamber (8) separated from the cylinder
bores (Bj) by a second partition wall (9) provided with discharge
holes (12j) and configured to communicate with the cylinder bores
(Bj) through the discharge holes; a piston (Pj) provided in each of
the cylinder bores (Bj) and configured to reciprocate in the
cylinder bores (Bj) in response to rotation of the drive shaft (10)
so as to perform a suction stroke and a compression and discharge
stroke alternately; and a rotary valve (71) configured to be in
rotary slidable contact with the first partition wall while
covering the suction holes (11j) and to rotate in synchronizing
with the rotation of the drive shaft (10), the rotary valve (71)
includes: a suction path (71c) configured to open the suction holes
(11j) of the cylinder bores (Bj) subjected to the suction strokes
so as to connect the cylinder bores (Bj) to the suction chamber
(7); and a release path (71e) configured to release a high pressure
residual refrigerant which could not be discharged in the
compression and discharge stroke from one of the cylinder bores
(Bj) subjected to an initial stage of the suction stroke to others
of the cylinder bores (Bj) having a lower pressure than the one of
the cylinder bores (Bj), the release path (71e) including: an inlet
(71f), a first outlet (71g) and a second outlet (71h) which are
provided on a rotational trajectory to overlap with the suction
holes (11j); and a communication part (71k) provided outside of the
rotational trajectory and connecting the inlet and the outlets;
wherein, a time period when the inlet (71f) of the release path
(71e) is connected to a first one of the cylinder bores (Bj)
subjected to an initial state of the suction stroke include: an
A-period when the first outlet (71g) is connected to a second one
of the cylinder bores (Bj) next to, in a counter-rotational
direction, a third one of the cylinder bores (Bj) which is located
180 degree opposite to the first one of the cylinder bores (Bj),
and after the A-period, a C-period when the second outlet (71h) is
connected to the third one of the cylinder bores (Bj) which is 180
degree opposite to the first one of the cylinder bores (Bj).
2. The compressor according to claim 1, wherein the A-period and
the C-period are partially overlapped so that the C-period follows
the A-period without a break therebetween.
Description
TECHNICAL FIELD
[0001] The present invention relates to a compressor.
BACKGROUND ART
[0002] Japanese Patent Publication No. 3079743 discloses a
compressor in which pistons are accommodated in cylinder bores
arranged around a rotating shaft. The pistons reciprocate according
to rotation of the rotating shaft. In this compressor, a rotary
valve is provided with a suction path for introducing a refrigerant
gas into compression chambers defined by the pistons in the
cylinder bores. The rotary valve connects the suction path to the
compression chambers sequentially in synchronization with
reciprocation of the pistons.
[0003] The rotary valve includes a release passage. The release
passage is configured to release a high pressure residual gas that
remains in one of the compression chambers in which the piston
therein is positioned at approximately an upper dead center thereof
to other compression chambers in which the piston therein is
positioned at approximately a lower dead center thereof.
[0004] This configuration reduces the high pressure residual gas
which remains in the compression chamber after the compression and
discharge stroke of the associated piston. That is, the amount of
the high pressure residual gas which would otherwise be re-expanded
in a suction stroke is decreased. Thereby, a larger amount of the
refrigerant gas can be suctioned into the compression chamber
during suction strokes, so as to improve the suction efficiency and
the compression efficiency of the compressor.
DISCLOSURE OF THE INVENTION
[0005] In general, it is considered that a highly efficient
compressor is achieved when high pressure residual gas is released
from one of the cylinder bores having a piston positioned at the
top dead center (a cylinder bore at an end of an compression and
discharge stroke, that is, a cylinder bore at a beginning of the
suction stroke) to another of the cylinder bores which is located
180-degree opposite to the one of the cylinder bores (a cylinder
bore at the end of the suction stroke, that is, a cylinder bore at
the beginning of the compression and discharge stroke). The highly
efficient compressor is achieved because these two cylinder bores
would have the largest pressure deference.
[0006] However, depending on layouts of the suction path of the
rotary valve, the residual gas may be unable to be released from
one of the cylinder bores having a piston positioned around the
upper dead center to another of the cylinder bores located
180-degree opposite to the one of the cylinder bores. One such
example is a structure in which a termination of a connection
between a cylinder bore and a suction path of a rotary valve is set
after a time when a piston is positioned at a lower dead center in
the cylinder bore (see Japanese Patent No. 3079741). With this
structure, the suction path is connected to the cylinder bore right
after an end of the piston's suction stroke. Therefore, residual
gas can not be released, to one cylinder bore which is in a state
right after its suction stroke, from another cylinder bore which is
180-degree opposite to the one cylinder bore (that is, a cylinder
bore right after its compression and discharge stroke).
[0007] The present invention was developed in view of the problems
described in the related art, an object of the present invention is
to provide a compressor capable of releasing a residual gas right
after a compression and discharge stroke, regardless of the layout
of a suction path of a rotary valve
[0008] An aspect of the present invention is a compressor (1)
comprising: an even number of at least four cylinder bores (Bj)
evenly spaced from each other in a circumferential direction
thereof around a drive shaft (10); a suction chamber (7) separated
from the cylinder bores (Bj) by a first partition wall (9, 85) and
communicating with the cylinder bores (Bj) through suction holes
(11j) formed in the first partition wall; a discharge chamber (8)
separated from the cylinder bores (Bj) by a second partition wall
(9) and communicating with the cylinder bores (Bj) through
discharge holes (12j) formed in the second partition wall; a piston
(Pj) reciprocatably provided in each of the cylinder bores (Bj) and
configured to reciprocate in the cylinder bores (Bj) in response to
rotation of the drive shaft (10) so as to perform a suction stroke
and a compression and discharge stroke alternately; and a rotary
valve (71) configured to be in rotary slidable contact with the
first partition wall while covering the suction holes (11j) and to
rotate in synchronizing with the rotation of the drive shaft (10).
The rotary valve (71) is formed with: a suction path (71c)
configured to open the suction holes (11j) of the cylinder bores
(Bj) subjected to the suction strokes so as to connect the cylinder
bores (Bj) to the suction chamber (7); and a release path (71e)
configured to release a high pressure residual refrigerant which
could not be discharged out in the compression and discharge stroke
from one of the cylinder bores (Bj) subjected to an initial stage
of the suction stroke to others of the cylinder bores (Bj) having
lower pressure than the one of the cylinder bores (Bj). The release
path (71e) is formed with an inlet (71f), a first outlet (71g) and
a second outlet (71h) which are provided on a rotational trajectory
to overlap with the suction holes (11j). The release path (71e) is
formed with a communication part (71k) provided outside of the
rotational trajectory and connecting the inlet and the outlets. A
time period when the inlet (71f) of the release path (71e) is
connected to a first one of the cylinder bores (Bj) subjected to a
initial state of the suction stroke includes: an A-period when the
first outlet (71g) is connected to a second one of the cylinder
bores (Bj) next to, in a direction opposite to the rotational
direction, a third one of the cylinder bores (Bj) which is located
180 degree opposite to the first one of the cylinder bores (Bj),
and after A-period, C-period when the second outlet (71h) is
connected to the third one of the cylinder bores (Bj) which is
located 180 degree opposite to the first one of the cylinder bores
(Bj).
[0009] In this application, a "suction stroke" is defined as a
duration when a piston moves from its upper (top) dead center to
its lower (bottom) dead center, and a "compression and discharge
stroke" is defined as a duration when a piston moves from its lower
(bottom) dead center to its upper (top) dead center. An "end of a
compression and discharge stroke" and a "beginning of a suction
stroke" are defined as a time when a piston is positioned at its
upper (top) dead center, an "end of a suction stroke" and a
"beginning of a compression and discharge stroke" are defined as a
time when a piston is positioned at its lower (bottom) dead center.
In the suction stroke, a fluid is suctioned through the suction
hole from the suction chamber into the cylinder bore. On the other
hand, in the compression and discharge stroke, a fluid is
compressed within the cylinder bore and the compressed fluid is
discharged through the discharge hole from the cylinder bore into
the discharge chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a sectional view of a compressor according to a
first embodiment of the present invention.
[0011] FIG. 2 is a sectional view taken along with the line Z-Z of
FIG. 1, showing a positional relation between suction paths and a
release path during a rotation of a rotary valve.
[0012] FIG. 3 is a sectional view taken along with the line Z-Z of
FIG. 1, showing a positional relation between the suction paths and
the release path during the rotation of the rotary valve.
[0013] FIG. 4 is a sectional view taken along with the line Z-Z of
FIG. 1, showing a positional relation between the suction paths and
the release path during the rotation of the rotary valve.
[0014] FIG. 5 is a sectional view taken along with the line Z-Z of
FIG. 1, showing a positional relation between the suction paths and
the release path during the rotation of the rotary valve.
[0015] FIG. 6 is a sectional view taken along with the line Z-Z of
FIG. 1, showing a positional relation between the suction paths and
the release path during the rotation of the rotary valve.
[0016] FIG. 7 is a view of superimposed pressure curves of
pressures in a cylinder bore B.sub.1, a cylinder bore B.sub.3 and a
cylinder bore B.sub.4; the solid line indicates the pressure curve
of the cylinder bore B.sub.1; the chain line indicates the pressure
curve of the cylinder bore B.sub.3; and the two-dot chain line
indicates the pressure curve of the cylinder bore B.sub.4.
[0017] FIG. 8 is a view enlarging a term in the view of FIG. 7,
showing an initial stage of a suction stroke in the cylinder bore
B.sub.1.
[0018] FIG. 9 is a front view of the rotary valve of the compressor
according to the first embodiment.
[0019] FIG. 10 is a front view of a first modification of the
rotary valve of the compressor according to the first
embodiment.
[0020] FIG. 11 is a front view of a second modification of the
rotary valve of the compressor according to the first
embodiment.
[0021] FIG. 12 is a sectional view of a compressor according to the
second embodiment of the present invention.
[0022] FIG. 13 is a sectional view taken along the Z-Z of FIG. 12,
showing a positional relation between suction paths and a release
path during a rotation of a rotary valve.
[0023] FIG. 14 is a sectional view taken along the line Z-Z of FIG.
12, showing a positional relation between the suction paths and the
release path during the rotation of the rotary valve.
[0024] FIG. 15 is a sectional view taken along the line Z-Z of FIG.
12, showing a positional relation between the suction paths and the
release path during the rotation of the rotary valve.
[0025] FIG. 16 is a sectional view taken along the line Z-Z of FIG.
1, showing a positional relation between the suction paths and the
release path during the rotation of the rotary valve.
[0026] FIG. 17 is a sectional view taken along the line Z-Z of FIG.
1, showing a positional relation between the suction paths and the
release path during the rotation of the rotary valve.
[0027] FIG. 18 is an expanded view of an outer peripheral surface
of the rotary valve of the compressor according to the second
embodiment.
[0028] FIG. 19 is a sectional view of a first modification of the
rotary valve of the compressor according to the second
embodiment.
[0029] FIG. 20 is a sectional view of a second modification of the
rotary valve of the compressor according to the second
embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] Embodiments of a compressor according to the present
invention will be described with reference to the drawings.
First Embodiment
[0031] A compressor of a first embodiment will be described with
reference to FIGS. 1 to 9.
[0032] FIG. 1 is a sectional view of the compressor of the first
embodiment and FIG. 2 is a sectional view taken along the line Z-Z
of FIG. 1. The compressor 1 of the present embodiment is a swash
plate type variable capacity compressor as shown in FIG. 1. The
compressor 1 has a cylinder block 2 which has substantially
column-shaped cylinder bores Bj (The "j" refers to "1 to 6" in this
embodiment) arranged in the circumferential direction at regular
intervals (see FIG. 2), a front head 4 which is attached to a front
end of the cylinder block 2 and forms therein a crank chamber 5
communicating with the cylinder bores Bj, a valve plate 9 which
constitutes a first partition wall and a second partition wall, and
a rear head 6 which is attached to a rear end of the cylinder block
2 with the valve plate 9 therebetween so as to form therein a
suction chamber 7 and a discharge chamber 8. The cylinder block 2,
the front head 4 and the rear head 6 are attached and fastened
together with through bolts 13 to constitute an overall housing of
the compressor.
[0033] A gasket 53 is provided between the valve plate 9 and the
rear head 6 to seal the suction chamber 7 and the discharge chamber
8. A gasket 54 is provided between the valve plate 9 and the
cylinder block 2 to seal the cylinder bores Bj. The valve plate 9
is formed in a substantially circular disk shape. The valve plate 9
is formed with suction holes 11j (The "j" refers to "1 to 6" in
this embodiment.) corresponding to the cylinder bores Bj to
communicate the cylinder bores Bj with the suction chamber 7, and
discharge holes 12j (The "j" refers to "1 to 6" in this embodiment)
corresponding to the cylinder bores Bj to communicate the cylinder
bores Bj with the discharge chamber 8.
[0034] On the rear head 6 side of the valve plate 9, a suction
valve mechanism 70 is provided to open and close the suction holes
11j and a discharge valve mechanism 60 is provided to open and
close the discharge hole 12j, as described below in detail.
[0035] A drive shaft 10 is rotatably supported by radial bearings
15, 19 at center through holes 14, 18 of the front head 4 and the
cylinder block 2 so that the drive shaft 10 is rotatable in the
crank chamber 5.
[0036] A thrust bearing 20 is provided between an inner surface of
the front head 4 and a front end surface of the rotor 21 fixed to
the drive shaft 10 in the crank chamber 5. A thrust bearing 16 is
provided between a step portion formed on the drive shaft 10 and an
adjusting screw 17 fixed to the center through hole 14 of the
cylinder block 2. This structure prevents axial movements of the
drive shaft 10.
[0037] In the crank chamber 5, a conversion mechanism is provided
to convert the rotary motion of the drive shaft 10 into
reciprocation motion of the pistons Pj (The "j" refers to "1 to 6"
in this embodiment). The conversion mechanism includes the circular
disk shaped rotor 21 fixed to the drive shaft 10, a circular disk
shaped swash plate 24 axially slidable on and attached at an
inclination to the drive shaft 10, and a linkage mechanism 40
connecting the rotor 21 and the swash plate 24 so that the rotor 21
and the swash plate 24 rotate together with allowing an inclination
angle of the swash plate 24 to change. The respective pistons Pj
are attached to the outer peripheral part of the swash plate 24
with a pair of hemispherical-shaped piston shoes 30, 30. When the
swash plate 24 rotates, the pistons Pj reciprocate within the
cylinder bores Bj according to the inclination angle of the swash
plate 24. As the pistons Pj reciprocate, a refrigerant is suctioned
from the suction chamber 7 into the cylinder bores Bj through the
suction holes 11j of the valve plate 9 and compressed in the
cylinder bores Bj. The compressed refrigerant is discharged to the
discharge chamber 8 through the discharge holes 12j of the valve
plate 9.
[0038] When the swash plate 24 moves toward the cylinder block 2
against the return spring 52, the inclination angle of the swash
plate 24 decreases. On the other hand, the inclination angle of the
swash plate 24 is increased when the swash plate 24 moves away from
the cylinder block 2 against a return spring 51.
[0039] Control of Variable Capacity
[0040] In order to change the amount of discharged refrigerant, the
inclination angle of the swash plate 24 is changed so as to change
the piston stroke. Concretely, based on a pressure difference
(pressure balance) between a crank chamber pressure Pc in back of
(below) the pistons Pj and a suction chamber pressure Ps in front
of (above) the pistons Pj, the inclination angle of the swash plate
24 is changed so as to change the piston stroke. For this purpose,
the variable capacity compressor includes a pressure control
mechanism. The pressure control mechanism includes a gas discharge
passage (not shown) which communicates the crank chamber 5 with the
suction chamber 7, a gas supply passage (not shown) which
communicates the crank chamber 5 with the discharge chamber 8, and
a control valve 33 provided in the midstream of the gas supply
passage to open and close the gas supply passage.
[0041] The gas discharge passage is kept open regardless of opening
and closing the gas supply passage controlled by the control valve
33, so that the refrigerant gas in the crank chamber 5 constantly
flows to the suction chamber 7 through the gas discharge
passage.
[0042] When the control valve 33 opens the gas supply passage, the
high-pressure refrigerant flows from the discharge chamber 8 into
the crank chamber 5 through the gas supply passage. This increases
the pressure in the crank chamber 5. When the pressure in the crank
chamber 5 increases, the swash plate 24 decreases its inclination
angle as it movies toward the cylinder block 2. As a result, the
piston stroke decreases and the amount of discharge of the
compressor decreases.
[0043] On the other hand, when the control valve 33 closes the gas
supply passage, the pressure difference between the pressure in the
suction chamber 7 and the pressure in the crank chamber 5 is
equalized. As a result, the inclination angle of the swash plate 24
increases as the swash plate 24 moves away from the cylinder block
2, so that the piston stroke increases and the amount of discharge
of the compressor increases.
[0044] Valve System
[0045] Next, valve systems 60, and 70 will be described.
[0046] A discharge valve mechanism 60 will be explained with
reference to FIG. 1. The discharge valve mechanism 60 has a
discharge valve plate 61. The discharge valve plate 61 is supported
between the valve plate 9 and the rear head 6 as shown in FIG. 1.
The discharge valve plate 61 is configured in an elastic and
flexible thin plate (such as a thin metal plate) and has reed
valves 63 located to correspond to the discharge holes 12j. When a
pressure in the cylinder bore Bj is equal to or less than a
predetermined level, the reed valve 63 keeps the discharge hole 12j
closed and, when the pressure in the cylinder bore Bj is greater
then the predetermined level, the reed valve 63 is deformed to open
the discharge hole 12j. In other words, the reed valve 63 closes
the discharge hole 12j during a suction stroke and a compressing
stroke but opens the discharge hole 12j during a discharging stroke
after the compressing stroke. Stoppers 65 provided on the gasket 53
stop the reed valves 63 at their maximum lift positions.
[0047] Next, a suction valve mechanism 70 will be described in
further detail with reference to FIGS. 1 and 2.
[0048] The suction valve mechanism 70 includes a rotary valve 71, a
stopper 73 and a coil spring 75 as a spring member. The rotary
valve 71, stopper 73 and coil spring 75 are all disposed in the
suction chamber 7 as shown in FIG. 1.
[0049] The rotary valve 71 is configured in a substantially
circular disk shape with a center through hole 71b at the center of
the rotary valve 71. An axial end 10a of the drive shaft 10 is
mounted in the center through hole 71b of the rotary valve 71 and
extends through the center through hole 9c of the valve plate 9
into the suction chamber 7. The center through hole 71b of the
rotary valve 71 and the axial end 10a of the drive shaft 10 are
formed in the same noncircular shape (a hexagonal shape in this
embodiment) as shown in FIG. 2 so that the rotary valve 71 is
axially slidable with respect to the driving shaft 10 and rotate
together with the drive shaft 10.
[0050] Axial movements of the stopper 73 are limited by a bolt 77
which serves as a fastening means at the axial end 10a of the drive
shaft 10. The stopper 73 has a pair of arms 73d extending toward
and being connected to the rotary valve 71 so that the stopper 73
rotates together with the rotary valve 71. The coil spring 75 is
compressed and supported between the stopper 73 and the rotary
valve 71 so that the rotary valve 71 is always in close contact
with the valve plate 9 as biased to the valve plate 9.
[0051] The rotary valve 71, as shown in FIG. 2, has a suction path
71c penetrating therethrough and formed in a circular arc hole
shape. When the rotary valve 71 rotates, the suction path 71c of
the rotary valve 71 sequentially overlaps with the suction holes
11j of the valve plate 9 to open the suction holes 11j in sequence
(see FIGS. 2 to 6).
[0052] Next, the timing of the valve open period when the suction
hole 11j is opened by the suction path 71c will be explained with
reference to FIGS. 2 to 6. Here, the timing of the valve open
period when the suction holes 11j is opened by the suction path 71c
is set in synchronization with the suction stroke of the piston
Pj.
[0053] FIGS. 2 to 6 show a process from when cylinder bore B.sub.1
starts a suction stroke (FIG. 2) to just before the cylinder bore
B.sub.1 starts to communicate with the suction path 71c (FIG. 6),
in a sequential order.
[0054] In a position shown in FIG. 2, the piston P.sub.1 of the
cylinder bore B.sub.1 is positioned at the upper (top) dead center
and the piston P.sub.4 of the cylinder bore B.sub.4 located 180
degree opposite to the cylinder bore B.sub.1 is positioned at the
lower (bottom) dead center. Thus, in the position shown in FIG. 2,
the piston P1 of the cylinder bore B.sub.1 finishes its compressing
and discharging stroke and is going to start its suction stroke,
and the piston of the cylinder bore B.sub.4 is going to start its
compressing and discharging stroke and finish its suction stroke.
Further, the cylinder bores B.sub.2 and B.sub.3 which are located
between the cylinder bore B.sub.1 subjected to the upper dead
center state and the cylinder bore B.sub.4 subjected to the lower
dead center state are subjected to compressing strokes. The
cylinder bores B.sub.5 and B.sub.6 which are located between the
cylinder bore B.sub.4 subjected to the lower dead center state and
the cylinder bore B.sub.1 subjected to the upper dead center state
are subjected to suction strokes.
[0055] In such a position shown in FIG. 2, the suction path 71c
does not communicate with the suction hole 11.sub.1 of the cylinder
bore B.sub.1 subjected to the upper dead center state but
communicates with the suction hole 11.sub.4 of the cylinder bore
B.sub.4 subjected to the lower dead center state and communicates
with the suction holes 11.sub.5, 11.sub.6 of the cylinder bores
B.sub.5, B.sub.6 subjected to the suction strokes.
[0056] Thus, regarding the cylinder bore B.sub.1 in FIGS. 2 to 6, a
start timing of the valve open period in which the suction hole
11.sub.1 (see FIG. 5) is opened by the suction path 71c is set
later than the timing at which the piston P.sub.1 in the cylinder
bore B.sub.1 is positioned at the upper dead center (FIG. 2).
Further, regarding the cylinder bore B.sub.4 in FIGS. 2 to 6, an
end timing of the valve open period in which the suction hole
11.sub.4 is opened by the suction path 71c (FIG. 4) is set after
the timing at which the piston P.sub.4 in the cylinder bore B.sub.4
is positioned at the lower dead center (FIG. 2).
[0057] In other words, regarding the cylinder bore B.sub.1, the
piston P.sub.1 is positioned at the upper dead center in FIG. 2,
and after that, the valve open period during which the suction hole
11.sub.1 is opened by the suction path 71 starts as shown in FIG.
4. Further, regarding the cylinder bore B.sub.4, the piston P.sub.4
is positioned at the lower dead center in FIG. 2, and after that,
the valve open period during which the suction hole 11.sub.4 is
opened by the suction path 71c ends as shown in FIG. 5.
[0058] That is, in each cylinder bore Bj, the start time of the
valve open period when the suction hole 11j is opened by the
suction path 71c is set after the time at which the piston Pj is
positioned at its upper dead center, and the end time of the valve
open period when the suction hole 11j is opened by the suction path
71c is set after the time that the piston Pj is positioned at its
lower dead center.
[0059] As described above, in each cylinder bores Bj, the end
timing of the valve open period when the suction hole 11j is opened
by the suction path 71c is set after the time the piston Pj is
positioned at the lower dead center. With this structure, suction
gas is introduced into the cylinder bore Bj even in an initial
stage of the compression and discharge stroke after the suction
stroke (when the piston Pj has started to move from the lower dead
center toward the upper dead center) because of an inertia of a
suction gas flow which was introduced during the suction stroke
(while the piston Pj moves from the upper dead center to the lower
dead center). This increases the suctioned amount so as to improve
the suction efficiency and the compression efficiency of the
compressor 1.
[0060] Residual Pressure Release Structure
[0061] A residual pressure release structure will be described with
reference to FIGS. 2 to 9.
[0062] As shown in FIGS. 1 to 6 and 9, the rotary valve 71 has a
release path 71e.
[0063] The release path 71e is formed as a groove which is a recess
on a surface of the rotary valve 71. The release path 71e has an
inlet 71f, two outlets 71g, 71h, and a communication part 71k which
communicates the inlet 71f and the outlets 71g, 71h. The inlet 71f
and outlets 71g, 71h are provided on a rotational trajectory which
is to overlap with the suction holes 11j and communicate with the
suction holes 11j in sequence as the rotary valve 71 rotates. The
communication part 71k is positioned out of the rotational
trajectory so as not to overlap with the suction holes 11j.
[0064] The release path 71e is configured to release a
high-pressure residual refrigerant, which was not discharged during
the compressing and discharging stroke and remained in one of the
cylinder bores Bj in the initial stage of the suction stroke, to
other of the cylinder bores Bj having a lower pressures than the
one.
[0065] The following description will describe how the release path
71e of the rotary valve 71 and the cylinder bores Bj communicate
with each other during a period from the time of a beginning of the
suction stroke in the cylinder bore B.sub.1 (FIG. 2) to the time
just before the cylinder bore B.sub.1 starts to communicate with
the suction path 71c (FIG. 6), with reference to FIGS. 2 to 6.
[0066] Through FIGS. 2 to 6, the cylinder bore B.sub.1 is in the
initial stage of the suction stroke (that is, a period after the
compressing and discharging stroke ends and before the suction path
71c communicates with the cylinder bore B.sub.1, in this example).
While the release path inlet 71f is communicating with the cylinder
bore B.sub.1 (FIGS. 3 to 5), the first outlet 71g firstly
communicates with the cylinder bore B.sub.3 located just
rotationally-prior to the cylinder bore B.sub.4 which is 180 degree
opposite to the cylinder bore B.sub.1 as shown in FIG. 3. Then, as
shown in FIG. 5, the second outlet 71h communicates with the
cylinder bore B.sub.4 which is 180 degree opposite to the cylinder
bore B.sub.1.
[0067] Hereinafter, "A-period" refers to a period when the first
outlet 71g communicates with the cylinder bore B.sub.3 (FIG. 3) and
"C-period" refers to a period when the second outlet 71h
communicates with the cylinder bore B.sub.4 (FIG. 5). Between the
A-period (FIG. 3) and C-period (FIG. 5), a "B-period" (FIG. 4)
intervenes for a moment. The "B-period is a period when the first
outlet 71g communicates with the suction hole 11.sub.3 of the
cylinder bore B.sub.3 and the second outlet 71h communicates with
the suction hole 11.sub.4 of the cylinder bore B.sub.4.
[0068] FIGS. 7 and 8 are graphs showing pressure curves of
pressures in the cylinder bore B.sub.1, the cylinder bore B.sub.3,
and the cylinder bore B.sub.4 which are superimposed on one
another. In FIGS. 7 and 8, the solid line indicates the pressure
curve of the cylinder bore B.sub.1; the chain line indicates the
pressure curve of the cylinder bore B.sub.3; and the two-dot chain
line indicates the pressure curve of the cylinder bore B.sub.4.
[0069] In FIGS. 7 and 8, ".theta." indicates a rotation angle of
the rotary valve. In FIGS. 7 and 8, when the cylinder bore B.sub.1
is subjected to the upper dead center state (when the piston
P.sub.1 of the cylinder bore B.sub.1 is positioned at its upper
dead center), that is, when the cylinder bore B.sub.4 is subjected
to the lower dead center state (when the piston P.sub.4 of the
cylinder bore B.sub.4 is positioned at its lower dead center), the
rotation angle .theta. is indicated by 0.degree.
(=360.degree.).
[0070] FIG. 8 is an enlarged view of the initial stage (.theta. is
from about 0.degree. to about 30.degree.) of the suction stroke in
the cylinder bore B.sub.1. The arrows in FIG. 8 indicate flows of
the high pressure residual gas from the cylinder bore B.sub.1 to
the cylinder bores B.sub.3 and B.sub.4. The A-period, B-period and
C-period in FIG. 8 correspond to the above described A-period (FIG.
3), B-period (FIG. 4) and C-period (FIG. 5), respectively.
[0071] According to the present embodiment as shown in FIG. 8,
regarding the cylinder bore B.sub.1 subjected to the initial stage
of the suction stroke, before the C-period (FIG. 5) when the second
outlet 71h communicates with the cylinder bore B.sub.4 which is 180
degree opposite to the cylinder bore B.sub.1, there is an A-period
(FIG. 3) when the first outlet 71g communicates with the cylinder
bore B.sub.3 next to, in an opposite direction to the rotational
direction, the cylinder bore B.sub.4 which is 180 degree opposite
to the cylinder bore B.sub.1. This configuration uses the cylinder
bore B.sub.3 located next to the cylinder bore B.sub.4 in the
direction opposite to the rotational direction, for the cylinder
bore B.sub.1 subjected to the initial stage (A-period to C-period)
of the suction stroke. Regardless of the layout of the suction path
71c, the high pressure residual refrigerant can be released right
after the end of the compression and discharge stroke (that is,
right after the beginning of the suction stroke). Therefore, a high
suction efficiency and compression performance of the compressor
can be maintained.
[0072] Although the cylinder bore B.sub.1 has been used as one
example in the above explanation in FIGS. 2 to 6, the release path
71e communicates with the other cylinder bores B.sub.2 to B.sub.6
in sequence in the same way as the cylinder bore B.sub.1.
[0073] Effects
[0074] Next, effects of the present embodiment will be
described.
[0075] (1) The compressor 1 of the present embodiment includes:
four or more even numbers of cylinder bores Bj spaced evenly apart
from each other along the circumferential direction around the
drive shaft 10; the suction chamber 7 separated from the cylinder
bores Bj by the first partition wall (or the valve plate 9 in this
embodiment) and communicating with the cylinder bores Bj through
the suction holes 11j formed in the first partition wall; the
discharge chamber 8 separated from the cylinder bores Bj by the
second partition wall (or the valve plate 9 in this embodiment) and
communicating with the cylinder bores Bj through discharge holes
12j formed in the second partition wall; the pistons Pj configured
to reciprocate in the cylinder bores Bj; and the conversion
mechanism (21, 24, 40, 30) configured to convert the rotation of
the drive shaft 10 to the reciprocations of the pistons Pj. The
pistons Pj reciprocate in the respective cylinder bores Bj, in
order, in conjunction with the rotation of the drive shaft 10 so
that each cylinder bore Bj has its suction stroke and its
compression and discharge stroke alternately. In the suction
stroke, the refrigerant is suctioned from the suction chamber 7
into the cylinder bore Bj through the suction hole 11j. In the
compression and discharge stroke, the refrigerant is compressed in
the cylinder bores Bj and then the compressed refrigerant is
discharged to the discharge chamber 8 through the discharge hole
12j. The compressor 1 further includes the rotary valve 71 disposed
to be in rotational, slidable contact with the first partition wall
9 while covering the suction hole 11j and connected to the drive
shaft 10 so as to rotate in synchronizing with the rotation of the
drive shaft (10). The rotary valve (71) is formed with a suction
path (71c) configured to open the suction holes 11j of the cylinder
bores Bj subjected to the suction strokes so as to connect the
cylinder bores Bj to the suction chamber 7. The rotary valve 71 is
formed with the release path 71e to release a high pressure
residual refrigerant which was not discharged in the compression
and discharge stroke from one of the cylinder bores Bj subjected to
an initial stage of the suction stroke to others of the cylinder
bores Bj having a lower pressure than the one of the cylinder bores
Bj. The release path 71e is formed with the inlet 71f, the first
outlet 71g and the second outlet 71h provided on the rotational
trajectory to overlap with the suction holes 11j. The release path
71e is formed with the communication part 71k provided outside the
rotational trajectory and communicating the inlet with the
outlets.
[0076] During the time period when the inlet 71f of the release
path 71e communicates with first one of the cylinder bore Bj which
is in the initial state of the suction stroke, (A) the first outlet
71g communicates with a second one of the cylinder bores Bj next
to, in a direction opposite to the rotational direction
(counter-rotational direction), a third one of the cylinder bore Bj
located 180 degree opposite to the first one of the cylinder bore
Bj; and after that, (C) the second outlet 71h communicates with the
third one of the cylinder bores Bj located at 180 degree opposite
to the first one of the cylinder bores Bj.
[0077] Regarding the cylinder bore B.sub.1 as one example, in a
time period (FIGS. 3 to 5) during which the inlet 71f of the
release path 71e communicates with the cylinder bore B.sub.1
subjected to an initial state of its suction stroke (that is, a
period after a compression and discharge stroke of the cylinder
bore B.sub.1 and before the suction path 71c communicates with the
cylinder bore B.sub.1), the first outlet 71g communicates with the
cylinder bore B.sub.3 next to, in the counter-rotational direction,
the cylinder bore B.sub.4 located 180 degree opposite to the
cylinder bore B.sub.1 (a A-period); and then, the second outlet 71h
communicates with the cylinder bore B.sub.4 located 180 degree
opposite to the cylinder bore B.sub.1 (a C-period).
[0078] As described above, the present embodiment uses the cylinder
bore B.sub.3 next to, in the opposite direction to the rotational
direction, the cylinder bore B.sub.4 located 180 degree opposite to
the cylinder bore B.sub.1 subjected to the initial stage of the
suction stroke. Thus, regardless of the layout of the suction path
71c, the high pressure residual refrigerant can be released right
after the end of the compression and discharge stroke (that is,
right after the beginning of the suction stroke). Therefore, a high
suction efficiency and compression performance of compressor can be
maintained.
[0079] Although the cylinder bore B.sub.1 has been used as one
example in the explanation through FIG. 2 to 6, the release path
71e communicates with the other cylinder bores B.sub.2 to B6 by
turns in the same way.
[0080] (2) According to the present embodiment, the layout of the
suction path 71c is designed such that the start timing of the
valve open period when the suction hole 11j is opened by the
suction path 71c is set later than the timing when the piston Pj in
the cylinder bore Bj is positioned at its upper dead center.
[0081] In other words, regarding the cylinder bores B.sub.1,
B.sub.4 which are 180 degree opposite to each other, the ending
time (FIG. 4) of the valve open period when the suction hole
11.sub.4 is opened by the suction path 71c is set after the timing
shown in FIG. 2 in which the piston P.sub.4 in the cylinder bore
B.sub.4 is positioned at the lower dead center.
[0082] Therefore, the suction gas is introduced into the cylinder
bore Bj even after the suction stroke (the initial stage of the
compression and discharge stroke, that is, a stage in which the
piston Pj has started to moves from the lower dead center toward
the upper dead center), by the inertia of the suction gas flow
which was introduced during the suction stroke (that is, during a
period when the piston Pj moves from the upper dead center to the
lower dead center). This process increases the suction amount of
gas so as to improve the suction efficiency and the compression
efficiency of the compressor 1.
[0083] This structure, however, can not release the residual gas
from one of the cylinder bores Bj having piston Pj at the upper
dead center to another of the cylinder bore Bj 180 degree opposite
to the one of the cylinder bores Bj. In other words, as for the
cylinder bores B.sub.1 and B.sub.4 that are 180 degree opposite to
each other, the residual gas can not be released from the cylinder
bores B.sub.1 (FIG. 3) having piston Pj positioned right after the
upper dead center to the cylinder bore B.sub.4 located 180 degree
opposite to the cylinder bore B.sub.4. In the same way, although
explanations by drawings are omitted here, in the case of the
cylinder bores B.sub.2 and B.sub.5 that are 180 degree opposite to
each other and the case of the cylinder bores B.sub.1 and B.sub.4
that are 180 degree opposite to each other, when their pistons are
positioned right after the upper dead center, a residual gas can
not be released. Therefore, the effect (1) will be more
effective.
[0084] (3) According to the present embodiment, the A-period and
C-period are partially overlapped so that the C-period follows
A-period without a break therebetween. This configuration allows
release of the residual gas without a break, and thereby, the
suction efficiency is further improved.
[0085] (4) The compressor 1 of the present embodiment includes a
rotatable drive shaft 10 extending into the suction chamber 7
through the through hole 9c provided in the valve plate 9, and the
plate shaped rotary valve 71 connected to the drive shaft 10 within
the suction chamber 7 so as to rotate with the drive shaft 10 and
configured to open and close the suction holes 11j of the valve
plate 9 as rotating with the drive shaft 10; and the stopper 73,
which is axially immovable, attached to the drive shaft 10, wherein
the rotary valve 71 is axially slidably attached to the drive shaft
10 and biased toward the valve plate 9 by the coil spring 75
serving as a spring supported by the stopper 73.
[0086] In other words, the rotary valve 71 rotates with the drive
shaft 10 with being axially slidable with respect to the drive
shaft 10 and is biased toward the valve plate 9 by the spring 75.
With this structure, the rotary valve 71 is firmly in close contact
with the valve plate 9, so that the compressed high pressure medium
in the cylinder bores Bj does not substantially leak from the
suction holes 11j of the cylinder bores Bj through the gap between
the valve plate 9 and the rotary valve 71 into the suction chamber
7. Thereby, the compression efficiency is improved. Moreover, if
the pressure within the cylinder bores Bj was to increase
excessively, the rotary valve 71 would move away from the valve
plate 9 to release the excessively high pressure medium from the
cylinder bores Bj to the suction chamber 7. Therefore, the
compressor 1 of the present embodiment has a safety for the
excessively high pressure in the cylinder bores Bj.
[0087] Unlike the conventional art (for example, Japanese Patent
Application Laid-Open No. 8-144946, FIGS. 3, 6, 9 and 12), the coil
spring 75 is not in contact with the rear head 6, so that vibration
of the rotary valve 71 is not transmitted to the rear head 6 via
the coil spring 75. Therefore, the compressor 1 of the present
embodiment achieves improved suppression of vibration.
[0088] Moreover, the stopper 73 for the coil spring 75 rotates with
the rotary valve 71 as one unit, unlike the conventional art (for
example, Japanese Patent Application Laid-Open No. 8-144946, FIGS.
3, 6, 9 and 12), so there is no need to have a thrust bearing
between the coil spring and the rotary valve or between the coil
spring and the stopper. Therefore, cost is reduced since expensive
thrust bearings are not required.
[0089] Next, modifications of the first embodiment will be
explained. In modifications or embodiments described below, the
same reference numerals and symbols will be used to designate the
same elements as the elements described in the first embodiment,
and redundant description for the elements and its effects will be
omitted.
First Modification
[0090] FIG. 10 is a view of a rotary valve according to a first
modification of the first embodiment.
[0091] Although the rotary valve 71 of the first embodiment has the
recessed communication part 71k of the release path 71e which is
recessed from the surface of the rotary valve 71 in a groove shape
(See, FIG. 9), the rotary valve 71 of the first modification shown
in FIG. 10 has a communication part 71k which penetrates through
the rotary valve 71 to form a hole therein. Such a first
modification can achieve the same or similar effect as that of the
first embodiment.
Second Modification
[0092] FIG. 11 is a view of a rotary valve according to a second
modification of the first embodiment.
[0093] The rotary valve 71 of the first embodiment has the release
path 71e in which one communication part 71k communicates one inlet
71f with two outlets 71g, 71h (See, FIG. 9). However, a rotary
valve 71 of the second modification shown in FIG. 11 has a release
path 71e with separate communication parts 71k-1, 71k-2 in which
one communication part 71k-i connects an inlet 71f to a first
outlet 71g and the other communication part 71k-2 connects the
inlet 71f to a second outlet 71h. The communication part 71k-1 and
the communication part 71k-2 meet in the middle. In other words,
the communication part 71k-1 and the communication part 71k-2
diverge from each other in midstream. Such a second modification
can achieve the same or similar effect as that of the first
embodiment.
Second Embodiment
[0094] Next, a second embodiment according to the present invention
will be explained with reference to FIGS. 12 to 18.
[0095] The compressor 1 of the first embodiment includes the
plate-shaped rotary valve 71 configured to be in slide contact with
the valve plate 9. The compressor 1 according to the second
embodiment includes a tubular-shaped rotary valve 71A which is
slidably received in a center through hole 14 of a cylinder block
2. Other configurations of the second embodiment are the same as
that of the first embodiment.
[0096] In particular, as shown in FIGS. 12 and 13, a tubular
portion 83 projects from a rear end of the cylinder block 2 around
a circumferential edge of the center through hole 1, and the
tubular portion 83 of the cylinder block extends into a suction
chamber 7 of a rear head 6 through a center through hole 9c of the
valve plate 9. With this configuration, the center through hole 14
of the cylinder block 2 communicates with the suction chamber 7.
The valve plate 9 (or, a second partition wall) is formed with
discharge holes 12 and without a suction hole. However, suction
holes 11j are formed at a partition wall 85 (or, a first partition
wall) by which the center through hole 14 of the cylinder block 2
and the cylinder bores Bj are separated from each other. The
tubular rotary valve 71A is rotationally slidably provided in the
center through hole 14 of the cylinder block 2 and is connected
with a drive shaft 10, so that the rotary valve 71A can rotate with
the drive shaft 10 as an integral unit.
[0097] Similar to the first embodiment, the rotary valve 71A is
formed with a suction path 71c configured to communicate the
suction chamber 7 to the suction holes 11j of the cylinder bores Bj
subjected to a suction stroke, in turn, as the rotary valve 71A
rotates. Like the first embodiment, the rotary valve 71A is
provided with a release path 71e. The release path 71e is formed as
a recess from a surface of the rotary valve 71A, and has an inlet
71f, a first outlet 71g, a second outlet 71h, and a communication
part 71k connecting the inlet 71f to the outlets 71g, 71h. The
inlet 71f and the outlets 71g, 71h are provided on a rotational
trajectory which overlaps the suction holes 11j so as to connect
with the suction holes 11j in sequential order as the rotary valve
71A rotates. The communication part 71k is outside of the
rotational trajectory.
[0098] FIGS. 13 to 17 show a connection process between the release
path 71e and the cylinder bores B.sub.1, B.sub.4 and B.sub.5 in a
sequential order during an initial stage of a suction stroke in the
cylinder bore B.sub.1. In a position shown in FIG. 13, a piston
P.sub.1 of a cylinder bore B.sub.1 is positioned at its upper dead
center and a piston P.sub.4 of a cylinder bore B.sub.4 which is 180
degree opposite to the cylinder bore B.sub.1 is positioned at its
lower dead center. Thus, in the position shown in FIG. 13, in
cylinder bores B.sub.2 and B.sub.3 which are located between the
cylinder bore B.sub.1 subjected to the upper dead center state and
the cylinder bore B.sub.4 subjected to the lower dead center state,
compressing strokes are performed, and in cylinder bores B5 and B6
which are located between the cylinder bore B.sub.4 subjected to
the lower dead center state and the cylinder bore B.sub.1 subjected
to the upper dead center state, suction strokes are performed.
[0099] In a period (FIGS. 14 to 16) during which the release path
inlet 71f is connected to the cylinder bore B.sub.1 subjected to
the initial stage of the suction stroke, the first outlet 71g
communicates with the cylinder bore B.sub.3 next to, in the
counter-rotational direction, the cylinder bore B.sub.4 which is
180 degree opposite to the cylinder bore B.sub.1 as shown in FIG.
14, and after that, the second outlet 71h communicates with the
cylinder bore B.sub.4 which is 180 degree opposite to the cylinder
bore B.sub.1 as shown in FIG. 16. Hereinafter, "A-period" refers to
a period when the first outlet 71g communicates with the cylinder
bore B.sub.3 (FIG. 14) and "C-period" refers to a period when the
second outlet 71h communicates with the cylinder bore B.sub.4 (FIG.
16). Between the A-period (FIG. 14) and the C-period (FIG. 16),
there is a momentary B-period (FIG. 15) when the first outlet 71g
communicates with the suction hole 11.sub.3 of the cylinder bore
B.sub.3 and the second outlet 71h communicates with the suction
hole 11.sub.4 of the cylinder bore B.sub.4.
[0100] With this configuration, the same or similar effect as to
the first embodiment can be achieved.
First Modification
[0101] FIG. 19 is a view of a rotary valve of a first modification
of the second embodiment. In the rotary valve 71A of the second
embodiment, the communication part 71k of the release path 71e is
recessed from an outer circumferential surface of the rotary valve
71A and formed in a groove shape (FIGS. 13 and 18). The first
modification has a communication part 71k which penetrates the
rotary valve 71A to form a hole therein. Such a first modification
can provide the same or similar effect as that of the second
embodiment.
Second Modification
[0102] FIG. 20 is a view of a rotary valve of a second modification
of the second embodiment.
[0103] The rotary valve 71A of the second embodiment is configured
which a communication part 71k to connect the inlet 71f with two of
the outlets 71g, 71h (FIGS. 13, 18). The second modification has
separate communication parts 71k-1, 71k-2 in which the
communication part 71k-1 connects an inlet 71f of a release path
71e with a first outlet 71g and the communication part 71k-2
connects the inlet 71f with a second outlet 71h. The communication
part 71k-1 and the communication part 71k-2 are connected to each
other in midstream. Such a second modification can achieve the same
or similar effect as that of the second embodiment.
[0104] It should be appreciated that the present invention is not
limited to the above detailed embodiments and modifications.
[0105] For example, although each of the above detailed embodiments
has such a structure with six cylinder bores, the present invention
can be applied to a structure having an even number of four or more
cylinder bores which is space apart from each other in a
circumferential direction. In addition, the present invention can
be implemented with various other modifications without departing
from technical scope of the present invention.
* * * * *