U.S. patent application number 11/883994 was filed with the patent office on 2008-08-14 for piston type compressor.
Invention is credited to Akinobu Kanai, Osamu Nakayama, Masaki Ota, Masaya Sakamoto, Yoshio Taneda, Akihito Yamanouchi.
Application Number | 20080193304 11/883994 |
Document ID | / |
Family ID | 37683302 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080193304 |
Kind Code |
A1 |
Kanai; Akinobu ; et
al. |
August 14, 2008 |
Piston Type Compressor
Abstract
Each suction port 43 of a cylinder block 11 has a narrow passage
50 located at a top dead center side and a wide passage 51 located
at a bottom dead center side. A suction communication passage 45 of
a rotary valve 41 passes by a first succeeding end 50b of the
narrow passage 50 before passing by a second succeeding end 51b of
the wide passage 51. A high-pressure groove 47 of a residual gas
bypass groove 46 faces only a narrow passage 50 of a suction port
43A that corresponds to a high-pressure side compression chamber 26
when in communication with the suction port 43A. A width Tc between
the first succeeding end 50b and a second preceding end 51a of the
wide passage 51 in the rotation direction of the rotary valve 41 is
smaller than a seal width W of a seal region S between the
high-pressure groove 47 and the outlet 45b of the suction
communication passage 45. This reduces the suction loss amount of
gas in each compression chamber and improves the compression
efficiency while advancing the timing at which the suction of gas
into the compression chamber starts.
Inventors: |
Kanai; Akinobu; (Kariya-shi,
JP) ; Ota; Masaki; (Kariya-shi, JP) ;
Yamanouchi; Akihito; (Kariya-shi, JP) ; Nakayama;
Osamu; (Kariya-shi, JP) ; Taneda; Yoshio;
(Kariya-shi, JP) ; Sakamoto; Masaya; (Kariya-shi,
JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
37683302 |
Appl. No.: |
11/883994 |
Filed: |
July 24, 2006 |
PCT Filed: |
July 24, 2006 |
PCT NO: |
PCT/JP06/14587 |
371 Date: |
August 6, 2007 |
Current U.S.
Class: |
417/269 ;
137/625.11; 91/499 |
Current CPC
Class: |
F04B 27/1018 20130101;
Y10T 137/86501 20150401 |
Class at
Publication: |
417/269 ;
137/625.11; 91/499 |
International
Class: |
F04B 1/14 20060101
F04B001/14; F04B 27/10 20060101 F04B027/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2005 |
JP |
2005-214836 |
Claims
1. A piston type compressor comprising a rotation shaft, a cylinder
block having a plurality of cylinder bores arranged around the
rotation shaft, a piston accommodated in each of the cylinder
bores, and a rotary valve rotated in synchronization with the
rotation shaft; wherein the piston defines a compression chamber in
the cylinder bore, the cylinder block (has a plurality of suction
ports each of which communicates a suction pressure region to the
corresponding compression chamber, and the piston reciprocates
between a bottom dead center that maximizes the volume of the
compression chamber and a top dead center that minimizes the volume
of the compression chamber so as to draw gas from the suction
pressure region into the compression chamber through the rotary
valve, compress the gas in the compression chamber, and discharge
the gas from the compression chamber; and the rotary valve has a
suction communication passage and a residual gas bypass passage,
the rotary valve is rotated so that the suction communication
passage sequentially communicates each of the suction port with the
suction pressure region and so that the residual gas bypass passage
communicates the suction port corresponding to the compression
chamber at the high-pressure side after discharging has been
performed with the suction port corresponding to the compression
chamber at the low-pressure side, and a portion of an outer
circumferential surface of the rotary valve facing openings of the
suction ports forms a seal region that prevents the residual gas
bypass passage from being communicated with the suction
communication passage through the openings of the suction ports,
the piston type compressor being characterized in that: each of the
suction ports has a narrow passage located at a top dead center
side and a wide passage located at a bottom dead center side, the
narrow passage has an opening facing the outer circumferential
surface of the rotary valve with a width in a rotation direction of
the rotary valve that is smaller than a width of an opening of the
wide passage; the opening of the narrow passage has a first
preceding end and a first succeeding end, wherein the suction
communication passage of the rotating rotary valve first passes by
the first preceding end and then passes by the first succeeding
end, and the opening of the wide passage has a second preceding end
and a second succeeding end, wherein the suction communication
passage of the rotating rotary valve first passes by the second
preceding end and then passes by the second succeeding end; the
suction communication passage passes by the first succeeding end
before passing by the second succeeding end; the residual gas
bypass passage has a high-pressure opening, and the high-pressure
opening faces only the narrow passage of the suction port that
corresponds to the high-pressure side compression chamber when in
communication with the suction port; the narrow passage is arranged
to enable communication with the compression chamber defined by the
piston located at the top dead center; and a width between the
first succeeding end and the second preceding end in the rotation
direction of the rotary valve is smaller than a dimension of a
portion of the seal region between the high-pressure opening and an
opening of the suction communication passage, and the opening of
the suction communication passage comes into communication with the
wide passage immediately after the narrow passage is closed by the
seal region.
2. The piston type compressor according to claim 1, wherein the
wide passage is arranged continuously with the narrow passage.
3. The piston type compressor according to claim 1, wherein the
narrow passage is arranged closer to the second preceding end with
respect to the wide passage.
4. The piston type compressor according to claim 3, wherein the
first preceding end and the second preceding end lie along the same
straight line.
5. A piston type compressor comprising a rotation shaft, a cylinder
block having a plurality of cylinder bores arranged around the
rotation shaft, a piston accommodated in each of the cylinder
bores, and a rotary valve rotated in synchronization with the
rotation shaft; wherein the piston defines a compression chamber in
the cylinder bore, the cylinder block has a plurality of suction
ports each of which communicates a suction pressure region to the
corresponding compression chamber, and the piston reciprocates
between a bottom dead center that maximizes the volume of the
compression chamber and a top dead center that minimizes the volume
of the compression chamber so as to draw gas from the suction
pressure region into the compression chamber through the rotary
valve, compress the gas in the compression chamber, and discharge
the gas from the compression chamber; and the rotary valve has a
suction communication passage and a residual gas bypass passage,
the rotary valve is rotated so that the suction communication
passage sequentially communicates each of the suction port with the
suction pressure region and so that the residual gas bypass passage
communicates the suction port corresponding to the compression
chamber at the high-pressure side after discharging has been
performed with the suction port corresponding to the compression
chamber at the low-pressure side, and a portion of an outer
circumferential surface of the rotary valve facing openings of the
suction ports forms a seal region that prevents the residual gas
bypass passage from being communicated with the suction
communication passage through the openings of the suction ports,
the piston type compressor being characterized in that: each of the
suction ports has a wide passage located at a top dead center side
and a narrow passage located at a bottom dead center side, the
narrow passage has an opening facing the outer circumferential
surface of the rotary valve with a width in a rotation direction of
the rotary valve that is smaller than a width of an opening of the
wide passage; the opening of the narrow passage has a first
preceding end and a first succeeding end, wherein the suction
communication passage of the rotating rotary valve first passes by
the first preceding end and then passes by the first succeeding
end, and the opening of the wide passage has a second preceding end
and a second succeeding end, wherein the suction communication
passage of the rotating rotary valve first passes by the second
preceding end and then passes by the second succeeding end; the
suction communication passage passes by the first succeeding end
before passing by the second succeeding end; the residual gas
bypass passage has a high-pressure opening, and the high-pressure
opening faces only the narrow passage of the suction port that
corresponds to the high-pressure side compression chamber when in
communication with the suction port; the wide passage is arranged
continuously with the narrow passage, and the wide passage is
arranged to enable communication with the compression chamber
defined by the piston located at the top dead center; and a width
between the first succeeding end and the second preceding end in
the rotation direction of the rotary valve is smaller than a
dimension of a portion of the seal region between the high-pressure
opening and an opening of the suction communication passage, and
the opening of the suction communication passage comes into
communication with the wide passage immediately after the narrow
passage is closed by the seal region.
6. The piston type compressor according to claim 5, wherein the
narrow passage is arranged closer to the second preceding end with
respect to the wide passage.
7. The piston type compressor according to claim 6, wherein the
first preceding end and the second preceding end lie along the same
straight line.
8. The piston type compressor according to claim 2, wherein the
narrow passage is arranged closer to the second preceding end with
respect to the wide passage.
9. The piston type compressor according to claim 8, wherein the
first preceding end and the second preceding end lie along the same
straight line.
Description
TECHNICAL FIELD
[0001] The present invention relates to a piston type compressor
using a rotary valve, and more particularly, to a piston type
compressor having a structure for bypassing gas remaining in a
high-pressure side compression chamber after discharging is
completed into a low-pressure side compression chamber.
BACKGROUND ART
[0002] Patent document 1 discloses a piston type compressor in
which a rotation shaft rotates to reciprocate a piston in each
cylinder bore. As a result, gas is drawn from a suction pressure
region into compression chambers through a rotary valve, compressed
in the compression chambers, and then discharged from the
compression chambers. During a suction stroke, a suction
communication passage of the rotary valve, which rotates in
synchronization with the rotation shaft, sequentially communicates
the suction pressure region with a passage extending from each
compression chamber. The suction communication passage is elongated
and extends in the axial direction of the rotary valve and has a
uniform width.
[0003] An outer circumferential surface of the rotary valve
includes a residual gas bypass groove that communicates a guide
passage for a high-pressure side compression chamber after
discharging is completed to a guide passage for a low-pressure side
compression chamber. Non-discharged gas remaining in the
compression chamber after discharging is completed, that is,
residual gas, is bypassed or recovered in the low-pressure side
compression chamber through the high-pressure side guide passage,
the residual gas bypass groove, and the low-pressure side guide
passage. This reduces re-expansion of gas in the compression
chambers that occurs during the suction stroke. This ensures that
gas is drawn from the suction pressure region into the compression
chambers and improves the volumetric efficiency of the piston type
compressor.
[0004] In the above piston type compressor, the passage of gas from
a high-pressure opening of the residual gas bypass groove to the
suction communication passage of the rotary valve via the guide
passages in a cylinder block must be prevented. For this purpose, a
seal region is formed in the outer circumferential surface of the
rotary valve facing the guide passages of the cylinder block. The
seal region closes the guide passages of the cylinder block between
the high-pressure opening of the residual gas bypass groove and the
suction communication passage of the rotary valve.
[0005] FIGS. 11 and 12 are development views showing a rotary valve
100 of which outer circumferential surface 100a is laid out on a
plane. A guide passage 101 of a cylinder block is in correspondence
with the outer circumferential surface 100a of the rotary valve
100. As shown in FIG. 11, the outer circumferential surface 100a of
the rotary valve 100 has a seal region S. The seal region S is
required to have an area that is large enough to close an opening
101a of the guide passage 101 in the cylinder block between a
high-pressure opening 103a of a residual gas bypass groove 103 and
an opening 102a of a suction communication passage 102 of the
rotary valve.
[0006] As the area of the seal region S increases, a seal width W
between the high-pressure opening 103a and the suction
communication passage 102 increases in the rotation direction of
the rotary valve 100. In other words, the high-pressure opening
103a becomes more distant from the opening 102a of the suction
communication passage 102. This increases the time difference
between when the opening 101a of the guide passage 101 in the
cylinder block comes into communication with the high-pressure
opening 103a and the when the opening 101a of the guide passage 101
comes into communication with the opening 102a of the suction
communication passage 102 in the rotary valve. The increase in the
time difference indicates an increase in the time between when the
gas in a high-pressure side compression chamber is recovered and
when gas is drawn into the high-pressures side compression chamber.
As a result, the timing at which gas is drawn into the compression
chamber is delayed. This decreases the amount of gas drawn into the
compression chambers and lower the compression efficiency.
[0007] Therefore, the area of the seal region S may be reduced, or
more specifically, the seal width W may be reduced as shown in FIG.
12. This would reduce the time difference between the timing at
which the opening 101a of the guide passage 101 in the cylinder
block starts communicating with the high-pressure opening 103a and
the timing at which the opening 101a of the guide passage 101
starts communicating with the opening 102a of the suction
communication passage 102 in the rotary valve.
[0008] However, the seal region S is required to close the opening
101a of the guide passage 101 in the cylinder block. Thus, if the
area of the seal region S is just reduced, this would reduce the
size of the opening 101a in the guide passage 101. This is not
desirable because the smaller opening 101a would increase the
suction loss of the gas drawn into the compression chambers and
lower the compression efficiency.
Patent Document Japanese Laid-Open Patent Publication No.
2004-239210
DISCLOSURE OF THE INVENTION
[0009] It is an object of the present invention to provide a piston
type compressor that reduces the suction loss of gas drawn into a
compression chamber and improves the compression efficiency while
advancing the timing for starting the suction of gas into the
compression chamber.
[0010] One aspect of the present invention is a piston type
compressor including a rotation shaft, a cylinder block having a
plurality of cylinder bores arranged around the rotation shaft, a
piston accommodated in each of the cylinder bores, and a rotary
valve rotated in synchronization with the rotation shaft. The
piston defines a compression chamber in the cylinder bore. The
cylinder block has a plurality of suction ports, each of which
communicates a suction pressure region to the corresponding
compression chamber. The piston reciprocates between a bottom dead
center that maximizes the volume of the compression chamber and a
top dead center that minimizes the volume of the compression
chamber so as to draw gas from the suction pressure region into the
compression chamber through the rotary valve, compress the gas in
the compression chamber, and discharge the gas from the compression
chamber. The rotary valve has a suction communication passage and a
residual gas bypass passage. The rotary valve is rotated so that
the suction communication passage sequentially communicates each of
the suction port with the suction pressure region and so that the
residual gas bypass passage communicates the suction port
corresponding to the compression chamber at the high-pressure side
after discharging has been performed with the suction port
corresponding to the compression chamber at the low-pressure side.
A portion of an outer circumferential surface of the rotary valve
facing openings of the suction ports forms a seal region that
prevents the residual gas bypass passage from being communicated
with the suction communication passage through the openings of the
suction ports.
[0011] Each of the suction ports has a narrow passage located at a
top dead center side and a wide passage located at a bottom dead
center side. The narrow passage has an opening facing the outer
circumferential surface of the rotary valve with a width in a
rotation direction of the rotary valve that is smaller than a width
of an opening of the wide passage. The opening of the narrow
passage has a first preceding end and a first succeeding end. The
suction communication passage of the rotating rotary valve first
passes by the first preceding end and then passes by the first
succeeding end. The opening of the wide passage has a second
preceding end and a second succeeding end. The suction
communication passage of the rotating rotary valve first passes by
the second preceding end and then passes by the second succeeding
end. The suction communication passage passes by the first
succeeding end before passing by the second succeeding end. The
residual gas bypass passage has a high-pressure opening. The
high-pressure opening faces only the narrow passage of the suction
port that corresponds to the high-pressure side compression chamber
when in communication with the suction port. The narrow passage is
arranged to enable communication with the compression chamber
defined by the piston located at the top dead center. A width
between the first succeeding end and the second preceding end in
the rotation direction of the rotary valve is smaller than a
dimension of a portion of the seal region between the high-pressure
opening and an opening of the suction communication passage. The
opening of the suction communication passage comes into
communication with the wide passage immediately after the narrow
passage is closed by the seal region.
[0012] Each of the suction ports may have a wide passage located at
the top dead center side and a narrow passage located at the bottom
dead center side. The wide passage may be arranged continuously
with the narrow passage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a vertical cross-sectional view showing a piston
type compressor according to a first embodiment of the present
invention;
[0014] FIG. 2 is a cross-sectional view taken along line 1-1 in
FIG. 1;
[0015] FIG. 3 is a diagram showing a rotary valve of FIG. 1 of
which outer circumferential surface is laid out on a plane;
[0016] FIG. 4 is a development view showing a state in which a
narrow passage shown in FIG. 3 is closed by a seal region;
[0017] FIG. 5 is a development view showing a state in which a
suction port is in communication with a suction communication
passage;
[0018] FIG. 6 is a diagram showing a rotary valve according to a
second embodiment of the present invention of which outer
circumferential surface is laid out on a plane;
[0019] FIG. 7 is a diagram showing a rotary valve according to a
third embodiment of the present invention of which outer
circumferential surface is laid out on a plane;
[0020] FIG. 8 is a development view showing another example of a
suction port;
[0021] FIG. 9 is a development view showing another example of a
suction port;
[0022] FIG. 10 is a development view showing another example of a
suction port;
[0023] FIG. 11 is a development view of a prior art rotary valve;
and
[0024] FIG. 12 is a development view of a prior art rotary valve
having a small region.
BEST MODE FOR CARRYING OUT THE INVENTION
[0025] A first embodiment of the present invention will now be
described with reference to FIGS. 1 to 5. In the description
hereafter, the directions of "up," "down," "front," and "rear" for
a piston type compressor 10 are indicated in FIG. 1 with the
directions of arrows Y1 showing the upward and downward directions
and the directions of arrows Y2 showing the frontward and rearward
directions.
[0026] As shown in FIG. 1, the piston type compressor 10 includes a
cylinder block 11, a front housing 12 joined to the front end of
the cylinder block 11, and a rear housing 13 joined to the rear end
of the cylinder block 11. A valve assembly 14 is arranged between
the cylinder block 11 and the rear housing 13. The cylinder block
11, the front housing 12, the rear housing 13, and the valve
assembly 14 are fastened together by a plurality of bolts B. FIG. 1
shows only one of the bolts B. The cylinder block 11, the front
housing 12, and the rear housing 13 form a housing for the piston
type compressor 10.
[0027] In the housing, a space defined in the front housing 12 and
the cylinder block 11 defines a crank chamber 17. A rotation shaft
19 is rotatably supported by the cylinder block 11 and the front
housing 12. The rotation shaft 19 is arranged in the crank chamber
17. The rotation shaft 19 is operably connected to an external
drive source, for example, an engine E, by a power transmission
mechanism PT. The rotation shaft 19 rotates when supplied with
power from the external drive source E. The rotation shaft 19 is
inserted through a shaft hole 20 extending through the cylinder
block 11 and a shaft hole 21 extending through the front housing
12.
[0028] The rotation shaft 19 has a front end supported by the front
housing 12 with a radial bearing 22, which is arranged in the shaft
hole 20 of the front housing 12. A lip-seal type shaft seal unit 23
is arranged between the front housing 12 and the rotation shaft 19.
The shaft seal unit 23 prevents leakage of refrigerant gas from the
crank chamber 17 along the rotation shaft 19. A lug plate 16 is
fixed on the rotation shaft 19 in the crank chamber 17 in a manner
that the lug plate 16 rotates integrally with the rotation shaft
19. A thrust bearing 18 is arranged between the lug plate 16 and
the front housing 12.
[0029] A swash plate 24 is accommodated in the crank chamber 17.
The swash plate 24 is supported on the rotation shaft 19 in a
manner that the swash plate 24 is slidable and tiltable on the
rotation shaft 19 such that its inclination angle relative to a
central axis L1 of the rotation shaft 19 is variable. A hinge
mechanism 25 is arranged between the lug plate 16 and the swash
plate 24. The swash plate 24, which is hinge-connected to the lug
plate 16 by the hinge mechanism 25, is supported by the rotation
shaft 19 and is rotatable in synchronization with the lug plate 16
and the rotation shaft 19. Further, the swash plate 24 is tiltable
with respect to the rotation shaft 19 while sliding in the axial
direction of the rotation shaft 19, or in the direction of the
central axis L1.
[0030] As shown in FIG. 2, the cylinder block 11 includes a
plurality of, five in the present embodiment, cylinder bores 11a
arranged around the rotation shaft 19. Each cylinder bore 11a
accommodates a single-headed piston 31 in a manner enabling
reciprocation. Each piston 31 is coupled to the peripheral portion
of the swash plate 24 in a tiltable manner by a pair of front and
rear shoes 30. The rotation of the swash plate 24, which occurs
when the rotation shaft 19 rotates, is converted to the
reciprocation of each piston 31 by the shoes 30.
[0031] The front and rear openings of each cylinder bore 11a are
closed by the valve assembly 14 and the corresponding piston 31. A
compression chamber 26 defined in the cylinder bore 11a changes its
volume as the piston 31 reciprocates. A suction passage 28, which
serves as a suction pressure region, and a discharge chamber 29 are
defined in the rear housing 13. The suction passage 28 is formed in
the central portion of the rear housing 13. The discharge chamber
29 is formed to surround the outer circumference of the suction
passage 28. The valve assembly 14 includes discharge ports 32 and
discharge valves 33. The discharge ports 32 communicate the
compression chambers 26 with the discharge chamber 29. The
discharge valves 33 open and close the discharge ports 32.
[0032] A rotary valve 41 and a residual gas bypass passage will now
be described.
[0033] A valve accommodation chamber 42 surrounded by the cylinder
bores 11a is defined in the central portion of the cylinder block
11. The rotary valve 41 is accommodated in a rotatable manner
within the valve accommodation chamber 42. A plurality of suction
ports 43 extending through the cylinder block 11 communicate the
valve accommodation chamber 42 with each compression chamber 26.
FIG. 1 shows only one of the suction ports 43. The rotary valve 41,
which is made of a metal material containing aluminum, is
cylindrical. The rotation shaft 19 has a rear end arranged in the
valve accommodation chamber 42. The rotary valve 41 has a front end
pressed fitted into a press-fitting recess 19a formed in the rear
end of the rotation shaft 19.
[0034] An outer circumferential surface 41a of the rotary valve 41
and a circumferential surface 42a of the valve accommodation
chamber 42 form a slide bearing surface for supporting the rotary
valve 41 in a rotatable manner within the valve accommodation
chamber 42. The rear end of the rotation shaft 19 is supported on
the cylinder block 11 by the rotary valve 41 in a rotatable manner.
The rotary valve 41 has a central axis L2 that is coaxial with the
central axis L1 of the rotation shaft 19. In other words, the
rotary valve 41 and the rotation shaft 19 are integrated to form a
coaxial structure. The rotary valve 41 rotates in synchronization
with the rotation of the rotation shaft 19, that is, in
synchronization with the reciprocation of the pistons 31.
[0035] The rotary valve 41 includes an inner space 44. The inner
space 44 is in communication with the suction passage 28 through a
hole 14a formed in the valve assembly 14. As shown in FIG. 2, a
suction communication passage 45, which extends from the inner
space 44 to the outer circumferential surface 41a of the rotary
valve 41, is formed in the peripheral wall of the rotary valve 41.
More specifically, an inlet 45a of the suction communication
passage 45 opens into the inner space 44, and an outlet 45b of the
suction communication passage 45 opens to the outer circumferential
surface 41a of the rotary valve 41. As the rotation of the rotary
valve 41 rotates the rotation shaft 19, the outlet 45b of the
suction communication passage 45 is intermittently communicated
with the openings, or inlets 43a, of the suction ports 43 of the
cylinder block 11. More specifically, the suction communication
passage 45 sequentially communicates the inner space 44, which
functions as a suction pressure region, with the inlets 43a of the
suction ports 43 extending from the compression chambers 26 in
synchronization with the rotation of the rotary valve 41.
[0036] The outlet 45b of the suction communication passage 45 of
the rotary valve 41 is in communication with the inlets 43a of the
suction ports 43 of the cylinder block 11 when a piston 31 shifts
to the suction stroke. Then, refrigerant gas from the suction
passage 28 flows sequentially through the hole 14a of the valve
assembly 14, the inner space 44 of the rotary valve 41, the suction
communication passage 45, and the suction port 43 in the cylinder
block 11 to be drawn into the compression chamber 26.
[0037] In the suction stroke, the position of a piston 31 at which
the volume of its compression chamber 26 becomes maximum is
referred to as the bottom dead center of the piston 31. When the
suction stroke of the piston 31 is completed, that is, when the
piston 31 is located at the bottom dead center, the outlet 45b in
the suction communication passage 45 of the rotary valve 41 is
completely separated from the inlet 43a of the suction port 43 of
the cylinder block 11 in the circumferential direction. In this
state, the suction of refrigerant gas from the inner space 44 into
the compression chamber 26 is suspended. Afterwards, as the piston
31 shifts to the compression stroke and the discharge stroke, the
outer circumferential surface 41a of the rotary valve 41 keeps the
inner space 44 closed from the compression chamber 26. Thus, there
is not interference with the compression of the refrigerant gas and
discharging of the compressed gas into the discharge chamber 29. In
the compression stroke and the discharge stroke, the position of
the piston 31 at which the volume of its compression chamber 26
becomes minimum is referred to as the top dead center of the piston
31. When the piston 31 is located at the top dead center, the
so-called top clearance exists between the valve assembly 14 and
the piston 31 in the cylinder bore 11a. Residual gas that was not
discharged remains in the top clearance of the compression chamber
26.
[0038] FIG. 3 is a diagram showing the rotary valve 41 of which the
outer circumferential surface 41a is laid out on a plane. The
suction port 43 of the cylinder block 11 faces the outer
circumferential surface 41a of the rotary valve 41. In FIGS. 3 to
5, the direction of arrow Y3 in FIG. 3 indicates the rotation
direction of the rotary valve 41, or the circumferential direction.
The rotary valve 41 moves to the left as viewed in FIG. 3. The
directions of arrow Y4 indicate the axial direction of the rotary
valve 41, that is, the direction of the central axis L2.
[0039] As shown in FIG. 3, a residual gas bypass groove 46, which
functions as a residual gas bypass passage, is formed in the outer
circumferential surface 41a of the rotary valve 41. The residual
gas bypass groove 46 includes a high-pressure groove 47, a
low-pressure groove 48, and a communication groove 49. The
high-pressure groove 47 extends in the direction of central axis L2
of the rotary valve 41, that is, in the direction of arrow Y4, and
functions as a high-pressure opening. The low-pressure groove 48
also extends in the direction of the central axis L2. The
communication groove 49 extends in the circumferential direction of
the rotary valve 41, that is, the direction of the arrow Y3, and
communicates an end of the high-pressure groove 47 at the top dead
center side with an end of the low-pressure groove 48 at the top
dead center side. In other words, the communication groove 49
communicates the end of the high-pressure groove 47 at the rear
side of the piston type compressor 10 with the end of the
low-pressure groove 48 at the rear side of the piston type
compressor 10.
[0040] The high-pressure groove 47 is arranged in the outer
circumferential surface 41a of the rotary valve 41 so as to come
into communication with the suction port 43 (43A) that corresponds
to the high-pressure side compression chamber 26 immediately after
discharging is performed, before the low-pressure groove 48
communicates with the suction port 43. Thus, the high-pressure
groove 47 comes into communicates with the top clearance of the
cylinder bore 11a through the suction port 43 of the cylinder block
11. Further, the low-pressure groove 48 is arranged in the outer
circumferential surface 41a of the rotary valve 41 to face the
suction port 43 (43B) that corresponds to the compression chamber
26 that has just completed suction, that is, the low-pressure side
compression chamber 26.
[0041] The outer circumferential surface 41a of the rotary valve 41
includes a seal region S located between the high-pressure groove
47 and the suction communication passage 45 of the rotary valve 41.
The seal region S prevents the passage of gas from the
high-pressure groove 47 of the residual gas bypass groove 46 to the
outlet 45b of the suction communication passage 45 of the rotary
valve 41 through the inlet 43a of a suction port 43 in the cylinder
block 11. The seal region S on the outer circumferential surface
41a of the rotary valve 41 faces the inlets 43a of the suction
ports 43, and separates the high-pressure groove 47 from the outlet
45b of the suction communication passage 45. The non-discharged
refrigerant gas remaining in a compression chamber 26 immediately
after discharging is performed flows sequentially through a suction
port 43 (43A) in the cylinder block 11, the high-pressure groove 47
of the rotary valve 41, the communication groove 49, the
low-pressure groove 48, and a suction port 43 (43B) of the cylinder
block 11 and is then bypassed to or recovered in the compression
chamber 26 that has just completed suction.
[0042] As indicated by the double-dashed lines in FIG. 3, each
suction port 43, which extends through the cylinder block 11, has
an opening, or an inlet 43a, facing the outer circumferential
surface 41a of the rotary valve 41. The inlet 43a has two different
opening widths Ta and Tb. The suction port 43 includes a narrow
passage 50 and a wide passage 51. The narrow passage 50 is arranged
at the top dead center side and the wide passage 51 at the bottom
dead center side in the direction of the central axis L2 of the
rotary valve 41. More specifically, the suction port 43 has a top
dead center side passage at the top dead center side and a bottom
dead center side passage at the bottom dead center side. In the
first embodiment, the top dead center side passage is the narrow
passage 50, and the bottom dead center passage is the wide passage
51.
[0043] The narrow passage 50, which has the first opening width Ta
that is uniform in the circumferential direction of the rotary
valve 41, extends in the direction of the central axis L2. The wide
passage 51, which has the second opening width Tb that is uniform
in the circumferential direction, extends in the direction of the
central axis L2. At the inlet 43a of the suction port 43, the first
opening width Ta of the narrow passage 50 is set to be narrower
than the second opening width Tb of the wide passage 51
(Ta<Tb).
[0044] The first opening width Ta of the narrow passage 50 is set
to be smaller than the distance between the high-pressure groove 47
and the suction communication passage 45 in the circumferential
direction, that is, a seal width W of a portion of the seal region
S (W>Ta). The second opening width Tb of the wide passage 51 is
set to greater than the seal width W (W<Tb). The boundary
between the narrow passage 50 and the wide passage 51 at the inlet
43a of the suction port 43 is formed in a stepped manner. When the
rotary valve 41 rotates, the high-pressure groove 47 passes by the
portion located toward the top dead center side, or the lower side
as viewed in FIG. 3, from the wide passage 51. Thus, the
high-pressure groove 47 is formed to come into communication with
the narrow passage 50 but not with the wide passage 51 when the
rotary valve 41 rotates.
[0045] The narrow passage 50 has a first preceding end 50a and a
first succeeding end 50b opposite the first preceding end 50a in
the rotation direction of the rotary valve 41. When the rotary
valve 41 rotates, the suction communication passage 45 first passes
by the first preceding end 50a and then passes by the first
succeeding end 50b. In the same manner, the wide passage 51 has a
second preceding end 51a and a second succeeding end 51b opposite
the second preceding end 51a in the rotation direction of the
rotary valve 41. When the rotary valve 41 rotates, the suction
communication passage 45 first passes by the second preceding end
51a and then passes by the second succeeding end 51b. The first
preceding end 50a side with respect to the first succeeding end 50b
is referred to as the preceding side, and the side opposite the
preceding side is referred to as the succeeding side. The second
preceding end 51a side with respect to the second succeeding end
51b is referred to as the preceding side, and the side opposite the
preceding side is referred to as the succeeding side.
[0046] A third opening width Tc from the first succeeding end 50b
of the narrow passage 50 to the second preceding end 51a of the
wide passage 51 in the rotation direction of the rotary valve 41 is
set to be slightly smaller than the seal width W of the seal region
S. Thus, the outlet 45b of the suction communication passage 45
comes into communication with the wide passage 51 immediately after
the high-pressure groove 47 passes by the narrow passage 50.
[0047] FIG. 3 shows a state in which the compression chamber 26
corresponding to the suction port 43A has just undergone
discharging, and the piston 31 in this high-pressure side
compression chamber 26 is located at the top dead center. At this
timing, the high-pressure groove 47 passes by the top dead center
side from the wide passage 51. More specifically, the high-pressure
groove 47 comes into communication with only the narrow passage 50
and does not come into communication with the wide passage 51 at
the inlet 43a of the suction port 43. The wide passage 51 at the
inlet 43a of the suction port 43 is closed by the seal region S.
The non-discharged residual refrigerant gas remaining in the top
clearance of the compression chamber 26 sequentially flows through
the suction port 43A of the cylinder block 11, the high-pressure
groove 47 of the rotary valve 41, the communication groove 49, the
low-pressure groove 48, and the suction port 43B of the cylinder
block 11 and is then bypassed or recovered in the compression
chamber 26 immediately after suction has been completed. This
reduces re-expansion of the residual gas during the suction stroke
of the compression chamber 26 that corresponds to the suction port
43A. This ensures that refrigerant gas is drawn from the
compression chamber 26 into the inner space 44 and improves the
volumetric efficiency of the piston type compressor 10.
[0048] Afterwards, as shown in FIG. 4, the rotary valve 41 rotates
and the high-pressure groove 47 passes by the narrow passage 50 so
that the narrow passage 50 at the inlet 43a of the suction port 43
is closed by the seal region S. In this state, the wide passage 51
at the inlet 43a of the suction port 43 has already been closed by
the seal region S. Thus, the narrow passage 50 and the wide passage
51, that is, the entire inlet 43a of the suction port 43, is closed
by the seal region S. The seal region S prevents gas passage
between the high-pressure groove 47 and the outlet 45b of the
suction communication passage 45 through the inlet 43a of the
suction port 43.
[0049] When the rotary valve 41 rotates slightly from the state
shown in FIG. 4, the outlet 45b of the suction communication
passage 45 comes into communication with the wide passage 51. More
specifically, immediately after the high-pressure groove 47 passes
by the narrow passage 50, or immediately after the high-pressure
groove 47 is separated from the inlet 43a of the suction port 43A,
the outlet 45b of the suction communication passage 45 comes into
communication with the inlet 43a of the suction port 43A. FIG. 5
shows the state in which both the narrow passage 50 and the wide
passage 51 come into communication with the suction communication
passage 45 of the rotary valve 41 after further rotation of the
rotary valve 41. Then, when the rotary valve 41 rotates further,
the entire inlet 43a of the suction port 43A, that is, the entire
narrow passage 50 and the entire wide passage 51, comes into
communication with the outlet 45b of the suction communication
passage 45. Refrigerant gas sequentially flows from the suction
passage 28 to the hole 14a of the valve assembly 14, the inner
space 44 of the rotary valve 41, the suction communication passage
45, and the suction port 43A of the cylinder block 11 to be drawn
into the compression chamber 26.
[0050] The first embodiment has the advantages described below.
[0051] (1) The inlet 43a of the suction port 43 includes the top
dead center side narrow passage 50 and the bottom dead center side
wide passage 51. More specifically, the top dead center side width
Ta of the inlet 43a of the suction port 43 in the rotation
direction of the rotary valve 41, that is, the circumferential
direction, is set to be smaller than the bottom dead side width Tb
of the inlet 43a. The high-pressure groove 47 is formed to
communicate with only the narrow passage 50 when the rotary valve
41 rotates. The width Ta of the opening of the narrow passage 50 is
smaller than the width Tb of the opening of the wide passage 51.
This reduces the seal width W of the seal region S for preventing
gas passage. As a result, the distance between the high-pressure
groove 47 and the outlet 45b of the suction communication passage
45 of the rotary valve 41 may be shortened. This reduces the time
difference between the timing at which the high-pressure groove 47
of the rotary valve 41 comes into communication with the suction
port 43A of the cylinder block 11 at the narrow passage 50 and the
timing at which the suction communication passage 45 of the rotary
valve 41 comes into communication with the suction port 43A of the
cylinder block 11 at the wide passage 51. More specifically, this
reduces the time difference from when the residual gas in the
high-pressure side compression chamber 26 corresponding to the
suction port 43A is recovered to when the suction of refrigerant
gas into the high-pressure side compression chamber 26 starts.
[0052] To prevent the passage of gas from the high-pressure groove
47 to the suction communication passage 45, the seal region S is
only required to close the narrow passage 50. Thus, the suction
port 43 may include the wide passage 51 in addition to the narrow
passage 50. Even when the seal width W of the seal region S is set
to be small in order to advance the timing at which the refrigerant
gas starts to be drawn into the compression chambers 26, the
suction loss of the refrigerant gas is prevented from increasing.
This structure reduces the suction loss amount of gas and improves
the compression efficiency while advancing the timing at which the
refrigerant gas starts being drawn into the compression chamber
26.
[0053] (2) The narrow passage 50 is arranged continuously with the
wide passage 51 at the inlet 43a of the suction port 43. Thus, as
compared with when, for example, the narrow passage 50 is separated
from the wide passage 51, the suction amount of refrigerant gas
from the inlet 43a of the suction port 43 into the compression
chamber 26 increases.
[0054] (3) As shown in FIG. 3, when the piston 31 is located at the
top dead center, the narrow passage 50 at the inlet 43a of the
suction port 43 is in direct communication with the compression
chamber 26. Thus, when the high-pressure groove 47 comes into
communication with the narrow passage 50, the residual gas in the
compression chamber 26 is readily recovered in the high-pressure
groove 47. This ensures the recovery of the residual gas. Thus,
re-expansion of the residual gas that occurs during the suction
stroke is reduced, and refrigerant gas is drawn into each
compression chamber 26 in an ensured manner. As a result, the
volumetric efficiency of the piston type compressor 10 is
improved.
[0055] A piston type compressor according to a second embodiment of
the present invention will now be described with reference to FIG.
6. The piston type compressor of the second embodiment differs from
the piston type compressor 10 of the first embodiment only in the
structure of each suction port 43. Components that are the same as
the first embodiment will not be described.
[0056] As shown in FIG. 6, at the inlet 43a of the suction port 43
in the second embodiment, a narrow passage 50 is formed closer to
the preceding side of a wide passage 51 in the rotation direction
of the rotary valve 41. In other words, the narrow passage 50 is
arranged closer to the second preceding end 51a of the wide passage
51. In the second embodiment, a first preceding end 50a of the
narrow passage 50 lies along the same straight line as the second
preceding end 51a of the wide passage 51. The first opening width
Ta of the narrow passage 50 and the second opening width Tb of the
wide passage 51 are set the same to be the same as in the first
embodiment.
[0057] The seal width W of a portion of a seal region S between a
high-pressure groove 47 and a suction communication passage 45 is
set to be slightly greater than the third opening width Tc. The
third opening width Tc, which is the distance from the first
succeeding end 50b of the narrow passage 50 to the second preceding
end 51a of the wide passage 51, is equal to the distance from the
first succeeding end 50b to the first preceding end 50a of the
narrow passage 50 (Ta=Tc). In this manner, the seal width W of the
seal region S in the second embodiment is set to be smaller than in
the first embodiment.
[0058] The second embodiment further has the advantage described
below.
[0059] (4) As shown in FIG. 6, the narrow passage 50 in the second
embodiment is arranged closer to the first preceding end 50a of the
wide passage 51 as compared with the first embodiment. The seal
width W in the second embodiment is set to be smaller than the seal
width W in the first embodiment. Thus, the distance between the
high-pressure groove 47 and the outlet 45b of the suction
communication passage 45 is further reduced. This further reduces
the time difference between when the high-pressure groove 47 of the
rotary valve 41 comes into communication with the narrow passage 50
of the cylinder block 11 and when the suction communication passage
45 of the rotary valve 41 comes into communication with the suction
port 43 of the cylinder block 11. As a result, the suction loss
amount of gas into each compression chamber 26 is reduced.
[0060] A piston type compressor according to a third embodiment of
the present invention will now be described with reference to FIG.
7. The piston type compressor of the third embodiment differs from
the piston type compressor of the first embodiment in that the
positional relationship of the narrow passage 50 and the wide
passage 51 is reversed in terms of the top dead center side and the
bottom dead center side, and the positional relationship between
the suction port 43 and the residual gas bypass groove 46 is
reversed in terms of the top dead center side and the bottom dead
center side. The components of the third embodiment that are the
same as those in the first embodiment will not be described.
[0061] As shown in FIG. 7, the high-pressure groove 47 and
low-pressure groove 48 of the residual gas bypass groove 46 in the
outer circumferential surface 41a of the rotary valve 41 are
located at a bottom dead center side of the suction port 43 with
respect to the direction of the center axis L2 of the rotary valve
41. More specifically, the high-pressure groove 47, which functions
as a high-pressure opening, is arranged toward the front of the
piston type compressor 10 from the suction port 43. A communication
groove 49 of the residual gas bypass groove 46 communicates the
ends of the high-pressure groove 47 and the low-pressure groove 48
at the bottom dead center side. More specifically, the
communication groove 49 communicates the front ends of the
high-pressure groove 47 and the low-pressure groove 48 in the
piston type compressor 10.
[0062] As indicated by the double-dashed lines in FIG. 7, an inlet
43a of each suction port 43 extending through the cylinder block 11
has two different opening widths Ta and Tb. More specifically, the
opening of the suction port 43 facing the outer circumferential
surface 41a of the rotary valve 41 has two different opening widths
Ta and Tb. The inlet 43a of the suction port 43 has a narrow
passage 50 arranged at the bottom dead center side and a wide
passage 51 at the top dead center side in the direction of the
central axis L2 of the rotary valve 41. The narrow passage 50,
which extends in the direction of the central axis L2, has the
first opening width Ta that is uniform in the circumferential
direction of the rotary valve 41. The wide passage 51, which
extends in the direction of the central axis L2, has the second
opening width Tb that is uniform in the circumferential
direction.
[0063] The first opening width Ta of the narrow passage 50 is set
to be smaller than the seal width W of the seal region S (W>Ta).
The second opening width Tb of the wide passage 51 is set to be
greater than the seal width W of the seal region S (W<Tb). The
narrow passage 50 is continuous with the wide passage 51 at the
inlet 43a of the suction port 43. The boundary between the narrow
passage 50 and the wide passage 51 is formed in a stepped manner.
When the rotary valve 41 rotates, the high-pressure groove 47
passes by the portion located toward the bottom dead center side,
or the upper side as viewed in FIG. 7, from the wide passage 51.
Thus, the high-pressure groove 47 comes into communication with the
narrow passage 50 but not with the wide passage 51 when the rotary
valve 41 rotates.
[0064] A third opening width Tc between the first succeeding end
50b of the narrow passage 50 and the second preceding end 51a of
the wide passage 51 in the circumferential direction is set to be
slightly smaller than the seal width W of the seal region S. Thus,
the outlet 45b of the suction communication passage 45 comes into
communication with the wide passage 51 immediately after the
high-pressure groove 47 passes by the narrow passage 50. The wide
passage 51 arranged at the lower side as viewed in FIG. 7, or the
bottom dead center side, comes into direct communication with the
compression chamber 26 immediately after discharging is performed
when the piston 31 is located at the top dead center.
[0065] The third embodiment further has the advantage described
below.
[0066] (5) The wide passage 51 is formed toward the top dead center
side from the narrow passage 50 in the direction of the central
axis L2 of the rotary valve 41. Thus, as compared with the first
embodiment, the first embodiment increases the area of the suction
port 43 of the cylinder block 11 that communicates with the suction
communication passage 45 of the rotary valve 41 when refrigerant
gas starts to be drawn into the compression chamber 26. As a
result, the amount of gas drawn into the compression chamber 26
increases. In the first embodiment, the narrow passage 50 is formed
toward the top dead center side from the wide passage 51, and the
first preceding end 50a is formed at the succeeding side of the
second preceding end 51a of the wide passage 51.
[0067] The above embodiments may be modified as described
below.
[0068] In the above embodiments, the narrow passage 50 may be
formed by a plurality of small passages that are separated from one
another as shown in FIG. 8. In this case, a first opening width Ta
of the narrow passage 50 is the distance between a first preceding
end 50a of the most preceding one of the small passages and a first
succeeding end 50b of the most succeeding one of the small
passages. The first preceding end 50a and a second preceding end
51a lie along the same line. Thus, Ta=Tc is satisfied. A third
opening width Tc is required only to be set smaller than the seal
width W between a high-pressure groove 47 and a suction
communication passage 45.
[0069] As shown in FIG. 9, in the first and second embodiments, the
narrow passage 50 may be formed by a pair of elongated holes. That
is, the shape of the narrow passage 50 is not limited to the shape
illustrated in the first to third embodiments and may be, for
example, an oval hole or a circular hole.
[0070] As shown in FIG. 9, the narrow passage 50 may be separated
from the wide passage 51. For example, the narrow passage 50 may be
formed by two small passages that are elongated holes extending in
the circumferential direction of the rotary valve 41. The first
preceding end 50a is defined by the most preceding end of the small
passages, and the first succeeding end 50b is defined by the most
succeeding end of the small passages. A third opening width Tc of
the narrow passage 50 is the distance between the second preceding
end 51a of the wide passage 51 and the first succeeding end 50b of
the narrow passage 50. The third opening width Tc is only required
to be smaller than the seal width W between the high-pressure
groove 47 and suction communication passage 45.
[0071] As shown in FIG. 10, the opening width of the wide passage
51, that is, the circumferential direction dimension, may decrease
as the narrow passage 50 becomes closer. In FIG. 10, the second
preceding end 51a and second succeeding end 51b of the wide passage
51 are formed by a portion of the wide passage 51 that has the
maximum opening width, that is, the end of the wide passage 51 at
the bottom dead center.
[0072] In the third embodiment, the narrow passage 50 may be formed
closer to the preceding side of the wide passage 51, or the second
preceding end 51a, in the rotation direction of the rotary valve
41. The first preceding end 50a of the narrow passage 50 may lie
along the same straight line as the second preceding end 51a of the
wide passage 51.
[0073] In the above embodiments, the suction port 43 is only
required to have the narrow passage 50 and the wide passage 51 at
the inlet 43a, and the shape of the outlet of the suction port 43
or the shape of the passage within the suction port 43 may be
modified freely.
[0074] In the above embodiments, the first succeeding end 50b of
the narrow passage 50 is only required to be located toward the
preceding side from the second succeeding end 51b of the wide
passage 51, and the narrow passage 50 may be formed closer to the
succeeding side of the wide passage 51.
[0075] The present invention may be applied to a double-headed
piston type compressor.
* * * * *