U.S. patent application number 11/136955 was filed with the patent office on 2005-12-01 for piston type compressor.
Invention is credited to Nakayama, Osamu, Oda, Kazutaka, Ota, Masaki, Sakamoto, Masaya, Sonobe, Masanori.
Application Number | 20050265855 11/136955 |
Document ID | / |
Family ID | 35425464 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050265855 |
Kind Code |
A1 |
Ota, Masaki ; et
al. |
December 1, 2005 |
Piston type compressor
Abstract
The piston type compressor includes a cylinder block, a rotary
shaft, a plurality of pistons, a rotary valve and radial load
transmission means. The radial load transmission means transmits a
radial load caused by compression reaction force acting on the
piston, which is on its compression stroke of the discharge stroke,
to the rotary valve, thereby pressing the rotary valve against an
inner peripheral surface of the valve chamber. The radial load
transmission means has a direction turning portion for turning the
radial load toward the inner peripheral surface of the valve
chamber between the suction port communicating with the cylinder
bore whose piston has completed the discharge stroke and the
suction port communicating with the cylinder bore whose piston is
on the compression stroke in a rotation direction of the rotary
valve from the suction port communicating with the cylinder bore
whose piston has completed the discharge stroke.
Inventors: |
Ota, Masaki; (Kariya-shi,
JP) ; Nakayama, Osamu; (Kariya-shi, JP) ;
Sakamoto, Masaya; (Kariya-shi, JP) ; Sonobe,
Masanori; (Kariya-shi, JP) ; Oda, Kazutaka;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
35425464 |
Appl. No.: |
11/136955 |
Filed: |
May 24, 2005 |
Current U.S.
Class: |
417/269 ;
417/510; 417/515 |
Current CPC
Class: |
F04B 27/1018
20130101 |
Class at
Publication: |
417/269 ;
417/515; 417/510 |
International
Class: |
F04B 001/12; F04B
027/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2004 |
JP |
P2004-154889 |
May 9, 2005 |
JP |
P2005-135822 |
Claims
What is claimed is:
1. A piston type compressor comprising: a cylinder block having a
valve chamber, a plurality of cylinder bores formed around the
valve chamber and a plurality of suction ports, wherein each
suction port connects the valve chamber and the respective cylinder
bore; a rotary shaft rotatably supported in the cylinder block, a
plurality of pistons, each of which is received in the respective
cylinder bore and is reciprocated therein in accordance with
rotation of the rotary shaft; a rotary valve received in the valve
chamber and connected to the rotary shaft so as to be rotated in
accordance with the rotation of the rotary shaft, thereby
selectively closing the suction port communicating with the
cylinder bore whose piston is on its discharge stroke; and radial
load transmission means for transmitting a radial load caused by
compression reaction force acting on the piston, which is on its
compression stroke or the discharge stroke, to the rotary valve,
thereby pressing the rotary valve against an inner peripheral
surface of the valve chamber, wherein the radial load transmission
means has a direction turning portion for turning the radial load
toward the inner peripheral surface of the valve chamber between
the suction port communicating with the cylinder bore whose piston
has completed the discharge stroke and the suction port
communicating with the cylinder bore whose piston is on the
compression stroke in a rotation direction of the rotary valve from
the suction port communicating with the cylinder bore whose piston
has completed the discharge stroke.
2. The piston type compressor according to claim 1, wherein the
direction turning portion is formed by integrally fixing the rotary
valve to the rotary shaft so that the rotary valve is eccentric
with respect to an axis of the rotary shaft.
3. The piston type compressor according to Claim 1, wherein an
eccentric pin is formed on an end of the rotary shaft on a side of
the rotary valve between the suction port communicating with the
cylinder bore whose piston has completed the discharge stroke and
the suction port communicating with the cylinder bore whose piston
is on the compression stroke in the rotation direction of the
rotary valve from the suction port communicating with the cylinder
bore whose piston has completed the discharge stroke, and the
direction turning portion is formed by loosely fitting the rotary
valve an the eccentric pin.
4. The piston type compressor according to claim 1, wherein a flat
pin, having a flat cross section and an elongated shape extending
in a radial direction perpendicular to a radial direction of the
inner peripheral surface of the valve chamber between the suction
port communicating with the cylinder bore whose piston has
completed the discharge stroke and the suction port communicating
with the cylinder bore whose piston is on the compression stroke in
the rotation direction of the rotary valve from the suction port
communicating with the cylinder bore whose piston has completed the
discharge stroke, is formed on an end of the rotary shaft on a side
of the rotary valve, and the direction turning portion is formed by
loosely fitting the rotary valve on the flat pin so as to be
capable of sliding only along the radial direction in which the
elongated shape of the flat pin extends.
5. The piston type compressor according to claim 1, further
comprising a bearing near the valve chamber for rotatably
supporting the rotary shaft, wherein the difference between an
inside diameter of the valve chamber and an outside diameter of the
rotary valve is smaller than the difference between an inside
diameter of the bearing and an outside diameter of the rotary
shaft.
6. The piston type compressor according to claim 1, further
comprising a coating near the valve chamber for rotatably
supporting the rotary shaft wherein the difference between an
inside diameter of the valve chamber and an outside diameter of the
rotary valve is smaller than the difference between an inside
diameter of the coating and an outside diameter of the rotary
shaft.
Description
BACKGROUND
[0001] The present invention relates to a piston type compressor
and more particularly to an improvement of sealing performance of a
rotary valve of the compressor.
[0002] There has been known a piston type compressor in which a
plurality of cylinder bores is arranged around a valve chamber and
the cylinder bores and the valve chamber are interconnected through
suction ports, respectively, so that a rotary valve received in the
valve chamber selectively opens and closes the suction ports. In
such a compressor, though the suction port communicating with the
cylinder bore whose piston is on its discharge stroke is closed by
the outer periphery of the rotary valve, there is a fear that
refrigerant gas in the cylinder bore may leak from tho suction port
into the valve chamber flowing along the outer peripheral surface
of the rotary valve because the pressure of the refrigerant gas in
the cylinder bore whose piston is on the discharge stroke is
increased high.
[0003] Unexamined Japanese Patent Publication No. 2003-222075 has
proposed a compressor in which compression reaction force acting on
a piston which is on its compression or discharge stroke is
transmitted to the rotary valve for urging the rotary valve toward
the suction port communicating with the cylinder bore whose piston
is on the discharge stroke.
[0004] By urging the rotary valve toward the suction port then
communicating with the cylinder bore whose piston is on the
discharge stroke by the compression reaction force, leakage of the
refrigerant gas from the suction port is prevented. In the case of
a compressor having a larger number of cylinder bores arranged
around a rotary shaft, the piston in the cylinder bore located
adjacent to the cylinder bore whose piston is on the discharge
stroke is on the discharge or compression stoke and, therefore, the
pressure of refrigerant gas in the adjacent cylinder bore is
relatively high. Therefore, even when a rotary valve 32 received in
a valve chamber 31 is urged toward a suction port 34 communicating
with the cylinder bore whose piston is on the discharge stroke by
urging force 33, as shown in FIG. 9, the refrigerant gas may leak
from the suction port communicating with the adjacent cylinder
bore, as indicated by arrow in FIG. 9.
SUMMARY
[0005] The present invention is directed to a piston type
compressor which effectively prevents leakage of refrigerant gas
even by using a rotary valve.
[0006] The present invention has the following features. The piston
type compression includes a cylinder block, a rotary shaft, a
plurality of pistons, a rotary valve and radial load transmission
means. The cylinder block has a valve chamber, a plurality of
cylinder bores formed around the valve chamber and a plurality of
suction ports. Each suction port connects the valve chamber and the
respective cylinder bore. The rotary shaft is rotatably supported
in the cylinder block. Each piston is received in the respective
cylinder bore and is reciprocated therein in accordance with
rotation of the rotary shaft. The rotary valve is received in the
valve chamber and connected to the rotary shaft so as to be rotated
in accordance with the rotation of the rotary shaft, thereby
selectively closing the suction port communicating with the
cylinder bore whose piston is on its discharge stroke. The radial
load transmission means transmits a radial load caused by
compression reaction force acting on the piston, which is on its
compression stroke or the discharge stroke, to the rotary valve,
thereby pressing the rotary valve against an inner peripheral
surface of the valve chamber. The radial load transmission means
has a direction turning portion for turning the radial load toward
the inner peripheral surface of the valve chamber between the
suction port communicating with the cylinder bore whose piston has
completed the discharge stroke and the suction port communicating
with the cylinder bore whose piston is on the compression stroke in
a rotation direction of the rotary valve from the suction port
communicating with the cylinder bore whose piston has completed the
discharge stroke.
[0007] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
The invention, together with objects and advantages thereof, may
best be understood by reference to the following description of the
presently preferred embodiments, together with the accompanying
drawing, in which:
[0009] FIG. 1 is a sectional view showing a piston type compressor
according to a first preferred embodiment of the present
invention;
[0010] FIG. 2 is a schematic view showing a rotary valve and its
vicinities according to the first preferred embodiment of the
present invention;
[0011] FIG. 3 is a view showing force acting on the rotary valve
according to the first preferred embodiment of the present
invention;
[0012] FIG. 4 is a schematic view showing a rotary valve and its
vicinities according to a second preferred embodiment of the
present invention;
[0013] FIG. 5 is a schematic view showing a rotary valve and its
vicinities according to a fourth preferred embodiment of the
present invention;
[0014] FIG. 6 is a schematic view showing the rotary valve and its
vicinities according to the fourth preferred embodiment of the
present invention;
[0015] FIG. 7 is a schematic view showing a rotary valve and its
vicinities according to a fifth preferred embodiment of the present
invention;
[0016] FIG. 8 is a schematic view showing the rotary valve and its
vicinities according to the fifth preferred embodiment of the
present invention; and
[0017] FIG. 9 is a schematic view showing a rotary valve and its
vicinities according to a prior art compressor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The following will describe preferred embodiments of the
present invention with reference to the drawings.
[0019] FIG. 1 shows a piston type compressor according to a first
preferred embodiment of the present invention. The left side of the
drawing is a front side and the right side thereof is a rear side.
The compressor has a cylinder block 1 which is connected at the
front end thereof to a front housing 2 and at the rear end thereof
to a rear housing 4 through a valve plate assembly 3. The cylinder
block 1 and the front housing 2 cooperate to define a crank chamber
5. A rotary shaft 6 extending through the crank chamber 5 is
rotatably supported by bearings 7, 28 which are provided in the
cylinder block 1 and the front housing 2, respectively. The front
end of the rotary shaft 6 protrudes from the front housing 2 and is
connected to a drive source (not shown) such as a vehicle engine or
a vehicle motor. A rotary support 8 is fixed on the rotary shaft 6
for rotation therewith and a swash plate 9 is engaged with the
rotary support 8 in the front housing 2. The swash plate 9 has
formed at the center thereof a through hole which the rotary shaft
6 extends and is rotated integrally with the rotary shaft 6 through
a linkage 10. In addition, the swash plate 9 is supported in such a
way that it is capable of sliding in the axial direction of the
rotary shaft 6 and of inclining relative to the axial direction.
Further, the rotary support 8 is supported for rotation by a thrust
bearing 11 arranged in the recess formed in the front end of the
front housing 2.
[0020] A plurality of cylinder bores 12 is formed in the cylinder
block 1 around the rotary shaft 6. Each cylinder bore 12 has
slidably received therein a piston 13. Each piston 13 engages with
the outer periphery of the swash plate 9 through a pair of shoes
14. As the swash plate 9 rotates with the rotary shaft 6, the
piston 13 reciprocates in the axial direction of the rotary shaft 6
in its associated cylinder bore 12 through the shoes 14.
[0021] The rear housing 4 has formed in the middle portion thereof
a suction chamber 15 located in facing relation to the valve plate
assembly 3. The rear housing 4 has also formed in the outer
peripheral portion thereof a discharge chamber 16 surrounding the
suction chamber 16.
[0022] The cylinder block 1 and the rear housing 4 have formed
therein a supply passage 25 which connects the crank chamber 5 and
the discharge chamber 16. On the supply passage 25 is located a
displacement control valve 17 formed by an electromagnetic valve.
In addition, the crank chamber 5 and the suction chamber 15 are in
communication via a bleed passage 26.
[0023] The cylinder block 1 has formed therethrough at the middle
portion thereof a valve chamber 18 extending in the axial direction
of the rotary shaft 6. In the valve chamber 18 is received a rotary
valve 19 which is mounted to the rear end of the rotary shaft 6 for
rotation. The rotary valve 19 is loosely fitted on an eccentric pin
20 which is integrally Formed with the rotary shaft 6. Thus, the
rotary valve 19 is rotated in the valve chamber 18 in accordance
with the rotation of the rotary shaft 6.
[0024] A compression chamber 27 defined in each cylinder bore 12 by
the valve plate assembly 3 and the respective piston 13 is in
communication with the valve chamber 18 in the cylinder block 1 via
a suction port 21. The suction ports 21 of the respective
compression chambers 27 are selectively opened and closed by the
outer peripheral surface of the rotary valve 19.
[0025] It is noted that the difference between the inside diameter
of the valve chamber 18 and the outside diameter of the rotary
valve 19 (hereinafter referred to "first clearance") is smaller
than the difference between the inside diameter of the bearing 7
and the outside diameter of the rotary shaft 6 (hereinafter
referred to "second clearance").
[0026] Tho magnitude relation between the first clearance and the
second clearance provides radial load transmission means for
transmitting a radial load caused by compression reaction force
acting on the piston 13, which is then on are discharge stroke, to
the rotary valve 19 through the shoes 14, the swash plate 9 and the
rotary shaft 6.
[0027] The following will describe the operation of the piston type
compressor according to the first embodiment. During suction stoke
of the piston 13 moving in the cylinder bore 12 from the top dead
center to the bottom dead center in accordance with rotation of the
rotary shaft 6, the rotary valve 19 which is synchronously rotated
with the rotary shaft 6 makes the suction port 21 for the cylinder
bore 12 to communicate with the suction chamber 15, so that
refrigerant gas in the suction chamber 15 flows into the cylinder
bore 12 through the suction port 21.
[0028] Subsequently, during compression and discharge stroke of the
piston 13 then moving in the cylinder bore 12 from the bottom dead
center to the top dead center, the rotary valve 19 closes the
suction port 21, so that the refrigerant gas in the cylinder bore
12 is compressed and then discharged into the discharge chamber 16
through a discharge port 24 and a discharge valve 29 of the valve
plate assembly 3. In the present embodiment, the compression stroke
is a state in which the discharge of the refrigerant gas from the
compression chamber 27 to the discharge chamber 16 is not performed
when the piston 13 moves in the cylinder bore 12 from the bottom
dead center to the top dead center, and the discharge stroke is a
state in which the discharge of the refrigerant gas from the
compression chamber 27 to the discharge chamber 16 is performed
when the piston 13 moves in the cylinder bore 12 from the bottom
dead center to the top dead center. In addition, the piston 13
completes the discharge stroke when the piston 13 reaches the top
dead center.
[0029] By setting the opening of the displacement control valve 17,
the balance between the amount of refrigerant gas introduced from
the discharge chamber 16 into the crank chamber 5 through the
supply passage 25 and the amount of refrigerant gas flowing from
the crank chamber 5 into the suction chamber 15 through the bleed
passage 26 is controlled, and pressure Pc in the crank chamber 5 is
determined, accordingly. If the pressure Pc in the crank chamber 5
is varied by changing the opening of the displacement control valve
17, the pressure differential between the crank chamber 5 and the
cylinder bore 12 across the piston 13 is varied and the inclination
of the swash plate 9 is varied, accordingly. Consequently, the
stroke length of the piston 13 or the displacement of the
compressor is adjusted.
[0030] As shown in FIG. 1, the compression reaction force which the
piston 13 on completion of the discharge stroke receives acts on
the radially outer peripheral portion of the swash plate 9 through
the shoes 14 as a force F1, which urges the swash plate 9 upward as
seen in FIG 1. As the swash plate 9 is urged upward, the rotary
shaft 6 is also urged upward as seen in FIG. 1 through the through
hole formed at the center of the swash plate 9. This urging force
serves as a moment load around the position or engagement between
the rotary shaft 6 and the bearing 28. At this time, a radial load
acts on the rear end of the rotary shaft 6 toward the suction port
21 communicating with the cylinder bore 12 whose piston 13 has just
completed the discharge stroke.
[0031] FIG. 2 is a schematic view showing the rotary valve 19 and
its vicinities as seen from the rear end of FIG. 1. The rotary
valve 19 is rotated in a counterclockwise direction as indicated by
an arrow A of FIG. 2. For example, in the case where five
suction-ports 21a, 21b, 21c, 21d, 21e are formed in the inner
peripheral surface of the valve chamber 18 for fluid communication
with the respective cylinder bores 12 as shown in FIG. 2, a radial
load Fr acts on the rear end of the rotary shaft 6 toward the
suction port 21a communicating with the cylinder bore 12 in which
its piston 13 has just completed the discharge stroke and is
located at the top dead center. Now, as a direction turning portion
for turning direction of load, the eccentric pin 20 is formed on
the rotary shaft 6 and the rotary valve 19 is loosely filled on the
eccentric pin 20. The eccentric pin 20 is located between the
suction port 21 communicating with the cylinder bore 12 whose
piston 13 has just completed the discharge stroke and the suction
port 21 communicating with the cylinder bore 12 whose piston 13 is
on the compression stroke in the rotation direction of the rotary
valve 19 from the suction port 21 communicating with the cylinder
bore 12 whose piston 13 has just completed the discharge stroke.
Specifically, when the position of the suction port 21a
communicating with the cylinder bore 12 whose piston 13 has just
completed the discharge stroke is defined as an angle of 0 degree,
the eccentric pin 20 is located in a range of rotation angle
between 0 degree and 90 degrees in the rotation direction of the
rotary valve 19 from the auction port 21a. Therefore, when the
radial load Fr acts on the rear end of the rotary shaft 6, firstly
the rotary valve 19 is contracted with the inner peripheral surface
of the valve chamber 18 in a range of rotation angle between 0
degree and 90 degrees in the rotation direction of the rotary valve
19 from the suction port 21a communicating with the cylinder bore
12 whose piston 13 has just completed the discharge stroke, by
virtue of the magnitude relation between the second clearance
(between the rotary shaft 6 and the bearing 7) and the first
clearance (between the rotary valve 19 and the valve chamber 18),
thereby receiving a drag Fb. Subsequently, the rotary shaft 6 is
rotated with the eccentric pin 20 as an axis of rotation and is
contacted with the inner peripheral surface of the bearing 7 in a
range of rotation angle between 270 degrees and 360 degrees in the
rotation direction of the rotary valve 19 from the suction port
21a, thereby receiving a drag Fa. Thus, the sum of the drags Fa and
Fb balances with the radial load Fr.
[0032] As the reaction of the drag Fb of the rotary valve 19 which
acts on the eccentric pin 20, the rotary valve 10 receives a load
Fc from the eccentric pin 20, thereby being pressed against the
inner peripheral surface of the valve chamber 18 in a range of
rotation angle between 0 degree and 90 degrees in the rotation
direction of the rotary valve 19 from the suction port 21a. At this
time, in the rotation direction of the rotary shaft 6 and the
rotary valve 19 from the suction port 21a communicating with the
cylinder bore 12 whose piston 13 has just completed the discharge
stroke, the cylinder bore 12 for the suction port 21e has its
piston 13 moving in the discharge or compression stroke, the
cylinder bore 12 for the suction port 21d has its piston 13 moving
in the compression stroke close to the suction stroke, and the
cylinder bores 12 for the suction ports 21c, 21b have their pistons
13 moving in the suction stroke. Therefore, although the
refrigerant gas in the cylinder bores 12 communicating with the
suction ports 21a, 21c is relatively high in pressure, leakage of
the refrigerant gas from the suction ports 21a,21e into the valve
chamber 18 is effectively prevented because the rotary valve 19 is
pressed in a range of rotation angle between 0 degree and 90
degrees by the load Fc.
[0033] When the rotary shaft 6 and the rotary valve 19 are rotated
in the rotation direction from the above state, firstly the
cylinder bore 12 for the suction port 21a has its piston 13 moving
in the suction stroke, the cylinder bore 12 for the suction port
21e has its piston 13 having just completed the discharge stroke,
the cylinder bores 12 for the suction ports 21d has its piston 13
moving in the discharge or compression stroke, the cylinder bore 12
for the suction port 21c has its piston 13 moving in the
compression stroke, and the cylinder bore 12 for the suction port
21b has its piston 13 moving in the suction stroke. In this case,
the radial load Fr acts on the rear end of the rotary shaft 6
toward the suction port 21e communicating with the cylinder bore 12
in which its piston 13 has just completed the discharge stroke and
is located at the top dead center. When the position of the suction
port 21e communicating with the cylinder bore 12 whose piston 13
has just completed the discharge stroke is defined as an angle of 0
degree, the rotary valve 19 is pressed against the inner peripheral
surface of the valve chamber 18 in a range of rotation angle
between 0 degree and 90 degrees in the rotation direction of the
rotary valve 19 from the suction port 21c. Meanwhile, when the
position of the suction port 21e is defined as an angle of 0
degree, the rotary shaft 6 is pressed against the inner peripheral
surface of the bearing 7 in a range of rotation angle between 270
degrees and 360 degrees in the rotation direction of the rotary
valve 19 from the suction port 21e, thereby receiving the drag
Fa.
[0034] That is, during the operation of the compressor, the radial
load Fr which is caused by the compression reaction force acting on
the piston 13 and acts on the rear end of the rotary shaft 6 toward
the suction port 21a is continuously supported at both of the
position at which the rotary valve 19 is pressed against the inner
peripheral surface of the valve chamber 18 by the load Fc and the
position at which the rotary shaft 6 is pressed against the inner
peripheral surface of the bearing 7 by the drag Fa. In this state,
the rotary valve 19 and the rotary shaft 6 are rotated respectively
in the valve chamber 18 and the bearing 7 while maintaining a
predetermined positional relationship. Therefore, during the
operation of the compressor, the rotary valve 19 prevents the
leakage of the refrigerant gas from the suction port 21
communicating with the cylinder bore 12 whose piston 13 is on its
discharge or compression stroke under relatively high pressure into
the valve chamber 18.
[0035] Now, the relationship among the mounting angle of the
eccentric pin 20 relative to the suction port 21a, the second
clearance (between the rotary shaft 6 and the bearing 7) and the
load which the rotary valve 19 receives from the eccentric pin 20
will be described with reference to FIG. 3.
[0036] Referring to FIG. 3, "00" is an angle made between the
direction of the resultant force F0 of the load which the rotary
valve 19 receives from the refrigerant gas in the cylinder bores 12
communicating with the suction ports 21a, 21b, 21c, 21d, 21e and an
imaginary line, as indicated by dashed line, extending axially
through the suction port 21a communicating with the cylinder bore
12 whose piston 13 has just completed the discharge stroke, and
".alpha." is an angle made between the direction of the load Fc
which the rotary valve 19 receives from the eccentric pin 20 and
the above imaginary line.
[0037] When the mounting angle ".alpha." of the eccentric pin 20
(the angle of the load Fc) relative to the suction port 21a
communicating with the cylinder bore 12 whose piston 13 has just
completed the discharge stroke is variously changed with the first
clearance (between the rotary valve 19 and the valve chamber 18)
maintained at a predetermined value, the load Fc is decreased with
an increase of the angle ".alpha.". When the second clearance
(between the rotary shaft 6 and the bearing 7) is decreased below a
predetermined value, the load Fc is decreased rapidly, and the
pressing force of the rotary valve 19 against the inner peripheral
surface of the valve chamber 18 is reduced, accordingly.
[0038] This is because when the length of the second clearance
(between the rotary shaft 6 and the bearing 7) approaches that of
the first clearance (between the rotary valve 19 and the valve
chamber 18) and the rotary shaft 6 then contacts the inner
peripheral surface of the bearing 7 after the rotary valve 19 has
contacted the inner peripheral surface of the valve chamber 18,
contact position between the rotary shaft 6 and the bearing 7
approaches the position of rotation angle of 0 degree relative to
the suction port 21a. Thus, the load Fc which the rotary valve 19
receives from the eccentric pin 20 is reduced.
[0039] Therefore, it is desirable that the second clearance
(between the rotary shaft 6 and the bearing 7) should be larger
than the first clearance (between the rotary valve 19 and the valve
chamber 18), or more precisely, larger than the sum of the first
clearance and a third clearance between the eccentric pin 20 and
the bore of the rotary valve 19 which is loosely fitted on the
eccentric pin 20.
[0040] In the present embodiment, when the position of the suction
port 21 communicating with the cylinder bore 12 whose piston 13 has
just completed the discharge stroke is defined as an angle of 0
degree, the rotary valve 19 is pressed against the inner peripheral
surface of the valve chamber 18 in a range of rotation angle
between 0 degree and 90 degrees in the rotation direction of the
rotary valve 19 from the suction port 21. This is because when the
position of the suction port 21 communicating with the cylinder
bore 12 whose piston 13 has just completed the discharge stroke is
defined as an angle of 0 degree, an angle of "80" made between the
direction of the resultant force F0 of the load which the rotary
valve 19 receives from the refrigerant gas in the cylinder bores 12
and the imaginary line is kept in a range of rotation angle between
180 degree and 270 degrees in the rotation direction of the rotary
valve 19 from the suction port 21.
[0041] In addition, in the present embodiment, the rotary valve 19
is loosely fitted on the eccentric pin 20 formed on the rear end of
the rotary shaft 6. In the structure, the first clearance and the
second clearance are easily set in comparison with a case that the
rotary valve 19 and the rotary shaft 6 are fixed to each other.
[0042] The first clearance between the rotary valve 19 and the
valve chamber 18 is generally set to be extremely small in
comparison with the second clearance between the rotary shaft 6 and
the bearing 7 in order to prevent the leakage of the refrigerant
gas from each suction port 21. Therefore, in the case where the
rotary valve 19 is fixed to the rotary shaft 6 so as to be
eccentric with respect to an axis of the rotary valve 19, unless
the second clearance between the rotary shaft 6 and the bearing 7
is set with high accuracy, the radial loud Fr is not supported at
both of the position at which the rotary valve 19 is pressed
against the inner peripheral surface of the valve chamber 18 by the
load Fc and the position at which the rotary shaft 6 is pressed
against the inner peripheral surface of the bearing 7 by the drag
Fa. At this time, the rotary valve 19 is not contacted with the
inner peripheral surface of the valve chamber 18 in a suitable
position.
[0043] That is, in the case where the rotary valve 19 is fixed to
the rotary shaft 6 so as to be eccentric with the axis of the
rotary shift 6, even if the rotary valve 19 is contacted with the
inner peripheral surface of the valve chamber 18, if the second
clearance between the rotary shaft 6 and the bearing 7 is larger
than the first clearance between the rotary valve 19 and the valve
chamber 18 in an area other than the position at which the rotary
valve 19 contacts the inner peripheral surface of the valve chamber
18, the rotary shaft 19 is not contacted with the bearing 7. At
this time, the rotary valve 19 is not pressed against the inner
peripheral surface of the valve chamber 18 in the range of rotation
angle between 0 degree and 90 degrees. Therefore, in the case where
the rotary valve 19 is fixed to the rotary shaft 6 so as to be
eccentric with the axis of the rotary shaft 6, the second clearance
between the rotary shaft 6 and the bearing 7 needs to be set to be
smaller than the first clearance between the rotary valve 19 and
the valve chamber 18 in an area other than the position at which
the rotary valve 19 contacts the inner peripheral surface of the
valve chamber 18. For the above reason, it is extremely difficult
to set the first clearance and the second clearance. In the present
embodiment, however, since the rotary shaft 6 is capable of
rotating with the eccentric pin 20 as an axis in the bearing 7
relative to the rotary valve 19 by loosely fitting the rotary valve
19 on the eccentric pin 20 of the rotary shaft 6, even if the first
clearance between the rotary valve 19 and the valve chamber 18 in
an area other than the position at which the rotary valve 19
contacts the inner peripheral surface of the valve chamber 18 is
smaller than the second clearance between the rotary shaft 6 and
the bearing 7, the radial load Fr is capable of being supported at
the above two positions by contacting the rotary shaft 6 with the
inner peripheral surface of the bearing 7 in a range of rotation
angle between 270 degrees and 360 degrees with the eccentric pin
20, which is loosely fitted on the rotary valve 19, as an axis.
[0044] FIG. 4 shows a rotary valve and its vicinities of a piston
type compressor according to a second preferred embodiment of the
present invention. In the first embodiment, the rotary valve 19 is
loosely fitted on the eccentric pin 20 formed on the rear end of
the rotary shaft 19. In the second embodiment, however, as the
direction turning portion, a flat pin 22 is formed on the rear end
of the rotary shaft 6, having a flat cross section and an elongated
shape extending in a predetermined radial direction and a rotary
valve 23 is loosely fitted on the flat pin 22 so as to be capable
of sliding along the above predetermined radial direction. The
structure of the second embodiment other than the flat pin 22 is
substantially the same as that of the first embodiment.
[0045] When the position of the suction port 21a communicating with
the cylinder bore 12 whose piston 13 has lust completed the
discharge stroke is defined as an angle of 0 degree, the flat pin
22 is radially elongated in a range of rotation angle between 270
degrees and 360 degrees in the rotation direction of the rotary
valve 23 from the suction port 21a. Therefore, the rotary valve 23
is capable of sliding radially in a range of rotation angle between
270 degrees and 360 degrees, but is incapable of sliding radially
in a range of rotation angle between 0 degree and 90 degrees. When
the eccentric pin 22 and the rotary valve 23 are used, if the
radial load Fr acts on the rear end of the rotary shaft 6 toward
the suction port 21a communicating with the cylinder bore 12 whose
piston 13 has just completed the discharge stroke, the rear end of
the rotary shaft 6 is contacted with the inner peripheral surface
of the bearing 7 in a range of rotation angle between 270 degrees
and 360 degrees in the rotation direction of the rotary valve 19
from the suction port 21a, thereby receiving the drag Fa. In
addition, the rear end of the rotary shaft 6 receives the drag Fb
from the rotary valve 23 through the flat pin 22. Thus, the sum of
the drags Fa and Fb balances with the radial load Fr.
[0046] Further, as the reaction of the drag Fb of the rotary valve
23 which acts on the flat pin 22, the rotary valve 23 receives load
Fc from the flat pin 22, thereby being pressed against the inner
peripheral surface of the valve chamber 18 in a range of rotation
angle between 0 degree and 90 degrees in the rotation direction of
the rotary valve 23 from the suction port 21a.
[0047] Consequently, as is the case with the first embodiment,
leakage of the refrigerant gas from the suction port 21a
communicating with the cylinder bores 12 whose piston 13 has just
completed the discharge stroke and the suction port 21e
communicating with the cylinder bores 12 whose piston 13 is on its
discharge or compression stroke under relatively high pressure into
the valve chamber 18 is effectively prevented.
[0048] In the first and second embodiments, as the direction
turning portion, the rotary valve 19 or 23 is loosely fitted on the
eccentric pin 20 or the flat pin 22. In a third preferred
embodiment, however, referring to FIG. 2, as the direction turning
portion, the rotary shaft 6 and the rotary valve 19 are fixed to
each other in such a way that the rotary valve 19 is eccentric with
respect to the axis of the rotary shaft 6.
[0049] Thus, as is the case with the first and second embodiments,
during the operation of the compressor, the rotary valve 19
prevents the leakage of the refrigerant gas from the suction port
21 communicating with the cylinder bore 12 whose piston 13 is on
its discharge or compression stroke under relatively high pressure
into the valve chamber 18.
[0050] FIG. 5 shows a rotary valve and its vicinities of a piston
type compressor according to a fourth preferred embodiment of the
present invention. In the first preferred embodiment, the rear end
of the rotary shaft 6 is rotatably supported by the bearing 7 in
the cylinder block 1, and the rotary valve 19 is loosely fitted on
the eccentric pin 20 formed on the rear end of the rotary Shaft 6.
In the fourth preferred embodiment, however, the compressor is not
provided with the bearing 7 which rotatably supports the rear end
of the rotary shaft 6, but is provided with a rotary valve 41 which
is fixed to the rear end of the rotary shaft 6 and is received in
the valve chamber 18 of the cylinder block 1. The other structure
of the fourth embodiment is substantially the same as that of the
first embodiment.
[0051] The rotary valve 41 includes a cylindrical valve portion 41a
which selectively opens and closes each suction port 21 which
connects the compression chamber 27, which is defined in each
cylinder bore 12 by the valve plate assembly 3 and the respective
piston 13, to the valve chamber 18 in the cylinder block 1. The
rotary valve 41 also includes a columnar support portion 41b which
is integrally fixed to the end in an axial direction of the valve
portion 41a. The support portion 41b is fixed to the rear end of
the rotary shaft 6.
[0052] The support portion 11b has the same outside diameter as the
rotary shaft 6, and is coaxially arranged on the rotary shaft 6.
The valve portion 41a has larger outside diameter than the support
portion 41b, and is arranged so as to be eccentric with respect to
an axis of the support portion 41b. The support portion 41b and the
valve portion 41a have substantially the same positional relation
as the rotary shaft 6 and the rotary valve 19 of FIG. 2 according
to the first preferred embodiment. That is, in the present
embodiment, as the direction turning portion, the valve portion 41a
is fixed to the support portion 41b of the rotary valve 41 so as to
be eccentric with the axis of the support portion 41b.
[0053] As shown in FIG. 6, the valve chamber 18 of the cylinder
block 1, which receives the rotary valve 41, includes a portion
18a, in which the valve portion 41a of the rotary valve 41 is
received, and a portion 18b, in which the support portion 41b is
received. The portion 18a and the portion 18b have a step
therebetween. The inside diameter of the portion 18b of the valve
chamber 18 is the same as that of the bearing 7 according to the
first embodiment.
[0054] In the above structure, even if the compressor is not
provided with the bearing 7 which rotatably supports the rear end
of the rotary shaft 6, as is the case with the first through third
embodiments, during the operation of the compressor, the rotary
valve 41 prevents the leakage of the refrigerant gas from the
suction port 21 communicating with the cylinder bore 12 whose
piston 13 is on its discharge or compression stroke under
relatively high pressure into the valve chamber 18.
[0055] It is noted that as shown in FIG. 6, coating 42 is desirably
provided in the cylinder block 1 so as to be applied to the inner
peripheral surface of the portion 18b of the valve chamber 18 which
the outer peripheral surface of the support portion 41b of the
rotary valve 41 contacts for reducing friction.
[0056] FIG. 7 shows a rotary valve and its vicinities of a piston
type compressor according to a fifth preferred embodiment of the
present invention. In the fifth preferred embodiment, as is the
case with the fourth preferred embodiment, the compressor is not
provided with the bearing 7 which rotatably supports the rear end
of the rotary shaft 6, but is provided with a rotary valve 51 which
is fixed to the rear end of the rotary shaft 6 and is received in
the valve chamber 18 of the cylinder block 1. The other structure
of the fifth embodiment is substantially the same as that of the
first embodiment.
[0057] The rotary valve 51 includes a cylindrical valve portion 51a
which selectively opens and closes each suction port 21 which
connects the compression chamber 27, which is defined in each
cylinder bore 12 by the valve plate assembly 3 and the respective
piston 13, to the valve chamber 18 in the cylinder block 1. The
rotary valve 51 also includes a columnar support portion 51b which
is integrally fixed to the end in an axial direction of the valve
portion 51a. The support portion 51b is fixed to the rear end of
the rotary shaft 6.
[0058] The support portion 51b has larger outside diameter than the
rotary shaft 6, and is arranged on the rotary shaft 6 so as to be
eccentric with an axis of the rotary shaft 6. The valve portion 51a
has slightly larger outside diameter than the support portion 51b,
and is arranged on the support portion 51b so as to be eccentric
with respect to an axis of the support portion 51b. The support
portion 51b and the valve portion 51a have substantially the same
eccentric relation as the rotary shaft 6 and the rotary valve 19 of
FIG. 2 according to the first preferred embodiment, and the support
portion 51b and the valve portion 51a are fixed to each other. That
is, in the present embodiment, as the direction turning portion,
the support portion 51b of the rotary valve 51 is fixed to the
rotary shaft 6 so as to be eccentric with the axis of the rotary
shaft 6, and the valve portion 51a is fixed to the support portion
51b so as to be eccentric with the axis of the support portion
51b.
[0059] As shown in FIG. 8, a portion of the valve chamber 18 in
which the valve portion 51a of the rotary valve 51 is received has
the same inside diameter as that of the valve chamber 18 in which
the support portion 51b is received.
[0060] It is noted that a clearance is formed between the outer
peripheral surface on the rear end of the rotary shaft 6 and the
inner surface of a through hole 1a of the cylinder block 1 through
which the rear end of the rotary shaft 6 extends such that the
outer peripheral surface on the rear end of the rotary shaft 6
contacts the inner surface of the through hole 1a of the cylinder
block 1 when the rotary shaft 6 is rotated.
[0061] In the above structure, even if the compressor is not
provided with the bearing 7 which rotatably supports the rear end
of the rotary shaft 6, as is the case with the first through fourth
embodiments, during the operation of the compressor, the rotary
valve 51 prevents the leakage of the refrigerant gas from the
suction port 21 communicating with the cylinder bore 12 whose
piston 13 is on its discharge or compression stroke under
relatively high pressure into the valve chamber 18.
[0062] According to the embodiments of the present invention,
leakage of the refrigerant gas from the suction port is effectively
prevented. Especially in the compressor which uses carbon dioxide
as the refrigerant gas, the pressure of carbon dioxide in the
cylinder bore whose piston is on its discharge or compression
stroke is increased to an extremely high level and, therefore, the
amount of carbon dioxide leaking from the suction port
communicating with cylinder bore whose piston is on the discharge
or compression stroke, increases unless an appropriate measure is
taken effectively. Therefore, the present invention is
advantageously applicable to the compressor using carbon dioxide as
the refrigerant gas.
[0063] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive and the invention is
not to be limited to the details given herein but may be
modified.
* * * * *