U.S. patent application number 11/003750 was filed with the patent office on 2005-07-21 for piston type compressor.
Invention is credited to Inoue, Yoshinori, Kawachi, Shigeki, Kawamura, Hisato, Masuda, Masanori, Takahata, Junichi.
Application Number | 20050158182 11/003750 |
Document ID | / |
Family ID | 34544887 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050158182 |
Kind Code |
A1 |
Inoue, Yoshinori ; et
al. |
July 21, 2005 |
Piston type compressor
Abstract
In a piston type compressor, a housing includes a cylinder block
that forms plural cylinder bores and an accommodating hole at a
center thereof. The valve port assembly connected to the cylinder
block includes suction and discharge ports, suction and discharge
valves made of flapper valves. An end portion of the drive shaft
rotatably supported by the housing is slidably accommodated in the
accommodating hole. The piston in each cylinder bore and the valve
port assembly form a compression chamber. The cylinder block forms
therein communication holes that connect each compression chamber
to the end portion that forms therein a residual gas bypass
passage. The residual gas bypass passage connects one communication
hole, which communicates with the high-pressure side compression
chamber that has finished discharge process of gas, to another
communication hole, which communicates with the compression chamber
that is lower in pressure than the high-pressure side compression
chamber.
Inventors: |
Inoue, Yoshinori;
(Kariya-shi, JP) ; Kawamura, Hisato; (Kariya-shi,
JP) ; Kawachi, Shigeki; (Kariya-shi, JP) ;
Masuda, Masanori; (Kariya-shi, JP) ; Takahata,
Junichi; (Kariya-shi, JP) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
ONE LIBERTY PLACE, 46TH FLOOR
1650 MARKET STREET
PHILADELPHIA
PA
19103
US
|
Family ID: |
34544887 |
Appl. No.: |
11/003750 |
Filed: |
December 3, 2004 |
Current U.S.
Class: |
417/269 ;
417/222.2 |
Current CPC
Class: |
F04B 27/0834 20130101;
F04B 39/122 20130101; F04B 39/123 20130101 |
Class at
Publication: |
417/269 ;
417/222.2 |
International
Class: |
F04B 001/26; F04B
001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2003 |
JP |
2003-406053 |
Claims
What is claimed is:
1. A piston type compressor comprising: a housing includes a
cylinder block that forms a plurality of cylinder bores and an
accommodating hole at a center thereof; a valve port assembly
connected to the cylinder block, the valve port assembly including
suction ports, suction valves made of flapper valves, discharge
ports, and discharge valves made of flapper valves; a drive shaft
rotatably supported by the housing and surrounded by the cylinder
bores, an end portion of the drive shaft being slidably
accommodated in the accommodating hole; and a piston accommodated
in each of the cylinder bores, the piston and the valve port
assembly forming a compression chamber, wherein the cylinder block
forms therein communication holes that connect each of the
compression chambers to the end portion of the drive shaft, the end
portion of the drive shaft forming therein a residual gas bypass
passage, wherein the residual gas bypass passage connects one
communication hole, which communicates with the compression chamber
on a high-pressure side that has finished discharge process of gas,
to another communication hole, which communicates with the
compression chamber that is lower in pressure than the
high-pressure side compression chamber, and wherein as the piston
reciprocates, gas being introduced into the compression chamber
through the suction port by pushing away the suction valve,
compressed in the compression chamber and discharged from the
compression chamber through the discharge port by pushing away the
discharge valve.
2. The piston type compressor according to claim 1, wherein the
residual gas bypass passage at least partially includes a groove
that is formed in an outer peripheral surface of the end portion of
the drive shaft sliding on an inner peripheral surface of the
accommodating hole.
3. The piston type compressor according to claim 2, wherein the
residual gas bypass passage is wholly formed by the groove.
4. The piston type compressor according to claim 1, wherein the
residual gas bypass passage at least partially includes a groove
that extends in a direction along an axis of the drive shaft.
5. The piston type compressor according to claim 1, wherein the
residual gas bypass passage at least partially includes a hole that
radially extends through the drive shaft.
6. The piston type compressor according to claim 5, wherein the
residual gas bypass passage is wholly formed by the hole.
7. The piston type compressor according to claim 1, wherein the
residual gas bypass passage includes: a groove formed in an outer
peripheral surface of the end portion of the drive shaft sliding on
an inner peripheral surface of the accommodating hole; and a hole
radially extending through the drive shaft.
8. The piston type compressor according to claim 1, wherein the
compressor includes the even-numbered cylinder bores.
9. The piston type compressor according to claim 8, wherein the
compressor includes six cylinder bores.
10. The piston type compressor according to claim 1, wherein the
compressor is a variable displacement type.
11. The piston type compressor according to claim 1, wherein the
piston is a single-headed type.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a piston type compressor
that is, for example, used for a vehicle air conditioner.
[0002] Such a piston type compressor is disclosed on pages 3 and 4,
and FIG. 1 of Unexamined Japanese Patent Publication No. 10-47241.
A cylinder block forms therein a plurality of cylinder bores that
surround a drive shaft. Each cylinder bore accommodates therein a
piston and defines therein a compression chamber by the piston and
a valve port assembly. The valve port assembly is provided with
suction ports, suction valves made of flapper valves, discharge
ports, and discharge valves made of flapper valves. As the piston
reciprocates, refrigerant gas is introduced into the compression
chamber through the suction port by pushing away the suction valve,
and is compressed in the compression chamber, and is discharged
from the compression chamber through the discharge port by pushing
away the discharge valve.
[0003] In the piston type compressor, the piston at a top dead
center is spaced at a clearance from the valve port assembly such
that the piston at the top dead center does not collide with the
valve port assembly. Additionally, the discharge ports, which are
formed in the valve port assembly, are constantly in communication
with the corresponding compression chambers. That is, even if the
piston is positioned at the top dead center, the compression
chamber still has its slight volume.
[0004] Accordingly, even in a state where the piston is positioned
at the top dead center, high-pressure refrigerant gas still remains
in the compression chamber, which is called residual gas. Then, the
residual gas in the compression chamber expands in a suction cycle
where the piston moves from the top dead center to the bottom dead
center, and new refrigerant gas is prevented from introduced into
the compression chamber through the suction port and the suction
valve during the expansion of the residual gas. As a result, the
amount of refrigerant gas introduced into the compression chamber
is smaller by the increase of the residual gas due to the
expansion, with the result of deteriorated efficiency of the
refrigerant gas introduced into the compression chamber. Therefore,
there has been a need for a piston type compressor that has a high
efficiency of gas introduced into the compression chamber.
SUMMARY OF THE INVENTION
[0005] In accordance with the present invention, a piston type
compressor has a housing, a drive shaft, a valve port assembly and
a piston. The housing includes a cylinder block that forms a
plurality of cylinder bores and an accommodating hole at a center
of the cylinder block. The valve port assembly is connected to the
cylinder block. The valve port assembly includes suction ports,
suction valves made of flapper valves, discharge ports, and
discharge valves made of flapper valves. The drive shaft is
rotatably supported by the housing. An end portion of the drive
shaft is slidably accommodated in the accommodating hole. The
piston is accommodated in each of the cylinder bores. The piston
and the valve port assembly form a compression chamber. The
cylinder block forms therein communication holes that connect each
of the compression chambers to the end portion of the drive shaft.
The end portion of the drive shaft forms therein a residual gas
bypass passage. The residual gas bypass passage connects one
communication hole, which communicates with the compression chamber
on a high-pressure side that has finished discharge process of gas,
to another communication hole, which communicates with the
compression chamber that is lower in pressure than the
high-pressure side compression chamber. As the piston reciprocates,
gas is introduced into the compression chamber through the suction
port by pushing away the suction valve, compressed in the
compression chamber and discharged from the compression chamber
through the discharge port by pushing away the discharge valve.
[0006] 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
[0007] 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
drawings in which:
[0008] FIG. 1 is a longitudinal cross-sectional view of a piston
type compressor according to a first preferred embodiment of the
present invention;
[0009] FIG. 2 is a cross-sectional view that is taken along the
line I-I in FIG. 1;
[0010] FIG. 3 is a linearly expanded plan view illustrating the
rotational motion of the rear end portion of a drive shaft
according to the first preferred embodiment of the present
invention;
[0011] FIG. 4 is a cross-sectional view of a drive shaft near the
rear end portion of another piston type compressor according to a
second preferred embodiment of the present invention;
[0012] FIG. 5 is a cross-sectional view of a drive shaft near the
rear end portion of another piston type compressor according to a
third preferred embodiment of the present invention; and
[0013] FIG. 6 is a linearly expanded plan view illustrating the
rotational motion of the rear end portion of a drive shaft
according to the third preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] A first preferred embodiment of a variable displacement
piston type compressor 10, which is a part of a refrigerant circuit
of a vehicle air conditioner, according to the present invention
will now be described with reference to FIGS. 1 through 3.
[0015] FIG. 1 illustrates a longitudinal cross-sectional view of
the compressor 10. The front side and the rear side of the
compressor 10 correspond to the left side and the right side of
FIG. 1, respectively. As shown in FIG. 1, the housing of the
compressor 10 includes a cylinder block 11, a front housing 12
fixedly connected to the front end of the cylinder block 11, and a
rear housing 14 fixedly connected to the rear end of the cylinder
block 11.
[0016] The compressor 10 also includes a valve port assembly 13,
which is interposed between the cylinder block 11 and the rear
housing 14. The valve port assembly 13 is formed by layering a
suction valve plate 13a, a valve port plate 13b, a discharge valve
plate 13c and a retainer plate 13d, in this order from the side of
the cylinder block 11.
[0017] The housing forms therein a crank chamber 16 between the
cylinder block 11 and the front housing 12. A drive shaft 17 is
rotatably supported between the cylinder block 11 and the front
housing 12 so as to extend through the crank chamber 16. The drive
shaft 17 is supported by the front housing 12 through a radial
bearing 18 at its front-end portion. The supporting structure of
the other end (a rear end portion 38) of the drive shaft 17 will be
described later. The drive shaft 17 is driven by a vehicle engine
(not shown).
[0018] In the crank chamber 16, a lug plate 22 is secured to the
drive shaft 17 so as to rotate integrally therewith. In the crank
chamber 16, a thrust bearing 19 is interposed between the inner
wall surface of the front housing 12 and the lug plate 22. The
crank chamber 16 accommodates therein a swash plate 23, which is
slidably and inclinably supported by the drive shaft 17. A hinge
mechanism 24 is interposed between the lug plate 22 and the swash
plate 23. The swash plate 23 is connected to the lug plate 22
through the hinge mechanism 24 and supported by the drive shaft 17
thereby synchronously rotate with the lug plate 22 and the drive
shaft 17, while it is inclinable to the drive shaft 17 with a slide
movement in the direction along the axis L of the drive shaft
17.
[0019] The cylinder block 11 forms therein a plurality (six in the
first preferred embodiment, two of which are shown in FIG. 1) of
cylinder bores 25, which are located at equiangular positions to
surround the rear end portion 38 of the drive shaft 17. Each
cylinder bore 25 accommodates therein a single-headed piston 26 so
as to reciprocate. The front and rear openings of the cylinder bore
25 are respectively closed by the front end surface of the valve
port assembly 13 (strictly, the suction valve plate 13a) and the
top end surface of the piston 26, thereby forming a compression
chamber 27 between the piston 26 and the valve port assembly 13
(strictly, the suction valve plate 13a). The piston 26 engages the
outer periphery of the swash plate 23 through a pair of shoes 28.
Accordingly, as the swash plate 23 rotates with the rotation of the
drive shaft 17, the swash plate 23 is oscillated frontward and
rearward in the direction of the axis L of the drive shaft 17. The
oscillation of the swash plate 23 reciprocates the piston 26
frontward and rearward along the axis L.
[0020] The housing forms therein a suction chamber 29 and a
discharge chamber 30 between the valve port assembly 13 and the
rear housing 14. The valve port assembly 13 forms therein suction
ports 31 in the valve port plate 13b and suction valves 32 made of
flapper valves in the suction valve plate 13a between the suction
chamber 29 and the compression chambers 27. The valve port assembly
13 forms therein discharge ports 33 in the valve port plate 13b and
discharge valves 34 made of flapper valves in the discharge valve
plate 13c between the discharge chamber 30 and the compression
chambers 27. The retainer plate 13d is formed to regulate the
maximum opening degree of the discharge valves 34.
[0021] Refrigerant gas in the suction chamber 29 is introduced into
the compression chamber 27 through the suction port 31 as the
piston 26 moves from the top dead center to the bottom dead center
to decrease the pressure in the compression chamber 27 and open the
suction valve 32. The refrigerant gas introduced in the compression
chamber 27 is compressed up to a predetermined pressure value as
the piston 26 moves from the bottom dead center to the top dead
center. After that the compressed refrigerant gas is discharged to
the discharge chamber 30 through the discharge port 33 by the
opening of the discharge valve 34. Compression reactive force
applied to the pistons 26 is received by the thrust bearing 19
through the swash plate 23, the hinge mechanism 24 and the lug
plate 22.
[0022] The housing of the compressor 10 includes a bleed passage
35, a supply passage 36 and a control valve 37. The bleed passage
35 connects the crank chamber 16 to the suction chamber 29. The
supply passage 36 connects the discharge chamber 30 to the crank
chamber 16. The control valve 37 is located in the supply passage
36. The regulation of the opening degree of the control valve 37
controls the balance between the amount of high-pressure discharged
gas into the crank chamber 16 through the supply passage 36 and the
amount of gas from the crank chamber 16 through the bleed passage
35 thereby determining the pressure in the crank chamber 16. In
response to variation of the pressure in the crank chamber 16, a
pressure differential between the pressure in the crank chamber 16
and the pressure in the compression chambers 27 though the pistons
26 is changed to vary the inclination angle of the swash plate 23,
with the result of adjusted stroke of the pistons 26 or adjusted
displacement of the compressor 10.
[0023] The bypass structure for residual gas in the compressor 10
will now be described.
[0024] As shown in FIG. 2, the cylinder block 11 forms therein an
accommodating hole 39 that extends through the central portion of
the cylinder block 11 so as to be surrounded by a plurality of the
cylinder bores 25. The accommodating hole 39 partially accommodates
therein the rear end portion 38 of the drive shaft 17 so as to be
slidable. The rear end portion 38 of the drive shaft 17 is
rotatably supported by the cylinder block 11 such that an outer
peripheral surface 38a of the rear end portion 38 directly slides
on an inner peripheral surface 39a of the accommodating hole 39.
That is, the outer peripheral surface 38a of the rear end portion
38 of the drive shaft 17 and the inner peripheral surface 39a of
the accommodating hole 39 cooperatively function as a plain bearing
surface for supporting the rear end portion 38 of the drive shaft
17 to receive radial road.
[0025] It is noted that the outer peripheral surface 38a of the
rear end portion 38 of the drive shaft 17 is treated with coating
for improving a slide-contact with the inner peripheral surface 39a
of the accommodating hole 39.
[0026] In the accommodating hole 39, a sliding member 21 and a coil
spring 20 are interposed between an end surface 38b of the rear end
portion 38 of the drive shaft 17 and the front end surface of the
valve port assembly 13 (strictly, the suction valve plate 13a). The
sliding member 21 slidably contacts with the end surface 38b of the
rear end portion 38 of the drive shaft 13. The coil spring 20 is
interposed between the sliding member 21 and the valve port
assembly 13 and urges the sliding member 21 toward the drive shaft
17. Accordingly, for example, even if compression reactive force is
not generated during stop of the compressor 10, the coil spring 20
urges the drive shaft 17, that is, the lug plate 22, toward the
thrust bearing 19. Thus, the coil spring 20 prevents the drive
shaft 17, the lug plate 22, the swash plate 23, and the like from
rattling forward and rearward in the direction of the axis L by the
effect of vehicle vibration and the like.
[0027] It is noted that the end surface 38b of the rear end portion
38 of the drive shaft 17 and the sliding member 21 are treated with
coating for improving a slide-contact therebetween.
[0028] The cylinder block 11 forms therein communication holes 40
that connect the compression chambers 27 to the rear end portion 38
of the drive shaft 17. These plural communication holes 40 (six in
the first preferred embodiment) are radially formed in the cylinder
block 11 about the axis L of the drive shaft 17. One end of each
communication hole 40 is opened at the inner peripheral surface of
the cylinder bore 25 near the valve port assembly 13, which is an
opening 40a. Accordingly, even if the piston 26 is positioned
either at the top dead center or at the bottom dead center, each
communication hole 40 is in communication with the corresponding
compression chamber 27. The other end of each communication hole 40
is opened at the inner peripheral surface 39a of the accommodating
hole 39 so as to face the outer peripheral surface 48a of the rear
end portion 38 of the drive shaft 17, which is an opening 40b.
[0029] FIG. 3 is a linearly expanded plan view illustrating the
rotational motion of the rear end portion 38 of the drive shaft 17
while the rotation of a certain point on the outer peripheral
surface 38a of the rear end portion 38 around the axis L is
converted to leftward movement according to the first preferred
embodiment of the present invention. As shown in FIG. 3, the outer
peripheral surface 38a of the rear end portion 38 of the drive
shaft 17 forms therein a residual gas bypass groove or a residual
gas bypass passage 41. The residual gas bypass groove 41 includes a
high-pressure side groove 41a, which extends in the direction along
the axis L of the drive shaft 17 (or the vertical direction in FIG.
3), a low-pressure side groove 41b, which extends in the direction
along the axis L, and a connecting groove 41c, which extends in the
circumferential direction of the drive shaft 17 (or the horizontal
direction in FIG. 3) to connect the front end portion of the groove
41a to the front end portion of the groove 41b.
[0030] The high-pressure side groove 41a is located on the outer
peripheral surface 38a of the rear end portion 38 of the drive
shaft 17 to face the compression chamber 27A in which the piston 26
is positioned at the top dead center, that is, the opening 40b of
the communication hole 40A that communicates with the high-pressure
side compression chamber 27A that has just finished discharge
process. The low-pressure side groove 41b is located on the outer
peripheral surface 38a of the rear end portion 38 of the drive
shaft 17 to face the compression chamber 27B in which the piston 26
is positioned at he bottom dead center, that is, the opening 40B
that communicates with the low-pressure side compression chamber
27B that has just finished suction cycle. Also, the connecting
groove 41c is located on the outer peripheral surface 38a of the
rear end portion 38 of the drive shaft 17 so as not to face the
opening 40b of the communication hole 40.
[0031] Accordingly, refrigerant gas (residual gas), which remains
due to an incomplete discharge in the compression chamber 27A that
has just finished discharge process is collected into the
compression chamber 27B through the communication hole 40A, the
residual gas bypass groove 41 (the high-pressure side groove 41a,
the connecting groove 41c and the low-pressure groove 41b), and
connecting hole 40B, in this order. Thus, residual gas in the
compression chamber 27 during a suction process substantially does
not expand, and may increase the amount of refrigerant gas
introduced into the compression chamber 27, with the result of
improved suction efficiency of refrigerant gas to the compression
chamber 27.
[0032] According to the first preferred embodiment, the following
advantageous effects are obtained.
[0033] (1) Since the rear end portion 37 of the drive shaft 17
slides in the accommodating hole 39, that is, since the rear end
portion 38 of the drive shaft 17 is slidably received by the
accommodating hole 39, a bearing, which is conventionally required
for supporting the rear end portion 38 of the drive shaft 17, was
omitted. Accordingly, the structure of the compressor 10 is
simplified, and manufacturing cost is reduced.
[0034] (2) The residual gas bypass groove 41 is formed in the outer
peripheral surface 38a of the rear end portion 38 of the drive
shaft 17. That is, the residual gas bypass groove 41 is directly
formed on the drive shaft 17. Accordingly, in comparison to a
structure in which the residual gas bypass groove 41 is formed in
the outer peripheral surface of a rotor that is prepared separately
from the drive shaft 17 so as to synchronously rotate therewith,
the number of components may be reduced and an assembling process
may be omitted.
[0035] (3) The residual gas bypass groove 41 supplies residual gas
in the compression chamber 27A to the compression chamber 27B that
has just finished suction process. Accordingly, residual gas may
further be fed from the compression chamber 27A that has just
finished discharge process to the compression chamber 27B that has
just finished suction process. Thus, the amount of refrigerant gas
introduced into the compression chamber 27 is increased, and the
suction efficiency of refrigerant gas to the compression chamber 27
is further improved.
[0036] (4) The residual gas bypass passage is substantiated as the
residual gas bypass groove 41, which is formed in the outer
peripheral surface 38a of the rear end portion 38 of the drive
shaft 17. Accordingly, lubricating oil (refrigerating machine oil)
contained in refrigerant gas that moves in the residual gas bypass
groove 41 remains between the residual gas bypass groove 41 and the
inner peripheral surface 39a of the accommodating hole 39, thereby
improving slide-contact between the outer peripheral surface 38a of
the rear end portion 38 of the drive shaft 17 and the inner
peripheral surface 39a of the accommodating hole 39. Particularly,
in the first preferred embodiment, the residual gas bypass passage
is formed only by a groove (the residual gas bypass groove 41), so
that the slide-contact may further be improved.
[0037] The present invention is not limited to the embodiment
described above but may be modified into the following alternative
embodiments.
[0038] In the first preferred embodiment, the residual gas bypass
passage is formed by a groove (the residual gas bypass groove 41),
which is formed in the outer peripheral surface 38a of the rear end
portion 38 of the drive shaft 17. In a second preferred embodiment,
as shown in FIG. 4, in the rear end portion 38 of the drive shaft
17 forms therein a hole 51 that extends radially (in the direction
that intersects with the axis L), and the hole 51 may be used as a
residual gas bypass passage. In this case, a first opening 51a of
the hole 51 is located on the outer peripheral surface 38a of the
rear end portion 38 of the drive shaft 17 to face the opening 40b
of the communication hole 40A that communicates with the
compression chamber 27A in which the piston 26 is positioned at the
top dead center. A second opening 51b of the hole 51 is located on
the outer peripheral surface 38a of the rear end portion 38 of the
drive shaft 17 to face the opening 40b of the communication hole
40B that communicates with the compression chamber 27B in which the
piston 26 is positioned at the bottom dead center.
[0039] According to the second preferred embodiment, the same
advantageous effect mentioned in paragraph (4) in the first
preferred embodiment is obtained. Additionally, the residual gas
bypass passage is formed by the hole 51 that radially extends
through the drive shaft 17. Generally, manufacturing of holes is
easier than manufacturing of grooves, and, according to the second
preferred embodiment, the drive shaft 17 is easily manufactured to
form the residual gas bypass passage. Particularly, in the second
preferred embodiment, the residual gas bypass passage is wholly
formed only by the hole 51, so that the residual gas bypass passage
is further easily manufactured.
[0040] In the first preferred embodiment, the residual gas bypass
passage is wholly formed by a groove (the residual gas bypass
groove 41). In addition, in the second preferred embodiment, the
residual gas bypass passage is wholly formed by the hole 51. In a
third preferred embodiment as shown in FIGS. 5 and 6, the residual
gas bypass passage partially includes grooves 41A, 41B that are
formed in the outer peripheral surface 38a of the rear end portion
38 of the drive shaft 17, and the remainder of the residual gas
bypass passage is formed by a hole 51A that radially extends
through the rear end portion 38 of the drive shaft 17.
[0041] In the first and second preferred embodiments, the residual
gas bypass passage is formed to connect the compression chamber
27A, in which the piston 26 is positioned at the top dead center,
to the compression chamber 27B, in which the piston 26 is
positioned at the bottom dead center. In an alternative embodiment,
the residual gas bypass passage is formed to connect the
compression chamber 27A, in which the piston 26 is positioned at
the top dead center, to the compression chamber 27, in which the
piston 26 is on the way from the top dead center to the bottom dead
center (during the suction process), or to the compression chamber
27, in which the piston 26 is on the way from the bottom dead
center to the top dead center (during the discharge process).
[0042] In the first and second preferred embodiments, the
compressor 10 includes the even-numbered cylinder bores 25. In an
alternative embodiment, the present invention is applied to a
compressor that includes the odd-numbered cylinder bores 25. In
this case, the residual gas bypass passage connects the compression
chamber 27, in which the piston 26 is positioned at the top dead
center, to the compression chamber 27, in which the piston 26 is
positioned at the bottom dead center.
[0043] In an alternative embodiment, the high-pressure side
compression chamber 27A, which is to supply residual gas, may
employ a compression chamber, in which the piston 26 is positioned
slightly offset forward or rearward to the top dead center.
[0044] In an alternative embodiment, the present invention is
applied to a fixed displacement piston type compressor.
[0045] In an alternative embodiment, the present invention is
applied to a double-headed piston type compressor. In this case,
the present invention may be applied to both a set of front
cylinder bores and a set of rear cylinder bores, or may be applied
to one of the set of front cylinder bores and the set of rear
cylinder bores.
[0046] In an alternative embodiment, the present invention is
applied to a wobble plate piston type compressor.
[0047] 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 within the scope of the appended claims.
* * * * *