U.S. patent application number 10/701679 was filed with the patent office on 2004-07-29 for variable displacement mechanism for scroll type compressor.
Invention is credited to Iguchi, Masao, Iwasa, Jiro, Kawaguchi, Masahiro, Odachi, Yasuharu, Yamanouchi, Akihito.
Application Number | 20040146419 10/701679 |
Document ID | / |
Family ID | 32321610 |
Filed Date | 2004-07-29 |
United States Patent
Application |
20040146419 |
Kind Code |
A1 |
Kawaguchi, Masahiro ; et
al. |
July 29, 2004 |
Variable displacement mechanism for scroll type compressor
Abstract
In a scroll type compressor having a movable scroll member and a
fixed scroll member, the movable scroll member and the fixed scroll
member defines compression chambers therebetween. The compression
chambers reduce in volume in accordance with orbital motion of the
movable scroll member relative to the fixed scroll member. Thus gas
is compressed. A variable displacement mechanism for the scroll
type compressor has a by-pass passage, a pivotal plate and an
actuator. The by-pass passage serves to interconnect the
compression chamber in a process of volume-reducing and a suction
pressure region. The pivotal plate has a communication hole that
partially constitutes the by-pass passage and is selectively
pivoted between a first pivotal position for opening the by-pass
passage by the communication hole and a second pivotal position for
closing the by-pass passage. The actuator serves to pivot the
pivotal plate.
Inventors: |
Kawaguchi, Masahiro;
(Kariya-shi, JP) ; Odachi, Yasuharu; (Kariya-shi,
JP) ; Iguchi, Masao; (Kariya-shi, JP) ; Iwasa,
Jiro; (Kariya-shi, JP) ; Yamanouchi, Akihito;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
32321610 |
Appl. No.: |
10/701679 |
Filed: |
November 4, 2003 |
Current U.S.
Class: |
418/55.1 |
Current CPC
Class: |
F04C 28/14 20130101 |
Class at
Publication: |
418/055.1 |
International
Class: |
F04C 018/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2002 |
JP |
2002-322947 |
Claims
What is claimed is:
1. A variable displacement mechanism in a scroll type compressor
having a movable scroll member and a fixed scroll member, the
movable scroll member and the fixed scroll member defining
compression chambers therebetween, the compression chambers
reducing in volume in accordance with orbital motion of the movable
scroll member relative to the fixed scroll member, whereby gas is
compressed, a suction pressure region being defined in the scroll
type compressor, the variable displacement mechanism comprising: a
by-pass passage provided for interconnecting the compression
chamber in a process of volume-reducing and the suction pressure
region; a pivotal plate having a communication hole that partially
constitutes the by-pass passage, the pivotal plate being pivotally
switched between a first pivotal position for opening the by-pass
passage by the communication hole and a second pivotal position for
closing the by-pass passage; and an actuator for pivoting the
pivotal plate.
2. The variable displacement mechanism according to claim 1,
wherein the by-pass passage is configured to regularly interconnect
the compression chamber in the process of volume-reducing and the
suction pressure region until volume of the compression chamber in
the process of volume-reducing is reduced to a predetermined value
in a state where the pivotal plate is switched to the first pivotal
position.
3. The variable displacement mechanism according to claim 1,
wherein the by-pass passage is plurally formed.
4. The variable displacement mechanism according to claim 3,
wherein the scroll type compressor includes a rotary shaft that has
a central axis, the by-pass passages being distributed around the
central axis and along an orthogonal direction relative to the
central axis.
5. The variable displacement mechanism according to claim 1,
wherein the by-pass passage is configured to interconnect the
compression chamber in the process of volume-reducing and the
suction pressure region after the volume of the compression chamber
in the process of volume-reducing has been reduced to a
predetermined value in a state where the pivotal plate is switched
to the first pivotal position.
6. The variable displacement mechanism according to claim 1,
wherein the fixed scroll member includes a base plate and a spiral
wall that extends from the base plate, the pivotal plate being
slidably laid on a back surface of the base plate.
7. The variable displacement mechanism according to claim 6,
wherein the back surface of the base plate of the fixed scroll
member includes an accommodating recess, a discharge hole opening
to the accommodating recess for communicating with the compression
chamber near a center of the spiral wall, a discharge chamber being
defined in such a manner that the accommodating recess is closed by
laying the pivotal plate on the back surface of the base plate.
8. The variable displacement mechanism according to claim 7,
wherein the suction pressure region is defined on a side that is
opposite to a side of the base plate relative to the pivotal plate,
the pivotal plate serving as a partition wall for partitioning the
suction pressure region and the discharge chamber.
9. The variable displacement mechanism according to claim 7,
wherein the pivotal plate has a donut-shape, a through hole being
formed at the center of the pivotal plate, a discharge passage
extending through the through hole for discharging the gas in the
discharge chamber.
10. The variable displacement mechanism according to claim 9,
wherein adherence between the pivotal plate and the fixed scroll
member seals the by-pass passage.
11. The variable displacement mechanism according to claim 10,
wherein a layer of lubricating oil is interposed between the
pivotal plate and the base plate of the fixed scroll member.
12. The variable displacement compressor according to claim 1,
wherein the scroll type compressor is used for a vehicle air
conditioner, the scroll type compressor being a hybrid type that is
selectively driven by power from an engine for traveling a vehicle
and by power from an internal electric motor.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a scroll type compressor
for use in a vehicle air conditioner and more particularly to a
variable displacement mechanism for varying the displacement of the
scroll type compressor.
[0002] A variable displacement mechanism of such type is, for
example, disclosed in Unexamined Japanese Patent Publication No.
2001-32787. A compression chamber communicates with a suction
pressure region through a by-pass passage in the process of
volume-reducing. A spool valve opens and closes the by-pass passage
to optionally vary the displacement of the scroll type
compressor.
[0003] In the spool valve, a spool is slidably accommodated in a
cylinder. The spool has an outer diameter that is substantially
equal to the inner diameter of the cylinder and includes a rod for
partially constituting the by-pass passage.
[0004] An unwanted feature is that the spool valve of the variable
displacement mechanism is configured to open and close a port that
opens at the inner circumferential surface of the cylinder (the
inner surface of the cylinder) by a valve portion (a column) of the
spool so that it is difficult to arrange a seal member at the valve
portion. Therefore, the valve portion of the spool contacts the
inner circumferential surface of the cylinder so as to prevent
refrigerant gas from leaking from the spool valve.
[0005] A small clearance between the valve portion of the spool and
the inner circumferential surface of the cylinder effectively
suppresses the leakage of the refrigerant gas from the by-pass
passage. However, as the clearance between the valve portion of the
spool and the inner circumferential surface of the cylinder is
small, sliding resistance increases between the spool and the
cylinder. Consequently, problems such as deterioration in response
to displacement variation and enlargement of an actuator for
actuating the spool are arisen.
[0006] Accordingly, in a prior art, in view of suppressing the rise
of cost for manufacturing the highly accurate clearance, the
clearance between the valve portion of the spool and the inner
circumferential surface of the cylinder is relatively large. Then,
for example, even if the scroll type compressor is tried to operate
at the maximum displacement by closing the by-pass passage, the
leakage from the spool valve (the by-pass passage) becomes an
obstacle to achieving a desired maximum displacement. Namely,
deterioration in performance of the scroll type compressor has
arisen. Therefore, there is a need for a variable displacement
mechanism that reliably seals a by-pass passage for a scroll type
compressor.
SUMMARY OF THE INVENTION
[0007] In accordance with the present invention, in a scroll type
compressor having a movable scroll member and a fixed scroll
member, the movable scroll member and the fixed scroll member
defines compression chambers therebetween. The compression chambers
reduce in volume as they move in accordance with orbital motion of
the movable scroll member relative to the fixed scroll member. Thus
gas is compressed. A variable displacement mechanism for the scroll
type compressor has a by-pass passage, a pivotal plate and an
actuator. The by-pass passage serves to interconnect the
compression chamber in a process of volume-reducing and a suction
pressure region. The pivotal plate has a communication hole that
partially constitutes the by-pass passage and is selectively
pivoted between a first pivotal position for opening the by-pass
passage by the communication hole and a second pivotal position for
closing the by-pass passage. The actuator serves to pivot the
pivotal plate.
[0008] 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
[0009] 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:
[0010] FIG. 1 is a longitudinal cross-sectional view of a hybrid
compressor according to a preferred embodiment of the present
invention;
[0011] FIG. 2 is a cross-sectional view that is taken along the
line I-I in FIG. 1;
[0012] FIG. 3 is a cross-sectional view that is taken along the
line II-II in FIG. 1;
[0013] FIG. 4 is a cross-sectional view that corresponds to FIG. 3
in a state where a pivotal plate is switched to a second pivotal
position; and
[0014] FIG. 5 is a cross-sectional view that is taken along the
line I-I in FIG. 1 according to an alternative embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] A preferred embodiment of the present invention will now be
described with reference to FIGS. 1 through 4. The preferred
embodiment applies the present invention to a hybrid compressor C
that is a scroll type. The left side and the right side of FIG. 1
respectively correspond to the front side and the rear side of the
compressor C.
[0016] The hybrid compressor C will schematically be described at
the beginning.
[0017] FIG. 1 illustrates a longitudinal cross-sectional view of
the compressor C according to the preferred embodiment of the
present invention. The compressor C partially constitutes a
refrigeration cycle of a vehicle air conditioner. The compressor C
accommodates a compression mechanism 12 and an electric motor 21 in
a housing 11. A power transmission mechanism 22 is arranged on an
outer wall of the housing 11. The compression mechanism 12 is a
scroll type and is configured to optionally vary displacement of
the compressor C. The power transmission mechanism 22 receives
power from an (internal combustion) engine E for traveling a
vehicle.
[0018] The compressor C is selectively driven by one of power from
the engine E through the power transmission mechanism 22 and power
from the electric motor 21. Thus, with the electric motor 21,
air-conditioning (cooling) is optionally enabled during stop of the
engine E. Accordingly, the vehicle air conditioner of the preferred
embodiment is particularly appropriate for an idle-stop vehicle or
a hybrid vehicle.
[0019] The compressor C will now be described in detail.
[0020] Still referring to FIG. 1, the housing 11 includes a casing
11a and a cover 11b. The casing 11a is cylindrical in shape and has
a bottom at one end. The cover 11b is fixedly connected to the rear
end of the casing 11a. The casing 11a of the housing 11 has a
through hole 34 at the center of the bottom of the housing 11, and
the through hole 34 extends through the bottom of the housing 11. A
pulley shaft 13 is inserted through the through hole 34 and is
rotatably supported by the is housing 11 through a bearing 35 in
the through hole 34.
[0021] A shaft support member 31 is fixed near the opening end of
the casing 11a in the housing 11. A through hole 31a extends
through the center of the shaft support member 31. A compressor
shaft 19 is coaxially arranged with the pulley shaft 13 in the
housing 11. The rear end of the compressor shaft 19 is inserted
into the through hole 31a of the shaft support member 31 and is
rotatably supported by the shaft support member 31 through a
bearing 32 in the through hole 31a. The front end of the compressor
shaft 19 is fitted to the rear end of the pulley shaft 13 through a
bearing 33 so as to rotate relative to the pulley shaft 13.
[0022] The power transmission mechanism 22 includes a pulley 17 and
an electromagnetic clutch 18. The pulley 17 is rotatably supported
by the housing 11 and transmits power from the engine E to the
pulley shaft 13. The electromagnetic clutch 18, when in an ON-state
(energized), permits power transmission between the pulley 17 and
the pulley shaft 13 and, when in an OFF-state (de-energized),
disrupts the power transmission therebetween.
[0023] A speed increasing mechanism 23 including a planetary gear
mechanism is provided between the pulley shaft 13 and the
compressor shaft. 19 in the housing 11 for increasing the
rotational speed of the pulley shaft 13 and for transmitting the
rotation of the pulley shaft 13 to the compressor shaft 19. This
speed increasing mechanism 23 has a known structure including a sun
gear 45, an internal gear 46, a holder 47 and a plurality of
planetary gears 48. With the speed increasing mechanism 23, for
example, even if the rotational speed of the pulley shaft13 is
relatively low due to an idling state of the engine, the compressor
shaft 19 is rotated at a relatively high speed so as to ensure a
large amount of refrigerant gas discharged from the compression
mechanism 12 per unit time, that is, to exert a relatively high
cooling performance.
[0024] A stator 15 is provided on the inner circumferential-surface
of the casing 11a of the housing 11 and is located on the front
side of housing 11. A rotor 14 is fixedly connected to the
compressor shaft 19 in the housing 11 so as to be arranged inside
the stator 15. The electric motor 21 includes the stator 15 and the
rotor 14. The electric motor 21 integrally rotates the rotor 14 and
the compressor shaft 19 by supplying electric current to the stator
15.
[0025] A fixed scroll member 41 is fixedly accommodated at the
opening end of the casing 11a in the housing 11. The fixed scroll
member 41 includes a base plate 61 which has a disc-shape, an outer
wall 62 which has a cylindrical shape and a spiral wall 63. The
outer wall 62 extends from the outer periphery of the base plate
61. The spiral wall 63 extends from the base plate 61 inside the
outer wall 62. The fixed scroll member 41 is fixedly connected to
the rear surface of the shaft support member 31 at the distal end
surface of the outer wall 62.
[0026] A crankshaft 43 is provided at the rear end of the
compressor shaft 19 and is located at a position that is offset
from an axis L of the compressor shaft 19. A bushing 51 is fixedly
fitted around the crankshaft 43. A movable scroll member 42 is
supported by the bushing 51 through a bearing 52 for rotation
relative to the fixed scroll member 41 so as to face the fixed
scroll member 41. The movable scroll member 42 includes a base
plate 65 which has a disc-shape and a spiral wall 66 that extends
from the base plate 65 toward the fixed scroll member 41.
[0027] The fixed scroll member 41 and the movable scroll member 42
engage each other by the spiral walls 63, 66 of the fixed and
movable scroll members 41, 42, while the distal ends of the spiral
walls 63, 66 respectively contact the base plates 65, 61 of the
movable and fixed scroll members 42, 41. Accordingly, the base
plate 61 of the fixed scroll member 41, the spiral wall 63 of the
fixed scroll member 41, the base plate 65 of the movable scroll
member 42 and the spiral wall 66 of the movable scroll member 42
define compression chambers 67.
[0028] A self-rotation blocking mechanism 68 is interposed between
the base plate 65 of the movable scroll member 42 and the shaft
support member 31 facing the base plate 65. The self-rotation
blocking mechanism 68 includes a plurality of cylindrical recesses
68a and a plurality of pins 68b. The cylindrical recesses 68a are
provided at the back surface (the front surface) of the base plate
65 of the movable scroll member 42. The pins 68b are arranged at
radially outer portions 64 of the shaft support member 31 and are
loosely fitted in the respective cylindrical recesses 68a.
[0029] A suction chamber 69 is defined between the outer wall 62 of
the fixed scroll member 41 and the outermost portion of the spiral
wall 66. An accommodating recess 61b is partially formed at a back
surface 61a of the base plate 61 of the fixed scroll member 41 in
the range from the adjacent center portion to the adjacent outer
periphery. A discharge hole 61c is formed through the center of the
base plate 61 of the fixed scroll member 41, and the compression
chamber 67 near the center of the base plate 61 communicates with
the inner space of the accommodating recess 61b through the
discharge hole 61c. A discharge valve 55 constituted of a reed
valve is arranged in the accommodating recess 61b of the fixed
scroll member 41 for opening and closing the discharge hole 61c.
The opening degree of the discharge valve 55 is regulated by a
retainer 56, which is fixedly arranged in the accommodating recess
61b of the fixed scroll member 41.
[0030] As the compressor shaft 19 is rotated by the engine E or by
the electric motor 21, the movable scroll member 42 orbits around
the axis L of the fixed scroll member 41 through the crankshaft 43
in the compression mechanism 12. Then, the self-rotation blocking
mechanism 68 blocks the self-rotation of the movable scroll member
42 and only permits the orbital motion of the movable scroll member
42. As the movable scroll member 42 orbits relative to the fixed
scroll member 41, the compression chambers 67 are gradually reduced
in volume and are moved from the outer side of the spiral walls 63,
66 of the scroll members 41, 42 toward the center side of the
spiral walls 63, 66 of the scroll members 41, 42. Thereby,
relatively low pressure refrigerant gas introduced from the suction
chamber 69 to the compression chambers 67 is compressed. The
compressed refrigerant gas is discharged from the compression
chamber 67 near the center of the spiral walls 63, 66 to the inner
space of the accommodating recess 61b through the discharge hole
61c by pushing away the discharge valve 55.
[0031] An accommodating chamber 36 is defined in the housing 11
between the base plate 61 of the fixed scroll member 41 and the
cover 11 b. A pivotal plate 37 which has a donut-shape is
accommodated in the accommodating chamber 36. The pivotal plate 37
is laid on the back surface 61a of the base plate 61 of the fixed
scroll member 41. The opening of the accommodating recess 61b of
the fixed scroll member 41 is shut by laying the pivotal plate 37
on the back surface ]o 61a of the base plate 61. Accordingly, the
accommodating chamber 36 is partitioned by the pivotal plate 37
into a discharge chamber 70 and an introducing chamber 38. The
inner space of the accommodating recess 61b provides the discharge
chamber 70. The space between the pivotal plate 37 and the cover
11b provides the introducing chamber 38 is. Namely, the pivotal
plate 37 also serves as a partition wall for partitioning the
accommodating chamber 36 into the introducing chamber 38 and the
discharge chamber 70.
[0032] A support portion 54 which has a cylindrical shape extends
from the middle portion of the cover 11b in the accommodating
chamber 36. A distal end surface of the support portion 54 is
elongated to contact the back surface 61a of the base plate 61 of
the fixed scroll member 41. A boss 37a is provided at the rear
surface and the middle portion of the pivotal plate 37. The pivotal
plate 37 is rotatably supported by the support portion 54 through
the boss 37a.
[0033] As shown in FIGS. 1, 3 and 4, an electromagnetic actuator 60
is arranged in the cover 11b of the housing 11. The actuator 60 is
configured to reciprocate a rod 60b by energizing and de-energizing
a solenoid 60a based upon an external command. A pin 37d is
connected to the pivotal plate 37, and the rod 60d of the actuator
60 is operatively connected to the pin 37d. Accordingly, the
pivotal plate 37 is pivotally switched between a first pivotal
position (a state shown in FIG. 3) and a second pivotal position (a
state shown in FIG. 4) by actuating the actuator 60. The first
pivotal position is performed by an ON-state of the actuator 60
(energizing the solenoid 60a). The second pivotal position is
performed by an OFF-state of the actuator 60 (de-energizing the
solenoid 60a).
[0034] As shown in FIG. 1, a seal member 57 is arranged on the
outer circumferential surface of the proximal portion of the
support portion 54. This seal member 57 serves to seal a contact
portion between the support portion 54 and the pivotal plate 37
(the boss 37a) with cylindrical contact region. A seal member 59 is
arranged on the back surface 61a of the base plate 61 in the fixed
scroll member 41 so as to surround the accommodating recess 61b.
This seal member 59 serves to seal a contact portion between the
back surface 61a of the base plate 61 and the pivotal plate 37 with
annular contact region. Namely, these seal members 57, 59 and
lubricating oil contained in the refrigerant gas intervene in layer
between the support portion 54 and the pivotal plate 37 (the boss
37a) and between the back surface 61a of the base plate 61 and the
pivotal plate 37. As a result, the introducing chamber 38 is
separated from the discharge chamber 70.
[0035] An inlet 50 is formed in the outer circumferential wall of
the casing 11a of the housing 11 so as to correspond with the
accommodating space for the electric motor 21. An external conduit
for connecting with an evaporator of an external refrigerant
circuit (not shown) is connected to the inlet 50. A suction passage
39 is formed at the outer circumferential portion of the shaft
support member 31 and the fixed scroll member 41 in the housing 11
for interconnecting the accommodating region of the electric motor
21 and the introducing chamber 38.
[0036] A suction hole 61d is formed at the radially outer portion
of the base plate 61 of the fixed scroll member 41. The suction
hole 61d opens to the suction chamber 69 at the front end and opens
at the back surface 61a at the rear end. A suction port 37b is
formed at the radially outer portion of the pivotal plate 37 for
interconnecting the introducing chamber 38 and the suction hole 61d
at any pivotal positions of the pivotal plate 37. Accordingly, the
relatively low pressure refrigerant gas from the external
refrigerant circuit is introduced into the suction chamber 69
through the inlet 50, the suction passage 39, the introducing
chamber 38, the suction port 37b and the suction hole 61d.
[0037] The middle portion of the cover 11b of the housing 11b forms
a discharge passage 58. The front end of the discharge passage 58
extends through the center of the support portion 54 and the center
of the pivotal plate 37 (the boss 37a) and then communicates with
the discharge chamber 70, while an external conduit, which connects
a condenser of the external refrigerant circuit (not shown), is
connected to the rear end of the discharge passage 58. Accordingly,
the relatively high pressure refrigerant gas in the discharge
chamber 70 is discharged to the external refrigerant circuit
through the discharge passage 58.
[0038] As shown in FIGS. 1 through 4, the base plate 61 of the
fixed scroll member 41 includes a plurality of by-pass holes 61e.
One end of each by-pass hole 61e opens to the compression chamber
67 that is volume-reducing, while the other end opens at the back
surface 61a. A plurality of the by-pass holes 61e is arranged in
such a manner that each of the by-pass holes 61e alternatively
communicates with the compression chamber 67 that is
volume-reducing during times when the compression chamber 67 at an
initial position that is the maximum volume reduces in volume to a
predetermined value (for example, 20% of the maximum volume). A
plurality of communication holes 37c extends through the pivotal
plate 37 in the direction of the axis L so as to correspond with
the by-pass holes 61e of the base plate 61.
[0039] In the preferred embodiment, the by-pass holes 61e of the
base plate 61 and the communication holes 37c of the pivotal plate
37 form by-pass passages (hereinafter the by-pass passages 37c,
61e) for interconnecting the compression chamber 67 that is
volume-reducing and the introducing chamber or a suction pressure
region 38. The pivotal plate 37 is pivotally switched between an
open position for opening the by-pass passages 37c, 61e by the
communication holes 37c and a close position for closing the
by-pass passages 37c, 61e by means of ON/OFF control of the
actuator 60.
[0040] Namely, as shown in FIG. 4, each communication hole 37c of
the pivotal plate 37 is offset from the corresponding by-pass hole
61e of the base plate 61 when the pivotal plate 37 is located at
the second pivotal position (the closing position) by turning off
the actuator 60. As a result, the by-pass holes 61e are closed by
the plate surface of the pivotal plate 37. Accordingly, the
compression chamber 67 that is volume-reducing does not communicate
with the introducing chamber 38 and completely compresses the
refrigerant gas so that the amount of refrigerant gas discharged
from the compression mechanism 12 per unit rotation, that is, the
displacement of the compression mechanism 12, becomes maximum.
[0041] The compression mechanism 12 performs the maximum
displacement, for example, when the engine E is selected to drive
the compression mechanism 12. Accordingly, even if the rotational
speed of the pulley shaft 13 is slow due to an idling state of the
engine E, the compression mechanism 12 ensures a large amount of
discharged refrigerant gas per unit time, that is, the compression
mechanism 12 exercises relatively high cooling performance.
[0042] As shown in FIG. 3, when the pivotal plate 37 is located at
the first pivotal position (the opening position) by turning on the
actuator 60, each communication hole 37c communicates with the
corresponding by-pass hole 61e. Accordingly, the compression
chamber 67 that is volume-reducing constantly communicates with the
introducing chamber 38 through one of the by-pass holes 61e and one
of the communication holes 37c during times when the volume of the
compression chamber 67 that is volume-reducing is reduced to a
predetermined value. As a result, the compression chamber 67 does
not completely compress the refrigerant gas so that the
displacement of the compression mechanism 12 reduces in comparison
to the maximum displacement.
[0043] The compression mechanism 12 reduces in displacement, for
example, when the electric motor 21 is selected to drive the
compression mechanism 12. As the displacement of the compression
mechanism 12 reduces, torque required for driving the compression
mechanism 12 also reduces. Accordingly, the compressor C becomes
compact by reducing the size of the electric motor 21.
[0044] According to the preferred embodiment, the following
advantageous effects are obtained.
[0045] (1) The opening and closing of the by-pass passages 37c,
61e, that is, the variation of the displacement of the compressor
C, is performed by pivotally switching the pivotal plate 37.
Accordingly, adherence between the pivotal plate 37 and the fixed
scroll member 41, on which the pivotal plate 37 slides, seals the
by-pass passages 37c, 61e around the pivotal plate 37. The
plate-like member such as the pivotal plate 37 easily enhances
adherence with relatively large area against a facing member on
which the plate-like member slides in comparison to, for example,
the cylindrical member (the valve portion of the spool) disclosed
in the Unexamined Japanese Patent Publication No. 2001-32787.
Additionally, a layer of lubricating oil is interposed between the
pivotal plate 37 and the base plate 61 of the fixed scroll member
41. Accordingly, the by-pass passages 37c, 61e around the pivotal
plate 37 are reliably sealed. As a result, the deterioration of the
performance of the compressor C due to the leakage of the
refrigerant gas from the by-pass passages 37c, 61e is
suppressed.
[0046] (2) The by-pass passage 37c, 61e is configured to constantly
interconnect the compression chamber 67 that is volume-reducing and
the introducing chamber 38 until the volume of the compression
chamber 67 that is volume-reducing is reduced to a predetermined
value when the pivotal plate 37 is switched to the opening
position. Namely, the compression chamber 67 does not completely
compress until the volume of the compression chamber 67 is reduced
to a predetermined value after the commencement of reducing volume.
Accordingly, for example, in comparison to a variable displacement
mechanism that interconnects a compression chamber that is
volume-reducing and a suction pressure region after the compression
chamber compresses until the volume of the compression chamber is
reduced to a predetermined value, power loss of the compressor C
due to re-compression of the refrigerant gas, that is, useless
compression work, is suppressed.
[0047] Particularly, in the preferred embodiment, a plurality of
the by-pass passages 37c, 61e is provided to achieve the above
described constant communication. Namely, the fixed scroll member
41 provides a plurality of the by-pass holes 61e. A plurality of
the by-pass holes 61e is distributed around the axis L and along
the orthogonal direction relative to the axis L. For example, when
a plurality of the by-pass holes 61e is opened or closed by the
spool valve as disclosed in the Unexamined Japanese Patent
Publication No. 2001-32787, a plurality of the spool valves needs
to be provided due to the distribution of the by-pass holes 61e.
However, the plate-like pivotal plate 37 of the preferred
embodiment easily forms a plurality of the communication holes 37c
distributed around the axis L and along the orthogonal direction
relative to the axis L so as to correspond with the distributed
by-pass holes 61e. As a result, the above described constant
communication may easily be achieved without any complicated
structure.
[0048] (3) The pivotal plate 37 is slidably laid on the back
surface 61a of the base plate 61 of the fixed scroll member 41. The
above arrangement of the pivotal plate 37 prevents the enlarged
compressor C in the direction of the axis L due to the provision of
the variable displacement mechanism. In other words, the employment
of the plate-like member such as the pivotal plate 37 for opening
and closing the by-pass passages 37c, 61e enables universally
compact design for laying the plate-like member on the back surface
61a of the base plate 61 of the fixed scroll member 41.
[0049] Particularly, the compressor C is a hybrid type that is
alternatively driven by the power from the engine E through the
power transmission mechanism 22 arranged in the housing 11 or by
the power from the electric motor 21 accommodated in the housing
11. Accordingly, the compressor C tends to become large due to the
power transmission mechanism 22 and the electric motor 21. When a
compact variable displacement mechanism is utilized for the
compressor C, increasing size of the compressor C is efficiently
suppressed.
[0050] (4) The pivotal plate 37 also serves as a partition wall for
partitioning the discharge chamber 70. Accordingly, an exclusive
partition wall is not required for partitioning the discharge
chamber 70 so that the compressor C is simplified and becomes
compact.
[0051] (5) The pivotal plate 37 also serves as a partition wall for
partitioning the introducing chamber 38 and the discharge chamber
70. Accordingly, an exclusive partition wall is not required for
partitioning the introducing chamber 38 and the discharge chamber
70 but the compressor C is simplified and becomes compact.
Furthermore, a portion of the pivotal plate 37 (the side of the
back surface) is exposed to the atmosphere in the introducing
chamber 38 so that the pivotal plate 37 is easily handled by
forming the by-pass passages 37c, 61e in relatively short.
[0052] (6) The pivotal plate 37 has a donut-shape, and the
discharge passage 58 passes through the center through hole of the
pivotal plate 37. As a through hole is formed at the center of the
pivotal plate 37 that is not utilized for opening and closing the
by-pass passages 37c, 61e, the discharge passage 58 is defined to
include the through hole. Thus, the radially inner compression
chamber 67 and the discharge passage 58 are interconnected at a
minimum distance. Accordingly, gas smoothly flows from the radially
inner compression chamber 67 to the discharge passage 58 so that
the compressor C is prevented from deteriorating efficiency of the
compressor C due to pressure loss based upon conduit resistance
between the compression chamber 67 and the discharge passage
58.
[0053] The present invention is not limited to the embodiments
described above but may be modified into the following alternative
embodiments.
[0054] The pivotal plate 37 is configured to be pivotally switched
between two positions (the first pivotal position and the second
pivotal position) in the preferred embodiment. In other words, the
displacement of the compressor C is configured to vary between the
maximum and the minimum. In alternative embodiments to those of the
above preferred embodiment, the number of pivotal positions is not
limited. The pivotal plate 37 is configured to be pivotally
switched among three or more pivotal positions and is configured to
selectively vary the displacement of the compressor C at an
intermediate displacement between the maximum and the minimum.
[0055] The by-pass passages 37c, 61e are configured to constantly
interconnect the compression chamber 67 that is volume-reducing and
the introducing chamber 38 until the volume of the compression
chamber 67 that is volume-reducing is reduced to a predetermined
value when the pivotal plate 37 is switched to the opening
position. In alternative embodiments to those of the above
preferred embodiment, the by-pass passages 37c, 61e are not limited
to the above structure. Referring to FIGS. 1 and 5, the by-pass
passages 37c and 61e are not formed at the radially outer side of
the base plate 61 of the fixed scroll member 41 and the pivotal
plate 37, respectively but are only formed at the radially inner
side of the base plate 61 of the fixed scroll member 41 and the
pivotal plate 37, respectively, in comparison to the above
described preferred embodiment. In this state, the by-pass passages
37c, 61e are configured to interconnect the compression chamber 67
that is volume-reducing and the suction pressure region after the
compression chamber 67 has compressed to reduce in volume to a
predetermined value, that is, after the volume of the compression
chamber 67 that is volume-reducing has reduced to a predetermined
value. This simplifies the structure of the by-pass passage.
[0056] 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.
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