U.S. patent application number 13/420941 was filed with the patent office on 2012-10-04 for swash plate type variable displacement compressor.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Nobuaki HOSHINO, Yoshio KIMOTO, Masaki OTA, Noriyuki SHINTOKU, Yusuke YAMAZAKI.
Application Number | 20120247319 13/420941 |
Document ID | / |
Family ID | 46845267 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120247319 |
Kind Code |
A1 |
KIMOTO; Yoshio ; et
al. |
October 4, 2012 |
SWASH PLATE TYPE VARIABLE DISPLACEMENT COMPRESSOR
Abstract
A housing has a peripheral wall that surrounds a crank chamber.
The peripheral wall has a valve chamber that is recessed radially
inward from an outer surface of the peripheral wall with respect to
the axis. A bimetal member, which deforms in correspondence with
the temperature in the crank chamber, is arranged in the valve
chamber. A valve body, which is supported by the bimetal member, is
arranged in the valve chamber. The peripheral wall has a first oil
discharge passage and allows communication between the crank
chamber and the valve chamber, and a second oil discharge passage
through which the valve chamber and a suction chamber communicate
with each other. When the temperature in the crank chamber exceeds
a predetermined value and deforms the bimetal member to move the
valve body, communication between the first and second oil
discharge passage is permitted through the valve chamber.
Inventors: |
KIMOTO; Yoshio; (Kariya-shi,
JP) ; OTA; Masaki; (Kariya-shi, JP) ;
SHINTOKU; Noriyuki; (Kariya-shi, JP) ; HOSHINO;
Nobuaki; (Kariya-shi, JP) ; YAMAZAKI; Yusuke;
(Kariya-shi, JP) |
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Aichi-ken
JP
|
Family ID: |
46845267 |
Appl. No.: |
13/420941 |
Filed: |
March 15, 2012 |
Current U.S.
Class: |
92/12.2 |
Current CPC
Class: |
F05C 2251/04 20130101;
F04B 27/16 20130101; F05C 2251/08 20130101 |
Class at
Publication: |
92/12.2 |
International
Class: |
F01B 13/04 20060101
F01B013/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2011 |
JP |
2011-071079 |
Claims
1. A swash plate type variable displacement compressor, comprising:
a housing having a cylinder bore, a suction chamber, a discharge
chamber, and a crank chamber; a drive shaft, which is rotatably
supported by the housing and exposed in the crank chamber; a swash
plate supported by the drive shaft in the crank chamber such that
the inclination angle of the swash plate is changeable; a piston
received in the cylinder bore in a manner reciprocally movable; a
movement conversion mechanism arranged between the swash plate and
the piston to convert swinging of the swash plate to reciprocation
of the piston; and a displacement control mechanism for adjusting
displacement using pressure in the crank chamber, wherein the
housing includes a peripheral wall that surrounds the crank chamber
in a circumferential direction with respect to the axis of the
drive shaft and has an outer surface and an inner surface, the
peripheral wall includes a valve chamber recessed radially inward
from the outer surface of the peripheral wall, a first oil
discharge passage that has an opening in the inner surface of the
peripheral wall and allows communication between the crank chamber
and the valve chamber, and a second oil discharge passage that
allows communication between the valve chamber and the suction
chamber, wherein a temperature sensitive member, which deforms in
correspondence with the temperature in the crank chamber, is
arranged in the valve chamber, and a valve body supported by the
temperature sensitive member is located in the valve chamber, and
when the temperature in the crank chamber exceeds a predetermined
value to deform the temperature sensitive member and move the valve
body, communication between the first oil discharge passage and the
second oil discharge passage is permitted through the valve
chamber.
2. The compressor according to claim 1, wherein the inner surface
has a cylindrical surface extending parallel to the axis, the first
oil discharge passage having the opening in the cylindrical
surface.
3. The compressor according to claim 1, wherein the valve body has
a surface facing the first oil discharge passage, and a recess is
formed in the surface.
4. The compressor according to claim 1, wherein the second oil
discharge passage is a bolt hole, through which a bolt for
fastening the housing is passed.
5. The compressor according to claim 1, further including an urging
member arranged in the valve chamber, wherein the urging member
urges the valve body in a direction opposite to the direction in
which the valve body moves when the temperature in the crank
chamber exceeds the predetermined value.
6. The compressor according to claim 1, wherein a bulging portion
that bulges radially outward is formed in the peripheral wall, and
the valve chamber is formed in the bulging portion.
7. The compressor according to claim 1, wherein the displacement
control mechanism has a centrifugal oil discharge valve mechanism,
which sends lubricant oil from the crank chamber to the suction
chamber when the drive shaft rotates at a speed greater than a
predetermined speed.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a swash plate type variable
displacement compressor.
[0002] Japanese Laid-Open Patent Publication No. 2007-9720
discloses a conventional swash plate type variable displacement
compressor. The compressor has a housing configured by a front
housing member, a cylinder block, and a rear housing member. The
housing includes a plurality of cylinder bores, a suction chamber,
a discharge chamber, and a crank chamber. A drive shaft is
rotatably supported by the front housing member. An end of the
drive shaft is exposed from the front housing member and received
in the crank chamber. In the crank chamber, a swash plate is
supported by the drive shaft such that the inclination angle of the
swash plate is changeable. Each of the cylinder bores accommodates
a piston and allows the piston to reciprocate. A pair of front and
rear shoes are arranged between the swash plate and each of the
pistons. Each pair of shoes convert swinging of the swash plate
into reciprocation of the associated piston. The compressor
includes a displacement control mechanism for adjusting
displacement through pressure in the crank chamber.
[0003] The displacement control mechanism has a bleed passage,
through which the crank chamber communicates with the suction
chamber, a supply passage, through which the crank chamber
communicates with the discharge chamber, and a displacement control
valve. The displacement control valve detects the pressure in the
suction chamber to change the opening degree of the supply passage
in correspondence with the detected pressure, thus varying the
displacement.
[0004] The compressor also has a valve chamber, which is formed in
the cylinder block to connect the crank chamber and the suction
chamber. The valve chamber accommodates a temperature sensitive
member, which deforms in correspondence with the temperature in the
crank chamber, and a valve body, which is supported by the
temperature sensitive member.
[0005] The compressor is employed as an air conditioner for a
vehicle, in combination with a condenser, an expansion valve, and
an evaporator. The compressor can be driven by the engine of the
vehicle without employing an electromagnetic clutch. In this case,
even when the air conditioner is turned off to stop air
conditioning in the passenger compartment, the compressor
continuously operates at the minimum displacement as long as the
engine operates. In other words, the compressor is maintained in
OFF operation. If the compressor continues its operation at
displacement other than the minimum displacement, such operation is
referred to as ON operation.
[0006] In the OFF operation, the inclination angle of the swash
angle is minimized, which substantially prevents refrigerant
circulation in an external refrigeration circuit outside the
compressor. As a result, lubricant oil in circulating refrigerant
is maintained in the crank chamber and sheared by components
including the swash plate, which is likely to heat the oil. This
effect is pronounced particularly when the vehicle is traveling at
a high speed. In this state, the temperature sensitive member
deforms due to the temperature rise in the crank chamber of the
compressor, thus causing the valve body to permit communication
between the crank chamber and the suction chamber. This moves the
lubricant oil from the crank chamber into the suction chamber to
prevent an excessive temperature increase. As a result, the
compressor maintains lubricating performance by means of lubricant
oil and exhibits improved durability brought about by a shaft
sealing device.
[0007] However, in the conventional compressor, the valve chamber
extends from the front surface of the cylinder block, which faces
the crank chamber, parallel to the axis of the drive shaft. It thus
becomes difficult for the lubricant oil in the crank chamber to be
drawn into the valve chamber via the front surface of the cylinder
block. This hampers movement of the lubricant oil from the crank
chamber to the suction chamber, thus making it difficult to prevent
a temperature rise. To solve this problem, the cross-sectional flow
passage area of the valve chamber may be increased. However, this
promotes movement of blow-by gas to enter the suction chamber
through the valve chamber and causes power loss, which decreases
efficiency of the compressor.
[0008] Also, the valve chamber extending parallel to the axis of
the drive shaft complicates machining and assembly of components,
thus increasing the manufacturing costs.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an objective of the present invention to
provide a swash plate type variable displacement compressor capable
of preventing a temperature rise in the compressor while minimizing
power loss and decreasing the manufacturing costs.
[0010] To achieve the foregoing objective and in accordance with
one aspect of the present invention, a swash plate type variable
displacement compressor is provided that includes a housing, a
drive shaft, a swash plate, a piston, a movement conversion
mechanism, and a displacement control mechanism. The housing has a
cylinder bore, a suction chamber, a discharge chamber, and a crank
chamber. The drive shaft is rotatably supported by the housing and
exposed in the crank chamber. The swash plate is supported by the
drive shaft in the crank chamber such that the inclination angle of
the swash plate is changeable. The piston is received in the
cylinder bore in a manner reciprocally movable. The movement
conversion mechanism is arranged between the swash plate and the
piston to convert swinging of the swash plate to reciprocation of
the piston. The displacement control mechanism is adapted for
adjusting displacement using pressure in the crank chamber. The
housing includes a peripheral wall that surrounds the crank chamber
in a circumferential direction with respect to the axis of the
drive shaft and has an outer surface and an inner surface. The
peripheral wall includes a valve chamber recessed radially inward
from the outer surface of the peripheral wall, a first oil
discharge passage that has an opening in the inner surface of the
peripheral wall and allows communication between the crank chamber
and the valve chamber, and a second oil discharge passage that
allows communication between the valve chamber and the suction
chamber. A temperature sensitive member, which deforms in
correspondence with the temperature in the crank chamber, is
arranged in the valve chamber. A valve body supported by the
temperature sensitive member is located in the valve chamber. When
the temperature in the crank chamber exceeds a predetermined value
to deform the temperature sensitive member and move the valve body,
communication between the first oil discharge passage and the
second oil discharge passage is permitted through the valve
chamber.
[0011] Other aspects and advantages of the present 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
[0012] 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:
[0013] FIG. 1 is a longitudinal cross-sectional view showing a
compressor according to a first embodiment of the present
invention;
[0014] FIG. 2 is an enlarged cross-sectional view showing a main
portion of the compressor of the first embodiment in a state where
the temperature in the crank chamber is lower than a predetermined
value;
[0015] FIG. 3 is an enlarged cross-sectional view showing the main
portion of the compressor of the first embodiment in a state where
the temperature in the crank chamber is higher than the
predetermined value;
[0016] FIG. 4 is an enlarged cross-sectional view showing a main
portion of the compressor of the first embodiment in a state where
a drive shaft rotates at a low speed;
[0017] FIG. 5 is an enlarged cross-sectional view showing a main
portion of the compressor of the first embodiment in a state where
the drive shaft rotates at a high speed; and
[0018] FIG. 6 is a lateral cross-sectional view showing a
compressor according to a second embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Swash plate type variable displacement compressors according
to first and second embodiments of the present invention will now
be described with reference to the attached drawings.
First Embodiment
[0020] As shown in FIG. 1, a swash plate type variable displacement
compressor 1 according to the first embodiment is connected to a
check valve 2, a condenser 3, an expansion valve 7, an evaporator
9, and a pipe 56 for connecting the aforementioned components
together. The compressor 1 thus forms part of an air conditioner
for a vehicle. The compressor 1 is a clutchless compressor driven
by an engine 6 of the vehicle without employing an electromagnetic
clutch.
[0021] The compressor 1 includes a housing having a cylinder block
10, a front housing member 12, and a rear housing member 14. The
cylinder block 10 has a plurality of cylinder bores 10a, which are
parallel to the axis O of a drive shaft 16 and extend through the
cylinder block 10. The left side in FIG. 1 corresponds to the front
side of the compressor 1, and the right side of the drawing
corresponds to the rear side of the compressor 1.
[0022] The rear housing member 14 has a suction chamber 20 and a
discharge chamber 22, which communicate with the cylinder bores 10a
through a valve unit 18. Broadly known suction and discharge valve
mechanisms are formed in the valve unit 18. The cylinder bores 10a
communicate with the suction chamber 20 through the suction valve
mechanism. The cylinder bores 10a also communicate with the
discharge chamber 22 through the discharge valve mechanism. The
suction chamber 20 is arranged at the center of the rear housing
member 14 and the discharge chamber 22 is formed in an outer
peripheral portion of the rear housing member 14. The front housing
member 12 and the cylinder block 10 form a crank chamber 24. A
shaft hole 12a and a shaft hole 10b are formed in the front housing
member 12 and the cylinder block 10, respectively. A shaft sealing
device 28 is arranged in the shaft hole 12a. The shaft sealing
device 28 is formed of rubber. A plain bearing 30 is mounted in the
shaft hole 10b. A rear chamber 10c, which communicates with the
shaft hole 10b, is formed at the center of the rear end of the
cylinder block 10. The rear chamber 10c faces the valve unit
18.
[0023] The drive shaft 16 is rotatably supported by the front
housing member 12 and the cylinder block 10. One end of the drive
shaft 16 is exposed from the front housing member 12 and a middle
portion of the drive shaft 16 is in the crank chamber 24. A
non-illustrated pulley is connected to the drive shaft 16. The
drive shaft 16 is driven in a clutchless manner by the engine 6
through a belt wound around the pulley. Each of the cylinder bores
10a accommodates a piston 32 and allows the piston 32 to
reciprocate. Each one of the pistons 32 forms a compression chamber
in the associated one of the cylinder bores 10a.
[0024] A lug plate 34, which receives compression reactive force,
is fixed to the drive shaft 16 in the crank chamber 24. A thrust
bearing 36 and a plain bearing 38 are located between the lug plate
34 and the front housing member 12. A swash plate 40 is mounted
around the drive shaft 16 and has a changeable inclination angle
with respect to an imaginary plane perpendicular to the drive shaft
16. The lug plate 34 has a hinge portion 34a, which projects toward
the swash plate 40. A hinge portion 40a is formed in the swash
plate 40 and projects toward the lug plate 34. The hinge portions
34a, 40a form a link mechanism 42. A pressing spring 44 is arranged
between the lug plate 34 and the swash plate 40 to urge the lug
plate 34 and the swash plate 40 apart from each other.
[0025] A pair of front and rear shoes 46 is mounted between the
swash plate 40 and each of the pistons 32. Specifically, the front
shoe 46 is arranged between the front surface of the swash plate 40
and the front seating surface of each piston 32 and the rear shoe
46 is located between the rear surface of the swash plate 40 and
the rear seating surface of the piston 32. Each of the shoes 46 has
a substantially semispherical shape. The shoes 46 form a movement
conversion mechanism.
[0026] The cylinder block 10 and the valve unit 18 have a bleed
passage 11, which has an opening in the front surface of the
cylinder block 10 facing the crank chamber 24 and extends parallel
to the axis O to allow communication between the crank chamber 24
and the suction chamber 20. The cylinder block 10, the valve unit
18, and the rear housing member 14 have supply passages 52a, 52b,
through which the crank chamber 24 communicates with the discharge
chamber 22.
[0027] The rear housing member 14 accommodates a displacement
control valve 48. The displacement control valve 48 is connected to
the suction chamber 20 through a detection passage 50 and allows
communication between the suction chamber 20 and the crank chamber
24 through the supply passages 52a, 52b. The displacement control
valve 48 changes the opening degrees of the supply passages 52a,
52b by detecting the pressure in the suction chamber 20, thus
varying displacement of the compressor 1. A known valve body and
valve seat (neither is shown) are arranged in the displacement
control valve 48. The space between the valve body and the valve
seat functions as a restriction.
[0028] The front housing member 12 has a peripheral wall 121, which
is located in an outer peripheral zone of the crank chamber 24 and
surrounds the crank chamber 24 in a circumferential direction about
the axis O. A bulging portion 121a and a bulging portion 14a, which
bulge radially outward, are formed in a portion of the peripheral
wall 121 and a portion of the rear housing member 14, respectively.
The bulging portion 121a and the bulging portion 14a have an
attachment leg 121b and an attachment leg 14b, respectively, to fix
the compressor 1.
[0029] With reference to FIGS. 2 and 3, the bulging portion 121a
has a valve chamber 80, which is recessed radially inward from an
outer surface 121c of the bulging portion 121a with respect to the
axis O. The valve chamber 80 includes a large diameter chamber 80a
and a small diameter chamber 80b. The large diameter chamber 80a is
arranged at the side corresponding to the outer surface 121c, which
is the radially outer side. The small diameter chamber 80b is
formed coaxially and integrally with the large diameter chamber
80a. The small diameter chamber 80b is located at the side
corresponding to an inner surface 121d of the peripheral wall 121,
which is the radially inner side. The diameter of the small
diameter chamber 80b is smaller than the diameter of the large
diameter chamber 80a.
[0030] The inner surface 121d has a cylindrical surface 121e, which
extends parallel to the axis O. The crank chamber 24 and the small
diameter chamber 80b communicate with each other through a first
oil discharge passage 81, which has an opening in the cylindrical
surface 121e and extends perpendicular to the axis O.
[0031] The small diameter chamber 80b communicates with a first
hole 82a, which is formed in the peripheral wall 121 and extends
parallel to the axis O. As illustrated in FIG. 1, the first hole
82a communicates with a second hole 82b, which is formed in the
cylinder block 10 and extends parallel to the axis O. The second
hole 82b communicates with a third hole 82c extending through the
valve unit 18. The third hole 82c communicates with the suction
chamber 20 through a fourth hole 82d, which is formed in the rear
housing member 14. The first, second, third, and fourth holes 82a,
82b, 82c, and 82d form a second oil discharge passage 82.
[0032] With reference to FIGS. 2 and 3, a casing 91 is received in
the large diameter chamber 80a of the valve chamber 80 and fixed
using a snap ring 92. An O-ring 93 is arranged in the outer
peripheral surface of the casing 91. A valve body chamber 91a,
which is coaxial with the small diameter chamber 80b, is formed in
the casing 91 at the side facing the small diameter chamber 80b. A
bimetal member chamber 91b is arranged around and formed integrally
with the valve body chamber 91a. The bimetal member chamber 91b
accommodates a bimetal member 94 serving as a temperature sensitive
member in a deformable manner. A valve body 95 is received in the
small diameter chamber 80b and the valve body chamber 91a.
[0033] The valve body 95 is configured by a small diameter portion
95a arranged at the side facing the first oil discharge passage 81
and a large diameter portion 95b having a diameter greater than the
diameter of the small diameter portion 95a. The bimetal member 94
is held in contact with the step between the small diameter portion
95a and the large diameter portion 95b. The small diameter portion
95a of the valve body 95 has an inner end surface that faces the
first oil discharge passage 81, and the inner end surface functions
as a valve portion for selectively opening and closing the first
oil discharge passage 81. A recess 95e is formed in the inner end
surface of the small diameter portion 95a. A part in the small
diameter chamber 80b that faces the inner end surface of the small
diameter portion 95a serves as a valve seat.
[0034] A spring seat 95c is formed in the outer end surface of the
large diameter portion 95b in a recessed manner. A compression
spring 96 serving as an urging member is arranged between the inner
bottom surface of the spring seat 95c and the bottom surface of the
valve body chamber 91a. The valve body 95 has a communication hole
95d, through which the small diameter chamber 80b communicates with
the spring seat 95c. The casing 91, the valve body 95, the bimetal
member 94, and the compression spring 96 form a temperature
sensitive on-off valve 90.
[0035] As illustrated in FIG. 1, the drive shaft 16 has a first
hole 62 and a second hole 64, each of which extends in a radial
direction. The drive shaft 16 also has a communication hole 66,
which extends in the axial direction, or, in other words, coaxially
with the axis O, to allow communication between the first hole 62
and the second hole 64. The drive shaft 16 further includes an
outlet hole 68, which extends coaxially with the communication hole
66 from the rear end of the second hole 64 communicating with the
communication hole 66 to the rear end of the drive shaft 16. The
boundary between the communication hole 66 and the outlet hole 68
is an opening degree regulation port 68a (see FIGS. 4 and 5).
[0036] The first hole 62 extends from the axis O to the outer
peripheral surface of the drive shaft 16 at a position between the
lug plate 34 and the front housing member 12 such that the length
of the first hole 62 corresponds to the radius of the drive shaft
16. The front housing member 12 has an oil guide groove 12b, which
extends from the outer peripheral zone of the crank chamber 24 to a
position between the front housing member 12 and the lug plate 34,
reaching the thrust bearing 36. The front housing member 12 also
includes an oil guide hole 12c, which communicates with the oil
guide groove 12b and reaches the plain bearing 38 and the shaft
sealing device 28. The oil guide hole 12c reaches the shaft sealing
device 28 and communicates with the shaft sealing device 28 in the
shaft hole 12a.
[0037] The second hole 64 is formed between the lug plate 34 and
the swash plate 40 at a position rearward to the first hole 62 and
extends through the drive shaft 16. As illustrated in FIGS. 4 and
5, the second hole 64 has a valve seat 64c, a first radial hole
64a, and a second radial hole 64b. The valve seat 64c is formed in
an outer peripheral portion of the drive shaft 16. The first radial
hole 64a extends from the valve seat 64c and through the drive
shaft 16, communicating with the crank chamber 24. The second
radial hole 64b extends from an opposite outer peripheral portion
of the drive shaft 16 toward the first radial hole 64a in a manner
extending through the drive shaft 16 and communicates with the
crank chamber 24. The diameter of the second radial hole 64b is
substantially equal to the diameter of the first radial hole 64a.
The first radial hole 64a and the second radial hole 64b
communicate with each other, with a spring seat 64d formed between
the first radial hole 64a and the second radial hole 64b.
[0038] The valve seat 64c is formed around the first radial hole
64a. In the second hole 64, the first radial hole 64a and the
second radial hole 64b communicate with the outlet hole 68 at the
opening degree regulation port 68a. The first radial hole 64a has a
first opening 64e, which communicates with the opening degree
regulation port 68a and extends to the crank chamber 24 through the
valve seat 64c. The second radial hole 64b includes a second
opening 64f, which communicates with the opening degree regulation
port 68a and extends to the crank chamber 24. With reference to
FIG. 1, the second opening 64f is located at the opposite side to
the hinge portion 34a of the lug plate 34 with respect to the axis
O of the drive shaft 16.
[0039] The second hole 64 receives a centrifugal on-off valve 70.
As illustrated in FIGS. 4 and 5, the centrifugal on-off valve 70
faces the first opening 64e, rather than the axis O of the drive
shaft 16. The centrifugal on-off valve 70 is configured by a valve
body 72, a mass body 74, a joint bar 76, and a spring 78. The valve
body 72 can be seated on the valve seat 64c. The joint bar 76 joins
the valve body 72 and the mass body 74 together such that the valve
body 72 is movable. The spring 78 urges the valve body 72 to open
the first opening 64e. The mass body 74 is located closer to the
second opening 64f than the axis O of the drive shaft 16 and
capable of changing the opening degree of the opening degree
regulation port 68a. The valve body 72 is received in the first
radial hole 64a. The mass body 74 is accommodated in the second
radial hole 64b. The valve body 72 and the joint bar 76 are both
formed of a material lighter than the material of the mass body 74.
The spring 78 is arranged between the valve body 72 and the spring
seat 64d.
[0040] With reference to FIG. 1, the rear end of the drive shaft 16
projects into the rear chamber 10c. A tubular spacer 60 is engaged
with the outer peripheral surface of the rear end of the drive
shaft 16. The spacer 60 makes sliding contact with the valve unit
18 and urges the drive shaft 16 forward. The valve unit 18 has a
restriction hole 18a, which extends through the valve unit 18 and
allows communication between the space in the spacer 60 and the
suction chamber 20.
[0041] The oil guide groove 12b, the oil guide hole 12c, the first
hole 62, the second hole 64, the communication hole 66, the outlet
hole 68, the restriction hole 18a, and the centrifugal on-off valve
70 form a centrifugal oil discharge valve mechanism. The bleed
passage 11, the supply passages 52a, 52b, the detection passage 50,
and the displacement control valve 48 form a displacement control
mechanism.
[0042] In the rear housing member 14, the check valve 2 is arranged
downstream to the discharge chamber 22. The pipe 56 is connected to
an outlet port 54b, which is downstream to the check valve 2. The
pipe 56 extends through the condenser 3, the expansion valve 7, and
the evaporator 9 and is connected to the suction chamber 20. The
compressor 1, the condenser 3, the expansion valve 7, the
evaporator 9, and the pipe 56 form a refrigeration circuit.
Circulating refrigerant, which is prepared by mixing lubricant oil
with refrigerant, is sealed in the refrigeration circuit.
[0043] In the air conditioner for a vehicle, which is configured as
described above, the displacement control valve 48 adjusts the
pressure in the crank chamber 24 of the compressor 1 based on the
pressure in the suction chamber 20, thus changing the angle between
the swash plate 40 and an imaginary plane that is perpendicular to
the drive shaft 16. This varies the displacement of the compressor
1.
[0044] When the compressor 1 is in OFF operation, in which the
compressor 1 continues its operation at the minimum displacement,
the inclination angle of the swash plate 40 is the minimum. This
substantially prevents refrigerant circulation in an external
refrigeration circuit outside the compressor 1. Meanwhile,
centrifugal force causes splashing of the lubricant oil adhered to
components including the drive shaft 16 and the swash plate 40.
This will thoroughly lubricate the inner surface 121d of the
peripheral wall 121, which is the outer peripheral zone of the
crank chamber 24. The lubricant oil in the crank chamber 24 is then
easily introduced into the first oil discharge passage 81, which
has an opening in the inner surface 121d. Accordingly, for example,
when the vehicle travels at a high speed and lubricant oil is
sheared intensely and heated in the crank chamber 24, the heated
lubricant oil is sent through the first oil discharge passage 81 to
act on the bimetal member 94 quickly.
[0045] Particularly, in the compressor 1, the inner surface 121d
has the cylindrical surface 121e extending parallel to the axis O
of the drive shaft 16 and the first oil discharge passage 81 has
the opening in the cylindrical surface 121e. This further reliably
sends lubricant oil from the crank chamber 24 into the first oil
discharge passage 81 through centrifugal force.
[0046] When the temperature in the small diameter chamber 80b
exceeds a predetermined value, the bimetal member 94 is raised from
the valve seat against the urging force produced by the compression
spring 96, as illustrated in FIG. 3. The compression spring 96
prevents unstable movement of the valve body 95. In this state, the
valve body 95 causes communication between the first oil discharge
passage 81 and the second oil discharge passage 82. The crank
chamber 24 thus communicates with the suction chamber 20. This
rapidly sends lubricant oil from the crank chamber 24 to the
suction chamber 20 via the valve chamber 80 and the second oil
discharge passage 82, thus preventing a temperature rise.
[0047] Particularly, in the compressor 1, if the vehicle runs at a
high speed, for example, and the drive shaft 16 rotates at a speed
exceeding a predetermined value, intense centrifugal force
separates the mass body 74 of the centrifugal on-off valve 70 from
the axis of the drive shaft 16 against the urging force of the
spring 78, as illustrated in FIG. 5, regardless of the inclination
angle of the swash plate 40, or, in other words, regardless of
whether the compressor 1 is in OFF operation or ON operation. This
causes the valve body 72 to decrease the opening degree of the
first opening 64e. As the rotation speed of the drive shaft 16
increases, the valve body 72 becomes seated on the valve seat 64c,
thus decreasing the opening degree of the second hole 64, which
communicates with the opening degree regulation port 68a. This
increases the opening degree of the opening degree regulation port
68a with respect to the first hole 62 illustrated in FIG. 1. In
other words, the centrifugal on-off valve 70 increases the opening
degree of the opening degree regulation port 68a with respect to
the first hole 62 and decreases the opening degree of the second
hole 64. The outer peripheral zone of the crank chamber 24 is a
lubricant-rich zone and lubricant oil is sent from the zone to the
first hole 62 through the oil guide groove 12b and the oil guide
hole 12c. At this stage, the lubricant oil is guided to the first
hole 62 via the shaft sealing device 28. As a result, a great
amount of lubricant oil is supplied to the shaft sealing device 28,
thus improving durability of the rubber used in the shaft sealing
device 28.
[0048] In this state, the amount of lubricant oil in the
circulating refrigerant sent to the refrigeration circuit external
to the compressor 1 increases. However, since the pistons 32
reciprocate at a high speed, refrigerating performance is prevented
from deteriorating.
[0049] As a result, the compressor 1 maintains lubricating
performance by means of lubricant oil and exhibits enhanced
durability through the shaft sealing device 28 compared to
conventional techniques.
[0050] If the temperature in the small diameter chamber 80b drops
to a value less than the predetermined value, the bimetal member 94
yields to the urging force of the compression spring 96 and
operates to seat the valve body 95 on the valve seat. Also in this
case, the compression spring 96 prevents unstable movement of the
valve body 95. In this state, the valve body 95 prohibits
communication between the first oil discharge passage 81 and the
second oil discharge passage 82. The crank chamber 24 is thus
prevented from communicating with the suction chamber 20. This
blocks movement of lubricant oil from the crank chamber 24 to the
suction chamber 20 via the valve chamber 80 and the second oil
discharge passage 82.
[0051] Particularly, in the compressor 1, the valve body 95 has the
recess 95e, which accommodates foreign matter when the valve body
95 is seated, thus preventing insufficient seating.
[0052] In the compressor 1, if the vehicle travels at a low speed,
for example, and the drive shaft 16 rotates at a speed lower than
the predetermined value, small centrifugal force causes the mass
body 74 of the centrifugal on-off valve 70 to yield to the urging
force of the spring 78 and approach the axis O of the drive shaft
16, as illustrated in FIG. 4, regardless of whether the compressor
1 is in OFF operation or ON operation. The valve body 72 thus
increases the opening degree of the first opening 64e. As the
rotation speed of the drive shaft 16 drops, the mass body 74
contacts the backside of the spring seat 64d, thus blocking a half
area of the opening degree regulation port 68a. This increases the
opening degree of the second hole 64 communicating with the opening
degree regulation port 68a and decreases the opening degree of the
opening degree regulation port 68a with respect to the first hole
62 illustrated in FIG. 1. An inner peripheral zone of the crank
chamber 24, which is close to the drive shaft 16, contains a small
amount of lubricant oil. Circulating refrigerant thus containing
less lubricant oil is sent from the zone to the second hole 64. The
second hole 64, which has a greater opening degree, thus introduces
the circulating refrigerant with less lubricant oil from the crank
chamber 24 to the suction chamber 20 via the outlet hole 68 and the
restriction hole 18a. This decreases the amount of lubricant oil in
the circulating refrigerant sent into the refrigeration circuit
external to the compressor 1, thus ensuring high refrigerating
performance.
[0053] At this stage, the amount of lubricant oil increases in the
crank chamber 24. However, components including the swash plate 40
simply stir the lubricant oil at a low speed. This substantially
prevents a temperature increase in the lubricant oil, thus
restricting viscosity decrease in the lubricant oil. As a result,
sliding portions are maintained in a desirably lubricated
state.
[0054] Since the compressor 1 operates in the above-described
manner, it is unnecessary to have excessively great cross-sectional
flow passage areas for the first oil discharge passage 81, the
valve chamber 80, and the second oil discharge passage 82. The
bleed passage 11 does not have to have an excessively great
cross-sectional flow passage area, either. As a result, blow-by gas
is prevented from entering the suction chamber 20 via the first oil
discharge passage 81, the valve chamber 80, and the second oil
discharge passage 82 or through the bleed passage 11. This
decreases power loss in the compressor 1, thus improving efficiency
of the compressor 1.
[0055] Further, in the compressor 1, the valve chamber 80 is shaped
in a manner recessed radially inward from the outer surface 121c.
The first oil discharge passage 81 extends from the valve chamber
80 and has the opening in the inner surface 121d of the peripheral
wall 121. This configuration facilitates machining of the front
housing member 12 and mounting of the bimetal member 94 and the
valve body 95. As a result, the manufacturing cost is
decreased.
[0056] Accordingly, the compressor 1 is capable of preventing a
temperature rise while minimizing power loss, as well as decreasing
the manufacturing costs.
[0057] The compressor 1 has the bulging portion 121a, which is
formed in the peripheral wall 121 and extends radially outward. The
attachment leg 121b and the valve chamber 80 are formed in the
bulging portion 121a. Since the valve chamber 80 is inside the
bulging portion 121a, the valve chamber 80 is prevented from
interference by peripheral devices of the vehicle. Also, since the
bulging portion 121a, in which the valve chamber 80 is arranged,
extends integrally from the attachment leg 121b, it is unnecessary
to form an additional bulging portion exclusively used for the
valve chamber 80. The housing is thus prevented from having a
complicated outline and increased weight.
Second Embodiment
[0058] In the compressor according to the second embodiment of the
invention, the front housing member 12, the cylinder block 10, and
the rear housing member 14 are fastened together using bolts 13, as
illustrated in FIG. 6. The cylinder block 10 has bolt holes 83,
through which the corresponding bolts 13 are passed. In the
compressor, each of the bolt holes 83 functions as a second oil
discharge passage.
[0059] The bulging portion 121a is formed in the peripheral wall
121 of the front housing member 12. A suction joint 122 and the
valve chamber 80 are formed in the bulging portion 121a. The
suction joint 122 communicates with the suction chamber 20 in the
rear housing member 14 and is connected to the evaporator 9 through
a pipe. The other portions of the compressor according to the
second embodiment are configured identically with the corresponding
portions of the compressor 1 according to the first embodiment.
[0060] The compressor of the second embodiment makes it unnecessary
to form a second bleed passage particularly and thus further
decreases the manufacturing cost. The compressor of the second
embodiment has the same advantages as the advantages brought about
by the first embodiment.
[0061] The first and second embodiments of the present invention
have been described. However, the invention is not restricted to
the first or second embodiment but may be embodied as modified as
needed without departing from the gist of the invention.
[0062] For example, in the compressor of the second embodiment, a
discharge joint and the valve chamber 80 may be formed in the
bulging portion 121a of the front housing member 12. The discharge
joint communicates with the discharge chamber 22 in the rear
housing member 14 and is connected to the check valve 2 through a
pipe.
[0063] In each of the above embodiments, in place of the bimetal
member 94, a shape-memory alloy may be used as the temperature
sensitive member.
[0064] 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 and equivalence of the appended claims.
* * * * *