U.S. patent application number 11/800892 was filed with the patent office on 2007-11-15 for variable displacement compressor.
Invention is credited to Yoshinori Inoue, Masaki Ota, Masanori Sonobe, Tomoji Tarutani.
Application Number | 20070264131 11/800892 |
Document ID | / |
Family ID | 38353880 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070264131 |
Kind Code |
A1 |
Ota; Masaki ; et
al. |
November 15, 2007 |
Variable displacement compressor
Abstract
A variable displacement compressor comprises a flange, a movable
body, and a detection sensor. The flange is joined to a housing and
forms a flange passage for connecting a refrigerant passage and an
external refrigerant circuit. The movable body is movably disposed
in the flange, is movable according to a flow rate of refrigerant
gas in the flange passage, and has a magnet. The detection sensor
is fixed to or in the flange for detecting magnetic flux density of
the magnet. The flow rate of the refrigerant gas is detected based
on the magnetic flux density detected by the detection sensor. The
flange is attachable to and detachable from the housing in a state
where the flange is provided with the movable body and the
detection sensor.
Inventors: |
Ota; Masaki; (Kariya-shi,
JP) ; Tarutani; Tomoji; (Kariya-shi, JP) ;
Sonobe; Masanori; (Kariya-shi, JP) ; Inoue;
Yoshinori; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
38353880 |
Appl. No.: |
11/800892 |
Filed: |
May 7, 2007 |
Current U.S.
Class: |
417/43 |
Current CPC
Class: |
F04B 39/0072 20130101;
F04B 27/1804 20130101; F04B 2205/09 20130101; F04B 27/1081
20130101; F04B 2027/1854 20130101; F04B 2205/04 20130101 |
Class at
Publication: |
417/43 |
International
Class: |
F04B 49/00 20060101
F04B049/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 2006 |
JP |
P2006-133838 |
Claims
1. A variable displacement compressor comprising: a housing having
a cylinder bore and a crank chamber; a refrigerant passage formed
in the housing, the refrigerant passage including a
suction-pressure region and a discharge-pressure region; a piston
disposed in the cylinder bore; a swash plate disposed in the crank
chamber, wherein an inclination angle of the swash plate is
controlled according to differential pressure between a pressure in
the crank chamber and a pressure in the cylinder bore across the
piston, and the pressure in the crank chamber is adjusted through a
supply passage for supplying the pressure in the discharge-pressure
region to the crank chamber and a bleed passage for releasing the
pressure in the crank chamber to the suction-pressure region; a
flange joined to the housing, the flange forming a flange passage
for connecting the refrigerant passage and an external refrigerant
circuit; a movable body movably disposed in the flange, the movable
body being movable according to a flow rate of refrigerant gas in
the flange passage, the movable body having a magnet; and a
detection sensor fixed to or in the flange for detecting magnetic
flux density of the magnet, wherein the flow rate of the
refrigerant gas is detected based on the magnetic flux density
detected by the detection sensor, and the flange is attachable to
and detachable from the housing in a state where the flange is
provided with the movable body and the detection sensor.
2. The variable displacement compressor according to claim 1,
wherein a heat insulating member is provided between the flange and
the housing.
3. The variable displacement compressor according to claim 2,
wherein the heat insulating member is a gasket which is formed of a
heat insulating material.
4. The variable displacement compressor according to claim 1,
wherein a throttle is provided in the flange passage, and the
movable body is movable by differential pressure between pressures
in the flange passage upstream of and downstream of the
throttle.
5. The variable displacement compressor according to claim 4,
wherein the throttle is formed by a partition of the flange.
6. The variable displacement compressor according to claim 1,
wherein the flange passage includes an accommodation chamber for
disposing the movable body therein.
7. The variable displacement compressor according to claim 1,
wherein the detection sensor is fixed to the flange through a
mounting member so that the detection sensor is spaced at a
predetermined clearance from the flange.
8. The variable displacement compressor according to claim 7,
wherein the mounting member is formed of a heat insulating
material.
9. The variable displacement compressor according to claim 1,
wherein the detection sensor is fixed in the flange through a
mounting member.
10. The variable displacement compressor according to claim 9,
wherein the mounting member is formed of a heat insulating
material.
11. The variable displacement compressor according to claim 1,
wherein the flange is formed of a heat insulating material.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a variable displacement
compressor which includes a body movable in response to a change of
flow rate of refrigerant gas and which detects magnetic flux
density of a magnet in the body, thereby detecting the flow rate of
refrigerant.
[0002] There has been known a variable displacement compressor
(hereinafter referred to merely as compressor) in which the
inclination angle of a swash plate is varied by adjusting the
opening degree of a displacement control valve, thus the
displacement of the compressor being changed.
[0003] In a conventional compressor, however, a flow rate changing
command is merely sent in controlling and changing the
displacement, and actual displacement cannot be known. As the
displacement is changed, the power of the compressor is varied, but
it is estimated by a calculated value based on a flow rate command
value.
[0004] Thus, the actual displacement is different from the
calculated value until the displacement reaches the commanded value
after the flow rate changing command has been sent. Especially,
when the compressor compresses gas at start-up of a vehicle engine,
the above difference is increased. Thus, it takes a longer time for
the vehicle interior temperature to reach desired level, and a
greater load acts on the vehicle engine. Namely, appropriate
control is hard to perform under this situation (cf. Japanese
Patent Application Publication No. 2002-332962).
[0005] If the flow rate of the refrigerant gas in the compressor is
accurately detected, the actual displacement and the actual power
of the compressor can be known, which is very useful. For the above
purpose, an electric flow meter which is disclosed in Japanese
Utility Model Application Publication No. 63-177715 may be used for
detecting the flow rate of the refrigerant gas.
[0006] Japanese Utility Model Application Publication No. 63-177715
discloses in FIG. 1 thereof an electric flow meter or an area flow
meter including a main body, a float (or a movable body), and a
guide which is provided to the main body above the float. A magnet
is fixed to the float through a rod which is provided on the upper
surface of the float. As the float is moved vertically, the magnet
is moved vertically in the guide. The magnetic field of the magnet
is formed perpendicularly to the film of a Hall element (or a
detection sensor) which is provided adjacent to the outer wall of
the guide. The magnet is moved in parallel with the film of the
Hall element. The Hall element is connected to a controller.
[0007] Japanese Utility Model Application Publication No. 63-177715
also discloses in FIG. 2 thereof an electric flow meter including a
differential-pressure detector which is connected to high-pressure
and low-pressure introducing passages which are provided on the
front and back sides of an orifice in a flow passage, respectively.
The inside of the detector is divided into two spaces hermetically
by a bellophragm (or a movable body). Pressures in the flow passage
on the front and back sides of the orifice are introduced through
the introducing passages into the divided two space on both sides
of the bellophragm, and a magnet which is provided on the
bellophragm is moved by the differential pressure therebetween. A
Hall element (or a detection sensor) is provided perpendicularly to
the direction in which the magnet is moved, and the magnetic pole
of the magnet faces the Hall element. The Hall element is connected
to a controller.
[0008] Even in the case of applying the electric flow meter of
Japanese Utility Model Application Publication No. 63-177715 to a
compressor, dimensional accuracy of elements for detecting flow
rate varies. Thus, accuracy of detecting flow rate is varied in
each compressor. For enhancing accuracy of flow rate detection,
sufficient refrigerant gas may be made to flow in the compressor
having the electric flow meter, and then the positions of the
magnet and the Hall element may be adjusted and the Hall element
may be calibrated.
[0009] When the electric flow meter of Japanese Utility Model
Application Publication No. 63-177715 is applied merely to a
compressor, however, refrigerant gas is made to flow in the
compressor and the elements for detecting flow rate are adjusted
and calibrated in a state where the movable body and the detection
sensor are installed in the housing of the compressor. Such
processes are troublesome and cannot be automated. In actual
production site for mass-producing compressors, a process of making
refrigerant gas flow in each compressor increases cost and
production time. Thus, the process is impossible to carry out in
the actual production site.
[0010] The present invention which is made in view of the above
problems is directed to a variable displacement compressor
including elements for detecting flow rate which are adjusted and
calibrated easier than conventional ones.
SUMMARY OF THE INVENTION
[0011] An aspect in accordance with the present invention provides
a variable displacement compressor which comprises a housing, a
refrigerant passage, a piston, a swash plate, a flange, a movable
body, and a detection sensor. A housing has a cylinder bore and a
crank chamber. The refrigerant passage is formed in the housing and
includes a suction-pressure region and a discharge-pressure region.
The piston is disposed in the cylinder bore. The swash plate is
disposed in the crank chamber. An inclination angle of the swash
plate is controlled according to differential pressure between a
pressure in the crank chamber and a pressure in the cylinder bore
across the piston, and the pressure in the crank chamber is
adjusted through a supply passage for supplying the pressure in the
discharge-pressure region to the crank chamber and a bleed passage
for releasing the pressure in the crank chamber to the
suction-pressure region. The flange is joined to the housing and
forms a flange passage for connecting the refrigerant passage and
an external refrigerant circuit. The movable body is movably
disposed in the flange, is movable according to a flow rate of
refrigerant gas in the flange passage, and has a magnet. The
detection sensor is fixed to or in the flange for detecting
magnetic flux density of the magnet. The flow rate of the
refrigerant gas is detected based on the magnetic flux density
detected by the detection sensor, and the flange is attachable to
and detachable from the housing in a state where the flange is
provided with the movable body and the detection sensor.
[0012] 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
[0013] 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:
[0014] FIG. 1 is a longitudinal cross-sectional view of a variable
displacement compressor of a first preferred embodiment according
to the present invention;
[0015] FIG. 2 is a cross-sectional view taken along the line A-A in
FIG. 1;
[0016] FIG. 3 is a partially enlarged cross-sectional view of a
flow meter of the first preferred embodiment when a spool is
located its uppermost position;
[0017] FIG. 4 is a partially enlarged cross-sectional view of a
flow meter of the first preferred embodiment when the spool is
located its lowermost position;
[0018] FIG. 5 is views showing adjustment and calibration of the
flow meter; and
[0019] FIG. 6 is a partially enlarged cross-sectional view of a
flow meter of a second preferred embodiment according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The following will describe a variable displacement
compressor (hereinafter referred to merely as compressor) of a
first preferred embodiment according to the present invention with
reference to FIGS. 1 through 5. FIG. 1 shows a schematic view of
the compressor. Referring to FIG. 1, the compressor has a housing
11 including a cylinder block 12, a front housing 13 and a rear
housing 14. The front housing 13 is joined to the front end of the
cylinder block 12. The rear housing 14 is joined to the rear end of
the cylinder block 12. In FIG. 1, the left and right sides
correspond to the front and rear sides, respectively.
[0021] The cylinder block 12 and the front housing 13 cooperate to
define a crank chamber 15 in the housing 11. A drive shaft 16 is
rotatably disposed in the crank chamber 15. The drive shaft 16 is
operatively connected to an engine 17 which is mounted in a vehicle
for rotation with the engine 17. In the first preferred embodiment,
the power of the engine 17 is constantly transmitted to the drive
shaft 16. In other words, the compressor is of a clutchless
type.
[0022] A lug plate 18 is fixed on the drive shaft 16 for rotation
therewith in the crank chamber 15. A swash plate 19 is accommodated
in the crank chamber 15. The swash plate 19 is provided and
supported on the drive shaft 16 with an inclination angle so that
the swash plate 19 is inclinable relative to the axis of the drive
shaft 16 and also slidable relative to the drive shaft 16. A hinge
mechanism 20 is disposed between the lug plate 18 and the swash
plate 19, allowing the swash plate 19 to rotate with the lug plate
18 and the drive shaft 16 and to incline relative to the axis of
the drive shaft 16. The inclination angle of the swash plate 19 is
controlled by a displacement control valve 34 which will be
described later.
[0023] A plurality of cylinder bores 21 are formed in the cylinder
block 12 (only one being shown in FIG. 1). A single-headed piston
22 is reciprocally disposed in each of the cylinder bores 21. Each
piston 22 is engaged with the outer peripheral portion of the swash
plate 19 through a pair of shoes 23. Thus, the rotation of the
swash plate 19 by the rotation of the drive shaft 16 is converted
into reciprocating movement of the pistons 22 through the shoes
23.
[0024] A valve-port assembly 24 is interposed between the cylinder
block 12 and the rear housing 14, and compression chambers 25 are
defined in the cylinder bores 8 on the back side (the right side in
FIG. 1) thereof by the pistons 22 and the valve-port assembly 24. A
suction chamber 26 as a suction-pressure region of the compressor
and a discharge chamber 27 as a discharge-pressure region of the
compressor are defined in the rear housing 14.
[0025] As the piston 22 moves from its top dead center toward its
bottom dead center, refrigerant gas in the suction chamber 26 is
drawn into the compression chamber 25 through a suction port 28 and
a suction valve 29 which are formed in the valve-port assembly 24.
As the piston 22 moves from its bottom dead center toward its top
dead center, the refrigerant drawn in the compression chamber 25 is
compressed to a predetermined pressure and discharged into the
discharge chamber 27 through a discharge port 30 and a discharge
valve 31 which are formed in the valve-port assembly 24.
[0026] A bleed passage 32 which connects the crank chamber 15 to
the suction chamber 26 are formed in the cylinder block 12 and the
valve-port assembly 24 for releasing the pressure in the crank
chamber 15 to the suction chamber 26. A supply passage 33 which
connects the discharge chamber 27 to the crank chamber 15 is formed
in the rear housing 14, the valve-port assembly 24 and the cylinder
block 12 for supplying the pressure in the discharge chamber 27 to
the crank chamber 15. The displacement control valve 34 is arranged
in the supply passage 33 in the rear housing 14.
[0027] The displacement control valve 34 is connected to the
suction chamber 26 through a first pressure-introducing passage 35,
and the opening degree of the displacement control valve 34 is
adjusted based on the pressure in the suction chamber 26. The
pressure in the crank chamber 15 depends on the balance between the
amount of high-pressure refrigerant gas introduced from the
discharge chamber 27 into the crank chamber 15 through the supply
passage 33 and the amount of the refrigerant gas flowing out from
the crank chamber 15 into the suction chamber 26 through the bleed
passage 32. The balance is controlled by adjusting the opening
degree of the displacement control valve 34 of the displacement
control valve 34. The difference between the pressure in the
cylinder bore 21 and the pressure in the crank chamber 15 across
the piston 22 is changed in response to a change of the pressure in
the crank chamber 15, thereby varying the inclination angle of the
swash plate 19 relative to the drive shaft 16. Thus, the compressor
changes the stroke of the piston 22 and hence its displacement.
[0028] As the pressure in the crank chamber 15 falls, the
inclination angle of the swash plate 19 is increased thereby to
increase the displacement of the compressor. The swash plate 19
indicated by the two-dot chain line in FIG. 1 is inclined at its
maximum inclination angle in contact with the lug plate 18. On the
other hand, as the pressure in the crank chamber 15 rises, the
inclination angle of the swash plate 19 is decreased thereby to
reduce the displacement of the compressor. The swash plate 19
indicated by the solid line in FIG. 1 is inclined at its minimum
inclination angle.
[0029] The refrigerant circuit (or refrigeration cycle) of a
vehicle air-conditioner includes the compressor and an external
refrigerant circuit 36 which connects the discharge chamber 27 to
the suction chamber 26. Carbon dioxide or chlorofluorocarbon is
used as refrigerant. The external refrigerant circuit 36 includes a
condenser 37, a receiver tank 38, an expansion valve 39 and an
evaporator 40 which are arranged in this order as viewed from the
discharge chamber 27 toward the suction chamber 26. A pressure
sensor 41 is arranged in the refrigerant passage which connects the
condenser 37 to the receiver tank 38 and adapted to send out
electrical detection signals to an amplifier 45 through a
connecting line 42, a data inputting means 43 and a connecting line
44. The amplifier 45 transmits a displacement-changing command
signal to the displacement control valve 34 through a connection
line 61 for controlling the displacement control valve 34. The
amplifier 45 stores therein data concerning the flow rate of the
refrigerant gas which is sent from a magnetic sensor 60 which will
be described later, various information such as vehicle interior
temperature provided from the data inputting means 43, and data of
the pressure of the refrigerant gas transmitted from the pressure
sensor 41. Further, the amplifier 45 is connected to an engine
controller (not shown).
[0030] A flow meter which is shown in detail in FIGS. 2 through 4
is provided on the upper surface of the cylinder block 12. More
specifically, the flow meter is provided to a flange 46 which is
joined to the upper surface of the cylinder block 12. The flange 46
includes a movable body or a spool 53 which is disposed in the
flange 46, a coil spring 56 as an urging member for urging the
spool 53, and the magnetic sensor 60 which is fixed to the surface
of the flange 46.
[0031] The flange 46 is formed of a metal and detachably joined to
the cylinder block 12 by bolts (not shown). A gasket 47 as a heat
insulating member is interposed between the flange 46 and the
cylinder block 12. The gasket 47 is formed of a heat insulating
material such as rubber or resin so that heat of the housing 11 is
hard to transmit to the flange 46.
[0032] A flange passage is formed in the flange 46 when the flange
46 is joined to the cylinder block 12. As shown in FIG. 2, the
flange passage includes high-pressure and low-pressure spaces 48a
and 48b which is connected to each other through a throttle 52
which is formed by a partition 46a of the flange 46, a flow passage
51 which is in communication with the low-pressure space 48b, an
accommodation chamber 49 which is in communication with the
low-pressure space 48b, and a communication passage 50 which
connects the high-pressure space 48a to the accommodation chamber
49. The high-pressure and low-pressure spaces 48a and 48b are
located upstream of and downstream of the throttle 52,
respectively. The spool 53 is disposed in the accommodation chamber
49 so as to slide therein for a predetermined distance.
[0033] Still referring to FIG. 2, the spool 53 is formed in a
cylindrical shape having an upper large-diameter portion 54 and a
lower small-diameter portion 55. A clearance is formed between the
lower small-diameter portion 55 and the inner wall of the
accommodation chamber 49, and the coil spring 56 is provided in the
clearance for urging the spool 53 upward. The coil spring 56 has a
predetermined spring constant so that the spool 53 is located at
any predetermined position when the spool 53 receives differential
pressure which will be described later. A magnet 57 is embedded in
the upper large-diameter portion 54 of the spool 53. The outer
diameter of the upper large-diameter portion 54 substantially
corresponds to the inner diameter of the accommodation chamber 49,
and a minute clearance is formed between the upper large-diameter
portion 54 of the spool 53 and the accommodation chamber 49 with
such a width that allows sliding movement of the spool 53. An
engaging member 58 having a hole is mounted to the lower end of the
accommodation chamber 49 for supporting the lower ends of the lower
small-diameter portion 55 and the coil spring 56 and preventing the
spool 53 and the coil spring 56 from falling out of the
accommodation chamber 49. The upper end surface of the upper
large-diameter portion 54 is a pressure receiving surface which
receives the pressure in the high-pressure space 48a, and the lower
end surface of the lower small-diameter portion 55 is a pressure
receiving surface which receives the pressure in the low-pressure
space 48b.
[0034] The magnetic sensor 60 as a detection sensor is fixed to the
upper surface of the flange 46 through a mounting member 59 in
facing relation to the magnet 57 of the spool 53 for detecting
magnetic flux density of the magnet 57. The magnetic sensor 60 is
spaced at a predetermined clearance from the flange 46 for
preventing the heat of the housing 11 from being transmitted
directly to the magnetic sensor 60. Further, the mounting member 59
is formed of a heat insulating material such as rubber or resin for
preventing heat of the flange 46 from being transmitted to the
magnetic sensor 60 therethrough.
[0035] The magnetic sensor 60 is connected to the amplifier 45
through a connecting line 65. The amplifier 45 recognizes that the
differential pressure between the high-pressure and low-pressure
spaces 48a and 48b is small based on the output from the magnetic
sensor 60 when the magnet 57 is close to the magnetic sensor 60.
The amplifier 45 recognizes that the differential pressure between
the high-pressure and low-pressure spaces 48a and 48b is large
based on the output from the magnetic sensor 60 when the magnet 57
is distant from the magnetic sensor 60. As shown in FIG. 1, the
high-pressure space 48a formed in the flange 46 is in communication
with the discharge chamber 27 through discharge passages 62 through
64 which are formed in the rear housing 14. Thus, high-pressure
refrigerant gas is supplied from the discharge chamber 27 into the
high-pressure space 48a. As shown in FIG. 2, holes 67 are formed in
the cylinder block 12 for inserting therethrough bolts for joining
the cylinder block 12 and the front and rear housings 13 and
14.
[0036] As constructed above, the high-pressure refrigerant gas
which is supplied into the high-pressure space 48a flows into the
low-pressure space 48b through the throttle 52 under a reduced
pressure. The high-pressure refrigerant gas in the high-pressure
space 48a is also introduced into the accommodation chamber 49
through the communication passage 50. The pressure of the
high-pressure refrigerant gas in the high-pressure space 48a is
received by the upper end surface of the upper large-diameter
portion 54 while the pressure of the low-pressure refrigerant gas
in the low-pressure space 48b is received by the lower end surface
of the lower small-diameter portion 55, thus differential pressure
therebetween acting on the spool 53. The spool 53 is moved
vertically by the differential pressure, accordingly. When the
displacement is changed by the displacement control valve 34, the
amount of the refrigerant gas being discharged from the discharge
chamber 27 is also changed. Thus, the differential pressure acting
on the spool 53 is varied, and the spool 53 is moved upward or
downward in response to the differential pressure. As the
displacement is increased, the differential pressure is increased
to move the spool 53 downward in FIG. 3. In FIG. 4, the spool 53 is
located at its lowermost position when the displacement is
maximum.
[0037] As the spool 53 is moved in response to the differential
pressure, magnetic flux density of the magnet 57 with respect to
the magnetic sensor 60 is changed. The flow rate of refrigerant gas
is known based on the magnetic flux density which is detected by
the magnetic sensor 60. The amplifier 45 calculates the current
displacement of the compressor based on the data of the flow rate
of refrigerant gas which is obtained from the magnetic sensor 60
and performs feedback control of the displacement control valve 34.
Thus, the displacement of the compressor can be appropriately
controlled. In addition, torque of the compressor can be calculated
based on the data of the flow rate of refrigerant gas which is
obtained from the magnetic sensor 60. Thus, the amplifier 45
performs feedback control of the engine controller in response to
the flow rate. Thus, the vehicle engine speed can be appropriately
controlled.
[0038] The following will describe adjustment and calibration of
the flow meter of the compressor of the first preferred embodiment.
In the first preferred embodiment, the flange 46 is provided with
the spool 53, the coil spring 56, the engaging member 58, the
magnetic sensor 60, and the mounting member 59. Thus, elements for
detecting flow rate do not have to be adjusted and calibrated in a
state where the flange 46 is mounted to the housing 11 of the
compressor. For example, the flange 46 is detached from the
compressor, and mounted to a regulator T for the flow meter as
shown in FIG. 5. The regulator T forms a test passage which is
similar to the flange passage of the compressor. Refrigerant gas
required for adjustment and calibration is made to flow in the
regulator T and the flange 46, and the output of the magnetic
sensor 60 is confirmed according to the flow rate of the
refrigerant gas. If the flow rate of refrigerant gas based on the
output of the magnetic sensor 60 is different from the actual flow
rate of the refrigerant gas flowing in the regulator T and the
flange 46, adjustment and calibration are performed on the elements
for detecting flow rate.
[0039] The adjustment includes adjusting the position of the
magnetic sensor 60 with respect to the mounting member 59,
adjusting the urging force of the coil spring 56, and adjusting the
position of the magnet 57 with respect to the spool 53. The
calibration includes calibrating the output of the magnetic sensor
60. In mass-producing compressors, the flange 46 does not have to
be mounted to each compressor when the adjustment and the
calibration are performed using the regulator T The compressor of
the first preferred embodiment offers the following advantageous
effects.
(1) The flange 46 is provided with the spool 53, the coil spring
56, the engaging member 58, the magnetic sensor 60 and the mounting
member 59 which form the flow meter. When the flange 46 is handled
independently of the housing 11 of the compressor, each element of
the flow meter does not have to be adjusted and calibrated in a
state where the flange 46 is mounted to the housing 11 of the
compressor. Thus, the adjustment and the calibration of the
elements of the flow meter of the compressor can be performed
easier than those in the conventional compressor. (2) In production
process, the flange 46 which is provided with the elements for
detecting flow rate is handled independently of the housing 11 of
the compressor. Thus, the adjustment and the calibration of the
elements for detecting flow rate can be automated. (3) The gasket
47 which is formed of the heat insulating material is interposed
between the flange 46 and the housing 11, so that the heat of the
housing 11 is hard to transmit to the flange 46. As a result,
adverse effects of heat on the magnetic sensor 60 is suppressed. In
addition, the mounting member 59 which holds the magnetic sensor 60
is formed of the heat insulating material, and the magnetic sensor
60 is spaced at the predetermined clearance from the flange 46.
Thus, heat transmission from the housing 11 to the magnetic sensor
60 is suppressed further.
[0040] The following will describe a compressor of a second
preferred embodiment with reference to FIG. 6. The second preferred
embodiment differs from the first preferred embodiment in structure
of mounting the magnetic sensor to the flange. The basic structure
of the second preferred embodiment is similar to that of the first
preferred embodiment, and, therefore, the description for the
identical components will not be reiterated.
[0041] Referring to FIG. 6, a flange 71 has a flange passage
including a high-pressure chamber 72, a communication passage 74, a
flow passage 75, and a branch passage 76 which is in communication
with an accommodation chamber 73 which is formed in the flange 71
and connected to the communication passage 74. The flange 71 has a
space 85 which is formed above the accommodation chamber 73, and a
magnetic sensor 84 is disposed in the space 85 through a mounting
member 83 which is formed of a heat insulating material. A C-ring
82 is disposed in the space 85 below the mounting member 83 for
preventing the mounting member 83 and the magnetic sensor 84 from
falling out of the space 85. A movable body or a spool 77 is
disposed in the accommodation chamber 73 and has an upper
small-diameter portion 78, a lower large-diameter portion 79, and a
magnet 81. The spool 77 is urged by a coil spring 80 downwardly
into the communication passage 74. When differential pressure does
not act on the spool 77, the spool 77 is in contact with the lower
portion of the inner wall of the communication passage 74. The
amplifier recognizes that the differential pressure between the
high-pressure chamber 72 and the flow passage 75 is large based on
the output from the magnetic sensor 60 when the magnet 57 is close
to the magnetic sensor 60. The amplifier recognizes that the
differential pressure between the high-pressure chamber 72 and the
flow passage 75 is small based on the output from the magnetic
sensor 60 when the magnet 57 is distant from the magnetic sensor
60. The second preferred embodiment offers the same advantageous
effects as the first preferred embodiment.
[0042] The present invention is not limited to the first through
fourth preferred embodiments described above, but it may be
practiced in various alternative embodiments, as exemplified
below.
[0043] In the first and second preferred embodiments described
above, the movable body is slid or moved vertically. Alternatively,
the movable body may be slid or moved in any direction such as
width direction or longitudinal direction of the compressor. In
such a case, the direction in which the movable body is slid or
moved may be set as a direction corresponding to the position where
the flange is mounted to the housing or may be set irrespective of
the mounted position of the flange.
[0044] In the first and second preferred embodiments described
above, the flow rate of refrigerant gas on the discharge side is
detected. Alternatively, the flow rate of refrigerant gas on the
suction side may be detected. For example, a flange is disposed
between the suction chamber of the compressor and the external
refrigerant circuit, and provided with a movable body, a magnetic
sensor and the like for detecting the flow rate of refrigerant gas
on the suction side.
[0045] In the first and second preferred embodiments described
above, the throttle is provided in the flange passage, the
differential pressure between pressures upstream of and downstream
of the throttle is detected by the detection sensor. Alternatively,
the detection sensor may be of a check valve type which function as
a check valve to open close in response to resistance against fluid
in the flange passage.
[0046] In the first and second preferred embodiments described
above, the flange is formed of the metal. Alternatively, the flange
may be formed of a heat insulating material such as resin or the
like. In this case, heat is harder to transmit to the magnetic
sensor than the case of using the metal flange. Thus, the materials
for the gasket and the mounting member do not have to be limited to
the heat insulating materials. Further, the gasket and the mounting
member can be removed. In the case of removing the gasket and the
mounting member, the magnetic sensor is mounted directly to the
flange.
[0047] The first and second preferred embodiments described above
show an example of a fixed throttle and an example of a variable
throttle using the movable body, respectively. As long as a
structure is provided so that the movable body is movable in
response to differential pressure, the high-pressure chamber, the
communication passage, the flow passage and the branch passage can
be changed optionally.
[0048] In the first preferred embodiment described above, the
displacement control valve is controlled based on the suction
pressure which is introduced through the first pressure-introducing
passage. The displacement control valve may be replaced by a
control valve which is connected to the external refrigerant
circuit through a second pressure-introducing passage and operable
to control in response to control signals and differential pressure
between two points, or by an ON/OFF electromagnetic valve which is
operable to control a valve body by its electromagnetic force.
[0049] 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.
* * * * *