U.S. patent application number 10/217556 was filed with the patent office on 2003-02-20 for compression capacity control device for refrigeration cycle.
Invention is credited to Hirota, Hisatoshi.
Application Number | 20030035733 10/217556 |
Document ID | / |
Family ID | 26607967 |
Filed Date | 2003-02-20 |
United States Patent
Application |
20030035733 |
Kind Code |
A1 |
Hirota, Hisatoshi |
February 20, 2003 |
Compression capacity control device for refrigeration cycle
Abstract
In a compression capacity control device for a refrigeration
cycle including a variable displacement compressor that compresses
refrigerant sucked from a suction chamber communicating with a
suction line, and discharges the refrigerant into a discharge
chamber communicating with a discharge line, while varying the
delivery quantity of the refrigerant by changing pressure in a
pressure-regulating chamber which has the pressure therein
controlled by an electromagnetic control valve, the electromagnetic
control valve arranged between the discharge chamber and the
pressure-regulating chamber is held in an open state to place the
variable displacement compressor in a state with the minimum
delivery quantity within a variable range, when the electromagnetic
control valve is in a deenergized state. This makes it possible to
dispense with a clutch for inhibiting operation of the compressor,
thereby largely reducing the device cost.
Inventors: |
Hirota, Hisatoshi; (Tokyo,
JP) |
Correspondence
Address: |
James E. Nilles
Nilles & Nilles, S.C.
U.S. Bank Center, Suite 2000
777 East Wisconsin Avenue
Milwaukee
WI
53202
US
|
Family ID: |
26607967 |
Appl. No.: |
10/217556 |
Filed: |
August 13, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10217556 |
Aug 13, 2002 |
|
|
|
PCT/JP02/00364 |
Jan 18, 2002 |
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Current U.S.
Class: |
417/222.2 ;
62/228.3; 62/228.5 |
Current CPC
Class: |
F04B 2027/1813 20130101;
F04B 27/1804 20130101; F04B 2027/1895 20130101; F04B 49/225
20130101; F04B 2027/1827 20130101 |
Class at
Publication: |
417/222.2 ;
62/228.3; 62/228.5 |
International
Class: |
F04B 001/26; F25B
001/00; F25B 049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2001 |
JP |
2001-011513 |
Apr 23, 2001 |
JP |
2001-123750 |
Claims
What is claimed is:
1. A compression capacity control device for a refrigeration cycle
including a variable displacement compressor that compresses
refrigerant sucked from a suction chamber communicating with a
suction line, and discharges the refrigerant into a discharge
chamber communicating with a discharge line, while varying a
delivery quantity of the refrigerant by changing pressure in a
pressure-regulating chamber, the pressure in the
pressure-regulating chamber being controlled by an electromagnetic
control valve, wherein the compression capacity control device is
configured to place the variable displacement compressor in a state
with a minimum delivery quantity within a variable range, when the
electromagnetic control valve is in a deenergized state.
2. The compression capacity control device according to claim 1,
wherein the electromagnetic control valve opens and closes
communication between the pressure-regulating chamber and the
discharge chamber such that differential pressure between pressure
in the discharge chamber and at least one of pressure in the
pressure-regulating chamber and pressure in the suction chamber is
held at a predetermined differential pressure, and wherein an
electromagnetic force of the electromagnetic control valve is
changed to thereby change the differential pressure to change the
pressure in the pressure-regulating chamber, whereby the delivery
quantity of the refrigerant is controlled.
3. The compression capacity control device according to claim 1,
wherein urging means is arranged for holding the electromagnetic
control valve in an open state when the electromagnetic control
valve is in the deenergized state, whereby by holding the
electromagnetic control valve in the open state, the variable
displacement compressor is placed in the state with the minimum
delivery quantity within the variable range.
4. The compression capacity control device according to claim 1,
wherein a suction line opening/closing valve is arranged for
closing communication between the suction line and the suction
chamber when the differential pressure between the pressure in the
discharge chamber and the pressure in the suction chamber becomes
equal to or smaller than a predetermined value.
Description
[0001] This application is a continuing application, filed under 35
U.S.C. .sctn.111(a), of International Application PCT/JP02/00364,
filed on Jan. 18, 2002.
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] This invention relates to a compression capacity control
device for a refrigeration cycle used in an automotive air
conditioner or the like.
[0004] (2) Description of the Related Art
[0005] A compressor used in a refrigeration cycle for an automotive
air conditioner is directly connected to an engine by a belt, and
hence is not capable of controlling the rotational speed thereof.
For this reason, a variable displacement compressor capable of
changing the compression capacity (delivery quantity) is employed
so as to obtain an adequate refrigerating capability without being
constrained by the rotational speed of the engine.
[0006] Such a variable displacement compressor is generally
configured such that it compresses a refrigerant sucked from a
suction chamber communicating with a suction line, and discharges
the refrigerant into a discharge chamber communicating with a
discharge line, while varying a delivery quantity of the
refrigerant by changing pressure in a pressure-regulating chamber
which has the pressure therein controlled by an electromagnetic
control valve or the like.
[0007] In the conventional device, a pulley receiving the rotation
of the belt directly connected to the engine is provided with an
electromagnetic clutch or the like so as to inhibit the compressor
from being driven when it is in an operating condition in which
compression of the refrigerant is not required. Thus, the trouble
of increasing the device cost is taken only for inhibiting
operation of the compressor.
SUMMARY OF THE INVENTION
[0008] It is an object of the invention to provide a compression
capacity control device for a refrigeration cycle, which is capable
of dispensing with a clutch for inhibiting operation of a
compressor, thereby largely reducing the device cost.
[0009] To attain the above object, there is provided a compression
capacity control device for a refrigeration cycle including a
variable displacement compressor that compresses refrigerant sucked
from a suction chamber communicating with a suction line, and
discharges the refrigerant into a discharge chamber communicating
with a discharge line, while varying a delivery quantity of the
refrigerant by changing pressure in a pressure-regulating chamber,
the pressure in the pressure-regulating chamber being controlled by
an electromagnetic control valve, characterized in that the
compression capacity control valve is configured to place the
variable displacement compressor in a state with a minimum delivery
quantity within a variable range, when the electromagnetic control
valve is in a deenergized state.
[0010] Further, the compression capacity control device may be
configured such that the electromagnetic control valve opens and
closes communication between pressure in the discharge chamber and
the pressure-regulating chamber and the discharge chamber such that
differential pressure between at least one of pressure in the
pressure-regulating chamber and pressure in the suction chamber is
held at a predetermined differential pressure, and that an
electromagnetic force of the electromagnetic control valve is
changed to thereby change the differential pressure to change the
pressure in the pressure-regulating chamber, whereby the delivery
quantity of the refrigerant is controlled.
[0011] Further, the compression capacity control device may be
configured such that urging means is arranged for holding the
electromagnetic control valve in an open state when the
electromagnetic control valve is in the deenergized state, whereby
by controlling the electromagnetic control valve in the open state,
the variable displacement compressor is placed in the state with
the minimum delivery quantity within the variable range.
[0012] Still further, the compression capacity control device may
be configured such that a suction line opening/closing valve is
arranged for closing communication between the suction line and the
suction chamber when the differential pressure between the pressure
in the discharge chamber and the pressure in the suction chamber
becomes equal to or smaller than a predetermined value.
[0013] The above and other objects, features and advantages of the
present invention will become apparent from the following
description when taken in conjunction with the accompanying
drawings which illustrate preferred embodiments-of the present
invention by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a longitudinal sectional view showing the whole
arrangement of a compression capacity control device for a
refrigeration cycle, according to a first embodiment of the
invention;
[0015] FIG. 2 is a longitudinal sectional view showing a capacity
control electromagnetic valve according to a second embodiment of
the invention; and
[0016] FIG. 3 is a longitudinal sectional view showing the whole
arrangement of a compression capacity control device for a
refrigeration cycle, according to a third embodiment of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The present invention will now be described hereafter with
reference to the accompanying drawings.
[0018] In FIG. 1, reference numeral 10 denotes a swash plate
variable displacement compressor which is used in a refrigeration
cycle for air conditioning of an automotive vehicle. Although R134A
or the like is used as refrigerant, the invention may be applied to
a refrigeration cycle using carbon dioxide as refrigerant.
[0019] Reference numeral 11 denotes a rotational shaft arranged in
a hermetically sealed crankcase 12 (pressure-regulating chamber).
The rotational shaft 11 is connected to an axial portion of a
pulley 13 which is driven for rotation by a drive belt, not shown,
directly connected to an engine. As the rotational shaft 11
rotates, a wobble plate 14 performs wobbling motion which is
arranged in the crankcase 12 in a manner inclined with respect to
the rotational shaft 11.
[0020] The crankcase 12 has cylinders 15 arranged at a peripheral
portion thereof. Each cylinder 15 has a piston 17 arranged therein
such that the piston 17 can perform reciprocating motion. The
piston 17 and the wobble plate 14 are connected to each other by a
rod 18.
[0021] As a result, when the wobble plate 14 performs wobbling
motion, each piston 17 is caused to reciprocate within the cylinder
15, whereby a low-pressure (suction pressure Ps) refrigerant is
sucked from a suction chamber 3 into the cylinder 15 to be
compressed therein. The refrigerant compressed to a high-pressure
(discharge pressure Pd) is delivered into a discharge chamber
4.
[0022] The suction chamber 3 has a refrigerant supplied therein
from an evaporator, not shown, which is arranged at a location
upstream thereof, via a suction line 1. The discharge chamber 4
delivers the high-pressure refrigerant to a condenser, not shown,
which is arranged at a location downstream thereof, via a discharge
line 2.
[0023] The degree of inclination of the wobble plate 14 is changed
according to pressure (crankcase pressure Pc) in the crankcase 12,
and the quantity (delivery quantity, i.e. compression capacity) of
the refrigerant delivered from the cylinder 15 is changed according
to the degree of inclination of the wobble plate 14.
[0024] The delivery quantity is increased when the wobble plate 14
is inclined as indicated by a solid line, whereas when the wobble
plate 14 is not inclined as indicated by a two-dot chain line, the
delivery quantity is small. The delivery quantity is reduced to
zero if the wobble plate 14 becomes perpendicular to the rotational
shaft 11.
[0025] However, as the wobble plate 14 is progressively brought
into a state in which the degree of inclination thereof is being
reduced to zero (state in which the wobble plate 14 is approaching
the two-dot chain line), a minimum-securing spring 19 mounted in
the manner surrounding the rotational shaft 11 is progressively
compressed by the wobble plate 14.
[0026] As a result, a reaction force exerted from the
minimum-securing spring 19 to the wobble plate 14 is progressively
increased whereby the wobble plate 14 is inhibited from becoming
perpendicular to the rotational shaft 11 to prevent the delivery
quantity from being smaller than e.g. approximately 3 to 5% of the
maximum delivery quantity.
[0027] The above operating condition in which the delivery quantity
is controlled to be minimum is referred to as "the minimum
operation". It should be noted that the minimum-securing spring 19
is known in the art and formed e.g. by a combination of a wavy
spring and a coil spring.
[0028] Reference numeral 20 denotes a capacity control
electromagnetic valve which is controlled by an electromagnetic
solenoid (electromagnetic control valve) for carrying out
compression capacity control by automatically controlling the
crankcase pressure (Pc). Reference numerals 21 and 22 denote an
electromagnetic coil and a fixed core, respectively.
[0029] A movable core 23 and a valve element 25 are connected to
each other by an axially movable rod 24 that is arranged in a state
extending through the fixed core 22, and are urged from opposite
ends thereof by respective compression coil springs 27, 28.
[0030] Reference numeral 29 denotes O rings as sealing members. It
should be noted that the urging forces of the two compression coil
springs 27, 28 are set such that the urging force of the spring 28
for opening the valve is larger than that of the spring 27 for
closing the valve.
[0031] A valve seat 26 is formed between a crankcase communication
passage 5 for communication with the crankcase 12, and a discharge
chamber communication passage 6 for communication with the
discharge chamber 4. The valve element 25 is arranged in a manner
opposed to the valve seat 26 from the side of the crankcase
communication passage 5. The crankcase communication passage 5 and
the suction line 1 are communicated with each other via a thin leak
passage 7.
[0032] The above construction permits the differential pressure
(Pd-Pc) between the discharge pressure (Pd) and the crankcase
pressure (Pc) to act on the valve element 25 in the valve-opening
direction, and the electromagnetic force (including the urging
forces of the compression coil springs 27, 28) of the capacity
control electromagnetic valve 20 to act on the valve element 25 in
the valve-closing direction.
[0033] Therefore, when the current value of current for energizing
the electromagnetic coil 21 is constant and hence the
electromagnetic force of the capacity control electromagnetic valve
20 is constant, the valve element 25 is opened and closed in
accordance with changes in the differential pressure (Pd-Pc)
between the discharge pressure (Pd) and the crankcase pressure (Pc)
such that the differential pressure (Pd-Pc) is held constant,
whereby the crankcase pressure (Pc) is controlled to have a value
corresponding to a value of the discharge pressure (Pd), for
holding constant the compression capacity (delivery quantity).
[0034] Then, when the current value of the current for energizing
the electromagnetic coil 21 is changed to change the
electromagnetic force of the capacity control electromagnetic valve
20, the differential pressure (Pd Pc) to be held constant is varied
in a manner corresponding to the change, whereby the compression
capacity (delivery quantity) is held constant at a level different
from that of the above compression capacity (delivery
quantity).
[0035] More specifically, when the electromagnetic force of the
capacity control electromagnetic valve 20 is reduced, the
differential pressure (Pd-Pc) to be held constant is reduced, so
that the crankcase pressure (Pc) is increased to become closer to
the discharge pressure (Pd), and the wobble plate 14 becomes closer
to a position where it is perpendicular to the rotational shaft 11,
resulting in a reduced delivery quantity of refrigerant.
[0036] Inversely, when the electromagnetic force of the capacity
control electromagnetic valve 20 is increased, the differential
pressure (Pd-Pc) to be held constant is increased, so that the
crankcase pressure (Pc) is decreased to be increasingly different
from the discharge pressure (Pd), whereby the degree of inclination
of the wobble plate 14 toward the rotational shaft 11 is increased,
which results in an increased delivery quantity of refrigerant.
[0037] It should be noted that to control the current value of the
current for energizing the electromagnetic coil 21, signals from a
plurality of sensors for detecting various conditions, such as
conditions of an engine, temperatures inside and outside the
vehicle cabin, and an evaporator sensor, are input to a control
section 40 incorporating a CPU, etc., and a control signal based on
results of computations thereof is delivered from the control
section 40 to the electromagnetic coil 21. The drive circuit of the
electromagnetic coil 21 is omitted from illustration.
[0038] If energization of the electromagnetic coil 21 is stopped,
the valve element 25 is moved away from the valve seat 26 to open
the capacity control electromagnetic valve 20, due to the
difference between the urging forces of the two compression coil
springs 27, 28 urging the valve element 25 of the capacity control
electromagnetic valve 20.
[0039] Then, the differential pressure between the discharge
pressure (Pd) and the crankcase pressure (Pc) is reduced to zero
(i.e. Pd-Pc 0), so that the wobble plate 14 is about to be
perpendicular to the rotational shaft 11. However, before this
position, the inclination of the wobble plate 14 is balanced with
the reaction force from the minimum-securing spring 19, whereby the
compressor 10 is placed in a state maintaining the minimum
operation.
[0040] As described above, if energization of the electromagnetic
coil 21 of the capacity control electromagnetic valve 20 is
stopped, the compressor 10 starts the minimum operation, so that
even if it is not necessary to operate the compressor 10, the
rotational shaft 11 can continue to be driven for rotation.
[0041] FIG. 2 shows a capacity control electromagnetic valve 20
according to a second embodiment of the invention. Since a
compressor 10 is similar to the compressor of the first embodiment,
it is omitted from illustration. Further, the leak passage is
arranged as appropriate.
[0042] In this embodiment, the valve element 25 has a piston rod
25p integrally formed therewith on a rear side thereof. The piston
rod 25p has a pressure-receiving area equal to that of the valve
seat 26. The piston rod 25p has a rear surface facing a space which
is communicated with a suction chamber communication passage 8, and
a side surface facing a space which is communicated with the
crankcase communication passage 5. Further, a space on a rear side
of the valve seat 26 as viewed from a valve element side is
communicated with the discharge chamber communication passage
6.
[0043] As a result, the crankcase pressure (Pc) applied to the
piston rod 25p, the valve element 25, and so forth is canceled out,
and the valve element 25 is opened and closed by the differential
pressure (Pd-Ps) between the discharge pressure (Pd) and the
suction pressure (Ps), whereby communication between the crankcase
12 and the discharge chamber 4 is opened and closed for execution
of compression capacity control.
[0044] If energization of the electromagnetic coil 21 is stopped,
the valve element 25 is moved away from the valve seat 26 to open
the capacity control electromagnetic valve 20, by the difference
between the urging forces of the two compression coil springs 27,
28, which maintains the minimum operation of the compressor 10.
[0045] As described above, the present invention can be applied to
a device in which communication between the crankcase 12 and the
discharge chamber 4 is opened and closed such that differential
pressure between the pressure (Pd) in the discharge chamber 4 and
at least one of the pressure (Pc) in the crankcase 12 and the
pressure (Ps) in the suction line 1 is held at a predetermined
differential pressure, and the electromagnetic force of the
capacity control electromagnetic valve 20 is changed to thereby
change the above differential pressure to change the pressure (Pc)
in the crankcase 12 whereby the delivery quantity is varied.
Further, it is also possible to apply the present invention to a
device which is controlled by a method other than the above.
[0046] FIG. 3 shows a third embodiment of the invention. In this
embodiment, the device having the same construction as the device
according to the first embodiment further includes a suction line
opening/closing valve 30 for closing communication between the
suction line 1 and the suction chamber 3 when the differential
pressure between the pressure in the discharge chamber 4 and the
pressure in the suction chamber 3 becomes equal to or lower than a
predetermined value.
[0047] In this embodiment, a valve element 32 is arranged in a
manner opposed to a valve seat 31 which is formed between the
suction line 1 and the suction chamber 3, from the suction line
side. The valve element 32 is urged by a compression coil spring 33
in the valve-closing direction. Reference numeral 34 denotes a
spring receiver having a large cut-away portion formed such that it
does not obstruct passing of the refrigerant.
[0048] A pressure-receiving piston 35, which receives the pressure
(Pd) from the discharge chamber 4 and the pressure (Ps) in the
suction chamber 3 from a front side and a rear side thereof,
respectively, is connected to the valve element 32. When then
differential pressure (Pd-Ps) between the pressure (Pd) in the
discharge chamber 4 and the pressure (Ps) in the suction chamber 3
is larger than a predetermined value, the valve element 32 is away
from the valve seat 31 to open the suction line opening/closing
valve 30, whereas when the compressor 10 starts the minimum
operation and the differential pressure (Pd-Ps) becomes smaller
than the predetermined value, the valve element 32 is pressed
against the valve seat 31 to close the suction line opening/closing
valve 30.
[0049] The above construction makes it possible to prevent fins of
the evaporator from collecting ice during the minimum operation
under a low operating load e.g. in winter, since a low-pressure
refrigerant in the suction line 1 is not sucked into the compressor
10.
[0050] According to the present invention, the variable
displacement compressor maintains the minimum delivery quantity
within a variable range when the electromagnetic control valve is
not energized. This makes it possible to dispense with a clutch for
inhibiting operation of the compressor, thereby largely reducing
the device cost.
[0051] The foregoing is considered as illustrative only of the
principles of the present invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and applications shown and described, and accordingly,
all suitable modifications and equivalents may be regarded as
falling within the scope of the invention in the appended claims
and their equivalents.
* * * * *