Technical Field
[0001] The present disclosure relates to an air-conditioning device, a railway vehicle air-conditioner
device, and a method for controlling the air-conditioning device.
Background Art
[0002] In an air-conditioning device, a degree of opening of an expansion valve is adjusted
based on a degree of superheat calculated from pressure and temperature of a refrigerant
to keep a circulation amount of the refrigerant a proper value in order to enable
efficient exchange heat by an indoor heat exchanger. Electronic expansion valves by
which the circulation amount of the refrigerant can be precisely controlled are widely
used (for example, refer to Patent Literature 1).
Citation List
Patent Literature
[0003] Patent Literature 1: Unexamined Japanese Patent Application Kokai Publication No.
H10-38350 (refer to paragraph 0023 and FIG. 2)
Summary of Invention
Technical Problem
[0004] Incidentally, capacity control mechanisms for controlling a compressor capacity are
widely applied to air-conditioning devices in order to adjust cooling and heating
performance. Examples of the capacity control mechanisms include an inverter-type
capacity control mechanism that is able to perform stepless control of the capacity
of the compressor and a mechanical capacity control mechanism that is able to perform
mainly two-stage control of the capacity of the compressor.
[0005] In an air-conditioning device provided with such a capacity control mechanism, a
change of a capacity of a compressor causes transient fluctuation in compressor suction
pressure or refrigerant pressure. For example, a reduction in the capacity of the
compressor causes a decrease in an amount of refrigerant discharged from the compressor.
As a result, the suction pressor of the compressor increases, thereby causing a temporary
increase in a circulation amount of the refrigerant in the indoor heat exchanger.
There is a risk that the increase in the circulation amount of the refrigerant in
the indoor heat exchanger may cause liquid flood back, in which a portion of the refrigerant
that the indoor heat exchanger fails to evaporate returns to the compressor.
[0006] As described above, although the circulation amount of the refrigerant is usually
adjusted based on the degree of superheat, for improvement of detection accuracy,
a relatively large time constant is set for each of various sensors used for calculation
of the degree of superheat. As a result, the influence of the change of the capacity
of the compressor as a fluctuation in degree of superheat is delayed. Accordingly,
in the method described in Patent Literature 1, even if the suction pressure of the
compressor or the refrigerant pressure transiently fluctuates due to the change of
the capacity of the compressor, there is a risk that the liquid flood back may occur
before the fluctuation in the pressure is detected as the fluctuation in the degree
of superheat and the degree of opening of the expansion valve changes.
[0007] Particularly, such fluctuation is more notably for a compressor equipped with the
mechanical capacity control mechanism than with in the inverter-type capacity control
mechanism that is able to finely control a rotational frequency.
[0008] In order to solve the aforementioned problem, an objective of the present disclosure
is to achieve: an air-conditioning device that is able to further suppress occurrence
of liquid flood back due to a change of a capacity of the compressor than conventional
devices; and an air-conditioning device for railway vehicles.
Solution to Problem
[0009] An air-conditioning device according to the present disclosure includes a compressor,
an outdoor heat exchanger, an indoor heat exchanger and an electronic expansion valve
that are connected to one another via refrigerant piping to constitute a refrigeration
cycle, wherein: the air-conditioning device includes (i) a bypass passage communicatively
connecting a middle compression chamber and a low pressure space, the middle compression
chamber being a chamber to accommodate a refrigerant undergoing compression by the
compressor, the low pressure space being a space to accommodate the refrigerant having
a pressure lower than a pressure of the refrigerant in the middle compression chamber,
(ii) a bypass valve to open or close the bypass passage, and (iii) a controller to
execute degree-of-superheat control in which a degree of opening of the electronic
expansion valve is set based on a degree of superheat of a refrigerant; and, based
on a change from a closed state of the bypass valve to an open state of the bypass
valve, the controller starts restriction processing in which the degree of opening
of the electronic expansion valve is corrected to a value that is less than the value
set by the degree-of-superheat control.
[0010] The air-conditioning device according to the present disclosure includes a refrigeration
circuit in which a compressor, an outdoor heat exchanger, an indoor heat exchanger
and an electronic expansion valve are connected to one another via the refrigerant
piping, wherein: the air-conditioning device includes a middle compression chamber
to accommodate a refrigerant undergoing compression by the compressor, a bypass passage
communicating with a low pressure space to accommodate a refrigerant having a pressure
lower than a pressure of the refrigerant in middle compression chamber, a bypass valve
to open or close the bypass passage, and a controller to execute degree-of-superheat
control in which a degree of opening of the electronic expansion valve is set based
on a degree of superheat of the refrigerant; and, upon detecting a change request
to change a state of the bypass valve from an open state to a closed state, the controller
starts facilitation processing in which the degree of opening of the electronic expansion
valve is corrected to a value that is greater than the value set by the degree-of-superheat
control, and, afterward, the controller changes the open state of the bypass valve
to the closed state of the bypass valve.
Advantageous Effects of Invention
[0011] According to the present disclosure, based on the change from the closed state of
the bypass valve to the open state of the bypass valve, the degree of opening of the
electronic expansion valve is corrected to a value that is less than the value set
by the degree-of-superheat control, thereby enabling a decrease in the circulation
amount of the refrigerant before a change in the capacity of the compressor has an
influence on the fluctuation in the degree of superheat. As a result, in comparison
to a conventional device, the device of the present disclosure can suppress occurrence
of the liquid flood back due to the change of the capacity of the compressor.
[0012] An increase in the capacity of the compressor results in an increase in an amount
of refrigerant discharged from the compressor, whereby the amount of the refrigerant
in the compressor temporarily decreases. Due to the decrease of the amount of the
refrigerant in the compressor, a sliding member of the compressor slides with the
sliding member in direct contact with another component, whereby there is a possibility
of occurrence of an abnormality such as galling. In regard to this point, according
to the present disclosure, the facilitation processing is started before the open
state of the bypass valve is changed to the closed state of the bypass valve, where
the facilitation processing is processing in which the degree of opening of the electronic
expansion valve is corrected to a value that is greater than the value set by the
degree-of-superheat control, and thus the amount of the refrigerant existing in the
compressor can be increased. This enables suppression of a sharp decrease of the amount
of refrigerant in the compressor due to the change from the open state of the bypass
valve to the closed state of the bypass valve. Accordingly, the occurrence of an abnormality
such as galling caused by the sliding movement of sliding member that is in direct
contact with the other component can be suppressed.
Brief Description of Drawings
[0013]
FIG. 1 is a schematic view illustrating an air-conditioning device according to Embodiment
1 of the present disclosure;
FIG. 2 is a cross-sectional view illustrating a compressor and a capacity control
mechanism according to Embodiment 1 of the present disclosure;
FIG. 3 is a flow chart illustrating control of the air-conditioning device according
to Embodiment 1 of the present disclosure;
FIG. 4 illustrates timing charts of a change in a degree of opening of an electronic
expansion valve, changes in a set temperature and in a detected temperature, a pressure
of refrigerant, and a an operation mode by restriction processing and facilitation
processing for the air-conditioning device according to Embodiment 1 of the present
disclosure;
FIG. 5 is a flow chart illustrating control of the air-conditioning device according
to Embodiment 2 of the present disclosure;
FIG. 6 illustrates timing charts of a change in a degree of opening of an electronic
expansion valve, changes in a set temperature and in a detected temperature, a change
in a pressure of refrigerant, and a change in an operation mode by restriction processing
and facilitation processing for the air-conditioning device according to Embodiment
2 of the present disclosure;
FIG. 7 is a flow chart illustrating control of the air-conditioning device according
to Embodiment 3 of the present disclosure;
FIG. 8 is a schematic view illustrating a railway vehicle according to Embodiment
4 of the present disclosure;
FIG. 9 is a side view illustrating a compressor according to Embodiment 4 of the present
disclosure; and
FIG. 10 is a schematic view illustrating an air-conditioning device according to another
embodiment of the present disclosure.
Description of Embodiments
[0014] Embodiments of the present disclosure are described with reference to attached drawings.
Components that are the same or equivalent are assigned the same reference signs throughout
the drawings. Duplicate descriptions are appropriately abbreviated or omitted. Also,
for illustrative purposes, each of the drawings may illustrate a component such that
the proportion of the size or the shape of the component to the size or shape of another
component is exaggerated.
Embodiment 1
[0015] An air-conditioning device 10 according to Embodiment 1 of the present disclosure
is described with reference to FIGS. 1 to 4. As illustrated in FIG. 1, the air-conditioning
device 10 according to the present embodiment includes: a compressor 1 to compress
a refrigerant; an electronic expansion valve 2 to reduce pressure of the refrigerant;
an outdoor heat exchanger 3 to function as a condenser during a cooling operation
and to exchange heat between outdoor air and the refrigerant; an indoor heat exchanger
4 to function as an evaporator during the cooling operation and to exchange heat between
indoor air and the refrigerant; and a controller 7 to control these components. The
controller 7 is connected to a room temperature sensor 14 to measure a temperature
in a room equipped with the air-conditioning device 10 and to a remote controller
15 by which a user performs on-off control of the air-conditioning device 10 and inputs
a desired set temperature To.
[0016] The compressor 1 compresses the refrigerant sucked into the compressor, and discharges
the refrigerant in the high temperature and high pressure state. The compressor 1
of the present embodiment is configured as a scroll compressor that includes a mechanical
capacity control mechanism 60, and is operated at a predetermined constant frequency
of compression per unit of time (seconds). The mechanical capacity control mechanism
60 is described later in detail.
[0017] The outdoor heat exchanger 3 is an outdoor-air heat exchanger to exchange heat between
outdoor air taken from outside the room and the refrigerant, and makes heat move from
the refrigerant to ambient air during the cooling operation. The indoor heat exchanger
4 is an indoor-air heat exchanger to exchange heat between indoor air and the refrigerant,
and makes heat move from indoor air to the refrigerant during the cooling operation.
[0018] The electronic expansion valve 2 is a component to reduce the pressure of the refrigerant
to expand the refrigerant so that the refrigerant has a low temperature and a low
pressure, and is an expansion valve for which the degree of opening is variably controllable.
Preferably, a linear expansion valve (LEV) is used as the electronic expansion valve
2.
[0019] The compressor 1, the outdoor heat exchanger 3, the electronic expansion valve 2,
and the indoor heat exchanger 4 are connected to one another via a refrigerant piping
20 in which the refrigerant flows, thus forming a refrigerant circuit in which the
refrigerant circulates. During the cooling operation, the refrigerant circulates in
the refrigerant piping 20 in a direction indicated by a solid arrow in FIG. 1. The
refrigerant is compressed by the compressor 1, so that the refrigerant turns into
a gas having a high temperature and a high pressure. After the refrigerant is condensed
and liquefied by the outdoor heat exchanger 3, the pressure of the refrigerant is
decreased by expanding the refrigerant by the electronic expansion valve 2, so that
the refrigerant is in a two-phase state of the refrigerant having a low temperature
and low pressure. Afterward, the refrigerant is evaporated and gasified by the indoor
heat exchanger 4, and then returns to the compressor 1. When the indoor air passes
through the indoor heat exchanger 4, the indoor air exchanges heat with the low-temperature
refrigerant, thereby decreasing temperature of the indoor air, and then the indoor
air is supplied to the interior of the room.
[0020] A pipe of the refrigerant piping 20 that connects the compressor 1, the outdoor heat
exchanger 3, and the electronic expansion valve 2 to one another is referred to as
a high pressure refrigerant pipe 26 through which the high pressure refrigerant discharged
from the compressor 1 passes. Also, a pipe of the refrigerant piping 20 that connects
the electronic expansion valve 2, the indoor heat exchanger 4 and the compressor 1
to one another is referred to as a low pressure refrigerant pipe 25 through which
the refrigerant having a pressure lower than the pressure in the higher pressure refrigerant
pipe 26 passes.
[0021] The high pressure refrigerant pipe 26 is connected to a high pressure control refrigerant
line 21 into which a portion of the high-pressure refrigerant discharged from the
compressor 1 flows. On the other hand, the low pressure refrigerant pipe 25 is connected
to a low pressure control refrigerant line 22 into which a portion of the low-pressure
refrigerant sucked by the compressor 1 flows. The high pressure control refrigerant
line 21 and the low pressure control refrigerant line 22 are connected to a control
pressure introduction pipe 23 that communicates with the capacity control mechanism
60.
[0022] A high pressure control valve 8 is disposed in the high pressure control refrigerant
line 21, and a low pressure control valve 9 is disposed in the low pressure control
refrigerant line 22. Each of the high pressure control valve 8 and the low pressure
control valve 9 includes a solenoid valve that can open or close to switch between
circulation and non-circulation of the refrigerant.
[0023] Both the high pressure control valve 8 and the low pressure control valve 9 are connected
to the controller 7 and are opened or closed based on a command from the controller
7. The controller 7 opens one of the high pressure control valve 8 and the low pressure
control valve 9 is opened and closes the other. In a case in which the high pressure
control valve 8 is closed and the low pressure control valve 9 is opened, a portion
of the low-temperature refrigerant flowing in the low temperature refrigerant pipe
25 flows into the control pressure introduction pipe 23. In a case in which the high
pressure control valve 8 is opened and the low pressure control valve 9 is closed,
a portion of the high-temperature refrigerant flowing in the high temperature refrigerant
pipe 26 flows into the control pressure introduction pipe 23.
[0024] Next, the compressor 1 of the present embodiment and a structure of the capacity
control mechanism 60 included in the compressor 1 are described in detail with reference
to FIGS. 1 and 2.
[0025] As illustrated in FIG. 2, the compressor 1 includes a sealed container 50 forming
an outer frame of the compressor 1. Also, the compressor 1 includes a fixed scroll
51 that is provided with, as components disposed in the sealed container 50 and functioning
as sliding members for compressing the refrigerant, a fixed spiral-shaped body 54
and an orbiting scroll 52 that is provided with an orbiting spiral-shaped body 55.
The fixed spiral-shaped body 54 and the orbiting spiral-shaped body 55 are joined
such that the fixed spiral-shaped body 54 and the orbiting spiral-shaped body 55 intermesh
with each other, thereby forming compression chambers P. A compression chamber P that
is located at the central portion communicates with the high pressure refrigerant
pipe 26.
[0026] The orbiting scroll 52 eccentrically orbits relative to the fixed scroll 51 at a
previously predetermined constant speed, and the compression chambers P are gradually
reduced in size from outside low-pressure compression chambers toward inside high-pressure
compression chambers. As illustrated by the solid arrows in FIG. 2, the refrigerant
that flows through the low pressure refrigerant pipe 25 into the compressor 1 flows
from the outside low-pressure compression chambers of the compression chambers P into
the compression chambers P and then flows toward the inside high-pressure compression
chambers while being compressed by the orbital movement of the orbiting scroll 52.
Afterward, the refrigerant is discharged through a discharge path 53 to the high pressure
refrigerant path 26.
[0027] The fixed scroll 51 is provided with the capacity control mechanism 60 that is to
control the capacity of the compressor 1. The capacity control mechanism 60 is configured
to include (i) a back pressure passage 61 into which either of the low-pressure refrigerant
or the high-pressure refrigerant flows from the control pressure introduction pipe
23, (ii) a back pressure chamber 62 housing the bypass valve 64 and communicating
with the back pressure passage 61, (iii) a coil spring 63 elastically supporting the
bypass valve 64, and (iv) a bypass passage 65 that is formed in the fixed scroll 51
and used for returning, to a low-pressure space, the refrigerant present in the middle
compression chamber and undergoing the compression process. The middle compression
chamber is freely determined based on a location at which the bypass passage 65 is
formed. The low-pressure space is any portion of the inner space of the compressor
1 in which refrigerant exists that has a pressure lower than the pressure of the refrigerant
in the middle compression chamber. The low-pressure space may be located outside the
compression chambers P or may be a low-pressure compression chamber located nearer
to the outside than the middle compression chamber is. In the present embodiment,
the bypass valve 64 is elastically supported by the coil spring 63. However, the coil
spring 63 may be replaced with another elastic body such as a rubber component.
[0028] Refrigerant pressure in the control pressure introduction pipe 23 and refrigerant
pressure in the middle compression chamber act on the above-described bypass valve
64. When the low-pressure refrigerant flows into the back pressure passage 61, the
refrigerant pressure in the control pressure introduction passage 23 becomes lower
than the refrigerant pressure in the middle compression chamber, and the bypass valve
64 opens. In this case, a portion of the refrigerant in the middle compression chamber
returns through the bypass passage 65 to the low-pressure space. An operation mode
in which, by opening the bypass valve 64, a portion of the refrigerant in the middle
compression chamber returns to the low-pressure space in this manner is referred to
as an unloading (UL) mode.
[0029] When the high-pressure refrigerant flows into the back pressure passage 61, the refrigerant
pressure in the control pressure introduction valve 23 becomes higher than the refrigerant
pressure in the middle compression chamber, and the bypass valve 64 closes. In this
case, after the whole of the refrigerant in the middle compression chamber is transferred
to the high-pressure compression chambers and then is compressed, the compressed refrigerant
is discharged to the discharge path 53. An operation mode in which, by closing the
bypass valve 64, the whole of the refrigerant in the middle compression chamber is
discharged to the discharge path 53 in this manner is referred to as a full-loading
(FL) mode.
[0030] Referring back to FIG. 1, the description of the present embodiment is continued.
The low-pressure refrigerant pipe 25 is provided with (i) a refrigerant temperature
sensor 11 to detect a refrigerant temperature Tm of the refrigerant sucked by the
compressor 1 and (ii) a refrigerant pressure sensor 12 to detect a refrigerant pressure
Pm of the refrigerant, where the sensor 12 correspond to pressure detecting means
recited in claims. The refrigerant temperature sensor 11, the refrigerant pressure
sensor 12, the high pressure control valve 8, the low pressure control valve 9, the
electronic expansion valve 2, the room temperature sensor 14 and the remote controller
15 are connected to the controller 7.
[0031] The controller 7 includes a central processing unit (CPU), a read only memory (ROM),
a random access memory (RAM) and the like that are not illustrated in the drawings,
and stores various types of programs, a function, fixed data and the like that are
used for driving the air-conditioning device 10. The controller 7 executes the various
types of programs using the above-described function and data, data inputted from
various types of sensors, and the like, so that the controller 7 drives the high-pressure
control valve 8 and the low-pressure control valve 9 to make the high-pressure control
valve 8 and the low-pressure control valve 9 open or close, adjusts a degree of opening
of the electronic expansion valve 2, and executes processing for other operations
for driving the air-conditioning device 10.
[0032] For example, the controller 7 calculates a degree SH1 of superheat of the refrigerant
flowing into the compressor 1 from (i) the refrigerant temperature Tm detected by
the refrigerant temperature sensor 11 and (ii) the refrigerant pressure Pm detected
by the refrigerant pressure sensor 12, and then the controller 7 adjusts the degree
of opening of the electronic expansion valve 2 based on the calculated degree SH1
of superheat.
[0033] The controller 7 compares the calculated degree SH1 of superheat with a previously-stored
threshold SHT and adjusts the degree of opening of the electronic expansion valve
2 based on a difference between the degree SH1 of superheat and the threshold SHT.
In a case in which the degree SH1 of superheat is greater than the threshold SHT,
the degree of opening of the electronic expansion valve 2 increases with increased
difference between the degree SH1 of superheat and the threshold SHT, so that the
degree SH1 of superheat is reduced. In a case in which the degree SH1 of superheat
is less than the threshold STH, the greater the difference between the degree SH1
of superheat and the threshold STH is, the more the degree of opening of the electronic
expansion valve 2 is reduced, so that the degree SH1 of superheat is increased. In
a case in which SH1 is equal to the threshold STH, the degree of opening of the electronic
expansion valve 2 remains unchanged. The threshold SHT is generally set to 5 to 10
°C, without particular limitation.
[0034] Also, the controller 7 uses the below-described formula (1) to calculate a difference
ΔT between (i) a temperature Tr detected by the room temperature sensor 14 and (ii)
a set temperature To set by a user through the remote controller 15, and then determines
an operation mode of the compressor 1 based on this difference ΔT.
[0035] The controller 7 stores the upper limit value Tu of and the lower limit value Tl
of the difference ΔT. In a case in which the controller 7 determines that the difference
ΔT is equal to or greater than the upper limit value Tu, the controller 7 makes the
compressor 1 to drive in the full-loading mode. On the other hand, in a case in which
the controller 7 determines that the difference ΔT is less than the lower limit value
Tl, the controller 7 makes the compressor 1 to drive in the unloading mode. In contrast,
in a case in which the difference ΔT is not less than the lower limit value Tl and
is less than the upper limit value Tu, the controller makes the air-conditioning device
10 to drive in the current operation mode without changing the operation mode.
[0036] Incidentally, when a closed state of the bypass valve 64 is changed to an open state
of the bypass valve 64 in order to change the operation mode from the full-loading
mode to the unloading mode, an amount of the refrigerant discharged from the compressor
1 decreases rapidly, so that an amount of the refrigerant flowing in the low-temperature
refrigerant pipe 25 temporarily rapidly increases. Since a relatively large time constant
is set for the refrigerant temperature sensor 11 and the refrigerant pressure sensor
12 for the purpose of accurately detecting the degree SH1 of superheat, the influence
by a change of the amount of the flow of the refrigerant accompanied by the change
of the operation mode occurs as fluctuation in the degree SH1 of superheat is delayed.
Occurrence of such a time lag causes the amount of the refrigerant flowing in the
low-pressure refrigerant pipe 25 to increase beyond the heat-exchange capacity of
the indoor heat exchanger 4 before the change of the amount of the flow of the refrigerant
is detected as the fluctuation in the degree SH1 of superheat, thereby causing a risk
that so-called liquid flood back may occur, where the liquid flood back is a phenomenon
in which a portion of the refrigerant, without evaporating, flows into the compressor
1.
[0037] Therefore, in the present embodiment, based on a change of operation modes of the
compressor 1 from the full-loading mode to the unloading mode, that is, based on a
change from the closed state of the bypass valve 64 to the open state of the bypass
valve 64, the controller 7 starts restriction processing in which the degree of opening
of the electronic expansion valve 2 is corrected, by subtraction, to a degree of opening
that is smaller, by a given degree θa of opening, than a degree of opening set based
on the degree SH1 of superheat. The given degree θa of opening is a degree of opening
necessary for suppressing an increase in the amount of the flow of the refrigerant
caused by the change from the closed state of the bypass valve 64 to the open state
of the bypass valve 64, and the given degree θa of opening is freely selected. Without
particular limitation, degree of opening of the electronic expansion valve 2 is preferably
corrected, by subtraction of the given degree θa of opening, to a value of a degree
of opening at which the electronic expansion valve 2 permits flow of the refrigerant
by the amount that corresponds to the lower limit of the heat-exchange capacity of
the indoor heat exchanger 4. If the given degree θa of opening is too great, a pressure
of the refrigerant in the compressor 1 rapidly decreases, and thus the orbiting spiral-shaped
body 55 slides directly on the fixed spiral-shaped body 54 without the refrigerant
existing therebetween, thereby causing a risk that an abnormality such as galling
may occur. Therefore, the given degree θa of opening is preferably set in consideration
of the amount of the refrigerant in the compressor 1.
[0038] In contrast, when the open state of the bypass valve 64 is changed to the closed
state of the bypass valve 64 so that the operation mode is changed from the unloading
mode to the full-loading mode, the amount of the refrigerant discharged from the compressor
1 temporarily increases even if the amount of the refrigerant sucked by the compressor
1 remains unchanged, so that the amount of the refrigerant in the compressor 1 is
temporarily rapidly reduced. The rapid reduction in the amount of the refrigerant
in the compressor 1 causes the orbiting spiral-shaped body 55 to slide directly on
the fixed spiral-shaped body 54 without the refrigerant existing therebetween, thereby
causing a risk that an abnormality such as galling may occur.
[0039] Therefore, in a case in which a request to change from the unloading mode to the
full-loading mode is detected, that is, upon detection, during the unloading mode,
that the difference ΔT becomes equal to or greater than the upper limit value Tu,
the controller 7 changes the operation mode of the compressor 1 to the full-loading
mode after executing facilitation processing in which the degree of opening of the
electronic expansion valve 2 is corrected by adding a given degree of opening θb to
the degree of opening set based on the degree SH1 of superheat. The given degree of
opening θb is a degree of opening necessary for suppressing a rapid decrease in the
amount of the refrigerant in the compressor 1 that is caused by the change from the
open state of the bypass valve 64 to the closed state of the bypass valve 64, and
the given degree of opening θb is freely set. For example, after the correction by
addition of the given degree θb of opening, the degree of opening of the electronic
expansion valve 2 is preferably set to a value at which the electronic expansion valve
2 permits flow of the refrigerant in the amount corresponding to the upper limit of
the heat-exchange capacity of the indoor heat exchanger 4, without particular limitation.
[0040] Next, operation of the air-conditioning device 10 according to the present embodiment
is described with reference to a flowchart illustrated in FIG. 3. In parallel with
the operation based on the flowchart of FIG. 3, the controller 7 is taken to calculate
the degree SH1 of superheat based on the refrigerant temperature Tm detected by the
refrigerant temperature sensor 11 and the refrigerant pressure Pm detected by the
refrigerant pressure sensor 12 and then to constantly calculate an appropriate degree
of opening of the electronic expansion valve 2 based on this degree SH1 of superheat.
[0041] First, upon a user operating the remote controller 15 to execute control for turning
on the air-conditioning device 10, driving of the compressor 1 starts. Operation of
the air-conditioning device 10 is started by driving the compressor 1.
[0042] Upon starting of the driving of the compressor 1, the controller 7 first calculates,
based on the above-described formula (1), the difference (ΔT) between the temperature
Tr detected by the room temperature sensor 14 and the set temperature inputted by
the user (Step S10).
[0043] Next, the controller 7 determines whether the calculated difference ΔT is equal to
or greater than the previously-stored upper limit value Tu (Step S11). In a case in
which the controller 7 determines that the difference ΔT is less than the upper limit
value Tu (No in Step S11), the controller 7 determines whether the difference ΔT is
less than the lower limit value T1 (Step S12).
[0044] In a case in which the controller 7 determines that the difference ΔT is not less
than the lower limit value T1 (No in Step S12), that is, in a case in which the controller
7 determines that the difference ΔT is less than the upper limit value Tu and is equal
to or greater than the lower limit value Tl, a change of the operation mode of the
compressor 1 is not made. In this case, the controller 7 does not make a correction
of the degree of opening of the electronic expansion valve 2.
[0045] On the other hand, upon determination that the difference ΔT is less than the lower
limit value Tl (Yes in Step S12), the controller 7 changes the operation mode of the
compressor 1 to the unloading mode. The controller 7 first determines whether the
operation mode of the compressor 1 is the full-loading mode (Step S13).
[0046] In the present embodiment, in a case in which the low pressure control valve 9 is
opened and the high pressure control valve 8 is closed, the bypass valve 64 is in
an open state, so that the controller determines that the compressor 1 is in the unloading
mode. However, in a case in which the low pressure control valve 9 is closed and the
high pressure control valve 8 is opened, the bypass valve 64 is in a closed state,
so that the controller determines that the compressor 1 is in the full-loading mode.
In the present embodiment, although the determination as to whether the compressor
1 is in the unloading mode or in the full-loading mode is made by determining whether
either of the low pressure control valve 9 and the high pressure control valve 8 is
in the open state, the determination of the operation mode of the compressor 1 may
be made by another publically well-known manner. For example, the determination of
the operation mode of the compressor 1 may be made on the basis of the refrigerant
pressure Pm in the control pressure introduction pipe 23 or using a sensor to detect
opening or closing of the bypass valve 64, without particular limitation, and other
publicly-well know manners may be used.
[0047] In a case in which the controller 7 determines that the operation mode of the compressor
1 is not the full-loading mode (No in Step S13), that is, in a case in which the controller
7 determines that the operation mode of the compressor 1 is the unloading mode, the
operation mode is unchanged, and correction of the degree of opening of the electronic
expansion valve 2 is not made.
[0048] However, in a case in which the controller 7 determines that the operation mode of
the compressor 1 is the full-loading mode (Yes in Step S13), the controller 7 changes
the operation mode of the compressor 1 to the unloading mode (Step S14) and then starts
restriction processing (Step S15). Upon starting the control processing, the controller
7 corrects the degree of opening of the electronic expansion valve by subtracting
the given degree of opening θa from the degree of opening of the electronic expansion
valve 2 that is calculated based on the degree SH1 of superheat, and then the degree
of opening of the electronic expansion valve 2 is set to the corrected degree of opening.
[0049] Next, the controller 7 determines whether an elapsed time period Ta of time elapsed
since the start of the restriction processing is equal to or longer than a given time
period T1 (Step S16). The given time period T1 is a time period that is sufficient
to reduce the refrigerant pressure Pm, and is freely set. For example, without particular
limitation, the given time period T1 is preferably a period of time taken by a certain
amount of refrigerant to pass through the electronic expansion valve 2, where the
certain amount of refrigerant corresponds to an amount of refrigerant that is returned
from the middle compression chamber to the low-pressure space.
[0050] Upon determination that the elapsed time period Ta is shorter than the given time
period T1 (No in Step S16), the restriction processing continues, and upon determination
that the elapsed time period Ta is equal to or longer than the given time period T1
(Yes in Step S16), the restriction processing ends (Step S17). That is, the correction
of the degree of opening of the electronic expansion valve 2 ends.
[0051] In contrast, in a case in which the controller 7 determines that the difference ΔT
is equal to or greater than the upper limit value Tu (Yes in Step S11), the controller
7 determines, in the above-described manner, whether the compressor 1 is in the unloading
mode (Step S18).
[0052] Upon determination that the compressor 1 is in the unloading mode (Yes in Step S18),
on the grounds that the difference ΔT is equal to or greater than the upper limit
value Tu and the operation mode is the unloading mode, the controller 7 determines
that a request to change the operation mode from the unloading mode to the full-loading
mode is made.
[0053] At this time in time, the controller 7 starts facilitation processing before changing
the operation mode to the full-loading mode (Step S19). Upon starting the facilitation
processing, the controller 7 corrects the degree of opening of the electronic expansion
valve by adding the given degree of opening θb to the degree of the opening of the
electronic expansion valve 2 calculated based on the degree SH1 of superheat, and
then the controller 7 sets the degree of opening of the electronic expansion valve
2 to a degree of opening obtained by the correction.
[0054] Next, the controller 7 determines whether an elapsed time period Tb of time elapsed
since the start of the facilitation processing is equal to or longer than a given
time period T2 (Step S20). The given time period T2 is a period of time that it takes
for the compressor 1 to secure therein an amount of refrigerant that does not cause
malfunction of the compressor 1 despite a rapid increase in an amount of refrigerant
discharged from the compressor 1 due to a change of the operation mode, and is freely
set. For example, without particular limitation, the given time period T2 is preferably
a period of time that is takes for the compressor 1 to secure therein an amount of
the refrigerant corresponding to the amount of refrigerant that is returned from the
middle compression chamber to the low-pressure space.
[0055] Upon determination that the elapsed time period Tb is shorter than the given time
period T2 (No in Step S20), the facilitation processing continues. However, upon determination
that the elapsed time period Tb is equal to or longer than the given time period T2
(Yes in Step S20), the facilitation processing (Step S21). That is, the controller
7 terminates the correction of the degree of opening of the electronic expansion valve
2. Also, the operation mode of the compressor 1 is changed to the full-loading mode
(Step S21).
[0056] On the other hand, in a case in which the controller 7 determines that the compressor
1 is not in the unloading mode (No in Step S18), that is, in a case in which the controller
7 determines that the compressor 1 is in the full-loading mode, the operation mode
of the compressor 1 is not changed. In this case, the controller 7 does not correct
the degree of opening of the electronic expansion valve 2.
[0057] Next, the controller 7 determines whether the operation of the air-conditioning device
10 is finished (Step S22). In a case in which the controller 7 determines that the
operation of the air-conditioning device 10 is finished (Yes in Step S22), the controller
7 terminates this process. In a case in which the controller 7 determines that the
air-conditioning device 10 is still in operation (No in Step S22), processing returns
to Step S10 and this processing continues.
[0058] FIG. 4 illustrates one example of each of transitions of (a) the degree of opening
of the electronic expansion valve 2, (b) the temperature Tr detected by the room temperature
sensor 14 and the set temperature To, (c) the refrigerant pressure Pm detected by
the refrigerant pressure sensor 12, and (d) the operation mode of the compressor 1,
in a case in which the process illustrated in FIG. 3 is performed.
[0059] In (a) of FIG. 4, one example of the transition of the degree of opening of the electronic
expansion valve 2 caused by execution of the above-described restriction processing
and the above-described facilitation processing is plotted as a solid line, and one
example of the transition of the degree of opening of the electronic expansion valve
2 without execution of the above-described restriction processing and facilitation
processing is plotted as a dashed double-dotted line. In (b) of FIG. 4, one example
of the transition of the set temperature To set by the user using the remote controller
15 is plotted as a solid line, and one example of the transition of the temperature
Tr detected by the room temperature sensor 14 is plotted as a dash-dotted line. In
(c) of FIG. 4, one example of the transition of the refrigerant pressure Pm caused
by execution of the above-described restriction processing and facilitation processing
is plotted as a solid line, and one example of the transition of the refrigerant pressure
Pm without execution of the above-described restriction processing and facilitation
processing is plotted as a long dashed double-dotted line. In (d) of FIG. 4, one example
of the transition of the operation mode of the compressor 1 caused by execution of
the above-described restriction processing and the above-described facilitation processing
is plotted as a solid line, and one example of the transition of the operation mode
of the compressor 1 without execution of the above-described restriction processing
and facilitation processing is plotted as a dash-dotted line.
[0060] As illustrated in FIG. 4, when the difference ΔT between the set temperature To and
the detected temperature Tr is equal to or greater than the upper limit value Tu,
the compressor 1 is operated in the full-loading mode (times t0 to t1).
[0061] When the difference ΔT further becomes less than the lower limit value Tl after becoming
less than the upper limit value Tu, the controller 7 changes the operation mode of
the compressor 1 from the full-loading mode to the unloading mode. At this point in
time, the controller 7 starts the restriction processing in which the given angle
θa is subtracted from the degree of opening of the electronic expansion valve 2 calculated
based on the degree SH1 of superheat (time t1). This restriction processing continues
over the given time period T1 (time t1 to t2).
[0062] Upon executing the restriction processing, the degree of opening of the electronic
expansion valve 2 decreases, thereby causing a reduction in an amount of the refrigerant
flowing in the low pressure refrigerant pipe 25. As a result, a temporary rise in
the refrigerant pressure Pm is suppressed. After the given time period T1 elapses,
the controller 7 terminates the restriction processing (time t2).
[0063] Afterward, when the set temperature To is changed and thus the difference ΔT becomes
equal to or greater than the upper limit value Tu (time t3), the controller 7 determines
that a request to change the operation mode is made. In this case, before the operation
mode is changed from the unloading mode to the full-loading mode, the controller 7
starts the facilitation processing in which the degree of opening of the electronic
expansion valve 2 is corrected by adding the given degree θb of opening to the degree
of opening calculated from the degree SH1 of superheat (the time t3). The facilitation
processing continues over the given time period T2 (time t3 to t4). The operation
mode is maintained as the unloading mode.
[0064] Upon executing the facilitation processing, the degree of opening of the electronic
expansion valve 2 is increased, thereby causing an increase in an amount of the refrigerant
flowing in the low pressure refrigerant pipe 25, and thus the refrigerant pressure
Pm increases (time t3 to t4). After the given time period T2 elapses, the controller
7 terminates the facilitation processing (time t4). That is, the controller 7 terminates
the correction of the degree of opening of the electronic expansion valve 2. Also,
the controller 7 changes the operation mode of the compressor 1 from the unloading
mode to the full-loading mode.
[0065] Embodiment 1 as described above can exhibit the following effects.
[0066] Since the restriction processing in which the given degree θa of opening is subtracted
from the degree of opening of the electronic expansion valve 2 is started based on
the change from the closed state of the bypass valve 64 to the open state of the bypass
valve 64, an amount of flow of the refrigerant can be reduced before the change in
the capacity of the compressor 1 is reflected in the fluctuation of the degree SH1
of superheat. As a result, occurrence of liquid flood back due to a change of the
capacity of the compressor 1 can be suppressed more than conventional devices.
[0067] Since the facilitation processing in which the given degree θb of opening is added
to the degree of opening of the electronic expansion valve 2 is started before the
open state of the bypass valve 64 is changed to the closed state of the bypass valve
64, an amount of the refrigerant existing in the compressor 1 can be increased before
the change in the capacity of the compressor 1. As a result, it is possible to suppress
occurrence of a situation in which, due to the rapid reduction in the amount of the
refrigerant existing in the compressor 1, the orbiting spiral-shaped body 55 slides
on the fixed spiral-shaped body 54 with the fixed spiral-shaped body 54 and the orbiting
scroll 50 directly coming into contact with each other.
[0068] Since the restriction processing is executed over the given time period T1, occurrence
of hunting is suppressed, and thus occurrence of liquid flood back can be more favorably
suppressed.
[0069] Since the facilitation processing is executed over the given time period T2, the
occurrence of hunting is suppressed, and thus the present embodiment can more preferably
suppress occurrence of the situation in which the orbiting spiral-shaped body 55 slides
on the fixed spiral-shaped body 54 with the fixed spiral-shaped body 54 and the orbiting
scroll 50 directly coming into contact with each other.
Embodiment 2
[0070] A method of controlling an air-conditioning device 10 according to Embodiment 2 is
described with reference to FIGS. 5 and 6 together with FIGS. 1 to 4. Unless otherwise
stated, reference signs that are the same as in Embodiment 1 denote components that
are the same, and steps that are the same are assigned step reference numbers that
are the same. Accordingly, detailed description of these components and these steps
is omitted as appropriate.
[0071] FIG. 5 illustrates a control flowchart of control of the air-conditioning device
10 according to Embodiment 2. Operation of a controller 7 according to Embodiment
2 is described with reference to FIG. 5. In the control flowchart illustrated in FIG.
5, Steps S15 to S17 of the flowchart of FIG. 3 are replaced with Steps S30 to S34,
and the other steps are the same. Accordingly, description of the contents of similar
control is omitted.
[0072] After changing the operation mode of the compressor 1 to the unloading mode (Step
S14), the controller 7 determines whether the refrigerant pressure Pm detected by
the refrigerant pressure sensor 12 is equal to or greater than a threshold P1 (corresponding
to a first given pressure recited in claims) (Step S30). It is preferable that the
threshold P1 corresponds to a refrigerant pressure at which the refrigerant the amount
of which corresponds to the upper limit of the heat-exchange capacity of the indoor
heat exchanger 4 passes.
[0073] In a case in which the controller 7 determines that the refrigerant pressure Pm is
less than the threshold P1 (No in Step S30), the controller 7 determines whether an
elapsed time period Tc since a change of the operation mode to the unloading mode
is equal to or longer than a given time period T3 (Step S31). The given time period
T3 is a period of time for a temporarily-increasing suction pressure to return to
a steady state after a change of the operation mode of the compressor 1 to the unloading
mode, and is freely set. The given time period T3, without particular limitation,
is preferably set to a time period during which a certain amount of refrigerant passes
through the electronic expansion valve 2, where the certain amount of refrigerant
corresponds to an amount of refrigerant that is returned from the middle compression
chamber to the low-pressure space.
[0074] In a case in which the controller 7 determines that the elapsed time period Tc of
time elapsed since the change of the operation mode to the unloading mode is shorter
than the given time period T3 (No in Step S31), processing returns to Step S30. However,
in a case in which the controller 7 determines that the elapsed time period Tc since
the change of the operation mode to the unloading mode is equal to or longer than
the given time period T3 (Yes in Step S31), the processing is terminated for now.
[0075] In contrast, in a case in which the controller 7 determines that the refrigerant
pressure Pm is equal to or greater than the threshold P1 (Yes in Step S30), the controller
7 starts the restriction processing (Step S32). Subsequently, the controller 7 determines
whether an elapsed time period Ta since the start of the restriction processing is
equal to or longer than the given time period T1 (Step S33). In a case in which the
controller 7 determines that the elapsed time period Ta since the start of the restriction
processing is equal to or longer than the given time period T1 (No in Step S33), processing
returns to Step S33. In a case in which the controller 7 determines that the elapsed
time period Ta since the start of the restriction processing is equal to or longer
than the given time period 1 (Yes in Step S33), this processing (Step S34) ends.
[0076] FIG. 6 illustrates one example of each of transitions of (a) the degree of opening
of the electronic expansion valve 2, (b) the temperature Tr detected by the room temperature
sensor 14 and the set temperature To, (c) the refrigerant pressure Pm detected by
the refrigerant pressure sensor 12, and (d) the operation mode of the compressor 1,
in a case in which the process illustrated in FIG. 5 is performed.
[0077] In (a) of FIG. 6, one example of the transition of the degree of opening of the electronic
expansion valve 2 caused by execution of the above-described restriction processing
and the above-described facilitation processing is plotted as a solid line, and one
example of the transition of the degree of opening of the electronic expansion valve
2 without execution of the above-described restriction processing and the above-described
facilitation processing is plotted as a dashed double-dotted line. In (b) of FIG.
6, one example of the transition of the set temperature To set by the user using the
remote controller 15 is plotted as a solid line, and one example of the transition
of the temperature Tr detected by the room temperature sensor 14 is plotted as a dash-dotted
line. In (c) of FIG. 6, one example of the transition of the refrigerant pressure
Pm caused by execution of the above-described restriction processing and facilitation
processing is plotted as a solid line, and one example of the transition of the refrigerant
pressure Pm without execution of the above-described restriction processing and facilitation
processing is plotted as a dashed double-dotted line. In (d) of FIG. 6, one example
of the transition of the operation mode of the compressor 1 caused by execution of
the above-described restriction processing and facilitation processing is plotted
as a solid line, and one example of the transition of the operation mode of the compressor
1 without execution of the above-described restriction processing and facilitation
processing is plotted as a dash-dotted line.
[0078] As illustrated in FIG. 6, when the operation mode is changed from the full-loading
mode to the unloading mode (time t1) after operating the compressor 1 in the full-loading
mode (a time t0 to the time t1), the controller 7 monitors the refrigerant pressure
Pm over the given time period T3 (time t1 to t7). When the refrigerant pressure Pm
is equal to or greater than the threshold PI, the controller 7 starts the restriction
processing in which a correction is made by subtracting the given degree θa of opening
from the degree of opening of the electronic expansion valve 2 calculated based on
the degree SH1 of superheat (time t5). This restriction processing continues over
the given time period T1 (time t5 to t6).
[0079] The present embodiment can exhibit the following effect in addition to the effects
described in Embodiment 1.
[0080] In a case in which the controller determines that the refrigerant pressure Pm is
equal to or greater than the threshold PI, the restriction processing is started,
and, in a case in which the refrigerant pressure Pm is less than the threshold PI,
the restriction processing is not started. Accordingly, the restriction processing
is started even if the refrigerant pressure P is sufficiently low, thereby suppressing
an excessive reduction in an amount of the circulating refrigerant. Accordingly, a
reduction in the cooling capacity can be suppressed.
Embodiment 3
[0081] A method of controlling an air-conditioning device 10 according to Embodiment 3 is
described with reference to FIG. 7 together with FIGS. 1 to 3. Unless otherwise stated,
reference signs that are the same as in Embodiment 1 denote components that are the
same, and steps that are the similar are assigned step reference numbers that are
the same, and accordingly detailed description of such is omitted as appropriate.
[0082] FIG. 7 is an explanatory drawing illustrating a control flowchart of control of the
air-conditioning device 10 according to Embodiment 3. Operation of a controller 7
according to Embodiment 3 is described with reference to FIG. 7. In the control flowchart
illustrated in FIG. 7, processing for starting up the air-conditioning device 10 (steps
S1 to S3) is added to the flowchart of FIG. 3, and the other steps of the flowchart
of FIG. 7 are the same as those in FIG. 3. Accordingly, description of the contents
of control that are similar is omitted.
[0083] At the time when the air-conditioning device 10 is started up, the refrigerant in
the compressor 1 has a low temperature, so that the refrigerant in the compressor
1 is in a state in which the refrigerant easily dissolves into lubricant. When a large
amount of the refrigerant dissolves in the lubricant in the compressor 1, there is
a risk of occurrence of so-called oil foaming that is a phenomenon in which the refrigerant
dissolving in the lubricant rapidly evaporates due to a reduction in a pressure in
the compressor 1 when the compressor 1 is started up. Occurrence of the oil foaming
may result in risk that the frothy lubricant in the compressor 1 is discharged to
the outside of the compressor 1.
[0084] Accordingly, in the present embodiment, the degree of opening of the electronic expansion
valve 2 is fixed at a given degree θc of opening (corresponding to a start-up degree
of opening recited in claims) at the time when the air-conditioning device 10 is started
up, thereby increasing an amount of the refrigerant flowing into the compressor 1
during the start-up of the air-conditioning device 10, and suppressing a reduction
in pressure in the compressor 1. Also, the operation mode of the compressor 1 is set
to the unloading mode during the start-up of the air-conditioning device 10, whereby
an amount of the refrigerant discharged from the compressor 1 is reduced, and thus
a reduction in the pressure in the compressor 1 is more favorably suppressed.
[0085] The processing at the start of operation of the air-conditioning device 10 according
to the present embodiment is described with reference to FIG. 7. Upon starting the
operation of the compressor 1 and then starting the operation of the air-conditioning
device 10, the controller 7 fixes the degree of opening of the electronic expansion
valve 2 at the previously-predetermined given degree θc of opening (Step S1). The
given degree θc of opening is a degree of opening necessary for supplying to the interior
of the compressor 1 an amount of the refrigerant that does not cause occurrence of
the oil foaming despite a reduction in pressure in the compressor 1 caused by discharging
the refrigerant from the compressor 1 during the start-up of the compressor 1. The
given degree θc of freely set. The given degree θc of opening is most preferably a
maximum degree of opening that the electronic expansion valve 2 can have.
[0086] Next, the controller 7 sets the operation mode of the compressor 1 to the unloading
mode (Step S2). Afterward, the controller 7 determines whether an elapsed time period
Td since the start of the operation of the air-conditioning device 10 is equal to
or longer than a given time period T4 (Step S3). The given time period T4 is a period
of time necessary for causing the air-conditioning device to make a transition to
a steady state after finishing the start-up of the air-conditioning device 10. For
example, the given time period T4 may be set to a previously determined period of
time for the degree SH1 of superheat to converge at a certain range after the start-up
of the air-conditioning device 10, where such a period of time may be previously found
by measurement. Also, the given time period T4 may be set to a previously determined
period of time for the refrigerant discharged from the compressor 1 to circulate in
the refrigerant piping 20 to return to the compressor 1 again, where such a period
of time may be previously found by measurement.
[0087] In a case in which the controller 7 determines that the elapsed time period Td of
time elapsed since the start of the operation of the air-conditioning device 10 is
shorter than the given time period T4 (No in Step S3), processing returns to return
to Step S3. However, in a case in which the controller 7 determines that the elapsed
time period Td since the start of the operation of the air-conditioning device 10
is equal to or longer than the given time period T4 (Yes in Step S3), processing proceeds
to Step S10.
[0088] The present embodiment can exhibit the following effect in addition to the effects
described in Embodiments 1 and 2.
[0089] Since the degree of opening of the electronic expansion valve 2 is fixed at the given
degree θc of opening and the operation mode of the compressor 1 is set to the unloading
mode at the time when the air-conditioning device 10 is started up, a reduction in
the pressure in the compressor 1 during the start-up of the air-conditioning device
10 can be suppressed. Accordingly, occurrence of liquid flood back and oil foaming
during the start-up of the air-conditioning device 10 can be suppressed.
Embodiment 4
[0090] An air-conditioning device 10 according to Embodiment 4 is described with reference
to FIGS. 8 and 9. In Embodiment 4, an example of an application of the air-conditioning
device 10 of Embodiment 1 or 2 to a railroad vehicle is described. Unless otherwise
stated, reference signs that are the same as in Embodiment 1 or 2 denote components
that are the same, and steps that are the similar are assigned step reference numbers.
Accordingly, detailed description of such components and steps is omitted as appropriate.
[0091] FIG. 8 is a view illustrating the appearance of a vehicle 70 equipped with the air-conditioning
device 10 of the present embodiment. FIG. 8 illustrates a case in which the air-conditioning
device 10 is mounted on a roof of the vehicle. However, the air-conditioning device
10 may be disposed under a floor of the vehicle.
[0092] As illustrated in FIG. 9, in the present embodiment, the compressor 1 is arranged
such that the discharge side of the compressor is located upward so that a center
shaft line of the compressor 1 inclines at an inclination angle A relative to a horizontal
plane. The inclination angle A is preferably 0° to 15°, more preferably 0° to 10°,
and most preferably 0° to 5°.
[0093] In a case in which the air-conditioning device 10 is mounted on the railroad vehicle,
space for disposal of the air-conditioning device 10 is limited, and particularly,
space for disposing the air-conditioning device 10 in the vertical direction is often
insufficient. Accordingly, height of the air-conditioning device 10 is to be reduced.
[0094] Lubricant 31 for lubricating the fixed spiral-shaped body 54, the orbiting spiral-shaped
body 55 and the like is stored in the compressor 1. If the compressor 1 is arranged
such that the shaft center line of the compressor 1 is parallel to the horizontal
plane for the purpose of the reduction in height of the air-conditioning device, there
is a risk that the lubricant 31 together with the compressed refrigerant may discharge
into the refrigerant piping 20. Also, in a case in which the liquid flood back occurs,
there is a risk that the lubricant 31 may discharge into the refrigerant piping 20.
[0095] In regard to this point, since the compressor 1 is arranged such that the shaft center
line of the compressor 1 inclines at the inclination angle A relative to the horizontal
plane in the present embodiment, discharge of the lubricant can be suppressed further
in comparison to arrangement of the shaft center line parallel to the horizontal plane.
Also, as described in Embodiments 1 to 3, the occurrence of the liquid flood back
can be suppressed by control of the electronic control valve 2, so that the discharge
of the lubricant can be favorably suppressed.
[0096] The present embodiment exhibits the following effects in addition to exhibiting effects
similar to the effects described in Embodiments 1 to 3.
[0097] According to the present embodiment, the reduction in height of the air-conditioning
device 1 can be achieved and the discharge of the lubricant 31 can be suppressed.
Another Embodiment
[0098] As illustrated in FIG. 10, an air-conditioning device 10 according to the present
embodiment may include an accumulator 28 disposed in the middle of the refrigerant
piping 20 connecting the indoor heat exchanger 4 and the compressor 1, a four-way
valve 29 to switch flow passages of the refrigerant, a hot gas bypass 27 to bypass
the refrigerant discharged from the compressor 1 to the inflow side of the compressor
1, and a solenoid 32 to switch between passage and non-passage of the refrigerant
through the hot gas bypass 27.
[0099] In the present embodiment, during a heating operation, through a switching operation
of the four-way valve 29, the refrigerant is compressed by the compressor 1 to become
a gas at high temperature and pressure, and then the refrigerant is condensed to be
liquefied by the indoor heat exchanger 4. Afterward, the refrigerant is made to expand
by using the electronic expansion valve 2 to reduce the pressure of the refrigerant,
so that the refrigerant becomes two phases at low temperature and pressure. Afterward,
the refrigerant is evaporated and gasified by the outdoor heat exchanger 3, passes
through the accumulator 28, and then returns to the compressor 1. When air in the
vehicle passes through the indoor heat exchanger, the air in the vehicle exchanges
heat with the high temperature refrigerant, so that the air in the vehicle becomes
high temperature air for return to the interior of the vehicle. The cooling operation
is different from the heating operation only in a direction of flow of the refrigerant
in the refrigerant circuit, as described above. Other matters and the structures of
the operations are the same.
[0100] According to the present embodiment, the lubricant flows in the hot gas bypass path
27 and then flows into the compressor 1 again even if the lubricant discharges from
the compressor 1, so that the depletion of the lubricant in the compressor 1 can be
suppressed. Also, since the liquid refrigerant is stored in the accumulator, occurrence
of the liquid flood back can be effectively suppressed.
[0101] In each of the above-described embodiments, the value ΔT is taken to be a value obtained
by subtracting the set temperature To from the detected temperature Tr. However, in
the present embodiment, the difference ΔT is preferably set to the absolute value
of the value obtained by subtracting the set temperature To from the detected temperature
Tr.
[0102] In each of the above-described embodiments, the high pressure control valve 8 and
the low pressure control valve 9 are solenoid valves to switch between passage and
non-passage of the refrigerant. However, the present disclosure is not limited to
such solenoid valves. For example, the high pressure valve 8 and the low pressure
valve 9 may be linear valves configured as electronic valves having an adjustable
degree of opening.
[0103] In the above-described embodiments, the degree SH1 of superheat is calculated based
on the temperature of and the pressure of the refrigerant flowing into the compressor
1. However, the present disclosure is not limited to such configuration. Temperature
sensors may be disposed at an inlet portion and an outlet portion of the indoor heat
exchanger 4, and the degree SH1 of superheat may be calculated based on temperatures
detected by these temperature sensors. Even in this case, the air-conditioning device
according to the present embodiment can exhibit effects similar to those described
in the above-described embodiments.
[0104] In Embodiment 3, the example in which the air-conditioning device is mounted on the
railroad vehicle is described. However, this configuration is not limiting, and the
air-conditioning device may be installed in a house, a building, a warehouse, an automobile
or the like. Even in these cases, the device according to the present embodiment can
exhibit effects similar to those described in Embodiment 3.
[0105] In the restriction processing of each of the above-described embodiments, the degree
of opening of the electronic expansion valve 2 is corrected by subtracting the previously-determined
given degree θa of opening from the degree of opening set based on the degree SH1
of superheat. However, the restriction processing of the present disclosure is not
limited to such a manner. The restriction processing used in the present disclosure
may be any processing in which the degree of opening of the electronic expansion valve
2 is corrected so as to be less than a degree of opening that is set on the basis
of the degree SH1 of superheat. For example, the degree of opening of the electronic
expansion valve 2 may be corrected to the minimum degree of opening possible for the
electronic expansion valve 2. Alternatively, the higher the refrigerant pressure Pm
at the start of the restriction processing, the more the given degree θa of opening
may be increased. Alternatively, after the refrigerant pressure Pm is monitored during
execution of the restriction processing, the given degree θa of opening may be adjusted
based on a result of such monitoring.
[0106] In the restriction processing of each of the above-described embodiments, the restriction
processing is terminated upon continuation of the restriction processing for the given
time period T1. However, a time period of the restriction processing of the present
disclosure is not limited to the given time period T1 and can be changed as appropriate.
For example, the higher the refrigerant pressure Pm at the start of the restriction
processing, the longer period the given time period T1 may be set to. Alternatively,
the restriction processing may be terminated when the refrigerant pressure Pm reduces
to a given pressure P2 of the refrigerant. The pressure P2 of the refrigerant is preferably
set to the pressure that the refrigerant has in a case in which an amount of the refrigerant
corresponding to the upper limit of the heat-exchange capacity of the indoor heat
exchanger 4 passes through the low pressure refrigerant pipe 25.
[0107] In the facilitation processing of each of the above-described embodiments, the degree
of opening of the electronic expansion valve 2 is corrected by adding the previously-determined
given degree θb of opening to the degree of opening set based on the degree SH1 of
superheat. However, the facilitation processing of the present disclosure is not limited
to such configuration. The facilitation processing used in the present disclosure
may be any processing in which the degree of opening of the electronic expansion valve
2 is corrected so as to be greater than a degree of opening that is set on the basis
of the degree SH1 of superheat. For example, the degree of opening of the electronic
expansion valve 2 may be corrected to the maximum degree of opening possible for the
electronic expansion valve 2. Alternatively, the lower the refrigerant pressure Pm
at the start of the facilitation processing, the more the given θb of opening may
be reduced. Alternatively, after the refrigerant pressure Pm is monitored during execution
of the facilitation processing, the given degree θb of opening may be adjusted based
on a result of the monitoring of the refrigerant pressure Pm.
[0108] In the facilitation processing of each of the above-described embodiments, the facilitation
processing is terminated upon continuation over the previously-defined given time
period T2. However, a time period during which the facilitation processing of the
present disclosure is executed is not limited to the time period T2 and can be changed
as appropriate. For example, the lower the refrigerant pressure Pm at the start of
the facilitation processing, the longer the given time period T2 may be set. Alternatively,
the facilitation processing may be terminated when the refrigerant pressure Pm rises
to a previously-determined pressure P3 of the refrigerant.
Reference Signs List
[0109]
- 1
- Compressor
- 2
- Electronic expansion valve
- 3
- Outdoor heat exchanger
- 4
- Indoor heat exchanger
- 7
- Controller
- 8
- High pressure control valve
- 9
- Low pressure control valve
- 10
- Air-conditioning device
- 11
- Refrigerant temperature sensor
- 12
- Refrigerant pressure sensor
- 14
- Room temperature sensor
- 15
- Remote controller
- 20
- Refrigerant piping
- 21
- High pressure control refrigerant line
- 22
- Low pressure control refrigerant line
- 23
- Control pressure introduction pipe
- 25
- Low pressure refrigerant pipe
- 26
- High pressure refrigerant pipe
- 27
- Hot gas bypass path
- 28
- Accumulator
- 29
- Four-way valve
- 32
- Solenoid valve
- 50
- Sealed container
- 51
- Fixed scroll
- 52
- Orbiting scroll
- 53
- Discharge path
- 54
- Fixed spiral-shaped body
- 55
- Orbiting spiral-shaped body
- 60
- Capacity control mechanism
- 61
- Back pressure passage
- 62
- Back pressure chamber
- 63
- Coil spring
- 64
- Bypass valve
- 65
- Bypass passage