U.S. patent application number 13/256669 was filed with the patent office on 2012-01-05 for air conditioning apparatus.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. Invention is credited to Hidehiko Kinoshita, Tsuyoshi Yamada.
Application Number | 20120000228 13/256669 |
Document ID | / |
Family ID | 42739484 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000228 |
Kind Code |
A1 |
Kinoshita; Hidehiko ; et
al. |
January 5, 2012 |
AIR CONDITIONING APPARATUS
Abstract
An air conditioning apparatus includes a compression element, a
refrigerant cooler, an expansion element, a refrigerant heater, a
magnetic field generator, a generated heat temperature sensor and a
control part. The magnetic field generator generates a magnetic
field in order to induction-heat a refrigerant tube circulating
refrigerant and/or a member in thermal contact with refrigerant
flowing through the refrigerant tube. The generated heat
temperature sensor senses temperature of a portion that generates
heat due to the induction heating. The control part performs
superheating protection control in order to increase an opening
degree of the expansion mechanism when the temperature sensed by
the generated heat temperature sensor reaches or exceeds a
predetermined generated heat temperature, or when a rate of
increase of the temperature sensed by the generated heat
temperature sensor reaches or exceeds a predetermined rate of
increase.
Inventors: |
Kinoshita; Hidehiko; (Osaka,
JP) ; Yamada; Tsuyoshi; (Osaka, JP) |
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
42739484 |
Appl. No.: |
13/256669 |
Filed: |
March 19, 2010 |
PCT Filed: |
March 19, 2010 |
PCT NO: |
PCT/JP2010/001994 |
371 Date: |
September 15, 2011 |
Current U.S.
Class: |
62/222 |
Current CPC
Class: |
F25B 13/00 20130101;
F25B 2600/19 20130101; F25B 2600/21 20130101; F25B 2313/0312
20130101; F25B 2313/0314 20130101; F25B 2600/2513 20130101; F25B
2313/0315 20130101; F25B 2313/008 20130101; F25B 2400/01 20130101;
F25B 2500/26 20130101; F25B 2313/005 20130101 |
Class at
Publication: |
62/222 |
International
Class: |
F25B 41/04 20060101
F25B041/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2009 |
JP |
2009-069119 |
Claims
1. An air conditioning apparatus comprising: a compression element;
a refrigerant cooler; an expansion element; a refrigerant heater; a
magnetic field generator arranged to generate a magnetic field in
order to induction-heat a refrigerant tube arranged to circulate
refrigerant to the compression element, the refrigerant cooler, the
expansion element, and the refrigerant heater, and/or a member in
thermal contact with refrigerant flowing through the refrigerant
tube; a generated heat temperature sensor arranged and configured
to sense temperature of a portion that generates heat due to the
induction heating by the magnetic field generator; and a control
part configured to perform superheating protection control in order
to increase an opening degree of the expansion mechanism when the
temperature sensed by the generated heat temperature sensor reaches
or exceeds a predetermined generated heat temperature, or when a
rate of increase of the temperature sensed by the generated heat
temperature sensor reaches or exceeds a predetermined rate of
increase.
2. The air conditioning apparatus according to claim 1, wherein the
magnetic field generator is arranged to generate a magnetic field
in order to induction-heat an intake refrigerant tube within the
refrigerant tube in an intake side of the compression element
and/or a member in thermal contact with refrigerant flowing through
the intake refrigerant tube.
3. The air conditioning apparatus according to claim 1, wherein the
control part is further configured to perform startup control in
which the magnetic field generator is caused to generate a magnetic
field so that the temperature of the portion where heat is
generated due to the induction heating by the magnetic field
generator reaches a predetermined startup target temperature while
driving of the compression element is initiated from a stopped
state of the compression element, and to perform post-startup
control after the startup control has ended; and when the
superheating protection control is performed at the same time the
post-startup control is being performed, the control part is
further configured to increase the opening degree of the expansion
mechanism when the temperature sensed by the generated heat
temperature sensor reaches or exceeds a post-startup predetermined
generated heat temperature, which is a temperature equal to or
greater than the predetermined startup target temperature.
4. The air conditioning apparatus according to claim 3, wherein
when the superheating protection control is performed at the same
time the startup control is being performed, the control part is
further configured to increase the opening degree of the expansion
mechanism when the rate of increase of the temperature sensed by
the generated heat temperature sensor at a time when the
predetermined startup target temperature is reached reaches or
exceeds the predetermined rate of increase.
5. The air conditioning apparatus according to claim 4, wherein
when the predetermined rate of increase is determined to have been
reached or exceeded, the control part is further configured to
increase the opening degree of the expansion mechanism only when
rotational speed of the compression mechanism reaches or exceeds a
predetermined rotational speed.
6. The air conditioning apparatus according to claim 3, further
comprising a cooler-side-refrigerant-state-perceiving part arranged
and configured to perceive a state of refrigerant passing through
from the refrigerant cooler to the expansion mechanism, when the
startup control has ended, the control part being further
configured to initiate subcooling-degree-fixing control in order to
control the opening degree of the expansion mechanism so that a
degree of subcooling of the refrigerant perceived using a value
perceived by the cooler-side-refrigerant-state-perceiving part is
kept fixed at a predetermined target degree of subcooling, and when
the superheating protection control is performed at the same time
the subcooling-degree-fixing control is being performed, the
control part being further configured to further increase the
opening degree of the expansion mechanism beyond the opening degree
controlled by the subcooling-degree-fixing control when the
temperature sensed by the generated heat temperature sensor reaches
or exceeds a predetermined subcooling-degree-fixing control
generated heat temperature, which is a temperature equal to or
greater than the predetermined startup target temperature.
7. The air conditioning apparatus according to claim 2, wherein the
control part is further configured to perform startup control in
which the magnetic field generator is caused to generate a magnetic
field so that the temperature of the portion where heat is
generated due to the induction heating by the magnetic field
generator reaches a predetermined startup target temperature while
driving of the compression element is initiated from a stopped
state of the compression element, and to perform post-startup
control after the startup control has ended; and when the
superheating protection control is performed at the same time the
post-startup control is being performed, the control part is
further configured to increase the opening degree of the expansion
mechanism when the temperature sensed by the generated heat
temperature sensor reaches or exceeds a post-startup predetermined
generated heat temperature, which is a temperature equal to or
greater than the predetermined startup target temperature.
8. The air conditioning apparatus according to claim 7, further
comprising a cooler-side-refrigerant-state-perceiving part arranged
and configured to perceive a state of refrigerant passing through
from the refrigerant cooler to the expansion mechanism, when the
startup control has ended, the control part being further
configured to initiate subcooling-degree-fixing control in order to
control the opening degree of the expansion mechanism so that a
degree of subcooling of the refrigerant perceived using a value
perceived by the cooler-side-refrigerant-state-perceiving part is
kept fixed at a predetermined target degree of subcooling, and when
the superheating protection control is performed at the same time
the subcooling-degree-fixing control is being performed, the
control part being further configured to further increase the
opening degree of the expansion mechanism beyond the opening degree
controlled by the subcooling-degree-fixing control when the
temperature sensed by the generated heat temperature sensor reaches
or exceeds a predetermined subcooling-degree-fixing control
generated heat temperature, which is a temperature equal to or
greater than the predetermined startup target temperature.
9. The air conditioning apparatus according to claim 4, further
comprising a cooler-side-refrigerant-state-perceiving part arranged
and configured to perceive a state of refrigerant passing through
from the refrigerant cooler to the expansion mechanism, when the
startup control has ended, the control part being further
configured to initiate subcooling-degree-fixing control in order to
control the opening degree of the expansion mechanism so that a
degree of subcooling of the refrigerant perceived using a value
perceived by the cooler-side-refrigerant-state-perceiving part is
kept fixed at a predetermined target degree of subcooling, and when
the superheating protection control is performed at the same time
the subcooling-degree-fixing control is being performed, the
control part being further configured to further increase the
opening degree of the expansion mechanism beyond the opening degree
controlled by the subcooling-degree-fixing control when the
temperature sensed by the generated heat temperature sensor reaches
or exceeds a predetermined subcooling-degree-fixing control
generated heat temperature, which is a temperature equal to or
greater than the predetermined startup target temperature.
10. The air conditioning apparatus according to claim 5, further
comprising a cooler-side-refrigerant-state-perceiving part arranged
and configured to perceive a state of refrigerant passing through
from the refrigerant cooler to the expansion mechanism, when the
startup control has ended, the control part being further
configured to initiate subcooling-degree-fixing control in order to
control the opening degree of the expansion mechanism so that a
degree of subcooling of the refrigerant perceived using a value
perceived by the cooler-side-refrigerant-state-perceiving part is
kept fixed at a predetermined target degree of subcooling, and when
the superheating protection control is performed at the same time
the subcooling-degree-fixing control is being performed, the
control part being further configured to further increase the
opening degree of the expansion mechanism beyond the opening degree
controlled by the subcooling-degree-fixing control when the
temperature sensed by the generated heat temperature sensor reaches
or exceeds a predetermined subcooling-degree-fixing control
generated heat temperature, which is a temperature equal to or
greater than the predetermined startup target temperature.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air conditioning
apparatus.
BACKGROUND ART
[0002] In conventional practice, there are known air conditioning
apparatuses in which the refrigerant circulation quantity or the
like is controlled in order to control the degree of superheating
of refrigerant drawn into the compressor.
[0003] For example, in the air conditioning apparatus disclosed in
Patent Literature 1 (Japanese Laid-open Patent Publication No.
7-120083), the refrigerant circulation quantity can be increased
and the degree of superheating of refrigerant drawn into the
compressor can be controlled by performing a control so that the
opening degree of an electric expansion valve is increased in
accordance with the temperature of the refrigerant drawn into the
compressor.
SUMMARY OF THE INVENTION
Technical Problem
[0004] There are cases in which, in the intake side of the
compressor, the refrigerant drawn into the compressor is indirectly
warmed by using an external heating apparatus to heat a refrigerant
tube or the like in thermal contact with the refrigerant.
[0005] In cases of using such an external heating device, when an
intake refrigerant temperature sensor of the compressor is disposed
between the portion to be heated by the external heating device and
the intake side of the compressor, for example, the heat applied to
the heated portion by the external heating device is thermally
transmitted to the vicinity where the downstream intake refrigerant
temperature sensor is attached, making an accurate sensing of the
intake refrigerant temperature difficult. With valve opening degree
control of the electric expansion valve, which is based on the
sensed value of the intake refrigerant temperature sensor of the
compressor disposed between the portion heated by the external
heating device and the intake side of the compressor, there is a
risk that the valve opening degree will be over-increased and the
refrigerant circulation quantity will increase by too much, and not
only will the excessive increase in the degree of superheating of
the refrigerant drawn into the compressor be minimized, but liquid
compression will occur.
[0006] When the portion heated by the external heating device is
provided so as to be downstream of the sensing position of the
intake refrigerant temperature sensor of the compressor and
upstream of the intake side of the compressor, for example, it is
not possible to perceive the temperature of the intake refrigerant
which is heated by passing through the heated portion. With valve
opening degree control of the electric expansion valve, which is
based on the sensed value of the intake refrigerant temperature
sensor disposed upstream of the portion heated by the external
heating device, there is a risk that the valve opening degree will
be over-reduced and the refrigerant circulation quantity will
decrease by too much, and the degree of superheating of the
refrigerant drawn into the compressor will increase
excessively.
[0007] The present invention was devised in view of the
circumstances described above, and an object thereof is to provide
an air conditioning apparatus capable of performing control taking
into account the heat quantity applied to the intake refrigerant in
superheating degree control of the refrigerant drawn into the
compression mechanism, even when the refrigerant in the intake side
of the compression mechanism is heated.
Solution to Problem
[0008] An air conditioning apparatus according to a first aspect is
an air conditioning apparatus which includes at least a compression
mechanism, a refrigerant cooler, an expansion mechanism, and a
refrigerant heater; the air conditioning apparatus comprising a
magnetic field generator, a generated heat temperature sensor, and
a control part. The magnetic field generator generates a magnetic
field in order to induction-heat a refrigerant tube for circulating
refrigerant to the compression mechanism, the refrigerant cooler,
the expansion mechanism, and the refrigerant heater, and/or a
member in thermal contact with the refrigerant flowing through the
refrigerant tube. The generated heat temperature sensor senses the
temperature of a portion that generates heat due to the induction
heating performed by the magnetic field generator. The control part
performs superheating protection control for increasing the opening
degree of the expansion mechanism either when the temperature
sensed by the generated heat temperature sensor reaches or exceeds
a predetermined generated heat temperature, or when the rate of
increase of the temperature sensed by the generated heat
temperature sensor reaches or exceeds a predetermined rate of
increase.
[0009] In this air conditioning apparatus, since a generated heat
temperature sensor is provided, it is possible to perceive the
temperature situation of the portion where heat is generated by the
induction heating of the magnetic field generator. Due to the
superheating protection control performed by the control part, the
opening degree of the expansion mechanism is increased and the
refrigerant quantity supplied to the intake side of the compression
mechanism becomes larger when either the temperature sensed by the
generated heat temperature sensor reaches or exceeds a
predetermined generated heat temperature, or the rate of increase
of the temperature sensed by the generated heat temperature sensor
reaches or exceeds a predetermined rate of increase. Therefore, it
is possible to minimize the abnormal increase in the the degree of
superheating of refrigerant drawn into the compression mechanism.
It is thereby possible to perform superheating degree control on
the refrigerant drawn into the compression mechanism while taking
into account the heat quantity applied to the drawn-in refrigerant,
even when the refrigerant in the intake side of the compression
mechanism is heated.
[0010] An air conditioning apparatus according to a second aspect
is the air conditioning apparatus according to the first aspect,
wherein the magnetic field generator generates a magnetic field for
induction-heating an intake refrigerant tube within the refrigerant
tube in the intake side of the compression mechanism and/or a
member in thermal contact with the refrigerant flowing through the
intake refrigerant tube.
[0011] In this air conditioning apparatus, refrigerant immediately
before being drawn into the compression mechanism is rapidly
heated, and not refrigerant flowing through the refrigerant tube
some distance away from the compression mechanism. The refrigerant
flowing through the intake side of the compression mechanism is
either very dry or superheated, and compared with cases in which
there is a change in the latent heat of gas-liquid two-phase
refrigerant flowing further upstream, it is easy to induce a change
in sensible heat and the temperature therefore increases
readily.
[0012] In this air conditioning apparatus, since superheating
protection control is performed either when the temperature sensed
by the generated heat temperature sensor reaches or exceeds the
predetermined generated heat temperature or when the rate of
increase of the temperature sensed by the generated heat
temperature sensor exceeds the predetermined rate of increase, it
is possible to prevent excessive induction heating of the
refrigerant passing through the intake side of the compression
mechanism. Thereby, even in a case of heating being performed on
the refrigerant passing through the intake side of the compression
mechanism with a rise in temperature readily occurring, it is
possible to suppress excessive heating of the induction-heated
portion.
[0013] An air conditioning apparatus according to a third aspect is
the air conditioning apparatus according to the first or second
aspect, wherein the control part performs startup control and
post-startup control. In startup control, the magnetic field
generator is made to generate a magnetic field so that the
temperature of the portion where heat is generated by the induction
heating by the magnetic field generator reaches a predetermined
startup target temperature while driving of the compression
mechanism is initiated from a stopped state of the compression
mechanism. Post-startup control is performed after the startup
control has ended. When the superheating protection control is
performed at the same time the post-startup control is being
performed, the control part increases the opening degree of the
expansion mechanism when the temperature sensed by the generated
heat temperature sensor reaches or exceeds a post-startup
predetermined generated heat temperature. This post-startup
predetermined generated heat temperature is a temperature equal to
or greater than the predetermined startup target temperature. The
post-startup predetermined generated heat temperature may also be a
temperature simply equal to the predetermined startup target
temperature.
[0014] In this air conditioning apparatus, in the post-startup
control, the opening degree of the expansion mechanism is increased
when the temperature of the portion that generates heat by
induction heating has increased to reach or exceed the post-startup
predetermined generated heat temperature, whereby the temperature
of the portion that generates heat by induction heating can be
reduced. Therefore, in post-startup control, it is possible to
suppress the abnormal temperature increase of the portion that
generates heat by induction heating.
[0015] When the post-startup predetermined generated heat
temperature is not a temperature equal to the predetermined startup
target temperature but is a temperature higher than the
predetermined startup target temperature, and even when a process
is performed for stopping or diminishing the supply of a magnetic
field from the magnetic field generator when the temperature of the
portion that generates heat by induction heating has increased too
much, the time duration in which a high refrigerant temperature can
be maintained by induction heating can be further lengthened.
[0016] An air conditioning apparatus according to a fourth aspect
is the air conditioning apparatus according to the third aspect,
wherein when the superheating protection control is performed at
the same time the startup control is being performed, the control
part increases the opening degree of the expansion mechanism when
the rate of increase of the temperature sensed by the generated
heat temperature sensor at the time the predetermined startup
target temperature is reached reaches or exceeds the predetermined
rate of increase.
[0017] In this air conditioning apparatus, in the startup control,
the opening degree of the expansion mechanism is increased when the
sensed temperature of the generated heat temperature sensor
increases fast enough for the temperature rate of increase to reach
or exceed a predetermined rate of increase. In the post-startup
control, the opening degree of the expansion mechanism is increased
when the sensed temperature of the generated heat temperature
sensor reaches or exceeds a predetermined generated heat
temperature. Therefore, since a determination is made based on the
sensed temperature in the post-startup control but a determination
is made based on the temperature rate of increase in the startup
control, the opening degree of the expansion mechanism is increased
at the point in time when the rate of increase either reaches or
exceeds the predetermined rate of increase even when a rapid
temperature increase is being induced during startup; therefore,
when the predetermined rate of increase is reached or exceeded
before the predetermined generated heat temperature is reached,
there is no need to wait for a process of increasing the opening
degree of the expansion mechanism until the predetermined generated
heat temperature is reached. Therefore, a large amount of
refrigerant can be more reliably supplied to the portion that
generates heat by induction heating. It is thereby possible to
suppress the extent by which the temperature steadily increases in
the portion that generates heat by induction heating.
[0018] An air conditioning apparatus according to a fifth aspect is
the air conditioning apparatus according to the fourth aspect,
wherein when the predetermined rate of increase is determined to
have been reached or exceeded, the control part increases the
opening degree of the expansion mechanism only when the rotational
speed of the compression mechanism reaches or exceeds a
predetermined rotational speed.
[0019] In this air conditioning apparatus, there are cases in which
the temperature rate of increase of the portion that generates heat
by induction heating reaches or exceeds the predetermined rate of
increase when a state is ensured in which the rotational speed of
the compression mechanism reaches or exceeds the predetermined
rotational speed. Even in such cases, the refrigerant circulation
quantity can be more reliably increased by increasing the opening
degree of the compression mechanism in a state in which the drive
state of the compression mechanism is ensured.
[0020] An air conditioning apparatus according to a sixth aspect is
the air conditioning apparatus according to any of the third
through fifth aspects, further comprising a
cooler-side-refrigerant-state-perceiving part for perceiving the
state of refrigerant passing through from the refrigerant cooler to
the expansion mechanism. When the startup control has ended, the
control part initiates subcooling-degree-fixing control for
controlling the opening degree of the expansion mechanism so that
the degree of subcooling of the refrigerant perceived using the
value perceived by the cooler-side-refrigerant-state-perceiving
part is kept fixed at a predetermined target degree of subcooling.
Furthermore, when the superheating protection control is performed
at the same time the subcooling-degree-fixing control is being
performed, the control part further increases the opening degree of
the expansion mechanism above the opening degree controlled by the
subcooling-degree-fixing control when the temperature sensed by the
generated heat temperature sensor reaches or exceeds a
predetermined subcooling-degree-fixing control generated heat
temperature. The predetermined subcooling-degree-fixing control
generated heat temperature is a temperature equal to or greater
than the predetermined startup target temperature.
[0021] In this air conditioning apparatus, it is possible to
minimize abnormal increases in the temperature of the portion that
generates heat by induction heating, even when
subcooling-degree-fixing control is being performed.
Effects of Invention
[0022] In the air conditioning apparatus according to the first
aspect, it is possible to perform superheating degree control on
the refrigerant drawn into the compression mechanism while taking
into account the heat quantity applied to the drawn-in refrigerant,
even when the refrigerant in the intake side of the compression
mechanism is heated.
[0023] In the air conditioning apparatus according to the second
aspect, it is possible to minimize the excessive heating of the
induction-heated portion, despite heating of the refrigerant
passing through the intake side of the compression mechanism, which
readily increases in temperature.
[0024] In the air conditioning apparatus according to the third
aspect, the abnormal temperature increase of the portion that
generates heat by induction heating can be suppressed in
post-startup control.
[0025] In the air conditioning apparatus according to the fourth
aspect, it is possible to suppress the extent by which the
temperature steadily increases in the portion that generates heat
by induction heating.
[0026] In the air conditioning apparatus according to the fifth
aspect, the refrigerant circulation quantity can be more reliably
increased.
[0027] In the air conditioning apparatus according to the sixth
aspect, it is possible to minimize abnormal increases in the
temperature of the portion that generates heat by induction
heating, even when subcooling-degree-fixing control is being
performed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a refrigerant circuit diagram of an air
conditioning apparatus according to an embodiment of the present
invention.
[0029] FIG. 2 is an external perspective view of an electromagnetic
induction heating unit.
[0030] FIG. 3 is an external perspective view showing a state in
which a shielding cover has been removed from the electromagnetic
induction heating unit.
[0031] FIG. 4 is an external perspective view of an electromagnetic
induction thermistor.
[0032] FIG. 5 is an external perspective view of a fuse.
[0033] FIG. 6 is a schematic cross-sectional view showing the
attached state of the electromagnetic induction thermistor and the
fuse.
[0034] FIG. 7 is a cross-sectional structural view of the
electromagnetic induction heating unit.
[0035] FIG. 8 is a view showing the details of a magnetic flux.
[0036] FIG. 9 is a view showing the various state transitions of
the superheating protection control.
[0037] FIG. 10 is a view showing a flowchart of the startup
superheating protection control.
[0038] FIG. 11 is a view showing a flowchart of the regular
superheating protection control.
[0039] FIG. 12 is an explanatory view of a refrigerant tube of
another embodiment (E).
[0040] FIG. 13 is an explanatory view of a refrigerant tube of
another embodiment (F).
[0041] FIG. 14 is a view showing an example of arranging coils and
a refrigerant tube of another embodiment (G).
[0042] FIG. 15 is a view showing an example of arranging bobbin
covers of another embodiment (G).
[0043] FIG. 16 is a view showing an example of arranging ferrite
cases of another embodiment (G).
DESCRIPTION OF EMBODIMENTS
[0044] An air conditioning apparatus 1 comprising an
electromagnetic induction heating unit 6 in one embodiment of the
present invention is described in an example hereinbelow with
reference to the drawings.
<1-1> Air Conditioning Apparatus 1
[0045] FIG. 1 shows a refrigerant circuit diagram showing a
refrigerant circuit 10 of the air conditioning apparatus 1.
[0046] In the air conditioning apparatus 1, an outdoor unit 2 as a
heat source-side apparatus and an indoor unit 4 as a usage-side
apparatus are connected by refrigerant tubes, and air conditioning
is performed in the space where the usage-side apparatus is
disposed; the air conditioning apparatus 1 comprising a compressor
21, a four-way switching valve 22, an outdoor heat exchanger 23, an
outdoor electric expansion valve 24, an accumulator 25, an outdoor
fan 26, an indoor heat exchanger 41, an indoor fan 42, a hot gas
bypass valve 27, a capillary tube 28, an electromagnetic induction
heating unit 6, and other components.
[0047] The compressor 21, the four-way switching valve 22, the
outdoor heat exchanger 23, the outdoor electric expansion valve 24,
the accumulator 25, the outdoor fans 26, the hot gas bypass valve
27, the capillary tube 28, and the electromagnetic induction
heating unit 6 are housed within the outdoor unit 2. The indoor
heat exchanger 41 and the indoor fan 42 are housed within the
indoor unit 4.
[0048] The refrigerant circuit 10 has a discharge tube A, an
indoor-side gas tube B, an indoor-side liquid tube C, an
outdoor-side liquid tube D, an outdoor-side gas tube E, an
accumulation tube F, an intake tube G, and a hot gas bypass circuit
H. The indoor-side gas tube B and the outdoor-side gas tube E pass
large quantities of gas-state refrigerant, but the refrigerant
passing through is not limited to a gas refrigerant. The
indoor-side liquid tube C and the outdoor-side liquid tube D pass
large quantities of liquid-state refrigerant, but the refrigerant
passing through is not limited to a liquid refrigerant.
[0049] The discharge tube A connects the compressor 21 and the
four-way switching valve 22. The discharge tube A is provided with
a discharge temperature sensor 29d for sensing the temperature of
the refrigerant passing through. An electric current supply part
21e supplies an electric current to the compressor 21. The amount
of electricity supplied by the electric current supply part 21e is
sensed by a compressor electricity sensor 29f. The drive rotational
speed of the piston of the compressor 21 is sensed by a rotational
speed perceiving part 29r. The indoor-side gas tube B connects the
four-way switching valve 22 and the indoor heat exchanger 41. A
first pressure sensor 29a for sensing the pressure of the
refrigerant passing through is provided at some point along the
indoor-side gas tube B. The indoor-side liquid tube C connects the
indoor heat exchanger 41 and the outdoor electric expansion valve
24. The outdoor-side liquid tube D connects the outdoor electric
expansion valve 24 and the outdoor heat exchanger 23. The
outdoor-side gas tube E connects the outdoor heat exchanger 23 and
the four-way switching valve 22. A second pressure sensor 29g for
sensing the pressure of the refrigerant passing through is provided
at some point along the outdoor-side gas tube E.
[0050] The accumulation tube F connects the four-way switching
valve 22 and the accumulator 25, and extends in a vertical
direction when the outdoor unit 2 has been installed. The
electromagnetic induction heating unit 6 is attached to a part of
the accumulation tube F. A heat-generating portion of the
accumulation tube F, whose periphery is covered at least by a coil
68 described hereinafter, is composed of a copper tube F1 through
which refrigerant flows and a magnetic tube F2 provided so as to
cover the periphery of the copper tube F1. This magnetic tube F2 is
composed of stainless used steel (SUS) 430. This SUS 430 is a
ferromagnetic material, which creates eddy currents when placed in
a magnetic field and which generates heat by Joule heat created by
its own electrical resistance. Aside from the magnetic tube F2, the
tubes constituting the refrigerant circuit 10 are composed of
copper tubes of the same material as the copper tube F1. By
performing electromagnetic induction heating in this manner, the
accumulation tube F can be heated by electromagnetic induction, and
the refrigerant drawn into the compressor 21 via the accumulator 25
can be warmed. The warming capability of the air conditioning
apparatus 1 can thereby be improved. Even in cases in which the
compressor 21 is not sufficiently warmed at the start of the
air-warming operation, for example, the lack of capability at
startup can be compensated for by the quick heating by the
electromagnetic induction heating unit 6. Furthermore, when the
four-way switching valve 22 is switched to the air-cooling
operation state and a defrosting operation is performed for
removing frost deposited on the outdoor heat exchanger 23 or other
components, the compressor 21 can quickly compress the warmed
refrigerant as a target due to the electromagnetic induction
heating unit 6 quickly heating the accumulation tube F. Therefore,
the temperature of the hot gas discharged from the compressor 21
can be quickly increased. The time required to thaw the frost
through the defrosting operation can thereby be shortened. Thereby,
even when the defrosting operation must be performed at the right
time during the air-warming operation, the air-warming operation
can be resumed as quickly as possible, and user comfort can be
improved.
[0051] The intake tube G connects the accumulator 25 and the intake
side of the compressor 21.
[0052] The hot gas bypass circuit H connects a branching point A1
provided at some point along the discharge tube A and a branching
point D1 provided at some point along the outdoor-side liquid tube
D. Disposed at some point in the hot gas bypass circuit H is the
hot gas bypass valve 27, which can switch between a state of
permitting the passage of refrigerant and a state of not permitting
the passage of refrigerant. Between the hot gas bypass valve 27 and
the branching point D1, the hot gas bypass circuit H is provided
with a capillary tube 28 for lowering the pressure of refrigerant
passing through. This capillary tube 28 makes it possible to
approach the pressure that follows the refrigerant pressure
decrease caused by the outdoor electric expansion valve 24 during
the air-warming operation, and therefore makes it possible to
suppress the rise in refrigerant pressure in the outdoor-side
liquid tube D caused by the supply of hot gas through the hot gas
bypass circuit H to the outdoor-side liquid tube D.
[0053] The four-way switching valve 22 is capable of switching
between an air-cooling operation cycle and an air-warming operation
cycle. In FIG. 1, the connection state during the air-warming
operation is shown by solid lines, and the connection state during
the air-cooling operation is shown by dotted lines. During the
air-warming operation, the indoor heat exchanger 41 functions as a
cooler of refrigerant and the outdoor heat exchanger 23 functions
as a heater of refrigerant. During the air-cooling operation, the
outdoor heat exchanger 23 functions as a cooler of refrigerant and
the indoor heat exchanger 41 functions as a heater of
refrigerant.
[0054] One end of the outdoor heat exchanger 23 is connected to the
end of the outdoor-side gas tube E side of the outdoor heat
exchanger 23, and the other end is connected to the end of the
outdoor-side liquid tube D side of the outdoor heat exchanger 23.
The outdoor heat exchanger 23 is also provided with an outdoor heat
exchange temperature sensor 29c for sensing the temperature of the
refrigerant flowing through the air conditioning apparatus 1.
Furthermore, the upstream side of the outdoor heat exchanger 23 in
the direction of air flow is provided with an outdoor temperature
sensor 29b for sensing the outdoor air temperature.
[0055] An indoor temperature sensor 43 for sensing the indoor
temperature is provided inside the indoor unit 4. The indoor heat
exchanger 41 is also provided with an indoor heat exchange
temperature sensor 44 for sensing the refrigerant temperature of
the indoor-side liquid tube C side where the outdoor electric
expansion valve 24 is connected.
[0056] An outdoor control part 12 for controlling the devices
disposed in the outdoor unit 2 and an indoor control part 13 for
controlling the devices disposed in the indoor unit 4 are connected
by a communication line 11a, thereby constituting a control part
11. This control part 11 performs various controls on the air
conditioning apparatus 1.
[0057] The outdoor control part 12 is also provided with a timer 95
for counting the elapsed times when the various controls are
performed.
[0058] A controller 90 for receiving setting input from the user is
connected to the control part 11.
[0059] <1-2> Electromagnetic Induction Heating Unit 6
[0060] FIG. 2 shows a schematic perspective view of the
electromagnetic induction heating unit 6 attached to the
accumulation tube F. FIG. 3 shows an external perspective view in
which a shielding cover 75 has been removed from the
electromagnetic induction heating unit 6. FIG. 4 shows a schematic
structural view of an electromagnetic induction thermistor 14. FIG.
5 shows a schematic structural view of a fuse 15. FIG. 6 shows a
cross-sectional view of the attached state of the electromagnetic
induction thermistor 14 and the fuse 15 to the accumulation tube F.
FIG. 7 shows a cross-sectional view of the electromagnetic
induction heating unit 6 attached to the accumulation tube F. FIG.
8 shows an explanatory view of a state of a magnetic field
generated by the coil 68.
[0061] The electromagnetic induction heating unit 6 is disposed so
as to cover the magnetic tube F2 from the radially outer side, the
magnetic tube F2 being the heat-generating portion of the
accumulation tube F, and the magnetic tube F2 is made to generate
heat by electromagnetic induction heating. This heat-generating
portion of the accumulation tube F has a double-layered tube
structure having the copper tube F1 on the inner side and the
magnetic tube F2 on the outer side.
[0062] The electromagnetic induction heating unit 6 comprises a
first hexagonal nut 61, a second hexagonal nut 66, a first bobbin
cover 63, a second bobbin cover 64, a bobbin main body 65, a first
ferrite case 71, a second ferrite case 72, a third ferrite case 73,
a fourth ferrite case 74, a first ferrite 98, a second ferrite 99,
the coil 68, the shielding cover 75, the electromagnetic induction
thermistor 14, the fuse 15, and other components.
[0063] The first hexagonal nut 61 and the second hexagonal nut 66
are made of a resin, and are used to stabilize the fixed state
between the electromagnetic induction heating unit 6 and the
accumulation tube F with the aid of a C ring (not shown). The first
bobbin cover 63 and the second bobbin cover 64 are made of a resin,
and are used to cover the accumulation tube F from the radially
outer side in the top end position and the bottom end position,
respectively. The first bobbin cover 63 and the second bobbin cover
64 have four screw holes for screws 69 in order for the first
through fourth ferrite cases 71 to 74 described hereinafter to be
screwed in via the screws 69. Furthermore, the second bobbin cover
64 has an electromagnetic induction thermistor insertion opening
64f for inserting the electromagnetic induction thermistor 14 and
attaching it to the outer surface of the magnetic tube F2. The
second bobbin cover 64 has a fuse insertion opening 64e for
inserting the fuse 15 and attaching it to the outer surface of the
magnetic tube F2. The electromagnetic induction thermistor 14 has
an electromagnetic induction thermistor sensor 14a, an outer
projection 14b, a side projection 14c, and electromagnetic
induction thermistor wires 14d for converting the sensing result of
the electromagnetic induction thermistor sensor 14a to a signal and
sending it to the control part 11, as shown in FIG. 4. The
electromagnetic induction thermistor sensor 14a has a shape that
conforms to the curved shape of the outer surface of the
accumulation tube F, and has a substantial contact surface area.
The fuse 15 has a fuse sensor 15a, an asymmetrical shape 15b, and
fuse wires 15d for converting the sensing result of the fuse sensor
15a to a signal and sending it to the control part 11, as shown in
FIG. 5. Having received from the fuse 15 a notification that a
temperature exceeding a predetermined limit temperature has been
sensed, the control part 11 performs a control for stopping the
supply of electricity to the coil 68, avoiding heat damage to the
equipment. The bobbin main body 65 is made of a resin, and the coil
68 is wound over the bobbin main body 65. The coil 68 is wound in a
helical shape over the outer side of the bobbin main body 65, with
the axial direction being the direction in which the accumulation
tube F extends. The coil 68 is connected to a control print board
(not shown), and the coil receives a supply of high-frequency
electric current. The output of the control print board is
controlled by the control part 11. The electromagnetic induction
thermistor 14 and the fuse 15 are attached in a state in which the
bobbin main body 65 and the second bobbin cover 64 have been joined
together, as shown in FIG. 6. When the electromagnetic induction
thermistor 14 has been attached, a satisfactory state of
pressurized contact with the outer surface of the magnetic tube F2
is maintained by a plate spring 16 pushing radially inward on the
magnetic tube F2. Similarly, in the attachment of the fuse 15, a
satisfactory state of pressurized contact with the outer surface of
the magnetic tube F2 is maintained by a plate spring 17 pushing
radially inward on the magnetic tube F2. Thus, since the
electromagnetic induction thermistor 14 and the fuse 15 stay
satisfactorily in firm contact with the outer surface of the
accumulation tube F, responsiveness is improved and sudden
temperature changes caused by electromagnetic induction heating can
be quickly detected. In the first ferrite case 71, the first bobbin
cover 63 and the second bobbin cover 64 are held in from the
direction in which the accumulation tube F extends and are screwed
in place by the screws 69. The first ferrite case 71 through the
fourth ferrite case 74 house the first ferrite 98 and the second
ferrite 99, which are composed of the highly magnetically permeable
material ferrite. The first ferrite 98 and the second ferrite 99
absorb the magnetic field created by the coil 68 and form a
magnetic flux pathway, thereby impeding the magnetic field from
leaking out to the exterior, as shown in the cross-sectional view
of the accumulation tube F and electromagnetic induction heating
unit 6 of FIG. 7 as well as the magnetic flux explanatory view of
FIG. 8. The shielding cover 75 is disposed around the outermost
periphery of the electromagnetic induction heating unit 6, and
collects a magnetic flux that cannot be contained with the first
ferrite 98 and the second ferrite 99 alone. The magnetic flux
mostly does not leak outside of the shielding cover 75, and the
location where the magnetic flux is created can be determined
arbitrarily.
[0064] <1-3> Electromagnetic Induction Heating Control
[0065] The electromagnetic induction heating unit 6 described above
performs a control for causing the magnetic tube F2 of the
accumulation tube F to generate heat, during startup in which the
air-warming operation is initiated when the refrigeration cycle is
caused to perform the air-warming operation, during air-warming
capability assistance, and during the defrosting operation.
[0066] The description hereinbelow pertains to the time of startup
in particular. FIG. 9 shows the details of the different states
transitioning.
[0067] (Initial Process During Startup)
[0068] The initial process during startup is a process performed
after the air-warming operation is initiated until the pressure
sensed by the first pressure sensor 29a reaches a target high
pressure.
[0069] When an air-warming operation command is inputted to the
controller 90 from the user, the control part 11 initiates the
air-warming operation. When the air-warming operation is initiated,
the control part 11 waits until the compressor 21 has started up
and the pressure sensed by the first pressure sensor 29a has risen
to the predetermined target high pressure of 39 kg/cm.sup.2 (shown
by point h in FIG. 9), and causes the indoor fan 42 to be driven.
This prevents discomfort for the user due to unwarmed air flowing
into the room in the stage at which the refrigerant passing through
the indoor heat exchanger 41 has not yet warmed.
[0070] Electromagnetic induction heating using the electromagnetic
induction heating unit 6 is performed here while the opening degree
of the outdoor electric expansion valve 24 is maintained at a fixed
opening degree, in order to shorten the time duration for the
compressor 21 to start up and the pressure sensed by the first
pressure sensor 29a to reach 39 kg/cm.sup.2. The control part 11
initiates the rapid pressure-increasing process after confirming
that a sufficient flow of refrigerant is ensured in the
accumulation tube F after the compressor 21 has started up. In the
rapid pressure-increasing process, in order to shorten the time
needed for the temperature sensed by the electromagnetic induction
thermistor 14 to reach the startup target accumulation tube
temperature of 80.degree. C., the control part 11 brings the supply
of electric current to the coil 68 of the electromagnetic induction
heating unit 6 to a predetermined maximum supplied electricity (2
kW). This output state of the electromagnetic induction heating
unit 6 at the predetermined maximum supplied electricity is
continued until the temperature sensed by the electromagnetic
induction thermistor 14 reaches a startup target accumulation tube
temperature of 80.degree. C.
[0071] Thus, control is performed for maintaining the opening
degree of the outdoor electric expansion valve 24 at a fixed
opening degree in order to shorten the time needed to reach the
predetermined target high pressure at startup, or for bringing the
output of the electromagnetic induction heating unit 6 to the
maximum supplied electricity in order to shorten the time needed
for the temperature sensed by the electromagnetic induction
thermistor 14 to reach the startup target accumulation tube
temperature, but there is a risk of this induction heating causing
an abnormal increase in the degree of superheating of the
refrigerant drawn into the compressor 21. Therefore, to prevent
such abnormal increases in the degree of superheating of the
drawn-in refrigerant, startup superheating protection control
(described hereinafter) is performed by the control part 11 at
startup.
[0072] (Secondary Process During Startup)
[0073] The secondary process during startup is a process during
startup which is performed after the pressure sensed by the first
pressure sensor 29a has reached the target high pressure.
[0074] In this secondary process during startup, after the pressure
sensed by the first pressure sensor 29a has reached the
predetermined target high pressure of 39 kg/cm.sup.2, steady output
control is performed for increasing the refrigerant circulation
quantity of the refrigeration cycle and increasing capability by
further increasing the rotational speed of the compressor 21 and
increasing the opening degree of the outdoor electric expansion
valve 24.
[0075] After the air-warming operation has been initiated. and once
the startup target accumulation tube temperature of 80.degree. C.
has been reached and the initial action at startup has ended, the
control part 11 holds the output at a steady supplied electricity
(1.4 kW) which is less than the predetermined maximum supplied
electricity (2 kW), and controls the output of the electromagnetic
induction heating unit 6 so that the temperature sensed by the
electromagnetic induction thermistor 14 is maintained at a
temperature near the target temperature of 80.degree. C., the same
as the startup target accumulation tube temperature. In this
control of maintaining the temperature near 80.degree. C., the
control part 11 performs a process in which induction heating by
the electromagnetic induction heating unit 6 is initiated at the
steady supplied electricity (1.4 kW) output when the temperature
sensed by the electromagnetic induction thermistor 14 is equal to
or less than 60.degree. C., and induction heating by the
electromagnetic induction heating unit 6 is stopped when the
temperature sensed by the electromagnetic induction thermistor 14
reaches 80.degree. C.
[0076] (Regular Process After the Process During Startup has
Ended)
[0077] Due to the steady output control continuing, the rotational
speed of the compressor 21 increasing, the opening degree of the
outdoor electric expansion valve 24 also being increased, and the
refrigerant circulation quantity of the refrigeration cycle
increasing, the process during startup ends when a circulation
quantity corresponding to the operation state is reached, after
which the regular operation is performed. In this regular
operation, subcooling-degree-fixing control whereby the control
part 11 controls the opening degree of the outdoor electric
expansion valve 24 is performed so that the degree of subcooling of
the refrigerant passing through the outlet side of the indoor heat
exchanger 41 in the air-warming operation circuit is kept fixed at
a predetermined value. This degree of subcooling is obtained by the
control part 11 calculating the difference between the saturation
temperature corresponding to the sensed pressure of the second
pressure sensor 29g and the temperature sensed by the indoor heat
exchange temperature sensor 44.
[0078] (Startup Superheating Protection Control)
[0079] The startup superheating protection control is a control for
increasing the opening degree of the outdoor electric expansion
valve 24 in order to prevent the degree of superheating of the
refrigerant drawn into the compressor 21 from increasing
abnormally, by induction heating by the electromagnetic induction
heating unit 6 at the initial maximum supplied electricity (2 kW)
during startup.
[0080] FIG. 10 shows a flowchart of the startup superheating
protection control.
[0081] In step S11, the control part 11 confirms that the
temperature sensed by the electromagnetic induction thermistor 14
has decreased after startup of the compressor 21 has been initiated
(shown by point a in FIG. 9), and then transitions to step S12.
[0082] In step S12, the control part 11 switches the output of the
electromagnetic induction heating unit 6 from a state of 0 to the
maximum supplied electricity (2 kW) (shown in FIG. 9 as the change
from point b to point c), and at the same time begins to count the
elapsed time through the timer 95.
[0083] In step S13, the control part 11 determines whether or not
the temperature sensed by the electromagnetic induction thermistor
14 has reached the startup target accumulation tube temperature of
80.degree. C. When the startup target accumulation tube temperature
of 80.degree. C. is reached (shown as point d in FIG. 9), the
process transitions to step S14.
[0084] In step S14, the control part 11 temporarily stops the
induction heating by the electromagnetic induction heating unit 6
(shown as point e in FIG. 9), and ends the count of the timer 95
initiated in step S12.
[0085] In step S15, the control part 11 determines whether or not
the rotational speed sensed by the rotational speed perceiving part
29r is greater than a superheat-minimizing estimated rotational
speed of 82 rps (82 rotations per second). This
superheat-minimizing estimated rotational speed is a rotational
speed set in advance as a rotational speed at which the degree of
superheating of the refrigerant drawn into the compressor 21 is not
likely to increase abnormally, based on the conditions established
for the refrigeration cycle. Since the intake pressure is not
likely to decrease by much when this superheat-minimizing estimated
rotational speed is not met, it is estimated that there is no risk
of an abnormal increase in the degree of superheating of the
refrigerant drawn into the compressor 21, and the startup
superheating protection control is ended. When the
superheat-minimizing estimated rotational speed is exceeded, the
process transitions to step S16.
[0086] In step S16, the control part 11 determines whether or not
the value of the timer 95 at the end of the count in step S14 is
less than a temperature increase rate judgment time of 20 seconds.
This temperature increase rate judgment time is a time duration set
in advance as a time duration corresponding to the temperature
increase rate at which the degree of superheating of the
refrigerant drawn into the compressor 21 is not likely to increase
abnormally, based on the set conditions of the refrigeration cycle.
Specifically, when the time needed to reach the startup target
accumulation tube temperature of 80.degree. C. after induction
heating by the electromagnetic induction heating unit 6 is
initiated is less than the temperature increase rate judgment time
(20 seconds), the temperature increase rate of the temperature
sensed by the electromagnetic induction thermistor 14 is too fast,
and a transition is made to step S17 and a protection routine is
performed on the premise that there is a risk of an abnormal
increase in the degree of superheating of the refrigerant drawn
into the compressor 21. Conversely, when the time needed reaches or
exceeds the temperature increase rate judgment time, it is
estimated that there is no risk of an abnormal increase in the
degree of superheating of the refrigerant drawn into the compressor
21, and the startup superheating protection control is ended.
[0087] In step S17, the control part 11 performs a valve opening
degree increasing process for increasing the opening degree of the
outdoor electric expansion valve 24 to increase the refrigerant
circulation quantity through the accumulation tube F, thereby
preventing too fast of a temperature increase in the accumulation
tube F caused by the induction heating by the electromagnetic
induction heating unit 6. In this valve opening degree increasing
process, the opening degree of the outdoor electric expansion valve
24 is increased in 20 pulse increments every 20 seconds. This
process of increasing in 20 pulse increments every 20 seconds is
repeated until the rate of increase in the temperature sensed by
the electromagnetic induction thermistor 14 caused by induction
heating is equal to or less than a predetermined rate.
Specifically, simultaneous with the action of increasing the
opening degree of the outdoor electric expansion valve 24, a
process is performed for determining whether or not the rate of
increase in the temperature sensed by the electromagnetic induction
thermistor 14 has ceased to exceed the predetermined rate, and when
the opening degree of the outdoor electric expansion valve 24 has
increased to the point of no longer exceeding the predetermined
rate, it is determined that there is no longer a risk of the
temperature of the accumulation tube F increasing too much, and the
valve opening degree increasing process is ended.
[0088] The startup superheating protection control is ended in the
above manner.
[0089] After the pressure sensed by the first pressure sensor 29a
has reached the target high pressure, the steady output control is
performed as described above, whereby the frequency of the
compressor 21 is increased, the opening degree of the outdoor
electric expansion valve 24 is further increased, the refrigerant
quantity circulating in the refrigeration cycle further increases,
and the capability of the refrigeration cycle is increased.
[0090] (Regular Superheating Protection Control)
[0091] The regular superheating protection control is a control for
preventing the degree of superheating from increasing abnormally
due to induction heating in a case where the opening degree of the
outdoor electric expansion valve 24 is increased, the temporary
decrease in the temperature sensed by the electromagnetic induction
thermistor 14 is sensed, and induction heating is performed by the
electromagnetic induction heating unit 6, when the
subcooling-degree-fixing control is performed.
[0092] FIG. 11 shows a flowchart of the regular superheating
protection control.
[0093] In step S21, when the temperature sensed by the
electromagnetic induction thermistor 14 is 80.degree. C. or less,
the control part 11 increases the output of the electromagnetic
induction heating unit 6 from a state of 0 to an output (steady
level) from a steady supply of electricity (1.4 kW; steady
level).
[0094] In step S22, the control part 11 determines whether or not
the temperature sensed by the electromagnetic induction thermistor
14 has reached 80.degree. C. If it has reached 80.degree. C., the
process transitions to step S23.
[0095] In step S23, the control part 11 temporarily stops the
induction heating by the electromagnetic induction heating unit
6.
[0096] In step S24, after stopping the induction heating by the
electromagnetic induction heating unit 6, the control part 11
continues to sense the manner in which the temperature sensed by
the electromagnetic induction thermistor 14 is increasing, and
determines whether or not the temperature exceeds an abnormally
increased temperature of 110.degree. C. Specifically, the control
part determines whether or not overshooting is occurring in which
the temperature sensed by the electromagnetic induction thermistor
14 continues to increase above 80.degree. C., regardless of the
induction heating by the electromagnetic induction heating unit 6
having ended. The abnormally increased temperature of 110.degree.
C. is a temperature set in advance, based on the design conditions
of the refrigeration cycle, as a temperature at which after its
value is exceeded, the degree of superheating of the refrigerant
drawn into the compressor 21 increases abnormally. If it is
determined that the abnormally increased temperature is exceeded,
the process transitions to step S25. If it is determined that the
abnormally increased temperature is not exceeded, it is estimated
that there is no risk of an abnormal increase in the degree of
superheating of the refrigerant drawn into the compressor 21 and
the startup superheating protection control is ended.
[0097] In step S25, the control part 11 performs an adjustment for
increasing the opening degree (valve opening degree adjustment
process) in which the opening degree of the outdoor electric
expansion valve 24 controlled by the subcooling-degree-fixing
control is increased from its pulse value by another 50 pulses. The
increase here is 50 pulses, which is greater than the single
20-pulse increase in the opening degree of the outdoor electric
expansion valve 24 in the startup superheating protection control
described above. It is thereby possible to more quickly prevent an
abnormal temperature increase in the accumulation tube F even when
it appears that an abnormal state will occur in the regular
superheating protection control.
[0098] The regular superheating protection control is ended in the
above manner.
[0099] In the regular superheating protection control, since the
rotational speed at which the compressor 21 is driven is already in
excess of 82 rps, the determination in the startup superheating
protection control is unnecessary.
[0100] <Characteristics of Air Conditioning Apparatus 1 of
Present Embodiment>
[0101] (1)
[0102] In induction heating by the electromagnetic induction
heating unit 6, the temperature is quickly increased not in
refrigerant flowing through portions in the refrigeration cycle
somewhat distanced from the compressor 21, but in the refrigerant
flowing through the accumulation tube F immediately before being
drawn into the compressor 21. The refrigerant flowing through the
intake side of the compressor 21 is either very dry or in a
superheated state, and this refrigerant is more likely to have a
change in sensible heat or a temperature increase, compared with
cases of a latent heat change in gas-liquid two-phase refrigerant
flowing further upstream. Since the refrigerant drawn into the
compressor 21 is heated, the heat generated in the magnetic tube F2
is affected by heat transfer or the like, and it is therefore
difficult to perceive the temperature of the refrigerant actually
being drawn into the compressor 21.
[0103] In the control performed by the air conditioning apparatus 1
of the present embodiment in such a situation, it is not the
temperature of the refrigerant actually drawn into the compressor
21 that is perceived by the electromagnetic induction thermistor
14, but rather the temperature situation of the magnetic tube F2 of
the accumulation tube F where heat is generated by induction
heating. Based on the temperature sensed by the electromagnetic
induction thermistor 14, the opening degree of the outdoor electric
expansion valve 24 can be increased and the refrigerant quantity
supplied to the intake side of the compressor 21 can be increased
so that there is no abnormal increase in the degree of superheating
of the refrigerant drawn into the compressor 21. It is thereby
possible, in cases of heating the refrigerant in the intake side of
the compressor 21, for the heat quantity applied to the drawn-in
refrigerant to be accounted for via the temperature sensed by the
electromagnetic induction thermistor 14 and to minimize any
abnormal increase in the degree of superheating in the refrigerant
drawn into the compressor 21, even in cases in which it is
difficult to perceive the actual temperature of the drawn-in
refrigerant.
[0104] (2)
[0105] In the startup superheating protection control of the
present embodiment, in situations in which the temperature of the
magnetic tube F2 of the accumulation tube F suddenly increases due
to induction heating during startup, it is possible to minimize
abnormal increases in the degree of superheating in the refrigerant
drawn into the compressor 21 by increasing the opening degree of
the outdoor electric expansion valve 24 and supplying more
refrigerant. This startup superheating protection control takes
into account the rotational speed at which the compressor 21 is
driven and increases the opening degree of the outdoor electric
expansion valve 24 only when the temperature of the magnetic tube
F2 suddenly increases even under circumstances in which the drive
state of the compressor 21 is ensured, by selecting a
pre-established superheat-minimizing estimated rotational speed as
a rotational speed at which an abnormal temperature increase
usually does not occur. Therefore, increases in the opening degree
of the outdoor electric expansion valve 24 can be avoided during
startup in the stage when the rotational speed at which the
compressor 21 is driven has not yet increased by much. It is
thereby unlikely that there will be a high-low pressure difference
due to a greater increase than is necessary in the opening degree
of the outdoor electric expansion valve 24, and it is possible to
prevent increases in the time duration needed for the sensed
pressure of the first pressure sensor 29a to reach the
predetermined target high pressure of 39 kg/cm.sup.2, and also to
prevent high-temperature refrigerant from being unable to be
supplied to the indoor heat exchanger 41.
[0106] The timing with which the opening degree of the outdoor
electric expansion valve 24 is increased in the startup
superheating protection control does not have a determination
reference of whether or not the temperature sensed by the
electromagnetic induction thermistor 14 has exceeded a certain
temperature, but instead uses the rate of temperature increase as a
determination reference. Therefore, there is no need to provide
another new judgment temperature that is higher than the startup
target accumulation tube temperature or to determine whether or not
this judgment temperature has been exceeded. It is more when it has
been perceived that a certain rate of temperature increase has been
exceeded than when it is perceived that the judgment temperature
has been exceeded that the subsequent temperature of the
accumulation tube F quickly increases more rapidly. Therefore,
reliability of the apparatus can be improved in the above
embodiment wherein it is possible to perceive cases in which such
abnormal increases in temperature occur readily.
[0107] For example, considering a case in which the control for
increasing the opening degree of the outdoor electric expansion
valve 24 when the judgment temperature has been exceeded, wherein
90.degree. C. is set as a temperature higher than the startup
target accumulation tube temperature, several minutes is needed for
the temperature sensed by the electromagnetic induction thermistor
14 to increase from 89.degree. C. to exceed 90.degree. C., and the
opening degree of the outdoor electric expansion valve 24 is
increased even when it is estimated that the temperature will
thereafter increase by no more than several degrees even with the
passage of a long moment. By contrast, in the startup superheating
protection control of the above embodiment, the opening degree of
the outdoor electric expansion valve 24 is increased only when a
rate of temperature increase is detected in which 80.degree. C. is
exceeded in 20 seconds, and it is therefore possible to prevent
decreases in the discharge refrigerant temperature caused by the
opening degree of the outdoor electric expansion valve 24 being
increased unnecessarily.
[0108] (3)
[0109] Furthermore, in the regular superheating protection control,
when the temperature sensed by the electromagnetic induction
thermistor 14 has exceeded the abnormally increased temperature of
110.degree. C. due to induction heating being performed during
subcooling-degree-fixing control, the opening degree is increased
further above the opening degree of the outdoor electric expansion
valve 24 controlled by subcooling-degree-fixing control. Therefore,
compared with control in which merely the opening degree of the
outdoor electric expansion valve 24 is adjusted to a certain
opening degree when the abnormally increased temperature of
110.degree. C. is exceeded, the refrigerant quantity passing
through the accumulation tube F can be more reliably increased and
any abnormal increases in the degree of superheating of the
refrigerant drawn into the compressor 21 can therefore be more
reliably minimized.
[0110] This regular superheating protection control is performed in
a state in which the refrigerant circulation quantity of the
refrigeration cycle is more stable than during startup, and sudden
increases in the temperature of the accumulation tube F are
unlikely; therefore, there is no need for determinations based on
the rate of temperature increase, and reliability can be
sufficiently ensured with a simple determination method for
determining whether or not the abnormally increased temperature of
110.degree. C. has been exceeded.
[0111] It is also thereby possible to lengthen the time duration in
which heat is input to the magnetic tube F2 by the induction
heating by the electromagnetic induction heating unit 6 because the
quantity of refrigerant drawn into the compressor 21 increases.
[0112] Until the electromagnetic induction thermistor 14 senses the
abnormally increased temperature of 110.degree. C., which is a
higher temperature than 80.degree. C. at which induction heating by
the electromagnetic induction heating unit 6 is stopped, the
opening degree of the outdoor electric expansion valve 24 is
maintained at the opening degree of the subcooling-degree-fixing
control and the opening degree of the outdoor electric expansion
valve 24 is not increased; therefore, the time duration during
which a high refrigerant temperature can be maintained by induction
heating can be lengthened further.
[0113] [Other Embodiments]
[0114] An embodiment of the present invention was described above
based on the drawings, but the specific configuration is not
limited to this embodiment, and modifications can be made within a
range that does not deviate from the scope of the invention.
[0115] (A)
[0116] In the embodiment described above, an example was described
of a case in which SUS430 is used as the material of the magnetic
tube F2.
[0117] However, the present invention is not limited to this
example. The magnetic tube can be, for example, iron, copper,
aluminum, chrome, nickel, other conductors, and alloys containing
at least two or more metals selected from these listed.
[0118] The example of the magnetic material given here contains,
e.g., ferrite, martensite, or a combination of the two, but it is
preferable to use a ferromagnetic metal which has a comparatively
high electrical resistance and which has a higher Curie temperature
than its service temperature range.
[0119] The accumulation tube F here requires more electricity, but
it need not comprise a magnetic substance and a material containing
a magnetic substance; it may include a material that will be the
target of induction heating.
[0120] The magnetic material may, e.g., constitute the entire
accumulation tube F, may be formed only in the inside surface of
the accumulation tube F, or may be present only due to being
included in the material constituting the accumulation tube F.
[0121] (B)
[0122] In the embodiment described above, an example was described
of a case in which the condition for increasing the opening degree
of the outdoor electric expansion valve 24 differs between the
startup superheating protection control and the regular
superheating protection control.
[0123] However, the present invention is not limited to this
example. The condition for increasing the opening degree of the
outdoor electric expansion valve 24 may be the same for both the
startup superheating protection control and the regular
superheating protection control, for example.
[0124] (C)
[0125] In the embodiment described above, an example was described
of a case in which control is performed for keeping the degree of
subcooling fixed after the control during startup is ended.
[0126] However, the present invention is not limited to this
example. For example, control may be performed for maintaining the
extent of change in the distribution state of the refrigerant in
the refrigeration cycle for a predetermined time duration either at
a predetermined distribution state or within a predetermined
distribution range. To sense this refrigerant distribution state,
the refrigerant distribution state may be perceived by providing a
sight glass to the condenser of the refrigeration cycle or adopting
another method to perceive the liquid surface of the refrigerant,
and stability control may be performed so that the distribution
state reaches a predetermined distribution state or comes within a
predetermined distribution range.
[0127] (D)
[0128] In the embodiment described above, a case was described in
which within the refrigerant circuit 10, the electromagnetic
induction heating unit 6 is attached to the accumulation tube
F.
[0129] However, the present invention is not limited to this
example.
[0130] For example, the electromagnetic induction heating unit 6
may be provided to another refrigerant tube besides the
accumulation tube F. In this case, the magnetic tube F2 or another
magnetic element is provided to the refrigerant tube portion where
the electromagnetic induction heating unit 6 is provided.
[0131] (E)
[0132] In the embodiment described above, a case was described in
which the accumulation tube F is configured as a double-layered
tube containing the copper tube Fl and the magnetic tube F2.
[0133] However, the present invention is not limited to this
example.
[0134] A magnetic member F2a and two stoppers F1a, F1b may be
disposed inside the accumulation tube F and a refrigerant tube as a
heated object, for example, as shown in FIG. 12. The magnetic
member F2a is a member containing a magnetic material whereby heat
is generated by electromagnetic induction heating in the embodiment
described above. The stoppers F1a, F1b are placed in two locations
inside the copper tube F1, normally permitting refrigerant to pass
through but not permitting the magnetic member F2a to pass through.
The magnetic member F2a thereby does not move despite the flow of
refrigerant. Therefore, the intended heating position in the
accumulation tube F, for example, can be heated. Furthermore, since
the heat-generating magnetic member F2a and the refrigerant are in
direct contact, heat transfer efficiency can be improved.
[0135] (F)
[0136] The magnetic member F2a described above in the other
embodiment (L) may be positioned within the tube without the use of
the stoppers F1a, F2b.
[0137] As shown in FIG. 13, for example, bent portions FW may be
provided in two locations in the copper tube F1, and the magnetic
member F2a may be disposed inside the copper tube F1 between the
bent portions FW provided in two locations. The movement of the
magnetic member F2a can be restricted while allowing refrigerant to
pass through in this manner as well.
[0138] (G)
[0139] In the embodiment described above, a case was described in
which the coil 68 is wound around the accumulation tube F in a
helical shape.
[0140] However, the present invention is not limited to this
example.
[0141] For example, a coil 168 wound around a bobbin main body 165
may be disposed around the periphery of the accumulation tube F
without being wound over the accumulation tube F, as shown in FIG.
14. The bobbin main body 165 is disposed so that its axial
direction is substantially perpendicular to the axial direction of
the accumulation tube F. Two bobbin main bodies 165 and coils 168
each are disposed separately so as to sandwich the accumulation
tube F.
[0142] In this case, a first bobbin cover 163 and a second bobbin
cover 164 which pass through the accumulation tube F may be
disposed in a state of being fitted over the bobbin main body 165,
as shown in FIG. 15, for example.
[0143] Furthermore, the first bobbin cover 163 and the second
bobbin cover 164 may be fixed in place by being sandwiched by a
first ferrite case 171 and a second ferrite case 172, as shown in
FIG. 16. In FIG. 16, an example is shown of a case in which two
ferrite cases are disposed so as to sandwich the accumulation tube
F, but they may be arranged in four directions similar to the
embodiment described above. The ferrite may also be housed similar
to the embodiment described above.
[0144] (H)
[0145] In the embodiment described above, an example was described
of a case in which whether or not the rate of temperature increase
is fast is determined by referring to whether or not a time
duration less than the temperature increase rate judgment time (20
seconds) is needed to reach the startup target accumulation tube
temperature of 80.degree. C. after the initiation of induction
heating by the electromagnetic induction heating unit 6.
[0146] However, the method of perceiving the rate of temperature
increase is not limited to this perceiving method.
[0147] For example, instead of actually perceiving the rate of
temperature increase, an information table may be stored in advance
in the controller 90, and the control part 11 may perform control
such as estimating the rate of temperature increase by referring to
this information table and then increases the valve opening degree
of the outdoor electric expansion valve 24.
[0148] An example of such an information table is data that
correlates the current temperature sensed by the electromagnetic
induction thermistor 14, the amount the accumulation tube F is
heated by the electromagnetic induction heating unit 6, the
refrigerant circulation quantity passing through the accumulation
tube F, the density of the refrigerant passing through the
accumulation tube F, the outdoor air temperature, and other
conditions, as well as values calculated in advance as rates of
temperature increase corresponding to these conditions. When the
rates of temperature increase are calculated in advance in this
manner, they are preferably calculated based on the thermal
conductivity of the magnetic tube F2 and the copper tube F1, the
thermal conductivity between the magnetic tube F2 and the copper
tube F1, the thermal conductivity between the copper tube F1 and
the refrigerant, and other factors.
[0149] The amount the accumulation tube F is heated by the
electromagnetic induction heating unit 6 can be converted from the
amount of electricity supplied by the electric current supply part
21e as sensed by the compressor electricity sensor 29f. The
refrigerant circulation quantity passing through the accumulation
tube F or the density of refrigerant passing through the
accumulation tube F can be converted from the drive rotational
speed of the piston of the compressor 21 as perceived by the
rotational speed perceiving part 29r, the high pressure perceived
by the first pressure sensor 29a, the low pressure perceived by the
second pressure sensor, or the like. The outdoor air temperature
can be perceived as the sensed temperature of the outdoor
temperature sensor 29b. When an information table has been stored
in advance in the controller 90 in this manner, the processing load
of the control part 11 can be reduced.
[0150] Instead of storing such an information table in the
controller 90, a predetermined relationship equation may be stored
in the controller 90 and the control part 11 may calculate
estimated rates of temperature increase on the basis of values
perceived from the sensors described above.
[0151] The information table and the calculation can be simplified
by establishing in advance the amount of electricity supplied to
the electromagnetic induction heating unit 6 by the electric
current supply part 21e in two patterns consisting of a
predetermined output (e.g. 2 kW) and another predetermined output
(e.g. 1.4 kW), on the basis of, e.g., the outdoor air
temperature.
[0152] Thus, when the control part 11 does not actually perceive
the rate of temperature increase but instead perceives it by
calculating it from the information table or a predetermined
relationship equation, or by another method, the time duration for
actually gauging the rate of temperature increase is unnecessary,
and a quicker process can therefore be performed.
[0153] (I)
[0154] In the embodiment described above, an example was described
of a case in which during steady output control following the
beginning of startup, a process is performed wherein induction
heating by the electromagnetic induction heating unit 6 is
initiated at the steady supplied electricity (1.4 kW) output when
the temperature sensed by the electromagnetic induction thermistor
14 is 60.degree. C. or less, and induction heating by the
electromagnetic induction heating unit 6 is stopped when the
temperature sensed by the electromagnetic induction thermistor 14
reaches 80.degree. C., so that the temperature sensed by the
electromagnetic induction thermistor 14 is maintained in the
vicinity of the startup target accumulation tube temperature of
80.degree. C.
[0155] However, the control for maintaining the temperature sensed
by the electromagnetic induction thermistor 14 in the vicinity of
80.degree. C. during the steady output control is not limited to
such control.
[0156] For example, the control part 11 may maintain the
temperature sensed by the electromagnetic induction thermistor 14
in the vicinity of 80.degree. C. by PI controlling the frequency of
supplying an electric current to the electromagnetic induction
heating unit 6 on the basis of the temperature sensed by the
electromagnetic induction thermistor 14. In this PI control,
wherein one set is the supply of an electric current to the
electromagnetic induction heating unit 6 at a continuous fixed
output of the steady supplied electricity (1.4 kW) for 30 seconds,
the control part 11 may adjust the frequency with which this set is
repeated, based on the elapsed time from the end of the most recent
electric current supply to the electromagnetic induction heating
unit 6 until the temperature sensed by the electromagnetic
induction thermistor 14 falls back down to 80.degree. C.
Specifically, control may be performed so that the longer this
elapsed time, the higher the frequency with which the
above-described set is repeated.
[0157] <Other>
[0158] Embodiments of the present invention were described above in
several examples, but the present invention is not limited to these
embodiments. For example, the present invention also includes
combined embodiments obtained by suitably combining different
portions of the above embodiments, within a range that can be
carried out based on the above descriptions by those skilled in the
art.
INDUSTRIAL APPLICABILITY
[0159] According to the present invention, even when refrigerant in
the intake side of the compression mechanism is heated, it is
possible to perform control that accounts for the heat quantity
applied to the drawn-in refrigerant during superheating degree
control of the refrigerant drawn into the compression mechanism,
and the present invention is therefore particularly useful in an
air conditioning apparatus which heats a refrigerant by induction
heating.
REFERENCE SIGNS LIST
[0160] 1 Air conditioning apparatus [0161] 11 Control part
(cooler-side-refrigerant-state-perceiving part) [0162] 14
Electromagnetic induction thermistor (generated heat temperature
sensor) [0163] 21 Compressor (compression mechanism) [0164] 23
Outdoor heat exchanger (refrigerant heater) [0165] 24 Outdoor
electric expansion valve (expansion mechanism) [0166] 29a First
pressure sensor (cooler-side-refrigerant-state-perceiving part)
[0167] 29g Second pressure sensor [0168] 41 Indoor heat exchanger
(refrigerant cooler) [0169] 44 Indoor heat exchange temperature
sensor (cooler-side-refrigerant-state-perceiving part) [0170] 68
Coil (magnetic field generator) [0171] F Accumulation tube
(refrigerant tube, intake refrigerant tube)
CITATION LIST
Patent Literature
[0171] [0172] <Patent Literature 1> Japanese Laid-open Patent
Publication No. 7-120083
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