Title: Refrigeration apparatus
Abstract: This invention makes it possible to charge a refrigeration apparatus with the amount of refrigerant that the refrigeration apparatus requires at the time of onsite installation. As a result, the optimum refrigerant charging amount can always be obtained. The refrigeration apparatus is provided with a refrigeration cycle in which an outdoor unit equipped with a compressor, a condenser, and a receiver is connected to an indoor unit equipped with an expansion valve and an evaporator via a liquid pipe and a gas pipe. The refrigeration cycle is charged with refrigerant while a refrigerant charging operation state is created in which the liquid pipe that connects the outdoor unit to the indoor unit is filled with liquid refrigerant having a prescribed density. Refrigerant charging ends when, during the refrigerant charging operation, it is detected that the level of the liquid inside the receiver has reached a prescribed level.
Patent Number: 6,845,626 Issued on 01/25/2005 to Matsuoka, et al.
| Inventors:
|
Matsuoka; Hiromune (Sakai, JP);
Shimoda; Junichi (Sakai, JP)
|
| Assignee:
|
Daikin Industries, Ltd. (Osaka, JP)
|
| Appl. No.:
|
333055 |
| Filed:
|
January 16, 2003 |
| PCT Filed:
|
May 20, 2002
|
| PCT NO:
|
PCT/JP02/04866
|
| 371 Date:
|
January 16, 2003
|
| 102(e) Date:
|
January 16, 2003
|
| PCT PUB.NO.:
|
WO02/10326 |
| PCT PUB. Date:
|
December 27, 2002 |
Foreign Application Priority Data
| May 22, 2001[JP] | 2001-152091 |
| Current U.S. Class: |
62/149; 62/292 |
| Intern'l Class: |
F25B 045/00 |
| Field of Search: |
62/149,292,298,77
|
References Cited [Referenced By]
U.S. Patent Documents
| 4591839 | May., 1986 | Charboneau et al. | 340/620.
|
| 4856288 | Aug., 1989 | Weber | 62/129.
|
| 4967567 | Nov., 1990 | Proctor et al. | 62/127.
|
| 5076063 | Dec., 1991 | Kamegasawa et al. | 62/48.
|
| 5201188 | Apr., 1993 | Sakuma | 62/149.
|
| 6264431 | Jul., 2001 | Triezenberg | 417/36.
|
| Foreign Patent Documents |
| 59-77275 | May., 1984 | JP.
| |
| 62-96529 | Jun., 1987 | JP.
| |
| 62-130371 | Aug., 1987 | JP.
| |
| 08-121848 | May., 1996 | JP.
| |
| 08-145510 | Jun., 1996 | JP.
| |
| 10-30853 | Feb., 1998 | JP.
| |
| 2000-65411 | Mar., 2000 | JP.
| |
| 2000-356388 | Dec., 2000 | JP.
| |
| 2001-21242 | Jan., 2001 | JP.
| |
Primary Examiner: Jones; Melvin
Attorney, Agent or Firm: Shinjyu Global IP Counselors, LLP
Claims
What is claimed is:
1. A refrigeration apparatus comprising:
a refrigerant circuit in which the following are connected together:
an outdoor unit having a compressor that compresses gaseous refrigerant, a
heat-source-side heat exchanger connected to the compressor, and a
receiver connected to the heat-source-side heat exchanger for collecting
liquid refrigerant condensed by the heat-source-side heat exchanger, and
an indoor unit having an expansion valve and a utilization-side heat
exchanger connected to the heat-source-side heat exchanger, a liquid pipe
connecting the receiver and the expansion valve together and a gas pipe
connecting the utilization-side heat exchanger and the compressor
together; and
a liquid level detecting member that detects if a surface of the liquid
refrigerant inside the receiver has reached a prescribed level.
2. A refrigeration apparatus equipped with a refrigerant circuit in which
the following are connected together: a compressor that compresses gaseous
refrigerant, a heat-source-side heat exchanger, a receiver for collecting
liquid refrigerant, an expansion valve, a liquid pipe that connects the
receiver and the expansion valve, a utilization-side heat exchanger, and a
gas pipe that connects the utilization-side heat exchanger and the
compressor; and
a liquid level detecting member that detects if a surface of the liquid
refrigerant inside the receiver has reached a prescribed level,
the liquid level detecting member comprising a bypass circuit that connects
the receiver and a suction side of the compressor and includes an ON/OFF
valve and a pressure reducing mechanism and a temperature detecting member
that detects a temperature of the refrigerant flowing in the bypass
circuit.
3. A refrigeration apparatus equipped with a refrigerant circuit in which
the following are connected together: a compressor that compresses gaseous
refrigerant, a heat-source-side heat exchanger, a receiver for collecting
liquid refrigerant, an expansion valve, a liquid pipe that connects the
receiver and the expansion valve, a utilization-side heat exchanger, and a
gas pipe that connects the utilization-side heat exchanger and the
compressor;
a liquid level detecting member that detects if a surface of the liquid
refrigerant inside the receiver has reached a prescribed level;
a refrigerant charging operation control member that executes charging of
the refrigerant circuit with refrigerant while creating a refrigerant
charging operation state in which the liquid pipe of the refrigerant
circuit is filled with liquid refrigerant having a prescribed density; and
a refrigerant charging ending member that ends the refrigerant charging by
the refrigerant charging operation control member based on a detection
signal from the liquid level detecting member.
4. The refrigeration apparatus as recited in claim 3, wherein
the heat-source-side heat exchanger is an air-cooled heat exchanger that
uses air supplied from an outdoor fan as the heat source; and
the refrigerant charging operation control member controls the outdoor fan
such that a condensation pressure of the heat-source-side heat exchanger
which acts as a condenser achieves a prescribed value and controls opening
of the expansion valve such that a prescribed degree of superheating can
be imparted to the refrigerant at an outlet of the utilization-side heat
exchanger which acts as an evaporator.
5. The refrigeration apparatus as recited in claim 2, wherein the following
are further provided:
a refrigerant charging operation control member that executes charging of
the refrigerant circuit with refrigerant while creating a refrigerant
charging operation state in which the liquid pipe of the refrigerant
circuit is filled with liquid refrigerant having a prescribed density; and
a refrigerant charging ending member that ends the refrigerant charging by
the refrigerant charging operation control member based on a detection
signal from the liquid level detecting member.
6. The refrigeration apparatus as recited in claim 5, wherein
the heat-source-side heat exchanger is an air-cooled heat exchanger that
uses air supplied from an outdoor fan as the heat source; and
the refrigerant charging operation control member controls the outdoor fan
such that a condensation pressure of the heat-source-side heat exchanger
which acts as a condenser achieves a prescribed value and controls opening
of the expansion valve such that a prescribed degree of superheating can
be imparted to the refrigerant at an outlet of the utilization-side heat
exchanger which acts as an evaporator.
7. A refrigeration apparatus comprising:
a refrigerant circuit in which the following are connected together: a
compressor that compresses gaseous refrigerant, a heat-source-side heat
exchanger, a receiver for collecting liquid refrigerant, an expansion
valve, a liquid pipe that connects the receiver and the expansion valve, a
utilization-side heat exchanger, and a gas pipe that connects the
utilization-side heat exchanger and the compressor; and
a liquid level detecting member arranged and configured to extract a part
of the liquid refrigerant collected in the receiver, conduct pressure
reducing evaporation to the extracted liquid refrigerant, and detect if a
surface of the liquid refrigerant in the receiver has reached a prescribed
level by evaluating a temperature of the evaporated refrigerant.
Description
TECHNICAL FIELD
The present invention relates to a split-type refrigeration apparatus. More
specifically, the present invention relates to a method of setting and
determining the refrigerant charging amount when a split-type
refrigeration apparatus is charged with refrigerant onsite.
BACKGROUND ART
Split-type refrigeration apparatuses comprising an outdoor unit equipped
with a compressor, a condenser, and a receiver and an indoor unit equipped
with an expansion valve and an evaporator are well known. The refrigerant
charging of split-type refrigeration apparatuses configured in this manner
has conventionally been handled by charging the outdoor unit with a
prescribed amount of refrigerant in advance and charging additional
refrigerant onsite in accordance with the length of the piping connecting
the outdoor unit to the indoor unit when the apparatus is installed.
When the refrigerant charging amount is determined onsite during
installation, the performance and reliability of the equipment becomes
dependent on the quality of the installation and, in some cases, the
maximum capacity of the refrigeration apparatus cannot be realized.
DISCLOSURE OF THE INVENTION
The object of the present invention is to make it possible to always obtain
the optimum refrigerant charging amount by making it possible to charge
the amount of refrigerant that the refrigeration apparatus requires at the
time of the onsite installation.
The refrigeration apparatus described in the first aspect of the present
invention is equipped with a refrigerant circuit--in which a compressor, a
heat-source-side heat exchanger, a receiver, an expansion valve, a liquid
pipe, a utilization-side heat exchanger, and a gas pipe are connected
together--and a liquid level detecting means. The receiver collects liquid
refrigerant. The liquid pipe connects the receiver to the expansion valve.
The gas pipe connects the utilization-side heat exchanger to the
compressor. The liquid level detecting means detects if the surface of the
liquid inside the receiver has reached a prescribed level.
Since this refrigeration apparatus is equipped with a liquid level
detecting means, it can be detected if the surface of the liquid inside
the receiver has reached a prescribed level during refrigerant charging
operation when the refrigerant circuit is charged with refrigerant.
Thus, for example, if the apparatus is configured such that it can be
detected when the liquid surface reaches a maximum liquid level (Lmax),
then overcharging of refrigerant into the refrigerant circuit can be
detected. Furthermore, even when the length of the liquid pipe, gas pipe,
and other connecting piping cannot be measured, the required amount of
refrigerant charging can be obtained easily by detecting when a prescribed
liquid level (L0) is obtained inside the receiver.
The refrigeration apparatus described in the second aspect of the present
invention is a refrigeration apparatus as recited in the first aspect,
wherein the liquid level detecting means comprises a bypass circuit and a
temperature detecting means. The bypass circuit means connects the
receiver and the suction side of the compressor and includes an ON/OFF
valve and a pressure reducing mechanism. The temperature detecting means
detects the temperature of the refrigerant flowing in the bypass circuit.
Since the liquid level detecting means of this refrigeration apparatus
comprises a temperature detecting means and a bypass circuit that includes
an ON/OFF valve and a pressure reducing mechanism, the liquid level can be
detected reliably at low cost.
The refrigeration apparatus described in the third aspect of the present
invention is a refrigeration apparatus as recited in the first or second
aspect, wherein the following are further provided: a refrigerant charging
operation control means that executes charging of the refrigerant circuit
with refrigerant while creating a refrigerant charging operation state in
which the liquid pipe of the refrigerant circuit is filled with liquid
refrigerant having a prescribed density; and a refrigerant charging ending
means that ends the refrigerant charging executed by the refrigerant
charging operation control means based on the detection signal from the
liquid level detecting means.
With this refrigeration apparatus, the refrigerant circuit is charged with
refrigerant while a refrigerant charging operation state is created in
which the refrigerant circuit is filled with liquid refrigerant having a
prescribed density. During this refrigerant charging operation,
refrigerant charging is ended when it is detected that the liquid surface
inside the receiver has reached a prescribed level. Thus, the reliability
of the refrigerant charging process is improved.
The refrigeration apparatus described in the fourth aspect of the present
invention is a refrigeration apparatus as recited in the third aspect,
wherein the heat-source-side heat exchanger is an air-cooled heat
exchanger that uses air supplied from an outdoor fan as the heat source.
The refrigerant charging operation control means controls the outdoor fan
such that the condensation pressure of the heat-source-side heat exchanger
(which acts as a condenser) achieves a prescribed value and controls the
opening of the expansion valve such that a prescribed degree of
superheating can be imparted to the refrigerant at the outlet of the
utilization-side heat exchanger (which acts as an evaporator).
With this refrigeration apparatus, collection of more liquid refrigerant
than is necessary in the heat-source-side heat exchanger (which acts as
the condenser) is avoided and the gas pipe disposed between the
utilization-side heat exchanger and the suction side of the compressor is
filled with gaseous refrigerant. Therefore, a refrigerant charging
operation state in which the liquid piping is filled with liquid
refrigerant having a prescribed density can be achieved easily.
BRIEF DESCRIPTIONS OF THE DRAWINGS
FIG. 1(a) is a block diagram showing the refrigeration circuit of an
embodiment of a refrigeration apparatus in accordance with the present
invention.
FIG. 2 is an enlarged view of key components of the embodiment of a
refrigeration apparatus in accordance with the present invention.
FIG. 3 is an enlarged view of key components of another embodiment of a
refrigeration apparatus in accordance with the present invention.
BEST MODES OF WORKING THE INVENTION
Below, preferred embodiments of the present invention are described while
referring to the attached drawings.
As shown in FIG. 1, this split-type refrigeration apparatus comprises an
outdoor unit X and an indoor unit Y. The outdoor unit is equipped with a
compressor 1, an air-cooled condenser 2 (heat-source-side heat exchanger)
combined with an outdoor fan 6, and a receiver 3. The indoor unit is
equipped with an expansion valve 4 and an evaporator 5 (utilization-side
heat exchanger). The outdoor unit and indoor unit are connected by a
liquid pipe 8 and a gas pipe 9 to form a refrigeration cycle A
(refrigerant circuit). Liquid pipe 8 and gas pipe 9 include an onsite
piping section Z. Item 7 is an indoor fan.
As shown in FIG. 2, receiver 3 is equipped with a liquid level detecting
means or member 10 that detects if the liquid surface level L has reached
a prescribed level L0 inside receiver 3. In this embodiment, liquid level
detecting member 10 comprises a bypass circuit 14 and a thermistor 15. The
bypass circuit connects the prescribed level L0 in receiver 3 with the
suction pipe 11 of compressor 1 and has a solenoid ON/OFF valve 12 that is
actuated so as to open when the liquid level is detected to be at the
prescribed level and a capillary tube 13 that acts as a pressure reducing
mechanism. The thermistor acts as a temperature detecting means that
detects the temperature of the refrigerant flowing in bypass circuit 14.
The prescribed level L0 is the surface level of the liquid refrigerant
collected in receiver 2 when the refrigerant is needed the least (i.e.,
when the amount of circulating refrigerant is the smallest) during
air-conditioning operation. The prescribed level is set such that the
liquid level L inside receiver 3 does not fall below a minimum level Lmin
when the refrigerant is needed the most (i.e., when the amount of
circulating refrigerant is the largest) during air-conditioning operation.
Item 16 is a pressure sensor that detects the suction pressure.
Refrigeration cycle A is equipped with a controller 18 that receives
detection signals from thermistor 15 and pressure sensor 16 and sends
control signals to compressor 1, expansion valve 4, outdoor fan 6, indoor
fan 7 and solenoid ON/OFF valve 12.
Controller 18 has a function whereby it acts as a refrigerant charging
operation control means that executes charging of refrigeration cycle A
with refrigerant while creating a refrigerant charging operation state in
which liquid pipe 8 is filled with liquid refrigerant having a prescribed
density and a function whereby it acts as a refrigerant charging ending
means that ends the refrigerant charging executed by the refrigerant
charting operation control means based on the detection signal from liquid
level detecting means 10. In the embodiment, the refrigerant charging
operation control means controls outdoor fan 6 such that the condensation
pressure at condenser 2 becomes a prescribed value (i.e., such that more
liquid refrigerant than is necessary does not collect in condenser 2) and
controls the opening of expansion valve 4 such that a prescribed degree of
superheating can be imparted to the refrigerant at the outlet of
evaporator 5 (i.e., such that the gas pipe 9 disposed between evaporator 5
and compressor 1 is filled with gaseous refrigerant). Here, the
refrigerant is charged through a shut-off valve (not shown in the
drawings) that connects the outdoor unit X to the onsite connection piping
section Z.
Next, the operation of the refrigeration apparatus during refrigerant
charging is explained.
The control signal from controller 18 controls outdoor fan 6 such that the
condensation pressure at condenser 2 becomes a prescribed value (i.e.,
such that more liquid refrigerant than is necessary does not collect in
condenser 2) and controls the opening of expansion valve 4 such that a
prescribed degree of superheating can be imparted to the refrigerant at
the outlet of evaporator 5 (i.e., such that the gas pipe 9 disposed
between evaporator 5 and compressor 1 is filled with gaseous refrigerant).
As a result, refrigeration cycle A is charged with refrigerant while a
refrigerant charging operation state exists in which liquid pipe 8 is
filled with liquid refrigerant having a prescribed density. During this
charging, solenoid ON/OFF valve 12 is in the opened state.
As the system is charged, the amount of refrigerant circulating in
refrigerant cycle A increases gradually and the liquid level L of the
refrigerant inside receiver 3 rises. When the liquid level L reaches
prescribed level L0, which is the inlet to bypass circuit 14, saturated
liquid refrigerant flows into bypass circuit 14. Up until this point, the
saturated gas refrigerant filling the gas phase section of receiver 3 was
flowing into bypass circuit 14 and thermistor 15 was detecting the
temperature of this gaseous refrigerant.
When saturated liquid refrigerant flows into bypass circuit 14 as just
described, its pressure is reduced by capillary tube 13 and it evaporates,
causing the temperature detected by thermistor 15 to decrease rapidly.
Thus, the fact that the liquid level has reached the aforementioned
prescribed level can be detected by detecting this rapid decrease in
temperature and refrigerant charging can be ended at the point in time
when the liquid level is detected to be at the prescribed level.
With this method of refrigerant charging, refrigeration cycle A is charged
with the required amount of refrigerant. The required amount of
refrigerant can be charged even if the length of the connecting pipes
cannot be measured onsite and the reliability of the equipment is
improved.
Furthermore, outdoor fan 6 is controlled such that the condensation
pressure at condenser 2 becomes a prescribed value (i.e., such that more
liquid refrigerant than is necessary does not collect in condenser 2) and
the opening of expansion valve 4 is controlled such that a prescribed
degree of superheating can be imparted to the refrigerant at the outlet of
evaporator 5 (i.e., such that the gas pipe 9 disposed between evaporator 5
and compressor 1 is filled with gaseous refrigerant). As a result, a
refrigerant charging operation state in which liquid pipe 8 is filled with
liquid refrigerant having a prescribed density can be created easily.
In order to prevent degradation of the COP, it is critical to select the
capacity of receiver 3 such that refrigerant will not overflow out of
receiver 3 during the operating state in which the amount of surplus
refrigerant is the most redundant, and with the refrigerant charging
amount that was judged during the portion of the air-conditioning cycle
when the liquid level L is the lowest (i.e., when the condensation
pressure is high and the density of the liquid in liquid pipe 8 is large).
There are conventional refrigeration apparatuses that, as shown in FIG. 3,
are provided with a bypass circuit 19 that connects the top edge part Lmax
of receiver 3 with suction pipe 11 of compressor 1 and has a solenoid
ON/OFF valve 20 and a capillary tube 21. This bypass circuit acts as a
protection device during defrost operation, but refrigerant overcharging
can be detected by providing bypass circuit 19 with a thermistor 22. In
short, a thermistor 22 can be used to detect if the level L of the liquid
refrigerant inside receiver 3 has reached a maximum level Lmax during test
running after refrigerant charging. In this arrangement, a liquid surface
sensor is used as the liquid level detecting means 10.
The embodiments presented herein were described regarding a dedicated
air-conditioning device, but the present invention can also be applied to
a refrigeration apparatus that is provided with a four-way switching valve
on the discharge side of compressor 1 of outdoor unit X so that the flow
direction of the refrigerant in refrigeration cycle A can be reversed and
both heating and cooling can be performed.
Industrial Applicability
This invention makes it possible to charge a refrigeration apparatus with
the amount of refrigerant that the refrigeration apparatus requires at the
time of onsite installation. As a result, the optimum refrigerant charging
amount can always be obtained.
*
