JP2005331187A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator capable of detecting leakage of a flammable refrigerant without using an expensive refrigerant leakage detecting instrument such as a gas sensor and without falsely detecting a behavior change caused by other factors as refrigerant leakage, in a refrigeration cycle using the flammable refrigerant. <P>SOLUTION: The refrigerant is provided with fans 8, 10 for respectively supplying cool air generated by each radiator in the refrigeration cycle 11 to a freezing space and refrigerating space, wherein the refrigeration cycle 11 with the flammable refrigerant sealed is structured of a capacity variable compressor 12, a switching valve 16 for switching a refrigerant flow passage provided on an outlet side of a condenser receiving discharge gas from the compressor, and a radiator 7 for freezing and a radiator 9 for refrigeration connected from the switching valve through respective decompressing mechanisms 17, 19. The refrigerant leakage on a refrigeration cycle low pressure side is detected from pressure fluctuation in the refrigeration cycle detected from a change rate of load fluctuation of the compressor, a pressure in the refrigeration cycle detected from an absolute value of a compressor load, an an abnormal operation signal of the compressor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigerator, and more particularly to a control device that detects refrigerant leakage in a refrigeration cycle that uses a flammable refrigerant such as a hydrocarbon.

  In recent years, from the viewpoint of environmental protection against ozone layer destruction and global warming caused by chlorofluorocarbon gas, the refrigerant used in the refrigerator refrigeration cycle has no ozone layer destruction from conventional HFC (hydrofluorocarbon), and has a global warming potential. The adoption of hydrocarbon refrigerants such as low-carbon hydrocarbons (hereinafter referred to as “HC refrigerants”) is expanding.

  However, since this HC refrigerant is a flammable refrigerant, there is a possibility of developing into a fire when ignited due to refrigerant leakage.

  Therefore, when using HC refrigerant, it is necessary to ensure safety without problems such as fire even if refrigerant leakage occurs due to problems during manufacture of the refrigerator or impact during transportation. A configuration in which a temperature sensor or a pressure sensor is disposed at the inlet and the outlet, and the presence or absence of refrigerant leakage is determined from a comparison between the temperature difference or pressure difference between the two and a preset value stored (for example, see Patent Document 1), There is a configuration in which a refrigerant leak detection device is provided around the cooler, and when the refrigerant leaks, the refrigerant leaked through the communication hole also serving as the defrost water drainage is forcibly discharged together with air (see Patent Document 2). It is considered.

In the above case, an apparatus for detecting refrigerant leakage is required, resulting in high costs and only post-processing after the refrigerant has leaked. A configuration in which refrigerant leakage is detected from pressure fluctuations in the refrigeration cycle and changes in compressor load due to refrigerant leakage when there are holes in the components such as coolers and connection pipes that are damaged due to damage. (See Patent Document 3).
JP-A-9-14811 JP-A-9-329386 JP 2003-139446 A

  However, according to the invention described in the above-mentioned Patent Document 3, a dedicated device for detecting refrigerant leakage is not necessary. However, it is determined that refrigerant leakage is caused only by load fluctuation or load change of the compressor. In addition, it is difficult to discriminate from behavior changes caused by environmental changes around the refrigerator, and these behavior changes are confused with refrigerant leaks, resulting in a problem of erroneous detection.

  The present invention has been made in consideration of the above points, and in the refrigeration cycle using the flammable HC refrigerant, without using an expensive refrigerant leak detection device such as a gas sensor, and other factors. It is an object of the present invention to provide a refrigerator that can detect a leakage of a flammable refrigerant from a refrigeration cycle without erroneously detecting a behavior change as a refrigerant leak.

  In order to solve the above problems, a refrigerator according to the present invention includes a variable capacity compressor, a switching valve that switches a refrigerant flow path provided on the outlet side of the condenser that receives the discharge gas from the compressor, and the switching valve. Supplying cold air generated by each cooler of the refrigeration cycle in which a flammable refrigerant composed of a refrigeration cooler and a refrigeration cooler connected via a decompression mechanism is enclosed to the refrigeration space and the refrigeration space, respectively In a refrigerator equipped with a fan, the pressure fluctuation in the refrigeration cycle detected from the change rate of the load fluctuation of the compressor, the pressure in the refrigeration cycle detected from the absolute value of the compressor load, and the abnormal operation of the compressor The refrigerant leakage on the low pressure side of the refrigeration cycle is detected based on the signal.

  According to the refrigerator of the present invention, it is possible to detect the occurrence of refrigerant leakage due to a crack in the refrigeration cycle or the like without using a dedicated leakage refrigerant detection device. In addition, it is possible to provide a safe control configuration that is not affected by load fluctuations in the refrigerator or that is not confused with load fluctuations and that does not erroneously detect the refrigerant leak and that may cause a fire.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view with the refrigerator door removed, with the inside of the refrigerator body (1) formed of a heat insulating box as a storage space at the top, the refrigerator compartment (2), and below it the vegetable compartment (3) The freezer compartment (4) is disposed independently at the bottom, and an automatic ice compartment (5) and a multi-purpose compartment are provided between the freezer compartment (4) and the vegetable compartment (3) through an insulating partition wall. The temperature switching chamber (6) is juxtaposed to the left and right, and although not shown, a dedicated door is provided at the front opening of each storage chamber to close the room so that it can be opened and closed.

  A refrigerator (7) and a cooling fan (8) for a freezing space such as a freezing room or an ice making room are arranged on the back of the freezer room (4), and a refrigerator room (2) is placed on the back of the vegetable room (3). The refrigeration cooler (9) and the cooling fan (10) for cooling the vegetable room (3) and the vegetable compartment (3) are provided, and the refrigerant compressor (12) installed in the machine room at the bottom of the main body drives the cooling for freezing. The cool air cooled by the cooler (7) and the refrigerating cooler (9) is blown to the respective chambers by the rotation of the cooling fans (8) and (10) to control the cooling of the respective storage chambers to a predetermined temperature.

  As shown in FIG. 2, each storage room discharges high-temperature and high-pressure refrigerant gas from a compressor (12) whose capacity can be changed according to frequency to a discharge pipe (13), and is provided at the periphery of the refrigerator body. From the three-way valve (16), which is introduced into the heat dissipating pipe (14) and the condenser (15) to liquefy the heat and change the refrigerant flow path, and the low-temperature side expansion device (17) and the refrigeration cooler ( 7) and a suction pipe (18) connected in series to form a circuit for returning to the compressor (12), and the three-way valve (16) to the high temperature side throttle in parallel with the low temperature side throttle device (17) The refrigeration cycle is formed by connecting the device (19) and the refrigeration cooler (20) on the high temperature side and connecting to the inlet of the refrigeration cooler (7). Each pipe is connected in the machine room where the compressor (12) is installed. As a refrigerant, an HC refrigerant such as isobutane that does not destroy the ozone layer and has a low global warming potential but is flammable is enclosed.

  The refrigerator is controlled by a control circuit (21) schematically shown in a block diagram in FIG. 3, and the high temperature side cooler is supplied by switching the flow path of the three-way valve (16) by the control device (22). (20) Or the low temperature side cooler (7) is alternately supplied, and the cold air circulation fans (8) and (10) are driven to rotate, so that the cold room (2) and vegetable room (3) on the high temperature side, or the low temperature side The freezing room (4) and the automatic ice making room (5) are controlled to be cooled to a predetermined temperature. When the storage rooms in both the refrigeration temperature zone and the freezing temperature zone are cooled to the predetermined temperature, the compressor (12) is stopped, and when any storage room temperature becomes higher than the set temperature due to a rise in the storage room temperature, the compressor and the cold air circulation fan are started again to cool the corresponding storage room.

The compressor (12) is operated by a compressor driving device (23), and the operation state is monitored via an operation detection circuit (24) from information such as a current value. The compressor drive unit (23) measures the load on the compressor (12) from data such as the current value obtained through the operation detection circuit (24). Although the load fluctuation of the machine (12) is monitored, the load fluctuation rate used in one embodiment of the present invention is:
"Load fluctuation rate = difference between the reference point and the current power / the absolute value of the power at the reference point x 100 (%)"
During the operation of the compressor (12), the load value of the refrigeration cycle (11) is monitored by applying the power value to the above equation.

  The reference point in the above formula is the control of the refrigerator so that it is not affected by the pressure change of the refrigeration cycle (11) caused by changing the operating frequency of the compressor (12) or switching the three-way valve (16) in the refrigerator control. It is determined at each time point after implementation. That is, when the refrigerant flow direction of the three-way valve (16) is switched in order to shift the operation from the refrigeration side cooling to the refrigeration side cooling, the reference value before switching is discarded and at the point of 1 minute after switching. The power value is used as a reference value.

  Therefore, FIG. 4 shows the cycle piping between the low pressure side, that is, the low temperature side and high temperature side expansion devices (17) and (19) to the suction port (12a) of the compressor (12) in the refrigeration cycle (11). It is a waveform graph which shows each driving | running behavior of a refrigerator when a refrigerant | coolant leaks from the generated pinhole and a crack.

  On the other hand, FIG. 5 is a graph showing a normal operation state of the refrigerator, and as understood from a comparison between FIG. 4 and FIG. 5, when damage occurs in the low-pressure side cycle pipe, Atmospheric air begins to be sucked into the cycle pipe from the perforated part, but initially the pressure of the outside air is large compared to the low pressure in the cycle pipe, so the suction amount is large due to the pressure difference, and the load of the refrigeration cycle suddenly That is, the power value fluctuation rate of the compressor (12) increases (see part A).

  If the outside air continues to be sucked in, the pressure difference between the inside and outside of the cycle piping will become smaller, so the amount of suction will gradually decrease with time, and although it is related to the size of the hole, it will be balanced in about 10 minutes and the outside air will be sucked in. When the internal pressure becomes equal to or higher than the atmospheric pressure, the refrigerant leaks outward.

  In addition, there is a possibility that refrigerant leakage may occur between the high pressure side of the refrigeration cycle (11), that is, between the discharge port (12b) of the compressor (12) and the expansion devices (17) and (19) on the low temperature side and the high temperature side. The piping section with is located in the machine room outside the refrigerator body, and when the gas concentration of the leaked refrigerant reaches the combustion lower limit or more, electrical contacts such as a start relay of the compressor installed in the machine room There is a possibility of igniting when opening and closing. However, in the machine room, the air cooling fan is driven during the operation of the compressor (12), and even if refrigerant leakage occurs, the risk of igniting is extremely low because it diffuses into the outside air. Must not. Moreover, since other cycle piping is embed | buried in the inside of the heat insulating material layer of a refrigerator main body (1), and a refrigerant | coolant does not stay and there is almost no possibility of igniting, it excludes from the object of this invention.

  As shown in FIG. 5, even during a normal cooling operation in which there is no perforation or the like in the refrigeration cycle, the load on the refrigeration cycle (11) is affected by changes in the state of the storage chamber such as opening of the storage chamber door and taking in and out of food. As shown in part B, it fluctuates and increases. In this case, the power value fluctuation rate is about 30% according to the above equation, but up to about 90% when perforation damage occurs in the cycle piping. The power value fluctuation rate is clearly different.

  Note that the fluctuation rate of the electric power value is not a constant value because it varies depending on the state of the storage room cooling operation such as the refrigeration side cooling operation or the refrigeration side cooling operation, the size of the damaged hole in the refrigeration cycle, and the like. That is, the larger the hole diameter, the greater the amount of outside air that is sucked in at a time, so the load increases rapidly and the rate of increase in power fluctuations is high. Since the pressure in the refrigeration cycle (11) is low, it goes without saying that the rate of increase in load is higher during refrigeration-side cooling even with the same hole diameter.

  Therefore, in consideration of the above circumstances, it is not appropriate to use only the power value fluctuation rate obtained by the above equation as a criterion for determining refrigerant leakage.

  Therefore, the determination based on the increase in the power value fluctuation rate is set as the primary determination, and the absolute value of the load power is set as the condition for the refrigerant leak detection determination. That is, it is detected whether or not the power value fluctuation rate exceeds 50% where the possibility of refrigerant leakage is large, and when the power value fluctuation rate exceeds 50% as shown in part A of FIG. Extract the absolute value of power.

  If there is no abnormality in the refrigeration cycle or compressor, the power value shows a stable value with respect to the operating frequency of the compressor (12) and the switching direction of the three-way valve (16) between refrigeration side cooling and refrigeration side cooling. When a refrigerant leak occurs on the low pressure side of the refrigeration cycle (11), outside air is sucked from the perforated portion, and the value increases as the load increases. Therefore, in normal operation, a value that hardly exceeds the absolute value of the power is set as a reference value, and it is detected whether the power value is equal to or higher than the reference value.

  The detection of the power value of the secondary determination is performed by obtaining a maximum value in consideration of various conditions such as the frequency of the compressor (12) and the switching direction of the three-way valve (16), for example, 150 W as a reference value, If the power value exceeds 150 W during this period (see part C), it is determined that there is a refrigerant leak.

  The reference value is determined in accordance with the actual operating conditions by determining the values in each state divided by the operating frequency of the compressor (12) and the cooling direction of the freezing side or the refrigerating side by the three-way valve (16). If judged based on the reference value, there is an advantage that detection with high accuracy is possible at an early stage, and it is effective if applied to a control configuration with few load conditions, but on the other hand, control is performed in proportion to the number of load conditions. There is a difficult point.

  Therefore, when there are various load conditions depending on the operating frequency of the compressor (12) and the switching direction of the three-way valve (16), measure the maximum value under the condition that the load is greatest during the operation of the refrigerator. In addition, by making this a common reference value regardless of the operation frequency and the operation of the three-way valve, detection is slightly delayed, but a simple control device can be realized. According to the experimental example, the maximum load condition in this case is the case where the compressor operating frequency is 63 Hz, which is the maximum in the refrigerator side cooling, and the obtained power reference value is 100 W.

  In the above description, the reason why the load fluctuation rate due to the power value is the primary determination and the absolute value of the power is the secondary determination is the abnormal mode, for example, the compressor (12) itself is in a locked state regardless of refrigerant leakage. This is because the absolute value of the electric power may exceed the reference value even when the error occurs, and this may be erroneously detected as refrigerant leakage.

  It should be noted that the absolute value of electric power suddenly increases during the lock phenomenon of the compressor (12), and the outside air is gradually sucked in as if a refrigerant leak occurs on the low pressure side of the cycle. This is not an increase in compressor load. And when a compressor (12) locks, it controls to stop a compressor, without determining with refrigerant | coolant leakage as an abnormal mode of compressor itself.

  According to the above, pressure fluctuation is detected by the power value fluctuation rate as the primary determination, and if the power value fluctuation rate is equal to or greater than the predetermined value, the increase in the pressure in the refrigeration cycle is detected by the power absolute value as the secondary judgment. Thus, the presence or absence of refrigerant leakage is detected, but it is difficult to say that the reference value of the power value fluctuation rate and the power reference value cover all variations in refrigerator operation. Therefore, in order to improve the probability of refrigerant leakage detection, abnormal operation of the compressor (12) is monitored as a tertiary determination after the secondary determination.

  In the refrigeration cycle (11), when the compressor (12) load becomes abnormally large and the compressor motor current increases and the current value exceeds 3.5A, the overcurrent protection device operates. The compressor is controlled to stop. Although the compressor (12) is temporarily stopped by the operation of the overcurrent protection device, it is normally controlled to restart (abnormal retry) after a predetermined time, for example, 6 minutes. For example, if it does not start even after 6 repetitions, the compressor is permanently stopped as an abnormality.

  Even in the refrigeration cycle (11) that continues to suck in the outside air due to refrigerant leakage on the low pressure side, if the outside air is sucked in, the inside of the refrigeration cycle becomes 1 atm and the load on the compressor (12) becomes abnormally large. The overcurrent protection device operates and cannot be restarted. Therefore, when the restart is not repeated even after repeated restart control (part D), the permanent stop mode is set as described above. Therefore, the abnormal stop determination of the compressor is performed in the third stage via the primary and secondary determinations. If it is performed, it is determined that the refrigerant leaks on the low pressure side of the cycle.

  In addition, when refrigerant leakage occurs, the compressor itself may fail before the overcurrent protection device of the compressor (12) operates. That is, as shown in FIG. 6, the pressure in the cycle rises due to the continuous intake of outside air from the perforated part, and as a result, the valve in the compressor (12) is damaged or the packing is removed. Occurs (E section). The compressor (12) thus configured is in a state where the refrigerant cannot be compressed and is only idling, and does not show any load fluctuation in response to changes in the operating frequency or switching of the three-way valve (16). (See section F).

  In the above, in a normal refrigeration cycle, if the refrigeration side space is cooled rather than the refrigeration side space, the refrigerant evaporating temperature is higher and the power value is larger than the refrigeration side space. In operation, a difference of about 10 W occurs. Therefore, when the reference value is set to 5 W or less and the switching of the three-way valve (16) is repeated once to several times after passing through the primary and secondary determinations, the refrigerating side cooling and the freezing side cooling are performed. If the difference between the electric power values is 5 W or less, it is determined that the compressor (12) is abnormal, and it is determined that the refrigerant leaks on the low pressure side.

  Therefore, as shown in the flowchart of FIG. 7, as a first stage, pressure fluctuation is detected based on the power value fluctuation rate, and if the power value fluctuation rate is 50% or more, there is a refrigerant leak on the refrigeration cycle low pressure side. Primary determination (step 1), and if the absolute value of electric power is 150 W or more in the second stage, secondary determination (step 2) is made that the pressure in the refrigeration cycle has increased due to refrigerant leakage.

  Next, as a third stage, the abnormal operation of the compressor (12) is monitored, and whether the number of operations (abnormal retry) of the overcurrent protection device of the compressor (12) is 6 times or more (step 3), or Otherwise, it is detected whether the fluctuation of the power value at the time of switching the three-way valve (16) is 5 W or less (step 4). Furthermore, it is detected whether or not there is no change in electric power even if the operating frequency is changed (step 5). If each of the detections is met, refrigerant leakage occurs in the low-pressure side piping of the refrigeration cycle (11). It is a third-order judgment that it is.

  If the refrigerant is leaking, the cooling power of the refrigeration cycle will be reduced, and when it is determined that there is a refrigerant leak, this will be displayed on the display panel surface of the refrigerator door or an alarm sound such as an alarm. Is notified to the user.

  The present invention can be used as a refrigerant leak detection control configuration in a refrigerator using a combustible refrigerant.

It is the front view which removed the door of the refrigerator which shows one Embodiment of this invention. It is the refrigerating cycle schematic of the refrigerator shown in FIG. It is a block diagram which shows the control circuit of the refrigerator of FIG. It is a waveform graph which shows the driving | running behavior in the state which the refrigerant | coolant leak generate | occur | produced from the refrigerating cycle of FIG. It is a waveform graph of the same part as FIG. 4 which shows the driving | running state of a normal refrigerator. It is a waveform graph of the same part as Drawing 4 showing the state where failure occurred in the compressor. It is a control flowchart of the refrigerant | coolant leak detection which shows one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator body 2 Refrigeration room 4 Freezing room 7 Refrigeration cooler 8 Refrigeration fan 9 Refrigeration cooler
10 Refrigeration fan 11 Refrigeration cycle 12 Compressor
12a Suction port 12b Discharge port 16 Three-way valve
17 Low temperature side expansion device 18 Suction pipe 19 High temperature side expansion device
21 Refrigerator control circuit 22 Controller 23 Compressor drive unit
24 Driving detection device

Claims (7)

  A variable capacity compressor, a switching valve for switching a refrigerant flow path provided on the outlet side of a condenser that receives discharge gas from the compressor, and a refrigeration cooler connected from the switching valve via a pressure reducing mechanism, respectively. And a refrigerator having a fan for supplying cold air generated by each cooler of the refrigeration cycle in which a flammable refrigerant composed of a refrigeration cooler is sealed to the refrigeration space and the refrigeration space, respectively, Refrigerant leakage on the low pressure side of the refrigeration cycle is detected based on the pressure fluctuation in the refrigeration cycle detected from the change rate of the fluctuation, the refrigeration cycle pressure detected from the absolute value of the compressor load, and the abnormal operation signal of the compressor. A refrigerator characterized by that.   Detecting pressure fluctuation in the refrigeration cycle based on the rate of change of the compressor load fluctuation over a predetermined value as the first stage, and then determining the second stage when the absolute amount of the compressor load is above the reference value The refrigerator according to claim 1.   The case where the absolute amount of the compressor load is equal to or more than the reference value is set as the second stage, and then the refrigerant leakage on the refrigeration cycle low pressure side is detected as the third stage when the abnormal operation of the compressor is detected. The refrigerator according to claim 2.   The refrigerator according to claim 1, wherein the refrigerator has a plurality of reference values corresponding to operating conditions of the refrigerator as reference values for the absolute amount of the compressor load.   2. The refrigerator according to claim 1, wherein a single reference value is set as a reference value for the absolute amount of the compressor load from a load value that is maximum in use of the refrigerator.   The refrigerator according to claim 2, wherein a case where the abnormal stop due to overcurrent is repeated a predetermined number of times is determined as an abnormal operation of the compressor.     The refrigerator according to claim 2, wherein a case where the compressor load does not change due to switching of the switching valve is determined as an abnormal operation of the compressor.

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