JP4937032B2 - Cooling device and refrigerator equipped with the same - Google Patents

Description

  The present invention relates to a cooling device provided with frost detection means by optical detection and a refrigerator (freezer refrigerator) provided with the cooling device.

  In the refrigerator-freezer, the inside of the refrigerator must be controlled to a temperature range lower than 10 ° C. In order to control the inside of the chamber to a temperature range lower than 10 ° C, it is necessary to make the evaporation temperature of the refrigerant lower than 0 ° C. For this reason, frost is generated in the fins of the cooler (evaporator) with time, thereby increasing the thermal resistance, reducing the air volume, and reducing the cooling capacity. Conventionally, this problem has been solved by attaching a heater to the evaporator and conducting a defrosting operation by periodically energizing the heater. However, in the case of controlling the defrosting operation at regular intervals as described above, the following problem occurs.

a. When the defrosting operation is not necessary, the defrosting operation may be performed. In this case, energy is wasted.
b. On the contrary, when the defrosting operation is necessary, the defrosting operation may not be performed. In this case, the internal temperature of the refrigerator / freezer is increased due to the decrease in the cooling capacity described above, and is stored in the storage. The quality of the existing goods deteriorates.
c. Due to frost formation on the cooler, the fan adjacent to the cooler and the cooler may come into contact with each other, which may cause abnormal noise or damage to the fan due to the rotation of the fan.

On the other hand, a frost amount detector composed of a light emitting part and a light receiving part is installed in the vicinity of the low-temperature and low-pressure refrigerant inlet where the frost formation of the outdoor heat exchanger (evaporator) is fast, and the frost amount detecting means detects There has also been proposed a heat pump refrigeration cycle in which a defrosting operation is started based on a frost icing state (see, for example, Patent Document 1).
JP-A-8-61813 (FIGS. 5 and 6)

  However, a frost formation detector that optically detects the frost formation state is installed near the low-temperature and low-pressure refrigerant inlet where the frost formation of the outdoor heat exchanger is fast, and based on the detection result of the frost formation detector. In the case where the defrosting operation is started, the timing of the start of the defrosting operation can be determined appropriately, but the location where the frosting progresses quickly and the location where the defrosting progresses slowly are not necessarily the same. Therefore, the optimization of the defrosting operation end timing cannot be stably obtained, and the efficiency of the stable system cannot be achieved.

  That is, if the determination of the end of the defrosting operation is erroneous and the defrosting operation is ended early, frost unmelted occurs. When frost melts away, it eventually grows into root ice. Since root ice cannot be completely melted by a normal defrosting operation, it leads to a reduction in the heat transfer area of the evaporator, and as a result, the cooling performance is greatly reduced. Conversely, when the defrosting operation is terminated late, the ambient temperature around the evaporator is rapidly increased by the heat of the defrosting operation.

  The present invention has been made in response to the above-described problems, and accurately detects the frosting state on the cooling device, and executes the start and end of the defrosting operation (same as the defrosting operation) at an appropriate timing. It is an object of the present invention to obtain a cooling device that can carry out the operation and a refrigerator including the same.

A cooling device according to the present invention optically detects a cooler having fins for heat transfer, a fan for air blown against the cooler, and an amount of frost adhering to the fins. A plurality of optical frost sensors, and an optical frost sensor that optically detects the amount of frost adhering to the blower fan, the optical type detecting the amount of frost adhering to the fin. frost sensor, the are arranged so as to detect the frosting of previous SL fins on both sides of the cooler air outlet side and an air inlet side of, and the amount of frost adhering to the fan The optical frost sensor to be detected is disposed so as to detect the amount of frost on the front end surface of the fan facing the cooler, and the amount of frost detected by the optical frost sensor is depending which operation start and operation end of the defrost adhering is defined in the cooler, the When the frost detection amounts of the plurality of optical frost sensors are equal to or greater than a predetermined value, the operation of defrosting attached to the cooler is started, and the frost detection amounts of the plurality of optical frost sensors are The defrosting operation is terminated when all the values are equal to or less than a predetermined value .

  According to the cooling device of the present invention, since the optical frost sensor detects the actual frost amount on the fins and the fan, it is possible to accurately determine the start time and end time of the defrost operation, Useless defrosting operation can be eliminated.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a cooling device according to Embodiment 1 of the present invention. The cooling device 1 includes a cooler (heat exchanger) 3 having a heat transfer fin 4 in a housing 2, a fan 6 for air blown by a motor 5, and frost attached to the fin 4. And at least one optical frosting sensor 7 for optically detecting the amount of. Here, a plurality of optical frosting sensors 7 are respectively arranged so as to detect the amount of frost attached to the tip surfaces 4A of the fins 4 located on both sides of the air outlet side and the air inlet side of the cooler 3. The defrosting attached to the cooler 3 is performed according to the amount of frost detected by the optical frosting sensor 7.

In addition, if it is a refrigerator for refrigeration (the set temperature in the iso-compartment is −20 ° C. or more, for example), it is easy to form frost from the outlet side of the cooler, and the cooler for freezing (the set temperature in the iso-compartment) Is less than −20 ° C., for example, it is easy to form frost from the suction port side, and accordingly, the optical frost sensor 7 is connected to either the air blower outlet side or the air suction port side of the cooler. You may install only in
Further, by providing a plurality of optical frost sensors 7 as shown in FIG. 1, it is possible to detect frost on the fins 4 finely. For example, even if only one optical frost sensor 7 is provided at a place where frost formation is most likely to occur. good.

  Here, the frost formation detection mechanism of the cooler 3 will be described. FIG. 2 is an overall configuration diagram of a frost detection mechanism using the optical frost sensor 7. The optical frosting sensor 7 includes a light emitting element 7a and a light receiving element 7b. A light emitting diode (LED) or the like can be used as the light emitting element 7a, and a light emitting diode or a photodiode can be used as the light receiving element 7b. In addition, infrared light emitting and receiving elements can also be used. However, according to experiments by the inventors, it is known that dew and frost can be clearly distinguished when the center wavelength of light emitted from the light emitting element 7a is 600 nm or less. preferable.

  The control of the light emitting element 7a and the light receiving element 7b and the determination of the received light amount (or received light intensity) of the light receiving element 7b are performed by a light amount determination control unit (light amount determination means and control means, which is constituted by a microcomputer or the like in which a determination program is incorporated in advance. Is comprised of 12). The light quantity determination control unit 12 also drives the defrosting mechanism 10 attached to the cooler 3 based on the determination result to execute the defrosting process.

  The operation of the optical frost sensor 7 is as follows. When frost adheres to the front end surface 4A of the fin 4 of the evaporator 3, the light emitted from the light emitting element 7a is reflected and absorbed by the frost and strikes the light receiving element 7b. A reverse bias voltage is applied to the light receiving element 7b in advance and charged. And when the light reflected by the frost hits the light receiving element 7b, it discharges. The relationship between the potential of the light receiving element 7b when discharged and the time is as shown in FIG. 20, for example. Therefore, the light intensity P can be obtained by measuring the time until the voltage Vt is reached. The relationship between the light intensity P and the time t until the voltage Vt is reached can be expressed by the following equation, and the light intensity P can be obtained. These calculation processes and data storage are performed by the light quantity determination control unit 12.

P = (aQo / t) × (1 / Vt−1 / V0)
Here, a is a constant, Qo is an initial charge amount of the light receiving element LED, and V0 is a potential at time 0.

If the light intensity P is a physical quantity (frosting amount) that changes, the frosting amount can be determined from the light intensity P if the relationship between the light intensity P and the frosting amount is previously stored as data. It should be noted that the amount of frost formation can be obtained by directly using the output voltage V for a certain time instead of the light intensity P. Therefore, a threshold value of light quantity corresponding to a predetermined frost formation amount, for example, an amount that requires defrosting processing, is stored in advance and compared with the light reception amount of the light receiving element 7b measured as shown in FIG. Thus, it is possible to detect a frosting state that requires defrosting processing.
Further, the time t may be compared instead of the light intensity P. In this case, it becomes a characteristic that t decreases as the amount of frost formation increases.

In the defrosting mechanism 10, a method using a heater provided in a cooler, a method using a discharge gas (hot gas) of a compressor that sends a refrigerant to the cooler, a method of spraying water on a cooling pipe of the cooler, A known mechanism such as a method of circulating the air in the cabinet in which the cooler is arranged can be used alone or in combination.
In particular, in order not to be affected by clogging of the cooler (heat exchanger), it is preferable to combine a heater and water spraying. According to this, since the dust accumulated between the fins of the cooler can be washed away at the same time as the frost is melted by the heater, it is possible to prevent a decrease in reliability due to the clogging of the cooler. is there.

Next, the operation of the frost detection mechanism of FIG. 2 will be described according to the operation flowchart of FIG. While the cooling device 1 is in the ON state, the frost formation detection mechanism performs the light emission from the light emitting element 7a and the reception of the reflected light from the light receiving element 7b at a predetermined interval, and the frost formation state on the tip surface 4A of the fin 4 Is always detected (S1).
The light quantity determination control unit 12 reads the light received by each light receiving element 7b and converts it into, for example, a voltage V (measured value), and sets a predetermined “frosting state” or “frosting amount that requires defrosting processing”. Is compared with the threshold voltage V1 corresponding to "(2)". Here, with respect to all the optical frosting sensors 7, when V <V1, the state is maintained as it is, and when V ≧ V1, the defrosting mechanism 10 is driven to start the defrosting process (S3). ).
The light quantity determination control unit 12 detects the frosting state on the front end surface 4A of the fin 4 during the defrosting process, reads the light received by the light receiving element 7b, converts the voltage V (measured value), and Comparison is made with a threshold voltage V2 corresponding to a predetermined “frosting amount that does not require defrosting processing” or “state without frosting” (S4). Here, with respect to all the optical frost sensors 7, when V> V2, the defrosting process is maintained, and when V ≦ V2, the defrosting mechanism 10 is terminated (S5). .

With the above operation, the cooling device 1 accurately detects the frosting state on the cooler 3 that requires or does not require a defrosting process for each place where the optical frosting sensor 7 is located, and starts the defrosting operation. And the termination can be carried out at an accurate timing, and useless defrosting operation can be avoided. Although it is preferable to use the optical frost sensor 7 for setting both the start and end of the defrosting operation as in this example, the optical frost sensor 7 is used for setting only one of them. Even if the other is set by other means, it is possible to avoid unnecessary defrosting operation as compared with the prior art.
Moreover, since the frost formation state to the cooler 3 is detected, even when the space | interval of the cooler 3 and the fan 6 is narrow, detection and defrost of frost are carried out before connecting between them with frost. This makes it possible to prevent fan damage and abnormal rotation noise due to frost, and to contribute to downsizing of the cooling device.

By the way, it is preferable to restart the cooling operation as soon as the frost in the cooler 3 melts. However, if the cooling operation is started before the melted water adhering to the fins 4 is dripped onto the drain pan of the cooling device, there is a risk that the frost will again form frost and remain on the fins or freeze with residual water in the drain pipe. To avoid this, stop the device for a certain period of time after defrosting, drop most of the melted water droplets onto the drain pan, and drain the drain pipe to the point where the drainage is zero. It is preferable to provide time and restart the cooling operation by starting the compressor after “stopping draining”. The draining stop time varies depending on the size of the cooler, and may be appropriately determined to be, for example, 3 minutes for a small cooler and 10 minutes for a large cooler. Moreover, if the cold storage thing in a store | warehouse | chamber contains much moisture, it is necessary to lengthen the draining stop time according to it.
The setting of the draining stop time is not limited to the first embodiment, but can be adopted in other embodiments of the defrosting operation described below.

Embodiment 2. FIG.
Here, an example of a frost detection method of the cooling device 1 using a one-dimensional linear image sensor that is an image sensor as the optical frost sensor 7 will be described.
Fig.4 (a) is a perspective view (a) which shows Embodiment 2 which is the frost formation detection method by the optical frost formation sensor 7 using a linear image sensor, FIG.4 (b) is the top view. is there. Here, the optical frosting sensor 7 includes a light emitting diode (for example, a red diode 650 nm) 7a as a light source that irradiates a portion to be imaged of the three fins 4 and 20 lines arranged in a line constituting a linear image sensor. And a photodiode 7b. In FIG. 4B, reference numeral 7c denotes a light source lens, and 7d denotes a light receiving element lens.
The light emitting diode 7a emits light at an arbitrary interval by control (for example, emits light for 10 seconds every minute), and irradiates the end face of the fin 4. The linear image sensor images the end face of the fin 4 at that time. The output of each photodiode 7b constituting the image sensor is proportional to the amount of received light. If 20 figures are arranged on a straight line by changing the gray brightness according to the output, a one-dimensional image is obtained.

  When the fin 4 is cooled to 0 degrees or less in indoor air, water vapor in the air becomes frost on the fin 4. The state of frost attached to the fins 4 at this time is represented with time, which is a schematic diagram showing the frosting state on the fins of the cooler as time passes in FIG. According to FIG. 5, after 120 minutes from the cooling, frost 90 begins to adhere to the end face and side surface of the fin 4, and then the frost 90 grows large, and the air passage is completely closed in 360 minutes. . Then, after 480 minutes, the entire frost 90 has increased to the width of the fin 4.

  FIG. 6 is a graph plotting the output of the linear image sensor at this time. FIG. 6 is a relationship diagram (graph) between each image sensor (photodiode) constituting the optical frost sensor and their outputs corresponding to the frost state on the fin. According to this, it turns out that the output of each image sensor changes depending on the amount of frost. From this graph, it can be seen that in order to detect the degree of blockage of the air path of the cooler, the number of photodiodes having an output equal to or higher than a predetermined threshold may be obtained. From FIG. 5, it is presumed that the air passage is still sufficiently secured after 120 minutes have passed since cooling, but after about 180 minutes have passed, about half are blocked and the efficiency of the heat exchanger is significantly reduced. Therefore, the output “4” of the photodiode corresponding to the maximum output value after 120 minutes from cooling is set as the threshold value. The number of photodiodes that output the threshold “4” or more is shown in FIG. 7 in correspondence with the elapsed time. FIG. 7 shows a relationship diagram between the number of elements in which the output of each image sensor constituting the optical frost sensor has a threshold value “4” or more and time. In practice, since the number of pixels (number of photodiodes (number of elements)) is an integer, the graph is stepped, but here it is smoothed.

Based on FIG. 5, it is presumed that the air path between the fins 4 is closed more than half after about 180 minutes have passed after cooling. Accordingly, the number of photodiode elements “5” exceeding the output threshold “4” corresponding to the time of 180 minutes in FIG. 7 is set as the pixel number threshold. If the defrosting operation is started when the pixel number threshold value is “5”, the air passage is not closed by frost, and the cooling device 1 can always exhibit a stable ability.
The number of fins 4 to be detected, the number of photodiodes 7b, the output threshold value, and the pixel number threshold shown above are only examples, and the interval and thickness of the fins 4, the operating state, and the installation of the image sensor. You may set suitably according to a position.
In addition, although a one-dimensional linear image sensor is used as the imaging element this time, a two-dimensional area image sensor used for a camera may be used. In that case, it is possible to cope with the same problem by setting an output threshold value and a pixel number threshold value corresponding thereto.
In the frost detection method that uses a large number of light receiving elements and sets the pixel number threshold value shown here, even if some of the pixels are fouled and the output becomes abnormal and exceeds the output darkness value, other pixels Does not exceed the output threshold value, there is an effect that the defrosting operation instruction is not greatly affected. In the above example, both the output threshold value and the pixel number threshold value are set in advance. However, the pixel output values are summed or averaged for all the pixels, or the output values excluding the maximum value and the minimum value are calculated. A threshold value for a value obtained by processing the output itself under a predetermined condition, such as summing or averaging, may be determined in advance, and determination may be made to start the defrosting operation when the threshold value is exceeded.
Furthermore, as a signal reading method of the light receiving element, a CCD, a MOS method, or the like can be used. Further, although the photodiode is used as the light receiving element, other elements such as the photoconductive cell CdS (cadmium sulfide) may be used. In any method, a threshold for defrosting can be determined and the defrosting operation can be terminated when the defrosting value or less is reached.

  In the second embodiment in which an image sensor is used as the optical frost sensor, the configuration of the frost detection mechanism shown in FIG. 2 can be applied. However, in the case of the second embodiment, the light quantity determination control unit 12 in FIG. 2 is replaced with an image analysis control unit (consisting of an image analysis unit and a control unit). The image analysis control unit performs the image analysis as described above, and controls the start and end of the defrosting mechanism 10 based on the image analysis, and a corresponding image analysis and control program is incorporated. It consists of a microcomputer.

Embodiment 3 FIG.
Embodiment 3 shows an example in which the optical frosting sensor 7 is movably arranged. FIG. 8: is a block diagram (a) of the cooling device which has arrange | positioned the optical frosting sensor 7 which concerns on Embodiment 3 of this invention so that a movement is possible, and an illustration figure of the movable sensor mounting plate (b) in that case is there. In FIG. 8, the optical frosting sensor 7 is mounted on the movable sensor mounting plate 20 and is disposed on the air inlet side of the cooler 3. The movable sensor mounting plate 20 has grooves 22 formed on the flat surface 21 for holding the optical frosting sensor 7 and allowing it to slide in the horizontal direction. 23 is slidably fitted to the housing 2 of the cooling housing 1, and the movable sensor mounting plate 20 itself can move in the vertical direction along the housing 2.
With this configuration of the movable sensor mounting plate 20, the optical frosting sensor 7 can be arranged at a desired position in the vertical and horizontal directions along the front end surface of the fin 4 located on the air inlet side of the cooler 3. It becomes possible. Therefore, the optical frosting sensor 7 can be easily changed to an appropriate position in accordance with the frosting mode that changes depending on the installation situation.

Embodiment 4 FIG.
The fourth embodiment shows an example effective when the cooler 3 and the fan 6 are arranged close to each other. FIG. 9 is a configuration diagram of a cooling device according to Embodiment 4 of the present invention. In FIG. 9, the optical frosting sensor 7 is arranged in a mode of detecting frosting on the front end surface 6 </ b> A of the fan 6 that faces the cooler 3. That is, the optical frosting sensor 7 is arranged on the housing 2 on the extension line of the front end surface 6A of the fan 6 orthogonal to the air path direction of the cooler 3.
According to this structure, since the frost formation state to the front-end | tip of the fan 6 which opposes the cooler 3 can be detected, frost is removed from the fan 6 by performing the defrosting process of the cooling device 1 when it detects it. Thus, breakage of the fan 6 and occurrence of abnormal rotation noise can be reliably avoided. Moreover, it contributes to downsizing of the cooling device 1.

Embodiment 5 FIG.
The fifth embodiment shows another example that is effective when the cooler 3 and the fan 6 are arranged close to each other. FIG. 10 is a configuration diagram of a cooling device according to Embodiment 5 of the present invention. In FIG. 10, in addition to the mode of FIG. 9, another optical frosting sensor 7 is arranged in a mode of detecting frosting on the front end surface 4 </ b> A of the fin 4 of the cooler 3 facing the fan 6. . That is, the optical frosting sensor 7 is arranged on the housing 2 on the extension line of the tip surface 4A of the fin 4 orthogonal to the air path direction of the cooler 3. In this case, defrosting is started when both of the optical frosting sensors 7 corresponding to the front end surface 4A of the fin 4 and the front end surface 6 of the fan 6 are equal to or more than the first predetermined value. It is good to end defrosting when it becomes below the predetermined value.
According to this structure, since the frost formation state to the front end surface 4A of the fin 4 of the cooler 3 and the front end surface 6A of the fan 6 can be reliably detected, the defrosting of the cooling device 1 is detected when this is detected. By performing the process, frost is removed from the cooler 3 and the fan 6, and the occurrence of breakage of the fan 6, abnormal rotation noise, and the like can be reliably avoided. Moreover, it contributes to downsizing of the cooling device 1.

Embodiment 6 FIG.
When the optical frost sensor 7 used in the present invention includes a lens, if the lens is exposed to the cooling space of the cooling device, it may become cloudy due to low temperature. Therefore, in the sixth embodiment, an example of a countermeasure for that will be described.
FIG. 11 is a configuration diagram of a cooling device according to Embodiment 6 of the present invention. In the configuration of FIG. 11, when the optical frost sensor 7 has a lens 30, the inner surface of a cylindrical member (such as an aluminum member) 31 having a good thermal conductivity and a heater 32 wound around the lens 30. It is the one that is tightly fixed to.
According to this, since the lens 30 is heated through the cylindrical member 31 by heating the cylindrical member 31 with the heater 32, the fogging of the lens 30 due to the low temperature can be prevented.

Embodiment 7 FIG.
In the seventh embodiment, some aspects in which the optical frost sensor 7 is detachably attached to the cooling device 1 will be described.
FIG. 12 is a first illustration of an optical frost sensor attachment / detachment mechanism in the cooling apparatus according to Embodiment 7 of the present invention. Here, the optical frosting sensor 7 is attached to the fixing plate 35 with the hole 35A, and the fixing plate 35 with the optical frosting sensor 7 is positioned in the screw hole 33A provided in the housing 33 of the cooler 3, The structure which fixes the fixing plate 35 with the optical frosting sensor 7 to the housing | casing 33 of the cooler 3 using a screw is shown. Note that reference numeral 7 </ b> A in FIG. 12 indicates a signal wiring extending from the optical frosting sensor 7.
According to this configuration, the optical frosting sensor 7 can be easily attached to the existing cooler 3 simply by providing the screw hole 33A in the casing 33 of the cooler 3, and is already attached. The optical frosting sensor 7 can be easily replaced.

FIG. 13 is another exemplary view of an attachment / detachment mechanism for the optical frost sensor in the cooling apparatus according to Embodiment 7 of the present invention. In FIG. 13A, the optical frost sensor 7 is attached to the attachment 71, and the lower end 71 </ b> A of the attachment 71 is at the end (folded portion) of the drain pan 202 arranged at the bottom of the cooler 3. The upper end 71 </ b> B of the attachment 71 is detachably fitted to the upper cover 201 of the cooler 3 and is fixedly attached to the cooling device 1. Note that the attachment 71 and the end of the drain pan 202 and the attachment 71 and the upper cover 201 may be directly attached or indirectly attached via something.
13B, the optical frost sensor 7 is attached to the attachment 72, and the lower end portion 72A of the attachment 72 is the end portion (bending portion) of the drain pan 202 disposed at the bottom of the cooler 3. ) Is detachably fitted and fixed to the cooler 3. In this case, the upper end portion of the attachment 72 is not fixed and is an open end. Further, the attachment 72 and the end of the drain pan 202 may be directly attached or indirectly attached via something.
By these aspects, the optical frosting sensor 7 can be easily attached to and detached from the cooling device 1.

  FIG. 14 is another exemplary cross-sectional view (a) and a perspective view (b) of an attachment mode of the optical frosting sensor related to the seventh embodiment. Here, as shown in the figure, the optical frost sensor 7 is attached to the attachment 73, and the leg 73A of the attachment 73 is removably fitted to the hairpin pipe 301 passing through the fin 4 of the cooler 3. Combined and fixed to the cooler 3. In this case, the attachment 73 can be attached to the hairpin pipe 301 without a screw or a tool. The attachment 73 and the hairpin pipe 301 may be directly attached or indirectly attached via something. Moreover, it is preferable to change the attachment position according to a frost formation state.

FIG. 15 is another exemplary view of an attachment mode of the optical frosting sensor 7 related to the seventh embodiment. Here, the optical frosting sensor 7 is attached to the attachment 74 by a fixture 75, and is attached to the casing 2 of the cooling device 1 via buffer members 80 such as rubber pressing members provided at both ends of the attachment 74. It is fixed. The housing 2 has a planar shape, and the buffer member 80 sandwiches the end portion of the housing 2. The buffer member 80 may be directly attached to the housing 2 or indirectly attached to the housing 2 through something.
The buffer member 80 has a purpose not to transmit the vibration of the fan 6 in the cooling device 1 to the optical frost sensor 7 and to electrically insulate the frost sensor 7 from the cooling device 1. Therefore, it is appropriate to use a member such as silicone or nitrile rubber that retains flexibility and insulation even at 25 ° C. below freezing. The buffer member 80 may be made of foamed plastic such as foamed polystyrene, foamed urethane, or foamed styrene, in addition to the rubber-based material. If it is desired to maintain heat insulation between the optical frost sensor 7 and the housing 2, it is advantageous to use foamed plastic for the buffer member 80.
In FIG. 15, the attachment 74 is fixed to the housing 2 on the upper surface and the lower surface of the housing 2, and the housing 2 is sandwiched between the upper and lower sides as a whole. The buffer member 80 is preferably fastened and fixed to the housing 2 or the like with bolts 81 and nuts 82. With this configuration, the attachment 74 can be reliably fixed to the cooling device 1.

In FIG. 15, an embodiment in which the optical frost sensor 7 is fixed via a joining member called a muff and a clamp is illustrated, but the optical frost sensor 7 including the optical frost sensor 7 may be integrated. Further, the optical frosting sensor 7 may be movably installed so that it can be finely adjusted in the horizontal direction and / or the vertical direction. By carrying out like this, the optical frosting sensor 7 can be installed toward the optimal frosting part according to the model of a cooling device, or the condition of the field.
The optical frosting sensor 7 can be easily attached to and detached from the cooling device 1 by the mounting modes shown in FIGS.

In the case of defrosting using a heater (heater defrost), the frost adhering to the fins of the cooling device is melted by the conduction of the heater heat. May cause frost. Further, in the upper part of the cooling device, the air whose temperature has been increased by the heat of the heater rises by natural convection, so that frost easily melts due to this influence. However, it is impossible in principle for heated air to flow downward by natural convection. Therefore, in the cooling device for the heater defrost, it is preferable to provide an optical frosting sensor at the lower end of the cooling device that is separated from the heater and hardly affected by the heat.
In addition, in the case of the heater defrost, since the amount of heat given to the frost is larger than other defrosting methods, the frost melts and may move upward as water vapor. Therefore, if the LED sensor or the like is provided above the heater, the lens of the LED sensor may be weighed under the influence of water vapor, and proper detection may not be possible. Also from this point, it is preferable to provide the optical frost sensor at the lower end of the cooling device.
An embodiment for this is shown in FIG. Here, the optical frost sensor 7 is provided at the corner portion of the lower end portion of the cooler 3 that is away from the portion where the heater 302 for defrosting is disposed and is not easily affected by the heat generated by the heater 302. The number of optical frosting sensors 7 is not limited to two and can be determined as appropriate.

Embodiment 8 FIG.
Embodiment 8 demonstrates the aspect at the time of using the cooling device 1 as an outdoor unit of an air conditioner. When the cooling device 1 is used as an outdoor unit of an air conditioner, sunlight hits the cooling device 1 and there is a possibility that the optical frost sensor 7 may be adversely affected. Therefore, an example of the countermeasure is shown here. FIG. 17 is an exemplary diagram showing a light shielding mechanism of the optical frosting sensor 7 in the cooler 3 according to the eighth embodiment of the present invention. A specific example of FIG. 17 is shown in FIG. FIG. 18A is a perspective view of an optical frost sensor mounting manner showing details of FIG. 17, FIG. 18B is a sectional view in the Y direction of FIG. 18A, and FIG. 18C is FIG. It is X direction sectional drawing of (a). Here, the optical frosting sensor 7 is attached to the hairpin pipe 301 in the manner described in FIG.
In FIGS. 17 and 18A to 18C, the optical frosting sensor 7, particularly the light emitting element 7 a and the light receiving element 7 b are surrounded by a light shielding plate 41. Further, it is preferable to surround the opposite projection surface sandwiching the cooler 3 with the light shielding plate 42 so that unnecessary light does not enter the light receiving element 7b.
With this configuration, even when the cooling device 1 including the cooler 3 is used as an outdoor unit of an air conditioner, the frosting state on the cooler 3 is accurately detected, and the start and end of the defrosting operation are accurately determined. Can be implemented at any time.

Embodiment 9 FIG.
In the ninth embodiment, a refrigerator including the cooling device 1 described in each of the above embodiments will be described. FIG. 19 is an illustration of a refrigerator (refrigerated warehouse) 50 according to Embodiment 9 of the present invention. As shown in FIG. 19, the cooling device 1 is arranged inside the refrigerator 50, and in a normal case, frost detection is performed by the optical frosting sensor 7, and defrosting is performed based on the detection. Therefore, the refrigerator 50 can also enjoy various effects similar to those of the cooling device 1.
However, when the door 51 of the refrigerator 50 is opened or when the interior lighting is turned on, lighting or illumination light may adversely affect the optical frosting sensor 7. Therefore, when the door 51 is opened or when the interior lighting is turned on, the light amount determination control unit (or image analysis control) is performed so that the frost detection by the optical frosting sensor 7 is stopped or disabled. Part) is preferably set to 12.

Embodiment 10 FIG.
In practical mode 10, a method of correcting the output of the frosting sensor so as to accurately correspond to the thickness of frost will be described. The frost that has formed on the cooler 3 is divided into a component that increases the thickness of the frost and a component that penetrates into the frost and increases the density of the frost. If the density of frost is different, the reflectance of light is different, so that the output of the landing sensor 7 changes even with the same frost thickness. Therefore, it is necessary to predict the density of the frost, correct the output of the frosting sensor 7 and convert it to the thickness of the frost.
The density at the time of initial frosting on the cooler 3 when the cooling operation is started includes the surface temperature of the fin 4 or the pipe of the cooler 3, the absolute temperature of the cooler intake air, and the surface temperature of the fin 4 of the cooler 3. It depends on the wind speed of the air. Furthermore, the amount of frost formation on the cooler 3 starts the cooling operation, the surface temperature of the fin 4 or the pipe of the cooler, the absolute temperature of the cooler intake air, the air velocity of the fin surface of the cooler 3, and the cooling operation. It depends on how much time has passed since then. The absolute temperature of the cooler intake air is determined by the temperature of the cooler intake air and the relative humidity. The relative humidity can be predicted to some extent from the load state, and the wind speed is determined by the specifications of the fan 6. Further, it is obtained by a value obtained by multiplying the frost density increase due to diffusion into the fog, the diffusion rate of water vapor, or the amount of frost formation by a certain ratio. Therefore, if at least the surface temperature of the fin 4 or the pipe of the cooler, the temperature of the cooler intake air, and the elapsed time since the start of the cooling operation are known, the amount of frost formation and the density of frost can be predicted. Thus, it is possible to correct the output of the frosting sensor 7 and calculate an accurate frost thickness.
In addition, each physical property value of frost is closely related, for example, there is a relational expression between frost density and frost thermal conductivity, such as frost thermal conductivity, frost thickness, frost surface If any one of the heat transfer rate, the mass transfer rate of the frost surface, and the surface temperature of the frost can be estimated, the density of the frost can be calculated and the output of the frosting sensor 7 can be corrected. It suffices to have a means to guess any of the values.

The block diagram of the cooling device which concerns on Embodiment 1 of this invention. The whole block diagram of the frost formation detection mechanism using the optical frost formation sensor which consists of a light emitting element and a light receiving element. The flowchart of the defrosting operation | movement using the optical frosting sensor of FIG. The perspective view (a) and top view (b) which show Embodiment 2 of the frost formation detection by an optical frost formation sensor. The schematic diagram which showed the frosting state to the fin of the cooling device with progress of time. FIG. 5 is a diagram showing the relationship between each image sensor constituting the optical frost sensor and their outputs corresponding to the frost state on the fins. FIG. 4 is a relationship diagram between an output threshold value of each image sensor constituting the optical frost sensor and time. The block diagram (a) of the cooling device which has arrange | positioned the optical frosting sensor which concerns on Embodiment 3 of this invention so that a movement is possible, and the illustration figure of the movable sensor mounting plate (b) in that case. The block diagram of the cooling device which concerns on Embodiment 4 of this invention. The block diagram of the cooling device which concerns on Embodiment 5 of this invention. The illustration figure of the lens fogging prevention mechanism of the optical frosting sensor in the cooling device concerning Embodiment 6 of the present invention. The illustration figure of the attachment or detachment mechanism of the optical frosting sensor in the cooling device concerning Embodiment 7 of the present invention. FIGS. 10A and 10B are other exemplary views showing how the optical frosting sensor is attached according to the seventh embodiment. The other example sectional drawing (a) and perspective view (b) of the attachment aspect of the optical frost formation sensor relevant to Embodiment 7. FIG. FIG. 20 is another exemplary view of an attachment mode of the optical frosting sensor related to the seventh embodiment. FIG. 20 is another exemplary perspective view of an attachment mode of the optical frosting sensor related to the seventh embodiment. The illustration figure of the light-shielding mechanism of the optical frosting sensor in the cooling device concerning Embodiment 8 of the present invention. The perspective view (a) of the attachment aspect of the optical frosting sensor which showed the detail of Embodiment 8, the Y direction sectional drawing (b), and the X direction sectional view (c). The illustration figure of the refrigerator which concerns on Embodiment 9 of this invention. FIG. 3 is a relationship diagram between potential and time when a light receiving element (LED) in the optical frost sensor of FIG. 2 is discharged.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Cooling device, 2 Cooling device housing, 3 Cooler, 4 Cooler fin, 4A Fin tip, 5 Fan motor, 6 Fan, 6A Fan tip, 7 Optical frost sensor, 7a Light emitting element or light emission Diode, 7b Light receiving element or photodiode, 8, 9 Optical frosting sensor mounting plate, 10 Defrosting mechanism, 12 Light quantity determination control unit, 20 Movable sensor mounting plate, 30 Lens, 31 Tube member with good thermal conductivity, 32 heater, 33 cooler casing, 33A screw hole, 35 sensor retrofit member, 35A screw hole, 41, 42 light shielding member, 50 refrigerator, 51 refrigerator door, 71-74 attachment.

Claims (15)

A cooler with fins for heat transfer;
A fan for blowing air disposed opposite to the cooler;
A plurality of optical frost sensors for optically detecting the amount of frost adhering to the fin ;
An optical frost sensor for optically detecting the amount of frost adhering to the blower fan;
With
The optical frost sensor that detects the amount of frost adhering to the fins, arranged to detect frost amount Previous Symbol fins on both sides of the air outlet side and the air inlet side of the cooler And the optical frost sensor for detecting the amount of frost adhering to the fan is arranged to detect the amount of frost on the front end surface of the fan facing the cooler. And
The operation start and the operation end of the defrosting attached to the cooler are determined according to the amount of frost detected by the optical frosting sensor ,
When all the frost detection amounts of the plurality of optical frosting sensors are equal to or greater than a predetermined value, the operation of defrosting attached to the cooler is started,
The cooling device , wherein the defrosting operation is terminated when all of the frost detection amounts of the plurality of optical frost sensors are equal to or less than a predetermined value . 2. The cooling device according to claim 1, wherein the defrosting operation is terminated after a predetermined time has elapsed after all of the frost detection amount of the optical frosting sensor is equal to or less than a predetermined value . 3. The cooling device according to claim 1, wherein after the defrosting operation is completed, the cooling operation is set to start after a predetermined time has elapsed . The optical frost sensor is composed of a light emitting element and a light receiving element that receives reflected light of light emitted from the light emitting element,
The cooling device according to claim 1, further comprising: a light amount determination unit that determines the amount of frost from the amount of light received by the light receiving element . The optical frost sensor is composed of an image sensor,
The cooling device according to claim 1, further comprising: an image analysis unit that determines the amount of frost from a pixel on the screen imaged by the image sensor . The cooling device according to claim 4 or 5, wherein a periphery of the optical frost sensor and a rear portion of a frost detection part targeted by the optical frost sensor are surrounded by a light shielding material . The optical frost sensor for detecting frost formation on the front end surface of the fan detects the amount of frost on the front end surface of the fan from an extension line of the fan front end surface orthogonal to the air path direction of the cooler. The cooling device according to claim 1, wherein the cooling device is arranged as described above. The optical frost sensor for detecting frost formation on the fin tip surface detects the amount of frost on the fin tip surface from an extension line of the fin tip surface orthogonal to the air path direction of the cooler. The cooling device according to claim 1, wherein the cooling device is arranged as described above. The cooling according to any one of claims 1 to 8, wherein the optical frost sensor includes a lens, and the lens is closely fixed to an inner surface of a cylindrical member around which a heater is wound. apparatus. The cooling device according to any one of claims 1 to 8, wherein the optical frosting sensor that detects the amount of frost adhering to the fin is provided at a lower end portion of the cooler. The optical frost sensor for detecting the amount of frost adhering to the fin is attached to an attachment, and the attachment is attached directly or indirectly to an end of a drain pan disposed at the bottom of the cooler. The cooling apparatus according to claim 1, wherein the cooling apparatus is provided. The optical frost sensor for detecting the amount of frost adhering to the fin is attached to an attachment, and the attachment is attached directly or indirectly to a pipe passing through the fin of the cooler. The cooling device according to any one of claims 1 to 8 , wherein The optical frosting sensor for detecting the amount of frost adhering to the fin is attached to an attachment, and the attachment is directly or indirectly attached to the casing of the cooler via a buffer member. The cooling device according to any one of claims 1 to 8 . The refrigerator provided with the cooling device of any one of Claims 1-13. The refrigerator according to claim 14, wherein frost detection by the optical frosting sensor is stopped or disabled when the door is opened or when the illumination in the cabinet is lit.

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