JP5765994B2 - Steam generator - Google Patents

Description

  The present invention relates to a steam generator used in a steam convection oven or the like.

  Patent Document 1 below discloses a steam convection oven that heats and cooks food with hot air containing steam, and this steam convection oven includes a heater and a blower fan in a cooking chamber provided in the housing. An induction heating type steam generator for supplying steam to the side of the cooking chamber in the housing is provided. When cooking food with hot air containing steam in this steam convection oven, steam is supplied from the steam generator into the cooking chamber, and the fan containing the steam in the cooking chamber is heated by the heater. Convection.

  The steam generator used in this steam convection oven includes a cylindrical steam generation container that stores a predetermined amount of water to generate steam, an induction heating coil wound around the outer periphery of the steam generation container, and steam generation A heating element housed in the container and generating heat by supplying a high frequency current to the induction heating coil, and a water level sensor for detecting the water level in the steam generating container are provided. The heating body has a resin holder supported on the upper part of the steam generating container, and a plurality of heating rods having upper ends fixed to the holder and suspended in the steam generating container. The plurality of heating rods are composed of a heating part that generates heat when a high-frequency current is supplied to the induction heating coil, and a non-heating part above and below the heating part, and the plurality of heating bars are the upper ends of the upper non-heating parts. Is fixed to a resin holder.

  When the steam generator generates steam by supplying high-frequency current to the induction heating coil, it is between the upper limit water level exceeding the heat generating part of the plurality of heating rods and the lower limit water level slightly below the upper end of the heat generating part. The water level is controlled.

JP 2010-255871 A

  In such a steam generator, as described above, when high-frequency current is supplied to the induction heating coil to generate steam, the upper limit water level exceeding the heating portion of the heating rod and a little lower than the upper end of the heating portion. The water level is controlled to be between the lower limit water level. However, if the water level sensor breaks down and the water level in the steam generating container becomes lower than the lower limit water level, a part of the heat generating part of the heating rod becomes overheated without heat exchange with water, and the heat of the heat generating part that has become overheated Is transmitted to the non-heat generating portion, and the non-heat generating portion is similarly overheated. When the non-heating part of the heating rod is overheated until it exceeds the melting point of the holder, the resin holder that integrally supports the plurality of heating rods and supports them on the upper part of the steam generating container is melted, and these heating rods are vaporized from the holder. There was a case where it dropped out into the generation container. The present invention aims to solve such problems.

In another embodiment of the present invention, a cylindrical steam generating container installed upright and storing a predetermined amount of water to generate steam, an induction heating coil wound around the outer periphery of the steam generating container, A heating element housed in the steam generation container and generating heat by supplying a high-frequency current to the induction heating coil, and a holder supported on the upper part of the steam generation container; In the steam generating apparatus constituted by a plurality of heating rods suspended in the steam generating container with a fixed part, the heating body is made of a magnetic member, and the holder is higher than the Curie temperature of the heating rod The supporting portion is made of a material having a melting point and is supported on the upper end portion of the steam generation container, and has a fixing portion for fixing the plurality of heating rods integrally with each other. And the plurality of heating rods A steam generator is provided, wherein a temperature sensor that detects the temperature of the heating rod is provided in a connecting portion that extends upward from the fixed portion and is connected to the support portion. is there.

In this embodiment, the heating rod is made of a magnetic member, and the holder is made of a material having a melting point higher than the Curie temperature of the heating rod, so the heating rod does not generate heat beyond the melting point of the holder, thereby There is no possibility that the heating rod melts the holder and falls off. Even if some of the plurality of heating rods are overheated, the heat is transmitted from the connecting portion of the heating rod extended upward from the fixed portion to the support portion of the holder. The sensor can detect the temperature of the heat transmitted to the support part by detecting the temperature of the connecting part of the heating rod. Thereby, the support part of the said heating rod will be in an overheated state, and a steam generator will not be damaged. In this case, the connecting portion extends any one of a plurality of heating rods from the fixed portion to the supporting portion, thereby reducing the number of parts and reducing the manufacturing cost.

Furthermore, in another embodiment of the present invention, a cylindrical steam generating container installed upright and storing a predetermined amount of water to generate steam, and an induction heating coil wound around the outer periphery of the steam generating container And a heating element housed in the steam generation container and generating heat by supplying a high frequency current to the induction heating coil, and the holder supported on the upper part of the steam generation container, and the holder A plurality of heating rods suspended in the steam generation container with the upper end fixed to the steam generation vessel, the plurality of heating rods being the same as the heat generating portion that generates heat by feeding power to the induction heating coil. A non-heat generating part formed on the upper side of the heat generating part and having an upper end fixed to the holder. At least one of the plurality of heating rods is perforated from the upper end to the heat generating part along the axial direction. Temperature test There is provided a steam generator, characterized in that the insertion of the temperature sensor for detecting the temperature of the heat generating portion in use in the hole.

In this embodiment, compared to when the temperature of the non-heat generating portion of the heating rod is detected, the time during which the heat of the heat generating portion of the heating rod is transmitted to the non-heat generating portion can be shortened, and the heating body becomes overheated. Can be detected at an early stage.

It is a front view of 1st Embodiment of the steam convection oven which incorporated the steam generator of this invention. It is a longitudinal cross-sectional view in the AA line of FIG. It is a longitudinal cross-sectional view in the BB line of FIG. It is a partially broken longitudinal cross-sectional view of a steam generator. It is a perspective view of the heating body of FIG. It is an expanded vertical sectional view which shows the upper end part of a heating rod. It is an expanded longitudinal cross-sectional view which shows the upper end part of the heating rod by another Example. It is a block diagram of the control apparatus of a steam convection oven. It is a partially broken longitudinal cross-sectional view of the steam generator of 2nd Embodiment. It is a perspective view of the heating body of FIG. It is a longitudinal cross-sectional perspective view of the heating body of the steam generator of 3rd Embodiment.

  Hereinafter, a first embodiment in which a steam generator according to the present invention is applied to a steam convection oven will be described with reference to the accompanying drawings. As shown in FIGS. 1 to 3, the steam convection oven 10 includes a food cooking chamber 12 disposed in a housing 11 and a heater 13 provided in the cooking chamber 12 for heating the cooking chamber 12. A fan 14 provided in the cooking chamber 12 for convection of the air in the cooking chamber 12, a temperature sensor 15 for detecting the temperature in the cooking chamber 12, and the cooking chamber 12 inside the housing 11. The steam generator 20 is provided in a machine room 16 formed on the side of the container 11 and supplies steam into the cooking chamber 12. An operation panel 17 is provided on the front panel of the housing 11.

  As shown in FIG. 4, the steam generator 20 of the present invention includes a steam generation container 21 that stores a predetermined amount of water to generate steam, an induction heating coil 27 wound around the outer periphery of the steam generation container 21, And a heating element 30 that is housed in the steam generation vessel 21 and generates heat by supplying a high-frequency current to the induction heating coil 27.

  The steam generating container 21 is made of a resin cylindrical member that is open at the top and bottom. The steam generating container 21 is installed on the floor surface of the machine room 16 and is connected to a drain tank 18 used for discharging water in the cooking chamber 12 via a connecting cylinder 22. It is erected. The upper end opening of the steam generating container 21 is a steam discharge port 21a, and a steam outlet tube 23 for leading the discharged steam into the cooking chamber 12 is connected to the discharge port 21a. Further, the connection tube 22 connected to the drain opening 21b at the lower end opening of the steam generation container 21 is provided with a drain valve 24. When the drain valve 24 is opened, the water in the steam generation container 21 enters the drain tank 18. Discharged. A tapered surface 21 c is formed on the upper part of the steam generating container 21 so as to be narrowed downward to support the heating body 30.

  Annular brackets 25 and 26 are provided on the outer periphery of the intermediate portion in the vertical direction of the steam generating container 21 so as to be separated from each other in the vertical direction, and an induction heating coil 27 is wound between the brackets 25 and 26. The brackets 25 and 26 are provided with a plurality of rod-shaped ferrites 28 to prevent electromagnetic waves leaking from the induction heating coil 27 along the circumferential direction thereof.

  As shown in FIGS. 4 and 5, a heating body 30 that generates heat by the induction heating coil 27 and heats the water in the steam generation container 21 is accommodated in the steam generation container 21. The heating body 30 includes a holder 31 supported on the upper part of the steam generation container 21, and seven heating rods 32 having an upper end fixed to the holder 31 and suspended in the steam generation container 21. Yes. The holder 31 is a substantially annular metal plate with a steam passage formed in the center, and six protrusions (abutment support portions) 31 a formed at equal intervals on the outer periphery are formed on the upper part of the steam generation container 21. The taper surface 21c is supported by being locked. The holder 31 is made of SUS304 as an austenitic stainless steel and has a melting point of 1400 to 1450 ° C.

  The upper ends of the seven heating rods 32 are fixed to the holder 31 at equal intervals along the circumferential direction. The seven heating rods 32 extend in the axial direction of the steam generating vessel 21 and are arranged at equal intervals on a concentric circle centered on the central axis. Each heating rod 32 is a conductive metal rod-like member made of a magnetic member, and NSSC-160R is used as a highly weather-resistant ferritic stainless steel in this embodiment. The Curie temperature of each heating rod 32 using NSSC-160R is about 500 ° C. Each heating rod 32 is at the same height as the induction heating coil 27 and generates heat when a high-frequency current is supplied thereto, and a non-heating portion that does not generate heat at the upper and lower portions of the heating portion 32a. 32b and 32c. Each heating rod 32 has an upper non-heating portion 32 b fixed to the holder 31.

  As shown in FIG. 6, the upper end of each heating rod 32 is caulked through a through hole 31 b formed in the holder 31, and a locking portion 32 d that is widened by caulking at the upper end of each heating rod 32 is formed. It is locked to the upper surface of the holder 31. Each heating rod 32 is not limited to caulking and fixing to the holder 31 as described above. For example, as shown in FIG. 7, the upper end of each heating rod 32 has a diameter of the through hole 31 b of the holder 31. A locking portion 32d ′ having a large diameter may be provided, and the locking portion 32d ′ may be locked to the upper surface of the holder 31.

  As shown in FIG. 5, a temperature sensor 33 is attached to the holder 31. The temperature sensor 33 is a thermistor and detects the overheating state of the heating body 30. The temperature sensor 33 is attached in surface contact with all the protrusions 31 a of the holder 31. In the steam generator 20 of the present embodiment, the temperature sensor 33 detects the temperature of all the protrusions 31 a, but the present invention is not limited to this, and the temperature sensor 33 is connected to one protrusion of the holder 31. You may attach so that the temperature of the part 31a may be detected.

  A substantially cylindrical water level detection container 40 for detecting the water level in the steam generation container 21 is erected on the side of the steam generation container 21, and the water level detection container 40 communicates with a lower part of the steam generation container 21. 41 is connected in communication. A water level sensor 42 for detecting the water level in the steam generation container 21 is provided in the water level detection container 40. The water level sensor 42 is composed of a float switch, and a water level that exceeds the heat generating part 32a of the heating rod 32 in the steam generating container 21 by a float supported by a support member so as to move up and down is slightly below the upper limit water level L1 and the heat generating part 32a. The lower limit water level L2 is detected as the water level on the side. A water supply means 44 is connected to a water supply section 43 provided at the upper part of the water level detection container 40. The water supply means 44 includes a water supply pipe 45 led out from a water supply source such as a water supply, and a water supply valve 46 interposed in the water supply pipe 45. If the water supply valve 46 is opened, water is supplied into the water level detection container 40, and the water supplied into the water level detection container 40 is sent into the steam generation container 21 through the communication pipe 41. Further, the water level detection container 40 is provided with an overflow pipe 47 for draining water of a water level slightly exceeding the upper limit water level L1.

  The steam convection oven 10 includes a control device 50, and as shown in FIG. 8, the control device 50 includes a heater 13, a blower fan 14, an internal temperature sensor 15, an operation panel 17, and a steam generator 20. Each device is connected to a drain valve 24, an induction heating coil 27, a temperature sensor 33, a water level sensor 42, and a water supply valve 46. The control device 50 includes a microcomputer (not shown), and the microcomputer includes a CPU, a RAM, a ROM, and a timer (all not shown) connected via a bus. The CPU is based on the input from the operation panel 17, the internal temperature sensor 15, the temperature sensor 33 of the steam generator 20, and the detection of the water level sensor 42, the heater 13, the blower fan 14, the drain valve 24, the induction heating coil 27, and the like. A program for controlling the operation of the water supply valve 46 is executed.

  The control device 50 also includes a control circuit (not shown) that variably controls the input power of the heater 13 by phase control or the like, and a control circuit that variably controls the input power of the induction heating coil 27 of the steam generator 20 by inverter control or the like. (Not shown) and variably control the outputs of the heater 13 and the steam generator 20.

  In the steam convection oven 10, when executing the cooking program in the combination mode, the control device 50 operates the heater 13, the steam generator 20, and the blower fan 14 so that the temperature and the steam amount suitable for cooking are obtained. The input power of the heater 13 and the induction heating coil 27 of the steam generator 20 is variably controlled by each control circuit.

  When the steam generating device 20 of the steam convection oven 10 is operated, the control device 50 controls the water level in the steam generating container 21 to be a water level between the upper limit water level L1 and the lower limit water level L2. Specifically, when the water level sensor 42 detects the lower limit water level L2, the control device 50 opens the water supply valve 46 to supply water, and when the water level sensor 42 detects the upper limit water level L1, the control device 50 closes the water supply valve 46. Controls to stop water supply. Further, the control device 50 controls the supply of the high-frequency current to the induction heating coil 27 so as to prevent the heating body 30 from being overheated and damaging the steam generating container 21. Specifically, when the steam is generated in a state where the water level of the steam generating container 21 is normally controlled, the temperature of the holder 31 is 100 ° C. or less due to the steam or the boiling hot water. When the temperature of the holder 31 detected by the temperature sensor 33 reaches 110 ° C. or more as the overheating temperature, the supply of the high-frequency current to the induction heating coil 27 is controlled to stop.

  In the steam generator 20 configured as described above, each heating rod 32 is a conductive metal rod-shaped member made of a magnetic member, and the Curie temperature of NSSC-160R used in this embodiment is about 500 ° C. It has become. On the other hand, SUS304 is used as the austenitic stainless steel for the holder 31 to which each heating rod 32 is fixed, and the melting point thereof is 1400 to 1450 ° C. For example, the water level in the steam generation container 21 becomes lower than the lower limit water level L2, the heating rod 32 generates heat without being exchanged with water and becomes overheated, and the temperature sensor 33 cannot detect the temperature. The high frequency current may be supplied to the induction heating coil 27 as it is. When the heating rod 32 generates heat and its temperature reaches about 500 ° C., which is the Curie temperature, each heating rod 32 loses its magnetism and no longer generates heat. Thereby, each heating rod 32 does not generate heat above the melting point of the holder 31, and the holder 31 is not melted by each heating rod 32. Therefore, each heating rod 32 does not fall into the steam generation container 21 from the holder 31.

  In addition, the upper end of the heating rod 32 is inserted into a through hole 31 b formed in the holder 31 and caulked. It has been stopped. Thereby, there is no risk of loosening when the upper end of each heating rod 32 is fixed to the holder 31 with a screw or corrosion when fixing by welding, and there is no possibility that each heating rod 32 falls off the holder 31. In addition, the same effect can be obtained also in the heating rod 32 shown in FIG.

  In the above-described embodiment, the holder 31 and each heating rod 32 may be integrally formed with NSSC-160R as a highly weather-resistant ferritic stainless steel. In addition, the heating rod 32 can be prevented from being detached from the holder 31.

  Further, when a high frequency current is supplied to the induction heating coil 27, a part of the seven heating rods 32 may be overheated. In such a case, in the case where the temperature of the non-heating part 32b of any one heating rod 32 is detected by the temperature sensor, if the temperature of the heating rod 32 in an overheated state is detected, the control device 50 However, if the temperature of the heating rod 32 that is not overheated is detected, the controller 50 cannot detect the overheated state of the heating body 30. However, in this steam generator 20, when a part of the seven heating rods 32 is overheated, the heat of the heating rod 32 that has been overheated is transmitted to the holder 31, and the holder 31 Therefore, the controller 50 can reliably detect the overheated state of the heating body 30 and the temperature of the heating body 30 becomes abnormally high as the steam generating container 21 is melted, causing the steam generating container 21 to be damaged. There is no.

  Further, since the temperature sensor 33 detects the temperatures of all the protrusions (abutment support portions) 31a that are in contact with and supported by the steam generating container 21 of the holder 31, a part of the holder 31 becomes abnormally hot. However, the temperature of all the portions where the heat of the holder 31 is transmitted to the steam generation container 21 can be directly detected by the temperature sensor 33, and the steam generation container 21 can be reliably prevented from being damaged.

  Next, a second embodiment of the steam generator according to the present invention will be described. In this steam generator 20A, the heating body 30A is different from the heating body 30 of the first embodiment described above, and the heating body 30A will be described below. As shown in FIGS. 9 and 10, the heating body 30 </ b> A includes a holder 31 </ b> A supported in contact with the upper tapered surface 21 c of the steam generation container 21, and an upper end fixed to the holder 31 </ b> A. And seven heating rods 32A suspended on the surface.

  The holder 31A is arranged to support the support plate (support part) 31Aa supported by the tapered surface 21c of the steam generation vessel 21 and the lower side of the support plate 31Aa so as to integrally fix the seven heating rods 32A. One of the plate (fixed portion) 31Ab and the seven heating rods 32A extends upward from the fixed plate 31Ab, and its upper end is fixed to the support plate 31Aa to connect the support plate 31Aa and the fixed plate 31Ab. It is composed of a connecting portion 32A′e (hereinafter, a heating rod having the connecting portion 32A′e is referred to as a connected heating rod 32A ′). For the support plate 31Aa and the fixed plate 31Ab, SUS304 is used as austenitic stainless steel. The support plate 31Aa is a substantially annular metal plate having a steam passage formed in the center, and has six protrusions 31Ac formed at equal intervals on the outer periphery and a tapered surface 21c formed above the steam generation vessel 21. It is supported by being locked. The upper end of the connecting heating rod 32A 'is fixed to the support plate 31Aa by caulking. The connecting portion 32A'e of the connecting heating rod 32A 'is formed to have a smaller diameter than its lower portion, and the fixing plate 31Ab is locked to the step between the connecting portion 32A'e and its lower portion. Yes. The fixed plate 31Ab is a substantially annular metal plate having a steam passage formed in the center, and seven heating rods 32A including the connected heating rods 32A ′ are arranged at equal intervals in the circumferential direction on the fixed plate 31Ab. ing. The seven heating rods 32A including the connected heating rods 32A 'extend in the axial direction of the steam generating vessel 21 and are arranged at equal intervals on a concentric circle centered on the central axis. As described above, the stepped portion of the connected heating rod 32A 'is locked to the fixed plate 31Ab, and the upper ends of the remaining six heating rods 32A are fixed to the fixed plate 31Ab by caulking.

  A temperature sensor 33A for detecting the temperature of the connecting portion 32A'e of the connecting heating rod 32A 'is attached to the steam generating container 21A. The temperature sensor 33A is a thermistor and detects the overheated state of the heating body 30A. The temperature sensor 33A is fitted into a temperature detection hole 32A'f formed in the connecting portion 32A'e in a direction orthogonal to the axial direction, and is in surface contact with the inner peripheral wall of the temperature detection hole 32A'f. About another structure, it is the same as that of 1st Embodiment mentioned above.

  In this steam generator 20A, a part of the seven heating rods 32A may be overheated without heat exchange with water. The heat of the heating rod 32A is transmitted from the connection portion 32A'e of the connection heating rod 32A 'to the support plate 31Aa, and the heat transmission path to the support plate 31Aa is limited to one of the connection portions 32A'e. The temperature sensor 33A detects the temperature of the connecting portion 32A'e, which is a heat transfer path limited to this one. Accordingly, when a part of the seven heating rods 32A (including the connected heating rod 32A ′) is overheated, the heat of the heated rod 32A in the overheated state is transmitted to the connecting portion 32A′e, and the temperature sensor 33A. Since the temperature of the connecting portion 32A'e is detected by the control device 50, the controller 50 can reliably detect the overheated state of the heating body 30A, and the support plate 31Aa of the holder 31A has an abnormally high temperature as the steam generating container 21 is melted. Thus, the steam generation container 21 is not damaged. In this embodiment, the connection heating rod 32A is extended upward from the fixed plate 31Ab to the connection portion 32A'e so as to reduce the number of parts and keep the cost low. However, the present invention is not limited to this, and the support plate 31Aa and the fixed plate 31Ab may be connected by a connecting member made of a single member having a single heat transfer path. In the steam generator 20A of this embodiment, the temperature of the connecting portion 32A'e can be detected by one temperature sensor 33A, so that the overheated state of the heating body 30A can be detected, and the support plate of the holder 31A The cost can be reduced as compared with the case where a plurality of temperature sensors are provided on the protrusion 31Ac of 31Aa or all the heating rods 32A.

  Next, a third embodiment of the steam generator according to the present invention will be described. In this steam generator 20B, the heating body 30B is different from the heating body 30 of the first embodiment described above, and the heating body 30B will be described. As shown in FIG. 11, one of the seven heating rods 32B of the heating body 30B is provided with a temperature detection hole 32Bf from the upper end to the intermediate position of the heat generating portion 32Ba along the axial direction. A temperature sensor 33B made of a thermocouple is inserted into the temperature detection hole 32Bf. When the temperature of the heat generating portion 32Ba is detected by the temperature sensor 33B in this way, the control device 50 stops supplying the high-frequency current to the induction heating coil 27 when the temperature detected by the temperature sensor 33B is 140 ° C. or more as the overheating temperature. You are in control. About another structure, it is the same as that of 1st Embodiment mentioned above.

  In this steam generator 20B, since the temperature of the heat generating part 32Ba of the heating rod 32B is directly detected, compared to when the temperature of the non-heat generating part 32Bb above the heating bar 32B is detected, The time during which the heat of the heat generating part 32Ba is transmitted to the non-heat generating part 32Bb can be shortened, and the overheated state of the heating body 30B can be detected at an early stage. Further, if the temperature sensing part of the temperature sensor 33B is arranged so as to be slightly below the lower limit water level L2, the temperature sensor 33B promptly determines that the heat generating part 32Ba of the heating rod 32B has become hot without heat exchange. Thus, the abnormality of the water level sensor 42 can be detected at an early stage.

   In the above embodiment, the holders 31 and 31B, the support plate 31Aa of the holder 31A, and the fixing plate 31Ab use SUS304 as austenitic stainless steel. However, the present invention is not limited to this, and the heating rods 32 and 32A are used. , 32B, other metals or ceramics may be used as a material having a melting point higher than the Curie temperature.

 20, 20A, 20B ... Steam generating device, 21 ... Steam generating container, 27 ... Induction heating coil, 30, 30A, 30B ... Heating body, 31, 31A, 31B ... Holder, 31b ... Through-hole, 32, 32A, 32B ... Heating rod, 32a, 32Aa, 32Ab ... exothermic part, 32b, 32Ab, 32Bb ... non-exothermic part, 32d ... locking part, 32Bf ... temperature detection hole, 33, 33A, 33B ... temperature sensor.

Claims (2)

A cylindrical steam generation container installed upright to store a predetermined amount of water and generate steam;
An induction heating coil wound around the outer periphery of the steam generating container;
A heating element housed in the steam generation container and generating heat by supplying a high frequency current to the induction heating coil;
In the steam generator comprising the holder supported by the upper part of the steam generating container, and a plurality of heating rods fixed at the upper end of the heating body and suspended in the steam generating container,
The plurality of heating rods are composed of a heat generating portion that generates heat by supplying power to the induction heating coil, and a non-heat generating portion that is formed on the upper side of the heat generating portion and has an upper end fixed to the holder. A steam generator, wherein a temperature sensor for detecting the temperature of the heat generating portion is inserted into at least one of the temperature detecting holes drilled from the upper end to the heat generating portion along the axial direction thereof. A cylindrical steam generation container installed upright to store a predetermined amount of water and generate steam;
An induction heating coil wound around the outer periphery of the steam generating container;
A heating element housed in the steam generation container and generating heat by supplying a high frequency current to the induction heating coil;
In the steam generator comprising the holder supported by the upper part of the steam generating container, and a plurality of heating rods fixed at the upper end of the heating body and suspended in the steam generating container,
The heating body is made of a magnetic member,
The holder is made of a material having a melting point higher than the Curie temperature of the heating rod, and a support portion supported on an upper end portion of the steam generating container and a plurality of the heating rods spaced apart below the support portion. A fixing portion for fixing the heating rod integrally, and detecting one of the plurality of heating rods from the fixing portion and detecting the temperature of the heating rod in a connecting portion connected to the support portion A steam generator characterized in that a temperature sensor is provided.

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