JP2015073477A - Thawing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thaw food products by stabilizing the output voltage of a step-up transformer so as to apply an intended voltage reliably to the food products.SOLUTION: A thawing apparatus 1 includes a thawing chamber 2 housing a conductive food shelf 6 to be mounted with a food product and a step-up transformer 29 which raises an AC voltage from a commercial power supply 100, and an AC voltage raised by the step-up transformer 29 is applied to the food product within the thawing chamber 2. In the step-up transformer 29, a high-voltage-side terminal 33 of the secondary coil 31 is connected to the food shelf 6, and the low-voltage-side terminal 34 of the secondary coil 31 is connected to an iron core 32 of the step-up transformer 29.

Description

    The present invention relates to a thawing device for thawing frozen food by applying a high voltage to the frozen food.

    For example, as disclosed in Patent Document 1, there is known a thawing device that boosts an AC voltage from a power source using a transformer and applies the boosted AC voltage to the object to be thawed to decompress the object to be thawed. . Specifically, this thawing device includes a thawing cabinet and a step-up transformer. In the thawing cabinet, a conductive shelf on which the object to be thawed is placed is accommodated. In the transformer, the terminal on the high potential side of the secondary coil is connected to a shelf in the defroster via a resistor. In this configuration, the AC voltage boosted by the transformer is applied to the object to be thawed through the shelf, and the object to be thawed is thawed.

Japanese Patent No. 2696310

    By the way, in the thawing device disclosed in Patent Document 1 described above, since the terminal on the low potential side of the secondary coil in the transformer is insulated and sealed, it is difficult to apply a desired voltage to the object to be thawed. There was a problem. That is, since the terminal on the low potential side of the secondary coil is in an open state (open state), the voltage generated by the transformer (output voltage) becomes unstable.

    This invention is made | formed in view of this point, The objective is to provide the thawing | decompression apparatus which can stabilize the output voltage of a transformer and can apply a desired voltage to a to-be-thawed object reliably. It is in.

    A thawing device according to the present invention includes a thawing container in which a conductive food shelf on which an object to be thawed is placed is housed, and a step-up transformer that steps up an AC voltage from a power source. The AC voltage thus applied is applied to the object to be thawed in the thawing cabinet. In the step-up transformer, the high-potential side terminal of the secondary coil is connected to the food shelf, while the low-potential side terminal of the secondary coil is connected to the iron core of the step-up transformer.

    According to said structure, the voltage generation | occurrence | production (output voltage) of a step-up transformer is supplied to a food shelf from a high potential side terminal, and is applied to a to-be-thawed object. Thereby, the material to be thawed is thawed. Moreover, since the low potential side terminal of the secondary coil (high voltage winding) in the step-up transformer is connected to the iron core of the step-up transformer, the secondary coil is effectively electrically closed loop (closed circuit). . Therefore, compared with the conventional configuration in which the low potential side terminal of the secondary coil is in the open state (open state), the generated voltage (output voltage) in the step-up transformer is stabilized.

    As shown in FIG. 4, the voltage applied to the object to be thawed attenuates as the object to be thawed increases in the thaw box. According to the present invention, since the voltage generated in the step-up transformer is stabilized, the degree of attenuation of the applied voltage to each object to be thawed that attenuates as the number of objects to be thawed increases significantly compared to the conventional configuration. . Further, since the secondary coil of the step-up transformer becomes a closed loop (closed circuit), the voltage generated by the step-up transformer (value when the number of food shelves is zero in FIG. 4) becomes higher than the conventional configuration.

    In the thawing device according to the present invention, it is preferable that the iron core of the step-up transformer is installed on an insulating member.

    According to said structure, since the iron core of a step-up transformer is attached to the insulating member, the voltage leak from a secondary coil can be suppressed in a step-up transformer. Therefore, it is possible to further stabilize the generated voltage in the step-up transformer.

    In the thawing device according to the present invention, it is preferable that the high potential side terminal and the low potential side terminal of the secondary coil of the step-up transformer are covered with a potting material.

    According to the above configuration, since both terminals of the secondary coil which is the high voltage part are covered with the potting material, the high voltage part can be easily and inexpensively compared with the case where an insulating wall is provided by molding, for example. Insulation treatment can be performed. Moreover, in the form which provides the insulating wall mentioned above, since a high voltage part is exposed, dust etc. tend to adhere to a high voltage part. If it does so, it will become difficult to ensure insulation over a long period of time. In that respect, according to the present invention, since the high voltage portion is covered with the potting material, it is possible to prevent adhesion of dust and the like and to ensure insulation for a long period of time.

    In the decompression device according to the present invention, it is preferable that a variable tap is provided at a terminal of a primary coil of the step-up transformer.

    According to the above configuration, since the variable tap is provided, the voltage generated by the step-up transformer (output voltage) can be adjusted appropriately according to the capacity (large or small) of the defroster. Therefore, the voltage applied to the object to be thawed can be optimized. In addition, since it is not necessary to generate an unnecessarily high voltage in the step-up transformer, the life of the insulating portion in the step-up transformer can be improved.

    As described above, according to the present invention, since the secondary coil of the step-up transformer can be closed loop (closed circuit) in terms of distributed capacity, the generated voltage (output voltage) in the step-up transformer is conventionally increased. Can also be stabilized. Therefore, the degree of attenuation of the applied voltage to each thawing object that attenuates as the number of thawing objects increases can be remarkably reduced. Therefore, it is possible to provide a thawing device that can reliably apply a desired voltage to an object to be thawed.

    Further, since the secondary coil of the step-up transformer becomes a closed loop (closed circuit), the voltage generated by the step-up transformer can be made higher (raised) than before. Therefore, the capacity of the step-up transformer can be reduced.

FIG. 1 is a cross-sectional view showing a schematic configuration of the thawing apparatus. FIG. 2 is an electric circuit diagram showing the configuration of the voltage application device. FIG. 3 is an electric circuit diagram showing a main part of the voltage applying device. FIG. 4 is a graph showing the relationship between the number of food shelves and the high voltage potential distribution. FIG. 5 is a cross-sectional view showing a main part of the voltage application device.

    Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

    The thawing device 1 according to the present embodiment applies a high voltage (high voltage static electricity) to a material to be thawed to thaw the material to be thawed. As shown in FIG. 1, the thawing device 1 includes a thawing cabinet 2 and a voltage applying device 10.

    The defroster 2 includes a substantially rectangular outer case 3 and a substantially rectangular inner case 4 accommodated in the outer case 3. The inside of the inner case 4 is a thawing chamber S, and a plurality of food shelves 6 are arranged in the vertical direction. The food shelf 6 is detachably provided on the inner case 4 and a food 7 that is an object to be thawed is placed thereon. The outer case 3, the inner case 4, and the food shelf 6 are each made of metal. The outer case 3 and the inner case 4 are completely insulated by an insulator 5. The outer case 3 is grounded by a ground 8.

    The voltage application device 10 applies a high voltage (high voltage static electricity) to the inner case 4 of the thawing cabinet 2 and is provided in the upper part of the thawing cabinet 2. The voltage application device 10 includes a substantially rectangular iron plate case 11 and a voltage application circuit 20 accommodated in the iron plate case 11. The iron plate case 11 is installed on the upper surface of the outer case 3.

    As shown in FIG. 2, the voltage application circuit 20 includes a magnetic leakage transformer 22 (leakage transformer) and a step-up transformer 29 (high-voltage transformer).

    The magnetic leakage transformer 22 includes a primary coil 23 and a secondary coil 24, and an iron core 25. Both terminals of the primary coil 23 are connected to the commercial power source 100. One terminal of the primary coil 23 is connected to the commercial power supply 100 via the fuse 21. A noise filter 26 is connected between both terminals of the primary coil 23. The ground phase on the primary coil 23 side and the ground phase on the secondary coil 24 side are short-circuited by a short circuit 27.

    The commercial power source 100 is, for example, an AC power source of 100V or 200V (frequency is 50 Hz or 60 Hz). The fuse 21 functions as an overcurrent prevention unit that prevents a current exceeding a predetermined value from flowing. The noise filter 26 absorbs an abnormal surge voltage such as noise entering from the commercial power supply 100 and protects the voltage application circuit 20 from the surge voltage. The magnetic leakage transformer 22 is configured such that the voltage ratio (the turns ratio of the primary coil 23 and the secondary coil 24) is 1: 1. When an overload occurs on the secondary coil 24 side (that is, the load side), the magnetic leakage transformer 22 instantaneously generates a leakage flux (leakage magnetic flux) in the iron core 25, and abruptly attenuates the secondary output voltage. Let

    The step-up transformer 29 includes a primary coil 30 on a low voltage side, a secondary coil 31 on a high voltage side, and an iron core 32. The primary coil 30 is connected to the secondary coil 24 of the magnetic leakage transformer 22. The high potential side terminal 33, which is one terminal of the secondary coil 31, is connected to the high voltage cable 37 via the protective resistor 35. The high voltage cable 37 is connected to the inner case 4 of the thawing cabinet 2 (see FIG. 1). With this configuration, the high potential side terminal 33 of the step-up transformer 29 is electrically connected to the food shelf 6 in the thawing box 2, and the high voltage output from the high potential side terminal 33 is supplied to the food 7 through the food shelf 6. Will be applied. The food 7 is thawed by applying a high voltage.

    The step-up transformer 29 steps up the AC voltage supplied from the commercial power supply 100 via the magnetic leakage transformer 22 to, for example, 10,000 V to 16000 V and outputs the boosted voltage from the high potential side terminal 33. The protective resistor 35 is composed of, for example, a high voltage resistor of several tens of kΩ, and when an overload occurs in the decompression cabinet 2, the secondary output voltage is rapidly attenuated to protect the step-up transformer 29. Is. Thereby, the electric shock when a person accidentally touches the food shelf 6 in the thawing box 2 is rapidly avoided.

    In the step-up transformer 29 of this embodiment, the low potential side terminal 34, which is the other terminal of the secondary coil 31, is connected to the iron core 32. As a result, as shown in FIG. 3, in the step-up transformer 29, the distributed capacitance CS (floating capacitance) existing between the secondary coil 31 and the iron core 32 becomes very stable. That is, the impedance on the secondary coil 31 side is stabilized.

    Further, in the step-up transformer 29 of the present embodiment, the iron core 32 is installed on a high-insulation plastic plate 36 that is an insulating member. That is, in the step-up transformer 29, the iron core 32 is attached to the iron plate case 11 via the highly insulating plastic plate 36. Since the iron core 32 of the step-up transformer 29 is insulated by the high-insulation plastic plate 36 in this way, a very large capacitance CE due to the high-insulation plastic plate 36 is added as an impedance on the secondary coil 31 side. The impedance on the secondary coil 31 side is more stable.

    By stabilizing the impedance on the secondary coil 31 side, the secondary coil 31 is effectively a closed loop (closed circuit) in terms of distributed capacity. Specifically, the circuit in which the current ia output from the high potential side terminal 33 of the step-up transformer 29 flows through the food 7 (distributed capacity CF) and becomes the charged minute current ib is effectively a closed loop. Thus, the secondary coil 31 becomes a closed loop, so that the generated voltage (output voltage) in the step-up transformer 29 can be stabilized.

    As shown in FIG. 4, in this embodiment (the present invention), the variation in the voltage applied to the food 7 (the high voltage potential distribution shown in FIG. 4) has been reduced due to the stable voltage generated in the step-up transformer 29. This is significantly smaller than the case (b1 shown in FIG. 4) (a1 shown in FIG. 4). In general, the voltage applied to each food 7 is attenuated as the number of foods 7 increases (the number of food shelves increases). In the present embodiment (the present invention), since the voltage generated in the step-up transformer 29 is stabilized, the degree of attenuation of the applied voltage to the food 7 that attenuates as the food 7 increases is the conventional case (b2 shown in FIG. 4). ) (A2 shown in FIG. 4). Further, in the present embodiment (the present invention), the voltage generated by the step-up transformer 29, that is, the voltage applied to the food 7 is improved as compared with the prior art (an improvement of about 10%).

    As described above, according to the present embodiment, in the step-up transformer 29, the low potential side terminal 34 is connected to the iron core 32 and the secondary coil 31 is closed loop (closed circuit), whereby the step-up transformer 29 The generated voltage (output voltage) can be stabilized. Therefore, the variation of the applied voltage to the food 7 and the degree of attenuation of the applied voltage to the food 7 that attenuates as the food 7 increases can be significantly reduced. Therefore, it is possible to provide the thawing device 1 that can reliably apply a desired voltage to the food 7.

    Further, by making the secondary coil 31 of the step-up transformer 29 in a closed loop (closed circuit), the voltage generated by the step-up transformer 29, that is, the voltage applied to the food 7 can be raised more than before. Therefore, the capacity of the step-up transformer 29 can be reduced.

    Moreover, in this embodiment, since the iron core 32 of the step-up transformer 29 is attached to the iron plate case 11 via the high-insulation plastic plate 36 (insulating member), the secondary coil 31 may be deteriorated due to insulation deterioration. Even when a current leaks into the iron core 32, the leakage current can be prevented from flowing into the iron plate case 11 or the outer case 3 of the thawing cabinet 2 by the high-insulation plastic plate 36. Therefore, it is possible to provide the thawing device 1 with extremely high insulating properties.

    Moreover, since current can be prevented from leaking from the iron core 32 to the iron plate case 11 and the outer case 3 of the thawing cabinet 2, voltage leakage from the secondary coil 31 to the iron core 32 can be suppressed. Therefore, it is possible to further stabilize the generated voltage in the step-up transformer 29.

    Moreover, in the voltage application apparatus 10 of this embodiment, as shown in FIG.2 and FIG.5, both terminals (the high potential side terminal 33 and the low potential side terminal 34) of the secondary coil 31 of the step-up transformer 29 are protected. The resistor 35 is accommodated in a resin potting case 40. The potting case 40 is filled with a potting material, and the high potential side terminal 33, the low potential side terminal 34, and the protective resistor 35 are covered with the potting material.

    Thus, by covering the high-potential side terminal 33, the protective resistor 35, and the like, which are high-voltage parts, with a potting material, for example, compared with the case where an insulating wall is provided by molding, the high-voltage part is easily and inexpensively provided. Insulation treatment can be performed. Moreover, in the form which provides the insulating wall mentioned above, since a high voltage part is exposed, dust etc. tend to adhere to a high voltage part. If it does so, it will become difficult to ensure insulation over a long period of time. In this respect, according to the present embodiment, since the high voltage portion is covered with the potting material, adhesion of dust and the like can be prevented, and insulation can be ensured for a long period of time.

    Moreover, in the voltage application apparatus 10 of this embodiment, the variable tap 28 is provided in the terminal of the primary coil 30 of the step-up transformer 29, as shown in FIG. Specifically, the variable tap 28 is configured such that the terminal P on the magnetic leakage transformer 22 side is switched and connected to one of the three input taps P1 to P3. By switching the input taps P1 to P3, for example, 90% and 80% are adjusted with respect to 100% of the voltage (output voltage) generated by the step-up transformer 29. Therefore, according to the voltage application device 10 of the present embodiment, it is possible to appropriately adjust the generated voltage (output voltage) of the step-up transformer 29 according to the capacity (large or small) of the decompression cabinet 2 to be attached. Therefore, the voltage applied to the food 7 can be optimized. Further, since it is not necessary to generate an unnecessarily high voltage in the step-up transformer 29, the life of the insulating portion in the step-up transformer 29 can be improved.

    As described above, the present invention is useful for a thawing apparatus that applies a high voltage to an object to be thawed to decompress the object to be thawed.

1 Defroster 2 Defroster 6 Food shelf 7 Food (Thawed object)
28 Variable tap 29 Step-up transformer 30 Primary coil 31 Secondary coil 32 Iron core 33 High potential side terminal 34 Low potential side terminal 36 High insulation plastic plate (insulation member)

Claims (4)

A thawing cabinet in which a conductive food shelf on which an object to be thawed is placed is housed, and a step-up transformer that boosts an AC voltage from a power source, and the AC voltage boosted by the step-up transformer is supplied to the thawing cabinet. A thawing device for applying to the object to be thawed,
In the step-up transformer, the high potential side terminal of the secondary coil is connected to the food shelf, while the low potential side terminal of the secondary coil is connected to the iron core of the step-up transformer. A defroster. In claim 1,
The thawing device, wherein the iron core of the step-up transformer is installed on an insulating member. In claim 1,
A thawing device, wherein a high potential side terminal and a low potential side terminal of a secondary coil of the step-up transformer are covered with a potting material. In claim 1,
A decompression device, wherein a variable tap is provided at a terminal of a primary coil of the step-up transformer.

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