JPH0327190B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency thawing device for thawing frozen products, etc., and an object of the present invention is to uniformly thaw the thawed products by preventing partial oxidation or discoloration of the thawed products.

Conventionally, high-frequency defrosting devices that perform defrosting using high-frequency dielectric heating of several MHz or higher are well known. For example, FIG. 1 shows a high-frequency thawing device having two upper and lower electrodes configured to sandwich an object to be thawed at a relatively low frequency such as 13 MHz. In the figure, reference numeral 1 denotes a thawing chamber, the bottom surface of which is a mounting plate 2 made of an insulator, and the side, rear, and top surfaces of the thawing chamber wall 3 made of a highly conductive material such as aluminum. Reference numeral 4 denotes an object to be thawed, on which an upper electrode 5 connected to the ground side is movably attached together with an insulating cover 6 by an electrode lifting device 7. Reference numeral 9 denotes an electrode box provided below the mounting plate 2 of the thawing chamber 1, and the electrode box 9 and the wall surface 3 of the thawing chamber are electrically connected. A lower electrode 10 is provided inside the electrode box 9 at a predetermined distance from the mounting plate 2 and the electrode box 9, and is connected to the high voltage side. Reference numeral 11 denotes a high-frequency oscillator that supplies high-frequency energy to the object 4 to be thawed, and the outside is shielded to prevent noise radio waves from leaking. 1
Reference numerals 2 and 13 indicate power supply lines that respectively feed power to the lower electrode 10 and the upper electrode 5. In terms of the circuit, the thawing chamber wall 3, the electrode box 9, and the chassis of the high frequency oscillator section 11 are grounded together with the upper electrode 5.

In this configuration, it is fully considered that the objects 4 to be thawed are stacked as shown in the figure and placed in the thawing chamber 1 to be thawed. When the objects 4 to be thawed are stacked together in this manner, the objects 4 to be thawed are generally uneven and come into contact with each other at only a portion, resulting in a stacked state. Then, when a high-frequency electric field is applied between the upper and lower electrodes 5 and 10 to thaw the object, energy enters the object to be thawed, which has a large dielectric loss. However, since the points of contact between the objects to be thawed are only a few, more energy is concentrated than in other parts where there is a layer of air, causing blisters and burns at the contact points, making it impossible to thaw uniformly, and This leads to quality deterioration and food loss due to drip leakage. Furthermore, if the items to be thawed are thawed without being piled up, extra time and expense will be required to thaw the same amount.

The present invention provides a high-frequency thawing method that can uniformly thaw such stacks without causing any blemish or damage. One embodiment will be described below based on the accompanying drawings.

In Fig. 2, 1 is a thawing chamber, the bottom surface of which is a mounting plate 2 made of an insulator, and the side, rear, and top surfaces of the thawing chamber wall 3 made of a material such as aluminum with good conductivity. There is. 4 is an object to be thawed, and an upper electrode 5 connected to the ground side is installed on the upper part.
is movably attached together with the insulating cover 6 by an electrode lifting device 7. Further, an insulating plate 8 having a low dielectric constant is sandwiched between the objects 4 to be thawed. Reference numeral 9 denotes an electrode box provided below the mounting plate 2 of the thawing chamber 1, and the electrode box 9 and the wall surface 3 of the thawing chamber are electrically connected. A lower electrode 10 is provided inside the electrode box 9 at a predetermined distance from the mounting plate 2 and the electrode box 9, and is connected to the high voltage side. Reference numeral 11 denotes a high frequency oscillator that supplies high frequency energy to the object 4 to be thawed, and the outside is shielded to prevent noise radio waves from leaking. Reference numerals 12 and 13 are power supply lines that respectively feed power to the lower electrode 10 and the upper electrode 5. 14 is a high voltage power supply section, and a power supply line 15
It is connected to the high frequency oscillation section 11 with a wire. In terms of the circuit, the thawing chamber wall surface 3, the electrode box 9, and the chassis of the high frequency oscillator section 11 are grounded together with the upper electrode 5. Also, 16 is a compressor for the refrigerator that sends cold air into the thawing chamber 1, and includes an evaporator 17 and a condenser 18.
and a fan 19 that sends cold air. The outside of these is a stainless steel body 20
covered with.

FIG. 3 shows a case where a flexible insulator 8 having a low dielectric constant is sandwiched between the objects 4 to be thawed. Further, FIG. 4 shows a foamed low dielectric constant insulator 8 between the objects 4 to be thawed.
Indicates the case where the two are in between. Further, FIGS. 5A and 5B show an example in which an insulator 8 sandwiched between an object 4 to be thawed is provided with irregularities or protrusions a on one or both sides.

Next, the operation in the embodiment of the present invention will be explained. As shown in FIG.
are stacked, the upper electrodes 5 are set with an appropriate gap, and the power supply section 14 and high frequency oscillation section 11 are operated, the object to be thawed 4 is heated due to dielectric loss and thawing begins. However, when the objects 4 to be thawed are piled up in this way, the shape of the objects 4 to be thawed is not necessarily square block-like, and in fact, the objects 4 to be thawed are only partially overlapped (section b). A gap c is formed in areas other than this joint, and when a high-frequency electric field is applied in such a state, the dielectric loss in the joint b is much larger than in the gap c, so as shown in the figure. The high-frequency electric field is concentrated and a large amount of energy is supplied to the junction. As a result, burns and stains occur at the joint b, leading to deterioration in quality and loss of food materials.

However, as shown in FIG. 2, by sandwiching the low dielectric constant insulator 8 according to the embodiment of the present invention between the objects 4 to be thawed, the objects to be thawed do not come into direct contact with each other, and the insulator 8 plays the same role as the air gap, and the high-frequency electric field is distributed uniformly throughout the joint without concentrating on the joint, which means that thawing can be done evenly over the whole area, reducing quality deterioration and food loss due to dripping. The effect of the insulator 8 is tremendous. Furthermore, by inserting a flexible insulator 8 as shown in Figure 3 between the objects 4 to be thawed, the insulator 8 can be bent freely even if the objects to be thawed differ in size and have a step. Therefore, the items to be thawed on the upper level do not fall down and hit the thawing chamber wall 3 or the front door, causing overcurrent to flow, and they can be stacked efficiently, allowing the thawing chamber to be used effectively. comes out. Further, when a foam insulator 8 as shown in FIG. 4 is used, the insulator 8 has a dielectric constant as low as that of air, which has the effect of further preventing concentration of high-frequency electric fields. Furthermore, as shown in FIGS. 5A and 5B, by providing unevenness or protrusions a on one or both sides of the insulator 8, the object 4 to be thawed can be
(The objects 4 to be thawed are in an ice state before thawing and are therefore very slippery.) This prevents the objects 4 on the upper stage from falling and hitting the wall 3 or front door of the thawing chamber, causing an overcurrent to flow. In addition to preventing the formation of an air layer due to the unevenness, it is possible to reliably prevent the concentration of high-frequency electric fields.

As described above, when thawing frozen products using a thawing device, it is common sense to stack the frozen products in order to thaw them efficiently. However, in the case of high-frequency thawing, burns occur in the stacked parts, leading to a decline in quality and loss, but by using an insulator as in the present invention, this drawback can be completely eliminated with a simple configuration. It has an extremely large effect.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a conventional high-frequency thawing device, FIG. 2 is a vertical sectional view of a high-frequency thawing device according to an embodiment of the present invention, and FIG. 3 is a sectional view of main parts showing another embodiment of the present invention. , FIG. 4 is a sectional view showing still another embodiment,
5A and 5B are perspective views of an insulator showing another embodiment different from those shown in FIGS. 3 and 4, and FIG. 6 is a sectional view showing a conventional defrosting operation. DESCRIPTION OF SYMBOLS 1... Thawing chamber, 2... Mounting plate, 5... Upper electrode, 10... Lower electrode, 11... High frequency oscillation part, 8... Insulator.

Claims (1)

[Scope of Claims] 1. Equipped with upper and lower electrodes configured to sandwich an object to be thawed, a thawing chamber for storing the object to be thawed, and a high-frequency oscillation unit that applies a high-frequency electric field between the upper and lower electrodes. The objects to be thawed are placed between the upper and lower electrodes in a stacked state, and a flexible insulator is interposed between the stacked objects to be thawed and the objects to be thawed. high frequency decompression method. 2. The high-frequency thawing method according to claim 1, wherein the insulator interposed between the objects to be thawed is a foamed insulator. 3. The high-frequency thawing method according to claim 1, wherein the insulator interposed between the objects to be thawed is an insulator having irregularities or protrusions on one or both surfaces.