JPS6237346Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to the configuration of a heating chamber of a high-frequency generator that can optionally perform electrical heating by installing a heater in the heating chamber. The goal is to improve performance.

Conventionally, various high-frequency heating devices have been devised in which a heater is provided in a heating chamber of the high-frequency heating device for the purpose of browning an object to be heated, and electrical heating can be performed.

FIG. 1 shows an example of this. Reference numeral 1 denotes a heating chamber, in which a sheathed heater 2 capable of electric heating is provided near an upper plate forming the heating chamber. On the other hand, heating chamber 1 is used to perform high frequency heating on the object to be heated.
A magnetron 5 that generates high frequency waves outside the magnetron, a waveguide 6 that guides the high frequency waves generated by the magnetron 5 to the heating chamber 1, and an opening provided on the upper plate 3 that connects the heating chamber 1 and the waveguide 6. 7 and an opening cover 8 made of a dielectric material to prevent foreign matter such as food particles from entering the waveguide from the heating chamber 1.
is blocking the

Reference numeral 9 denotes a blower motor that cools the magnetron 5, and at the same time the shaft output is transmitted to the deceleration means 10.
A turntable 11 provided at the bottom of the heating chamber is magnetically driven through the heating chamber.

There were several problems with the above configuration. First, regarding heating unevenness,
When heating an object with high frequency, the center of the object is less likely to be heated. A uniform high-frequency mode is generated throughout the heating chamber, and even if a turntable method is used as in the previous example, the heating progresses from the outside of the object to be heated and gradually moves toward the center, which is the same pattern as before.

Next, regarding heating unevenness performance during electrothermal heating, it is thought that in this case as well, it is sufficient that the turntable 11 rotates, and various methods have been devised for this purpose. However, in this case, if the whole thing was roasted in the same way, the time required for this would be very long, and during that time, the water would evaporate rapidly, resulting in the taste of the heated object 4 being very unpleasant.

Therefore, a method was devised to stop the rotation of the turntable 11 during electric heating. The conventional example shown in FIG. 1 is of this type, in which the rotation of a blower motor 9 for cooling the high-frequency generator 5, which is necessary only during high-frequency heating, is transmitted to the turntable 11 via a deceleration means 10. Although not shown, the blower motor is configured to rotate only while high frequency waves are being generated by the circuit.

However, this method conversely causes uneven browning due to the radiant heat of the heater, so when actually cooking with electric heating, the uneven heating performance results in uneven browning due to the shape of the heater. It wasn't. In particular, the pipe diameter of the sheathed heater 2 is smaller than that of the heating chamber 1, and the appearance of the heater-shaped burnt marks on the surface of the object to be heated 4 is not appetizing.

The present invention was devised in such a situation to improve the heating unevenness performance during both electric heating and high frequency heating without degrading the taste of the heated object 4, and the heater is surrounded by a shielding case. The amount of radiant heat from the heater is adjusted by the aperture ratio of the punching, and the position of the opening 7 is set so that it acts as a reflection plate for high frequency waves with the shield case part, so that the electric field in the central part is stronger than in the peripheral part. It was made in a similar manner.

An embodiment of the present invention will be described below based on FIG. 2.

The structure of the present invention is the same as that shown in FIG. 1 except for the structure of the heater 2 portion shown in FIG. 1, and the same numbers are used for explanation purposes. In the present invention, a quartz tube heater 12 is used as the heater 2. This is a direct heating type compared to conventional sheathed heaters, and it is possible to significantly shorten the start-up time. Moreover, the pipe temperature of a quartz tube is compared to that of a sheathed heater, etc.
It can be heated to about 200℃. This made it possible to improve heating efficiency. However, this quartz tube heater 12 does not have a shielding ability against high frequency waves, and if it is installed in the heating chamber 1 as it is, the heater coil will instantly burn out during high frequency heating, making it unusable. In the present invention, the quartz tube heater 12 is surrounded by a shield case 13 to prevent direct application of power to the high frequency heater 12. Specifically, each end of the shield case 13 having a U-shaped cross section is bent outward by 90 degrees to provide a flange, and this flange portion is placed above the heating chamber 1 having the opening 7 that serves as a high-frequency power supply port. They are fixed to the wall portion by spot welding symmetrically with respect to the center line of the left and right sides of the heating chamber 1. Needless to say, the shield case 13 is made of metal. And this case 1
3 has a large number of punched holes, and direct radiant heat from the heater 12 is added from these holes. In addition, the size of each punched hole was set to about 10 mm or less for a plate thickness of 0.6 mm, so that all high frequencies were reflected, just like a flat plate. Another effect of this shield case 13 is that the quartz tube heater 1
A part of the radiant heat from No. 2 directly advances toward the object to be heated, but since the metal portion stores the heat in the shield case 13 itself, it heats the atmosphere in the heating chamber rather than directly roasting the object. Therefore, the object to be heated is heated in a well-balanced manner by both the atmosphere and direct radiation, and by appropriately varying the area of the punched holes with respect to the entire surface area of the shield case 13, the object can be sufficiently browned and tasted. This was achieved through a quick heating time.

In order to further increase this effect, the present invention divides the quartz tube heater 12 into a plurality of parts and arranges them at symmetrical positions with respect to the center of the heating chamber in the left-right direction so as to be equidistant from the object to be heated. It goes without saying that when this electrothermal heating is performed, the circuit is constructed so that the turntable 11 is not rotated, as in the conventional example.

Next, the case of heating using high frequency will be described. In the present invention, the position of the opening 7, which is the connecting part of the heating chamber 1 and the waveguide 6, is provided between the two shield cases 13, and even between the two shield cases 13, as seen from the center of the opening 7. The distance between them is different.

By arranging the opening 7 in this manner, the following effects could be obtained. First of all, creating an opening between the two shield cases means that
As mentioned above, the shield case 13 acts as a reflection plate in terms of high frequencies, and as a result, the high frequency waves that exit the opening are reflected by this reflection plate, that is, the shield case 13, and the amount scattered around the heating chamber is suppressed.
A stronger high frequency wave is irradiated directly below, that is, near the center of the object to be heated. If this opening 7 is provided in the center of the shield case 13, the distance to the opening is the same for both the left and right shield cases, so the electric field created between the shield cases 13 becomes symmetrical, and as a result, the object to be heated 4
Since the high frequency waves irradiated to the object are also symmetrical, the effect is the same whether or not the turntable 11 rotates, and there is no fine-grained heating state of the object to be heated.

On the other hand, if the position of the opening is shifted from the horizontal center of the two shield cases 13 as in the present invention, the electric field created between the shield cases 13 will become bilaterally asymmetrical, and the high frequency irradiated to the heated object 4 will also become horizontally asymmetrical. . Therefore, as the turntable rotates, the high frequency waves alternately pass through areas where they are stronger and areas where they are weaker. As a result, the heating state of the heated object became very fine-grained, and the performance of heating unevenness due to high frequency was significantly improved.

As explained above, according to the present invention, the following effects can be expected.

1. When heating with electric heat, it is possible to burn the heated object with a good balance of atmosphere and radiation.

2. By using a shield case, the electric field near the center of the turntable can be strengthened during high-frequency heating, resulting in more uniform heating.

3 By offsetting the opening from the center, the heating state of the object to be heated could be made more precise.

4 By setting the opposing angle between the aperture, which is the source of high-frequency radiation, and the reflector at approximately 90 degrees, the amount of high-frequency waves returned to the high-frequency generator can be reduced compared to when the reflector is installed parallel to the aperture. It was possible to reduce the amount of heat and improve heating efficiency. Of course, by dividing the shield case into two parts during electric heating, it is possible to achieve uniform heating with significantly less uneven heating during electric heating.

In addition to the above effects, we were also able to obtain the following effects as a ripple effect.

Generally, during electric heating, the temperature of the upper plate reaches 300℃. At this time, due to thermal expansion of the upper plate 3, the vicinity of the center of the upper plate is considerably deformed. When switching to high-frequency heating at this time, this deformation causes a shift in the operating point of the high-frequency generator, resulting in unstable operation such as occurrence of moding.

However, according to the present invention, the effect of the shield case as a flange prevents deformation of the heating chamber, and as a result, the operation during high frequency heating can be made very stable.

Furthermore, if high-frequency heating is performed immediately after the electric heating by the heater is completed, this flange effect may cause the blower motor to shift due to distortion of the upper plate of the heating chamber, malfunction of the deceleration means, or the belt may come off due to distortion of the upper plate of the heating chamber. This prevents gear misalignment and allows the turntable to rotate stably. This effect is particularly noticeable at the start of rotation, and can prevent the belt from coming off.

Additionally, the opening cover provided over the opening is made of a dielectric material to allow only high-frequency waves to pass through, and if food particles, etc. adhere to this part, this will also cause the operation of the high-frequency generator to become unstable. shall be. If the position of the opening is shifted from the center as in the present invention, food waste and oil smoke will occur in the center where the probability of occurrence is high (the probability is that the object to be heated will be placed in the center), and furthermore, if there is no wind, The heated oil smoke rises directly to the top of the eyelashes)
By avoiding this, dirt was eliminated, and as a result, this also made it possible to stabilize the operation of the high frequency generator. Furthermore, it is clear as mentioned above that by shifting the center of the opening between the shield cases, if the heating chamber is shifted not only in the left-right direction but also in the front-back direction, the uneven heating performance of the heated object can be further improved. It is.

[Brief explanation of the drawing]

FIG. 1 is a lateral sectional view of a heating chamber showing a conventional example, and FIG. 2 is a lateral sectional view of a heating chamber of a high-frequency heating device equipped with a heater showing an embodiment of the present invention. 1... Heating chamber, 2... Sheathed heater, 5... High frequency generator (magnetron), 6... Waveguide, 7
...opening, 8...opening cover, 13...shield case.

Claims (1)

[Scope of utility model registration request] In order to enable electric heating in the heating chamber, multiple quartz tube heaters are installed symmetrically around the horizontal center of the heating chamber near the top plate of the heating chamber, and these quartz tube heaters are directly irradiated with high frequency waves. a pair of U-shaped shield cases that are symmetrical and fixed to the upper plate of the heating chamber, a high frequency generator that enables high frequency heating, and a high frequency generator that uses the high frequency waves emitted by the high frequency generator to heat the heating chamber. A waveguide leading to the heating chamber, an opening provided in the upper plate portion of the heating chamber between the pair of shield cases to connect the waveguide and the heating chamber, and an opening provided on the heating chamber surface of this opening. It is equipped with an opening cover made of an inductor, and a turntable that is provided at the bottom of the heating chamber and is driven by a blower motor for cooling the high-frequency generator via a deceleration means and rotates only during high-frequency heating, and the turntable rotates only during high-frequency heating. A high-frequency heating device equipped with a heater configured to be located between a pair of shield cases and offset from a center line in the left-right direction.