JPH05187644A - Heat cooking appliance - Google Patents

Abstract

PURPOSE:To obtain a high deodorization efficiency by suppressing occurrence of an intermediate product of high stimulus by preventing incomplete decomposition of bad odor by a deodorizing catalyst. CONSTITUTION:A cooking heater 10 provided in a ceiling part of a cooking chamber 2 is constructed by providing a heater wire inside a tubular body of heat resistance. A deodorizing catalyst layer is provided in a part except the vicinity of the opposite end parts on the peripheral surface of the tubular body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to cooking food by heating.
For example, the present invention relates to a heating and cooking device such as a household oven grill range, and particularly to its deodorizing function.

[0002]

2. Description of the Related Art Generally, in an oven grill range,
Odor and smoke are generated during cooking. In recent houses, the airtightness is good, and the odor and smoke generated during such cooking not only make the user uncomfortable, but sometimes the odor sticks to the walls and furniture of the room. As a method of removing this odor, the odor was forced out of the exhaust duct by the fan for the oven grill range, and fresh air was taken into the kitchen (cooking room) to remove the odor inside the kitchen. There is a way. The odor is oxidatively decomposed by the heated deodorization catalyst placed in the exhaust duct, and the deodorized odor is released to the outside. The odor sources are gas and mist components generated from the cooked food placed inside the cooking cabinet and the oil and meat juice adhering to the inner wall, but the odor concentration decreases exponentially by sending in fresh air. Do it. As the deodorizing catalyst, there are a catalyst in which a precious metal catalyst such as platinum or palladium is supported on a racemic honeycomb or a silica paper corrugate, or a catalyst supported on a metal foam.

The odor which is a problem during cooking is
In addition to the odor generated during cooking, there is an odor remaining in the refrigerator after cooking. This is a small amount but high in concentration,
If the odor remains after cooking, the odor of another food may be attached to the food during the next cooking, which gives the user an unpleasant feeling.

Conventionally, during grill cooking, the above mechanism is used to deodorize, and cooking is performed by radiant heating of infrared rays from the upper surface of the food by a heater on the ceiling. In the case of oven cooking, the hot air circulation fan on the back of the apparatus or the like circulates the air warmed by the heater through the inside of the oven to uniformly heat the inside of the oven for cooking. Therefore, it is necessary to quickly keep the temperature inside the oven constant during cooking in the oven. For this reason, in the case of oven cooking, send cold outside air into the refrigerator like the deodorizing method used when grilling.
It is not desirable to send warm air in the refrigerator to the exhaust duct for deodorization because the inside of the refrigerator will cool and uniform heating will not be possible. Therefore, in oven cooking, it is generally difficult to activate the deodorizing function by the catalyst placed in such an exhaust duct. Further, in this deodorizing method, the odor remaining in the refrigerator is diluted and removed by the air taken in from the outside, but in the oven cooking in which the outside air cannot be taken in this way, depending on this method, The odor remaining in the chamber could not be removed.

However, there are cases where meat and fish are used even when cooking in an oven, and it is also preferable to be deodorized. Therefore, it may be possible to provide a deodorizing catalyst in the refrigerator. This method is generally used in a glass or ceramic tube, such as a heat-resistant glass, which is attached to the ceiling.
Enclose a heater wire such as a Cr wire as a cooking heater,
The surface of the heater tube is coated with alumina or the like, and a deodorizing catalyst such as a noble metal is attached thereto. Deodorization is performed by contacting the deodorizing catalyst on the surface of the heater with the air containing the odor.

[0006]

By the way, Fe--Cr
A heater wire such as a wire or a Ni-Cr wire may be cut if the watt density is high. Therefore, generally, the heater wire is spirally enclosed in a heat-resistant glass or ceramic tube, and both ends are Has a current-introducing terminal for taking in current from the outside. In many cases, the contact point between the current introduction terminal and this heater wire is obtained by linearly extending the heater wire and welding the metal portion of the terminal thereto. For this reason, when the entire heater tube is viewed, the temperature is naturally low at both ends because the watt density of the heater wire is low. Also, since both ends of the heater tube are heated by heat conduction from the central portion, the heat capacity increases when the catalyst is attached, and the temperature drop at both ends is larger than that of a normal heater tube. ..

Here, the oxidation catalyst needs to be heated to an activation temperature in order to decompose odorous substances. In general,
Since the temperature of the heater tube is 500 ° C. or higher, palladium is a catalyst that can withstand this temperature, although it depends on the type of odorous substance that is oxidatively decomposed. In order to fully decompose odor with this palladium oxidation catalyst, the catalyst temperature needs to be about 400 ° C. At temperatures lower than this, not only the processing speed of the catalyst becomes slow, but also intermediate products are generated when processing complicated materials. The intermediate products are generally oxides such as aldehydes in many cases, but they may have an irritating strong odor different from the initial odor substance. For this reason, it is not preferable that a part of the catalyst, such as both end portions of the heater tube, has a low temperature because it increases the amount of odorous substances that are highly irritating.

[0008] Therefore, an object of the present invention is to provide a heating and cooking apparatus which prevents incomplete decomposition of odor by a deodorizing catalyst to suppress generation of highly stimulating intermediate products and has high deodorizing efficiency.

[0009]

In order to solve the above-mentioned problems, the present invention provides a cooking heater installed on the ceiling of a cooking chamber to heat a food, and a heater wire is internally provided in a heat-resistant tubular body. The gist is that a deodorizing catalyst layer is provided on the peripheral surface of the tubular body except for the vicinity of both ends.

[0010]

With the above structure, when the cooking heater installed on the ceiling of the cooking chamber is energized during heating and cooking, the deodorizing catalyst layer provided on the peripheral surface of the tubular body except for both ends is simultaneously heated. Is activated. The air in the cooking chamber containing the odor is agitated by the natural convection of warm air, contacts the activated deodorizing catalyst layer, and is efficiently decomposed and deodorized.
At this time, since the deodorizing catalyst layer is not provided in the low temperature portion near both ends on the peripheral surface of the tubular body, incomplete decomposition of odor is prevented and generation of highly stimulating intermediate product is suppressed. As a result, high deodorization efficiency can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

This embodiment is applied to an oven grill range.

In FIGS. 1 to 3, 1 is a main body cabinet, 2 is an oven inner box forming a cooking chamber, 3 is a door of the cooking chamber, 4 is a glass barrier, and 5 is a handle. 6 is a square plate, 7 is food to be cooked, and a catalyst-supporting cooking heater 10 for heating a cooking product, which has a deodorizing catalyst layer supported on the surface thereof, is installed in the ceiling portion of the cooking chamber 2. .. On the back side (upper side) of the catalyst-supporting cooking heater 10, there is formed a reflection plate 8 for reflecting the radiant heat emitted from the heater 10 to the lower cooking product 7, and the exhaust duct 16 is provided at the reflection plate 8 portion. An exhaust port 9 leading to the is formed. Also,
A sirocco fan 17, a motor 18 for driving a sirocco fan, and an oven heater 19 that circulate hot air in the cooking chamber 2 (inside the chamber) when the oven function is used are arranged on the rear side of the cooking chamber. .. Reference numeral 21 is a blowout hole for blowing hot air into the inside of the refrigerator, and 22 is a suction hole for taking in the inside air into the heater chamber. Reference numeral 23 denotes an air-blowing fan, which blows air from the intake duct 24 into the refrigerator. The air supply fan 23 also has a function of cooling the magnetron 25 at the inlet of the intake duct 24. The exhaust port 9 is made of a metal mesh or a punching metal that does not leak microwaves to the outside.

FIG. 4 is a partially cutaway enlarged view of the structure of the catalyst-supporting cooking heater 10. Reference numeral 11 is a heat-resistant glass-ceramic tube having infrared transparency as a tubular body, and has a thickness of about 1 mm. Glass ceramic tube 11
A heater wire 12 made of a spiral Fe—Cr wire is enclosed in the box. The heating value of the heater wire 12 is 80
It is 0W. This glass ceramic tube 11 and heater wire 1
A heater tube is constituted by 2 and. Then, on the outer peripheral surface of the glass ceramic tube 11 except for 8 mm at both ends, a deodorizing catalyst layer 13 in which palladium is supported on an alumina base and 30 mg / cm ^{2 is} attached is formed. The deodorizing catalyst layer 13 also has infrared transparency. Reference numeral 14 is a fixed plate connected to the heater wire 12, and 15 is an insulator for supporting the heater wire 12 and the fixed plate 14 and maintaining insulation.

Next, the operation of the heating and cooking device configured as described above will be described.

FIG. 5 shows the temperature of the deodorizing catalyst 13 during cooking of the grill ((a) in the figure), the energization amount of the heater 10 ((b) in the figure), and the energization rate of the fan 17 ((c) in the figure). , The acetaldehyde deodorization efficiency ((d) of the same figure) with time is shown. The catalyst-carrying heater 10 shown in FIG. 4 is used. Simultaneously with the start of cooking, a catalyst-supporting cooking heater 10
The temperature of the surface of the central portion of the heater 10 reaches 600 ° C. in about 2 minutes, and the temperature of the deodorizing catalyst 13 also reaches about 610 ° C. in the central portion. When the temperature of both ends of the heater 10 not coated with the deodorizing catalyst is measured here, it is 460
It is only ℃. In the central portion where the deodorizing catalyst 13 is attached, the food is sufficiently activated by the time when the food is heated and the odor is generated. Next, the motor 18 is driven and the fan 17 starts to rotate, and the air in the refrigerator repeats the flow of returning to the inside of the refrigerator through the suction hole 22 as shown by the arrow W in FIG. During this time, the odor circulates in the refrigerator at the same time as the warm air, and comes into contact with the deodorizing catalyst 13 to be oxidatively decomposed.

During cooking, the heater 10 is supplied with 800 W of electric power, and the catalyst temperature is about 630 ° C. in the central portion of the heater tube.
Reach Then, two minutes later, the motor 18 is energized and the fan 17 rotates. The catalyst-supporting cooking heater 10 repeats ON / OFF energization so as to keep the internal temperature at 260 ° C. At this time, the catalyst temperature is about 6 at the center of the heater tube.
Maintained at 30 ° C. Here, acetaldehyde is one of the components of cooking odor and is an odor generated when relatively large amounts of foods are heated and cooked. The deodorizing efficiency is represented by the amount of deodorized air in the air contacting the deodorizing catalyst 13,
At the same time that the deodorizing catalyst 13 reaches the activation temperature,
As indicated by the characteristic line a in (d), it exceeded 90%, and this value was maintained thereafter, indicating that the odor in the refrigerator was almost completely decomposed. After about 15 minutes, the cooking was completed, and the surface of the food 7 was uniformly browned, and it did not seem that it was dry. Almost no cooking residual odor remained in the refrigerator.

Next, as a comparative example, the same cooking was performed on the heater tube in which the entire outer peripheral surface of the glass ceramic tube 11 was coated with the deodorizing catalyst. As a result, the decomposition performance of acetaldehyde, which is an odorous substance that is a strong stimulant and is an intermediate product of odorous substances generated during cooking, is about 80% as shown by the characteristic line b in FIG. It turns out that no major disassembly has taken place.

In order to understand this easily, the temperature distribution and the decomposition performance of the deodorizing catalyst 13 on the heater tube were measured. First, FIG. 6 shows the results of measuring the temperature distribution of each portion of the heater tube catalyst in the longitudinal direction. When the deodorizing catalyst is not attached, both ends of the deodorizing catalyst are 5 at steady state.
When the temperature is higher than 00 ° C (broken line in Fig. 6 (c)), the temperature drop is small, but when the deodorizing catalyst is attached, the heat capacity of the deodorizing catalyst causes the both ends of the deodorizing catalyst to be difficult to warm up, and It is found that the temperature is constantly above 610 ° C. as described above, but both end portions where the heater linear density is low are around 450 ° C. In particular, immediately after the heater is energized, the central portion rises quickly, but, for example, one minute after the energization, both end portions that rise by heat conduction are expected to be 300 ° C. or lower and the deodorizing performance is low.

The results of measuring the deodorizing performance of the catalyst are shown in FIG. The measuring method was a flow method as shown in FIG. In this method, the heater tube 11 is passed through a SUS closed container 26, and triethylamine having a constant concentration (100 ppm) is passed from one side thereof at a constant speed, and the concentration at the outlet at this time is analyzed. As a result, the heater with a deodorizing catalyst can decompose approximately 90% or more of the original odor substance, triethylamine, at 400 ° C. or higher (characteristic line a).
At this time, acetaldehyde is produced at the same time, and it can be seen that complete decomposition is not achieved (characteristic line b). It can be seen that temperatures above 500 ° C. are required for complete decomposition. Further, it can be seen that the base glass tube has poor reactivity and triethylamine cannot be decomposed, but at the same time, generation of highly stimulating acetaldehyde is suppressed (characteristic line c). That is, in order to completely decompose the odorous substance, in the case of this embodiment, 50
It is necessary to have a temperature of 0 ° C. or higher, and it can be seen that odorous substances are generated at lower temperatures. That is, in the catalyst-supporting cooking heater 10 shown in the present embodiment, it is found that the portion having the deodorizing catalyst 13 is at the activation temperature of 500 ° C. or higher after 2 minutes of energization, and thus has sufficient deodorizing ability. ..

In this embodiment, the portion not attached with the deodorizing catalyst is 8 mm, but this may be changed according to the performance of the deodorizing catalyst and the capacity of the heater tube. As long as the upper catalyst temperature reaches a temperature at which the deodorizing catalyst is activated to decompose the odorous substance sufficiently and does not produce an intermediate product, the deodorizing catalyst layer may be provided, and on the contrary, deodorizing ability is required. Sometimes it is not necessary to attach a deodorizing catalyst to a position where the temperature does not rise sufficiently.

Further, although the present embodiment has been described in the case of being applied to an oven grill range, the present invention can be applied to other heating cookers such as an electric oven and an oven toaster.

[0023]

As described above, according to the present invention,
Since the deodorizing catalyst is not attached to the low temperature area near both ends of the peripheral surface of the tubular body containing the heater wire, it is possible to prevent incomplete decomposition of odors and generate highly stimulating intermediate products. Is suppressed, and high deodorization efficiency can be obtained as a whole.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an embodiment of a heating and cooking device according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is an enlarged view showing a partially cutaway view of the catalyst-supporting cooking heater in FIG.

FIG. 5 is a diagram showing changes over time in catalyst temperature, heater energization amount, fan energization ratio, and deodorization efficiency in the case of grill cooking in the present embodiment.

FIG. 6 is a diagram for explaining the surface temperature distribution of the catalyst-supporting cooking heater in the present embodiment.

FIG. 7 is a diagram showing the results of performance evaluation of the deodorizing catalyst in this example.

FIG. 8 is a cross-sectional view showing an apparatus used for evaluation of deodorizing performance in FIG.

[Explanation of symbols]

 2 Cooking room 7 Food (stuff to be cooked) 10 Heater for catalyst-supported cooking 11 Glass ceramic tube (tubular body) 12 Heater wire 13 Deodorizing catalyst layer

Claims (1)

[Claims] 1. A cooking heater installed on a ceiling of a cooking chamber to heat a food product is constructed by internally incorporating a heater wire into a heat-resistant tubular body, and excluding the vicinity of both ends on the peripheral surface of the tubular body. A heating and cooking device characterized in that a deodorizing catalyst layer is provided on a part thereof.