JP2518817B2 - Fire detection device for fired objects in oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a device for detecting a fire of an object to be fired in an oven.

(B) Conventional technology Conventionally, in order to detect the fire flow inside an object to be baked (baked confectionery bread, etc.) that is being baked in an oven, it is judged from the color of the surface of the object to be baked or a gold skewer is pierced. Then, methods such as confirming the internal fire passage are used.

(C) Problems to be Solved by the Invention However, since the oven door is opened and closed for this confirmation work, the temperature inside the oven is lowered, which adversely affects the material to be fired and is inefficient. Especially in an oven that has recently been developed that can efficiently heat the inside of the object to be fired by using far infrared rays, the inside of the oven passes through very rapidly, and the inside of the object is burned due to the burning color on the surface of the object to be fired. Judgment based on the conventional experience of confirming the street of fire is no longer valid.

(D) Means for Solving the Problems The present invention is an oven in which a far-infrared radiator is arranged and the object to be fired is heated by the radiator. A means for measuring, a means for comparing the same temperature and a preset firing temperature, a means for calculating a differential value with respect to time at the same temperature, and a means for comparing the differential value and a preset temperature increase rate. Is provided, and when the differential value becomes larger than the temperature increase rate, it is configured to output a control signal for stopping the heating of the far-infrared radiator, the fire of the object to be fired in the oven. The present invention relates to a street detection device.

(E) Action / Effect In the present invention, it was discovered that the temperature of the far-infrared radiator that is heating the inside of the object to be fired rapidly rises almost at the same time when the inside of the fire is completed. By capturing the rise by comparing the time derivative of the same temperature with a preset rate of temperature rise, it is possible to reliably detect the fire passage of the object to be fired from the outside of the oven. A control signal is output to stop the heating of the product, or an alarm is issued to notify that effect to prevent deterioration of quality due to overfiring, save energy consumption, and improve work efficiency. Is.

The discovery of the rapid increase in the temperature of the far-infrared radiator upon completion of the above-mentioned burning was obtained as a result of the experiment, but is considered to be due to the following reasons.

That is, in the material to be fired before the fire, there was water that could move freely between the starch particles of the raw material, and this water resonated with far infrared rays and absorbed the energy on the same line. At the same time, it is considered that the movement is restrained by being incorporated into the starch particles, and in combination with the pregelatinization of starch, the energy absorption from the far-infrared radiator is reduced and the temperature of the radiator is rapidly increased. To be

(F) Embodiment An embodiment of the present invention will be described with reference to the drawings.
(A) shows an oven for baking confectionery and breads. The oven (1) is provided on the right side and the display / control section (2) is provided on the left side to configure the oven (A).

The furnace (1) has a furnace body outer wall (3) having a substantially rectangular parallelepiped space for accommodating the object to be fired therein, and an opening for loading and unloading the object to be fired in front of the outer wall (3) of the furnace body. A door body (4) that closes the door and is openable and closable. The outer wall (3) and the door body (4) are formed by enclosing the inner and outer peripheral surfaces of a heat insulating material with a metal plate or the like. 4) is provided with a heat-resistant glass window (5) for observing the inside of the furnace, and is configured so that the upper part of the door pivots forward and backward around a pivot (6) horizontally installed to open and close the opening. ing.

The inner bottom surface (9) of the furnace (1) is located below the furnace (1).
A thick iron plate (11) for laying the object to be fired (10) at a predetermined distance is horizontally laid, and between the inner bottom surface (9) of the furnace and the iron plate (11). A lower heat source (13) including an electric resistance heating element such as a chromium wire is provided.

A far-infrared radiation plate (16) as a far-infrared radiation body (R) is horizontally arranged above the furnace (1), and a predetermined interval is provided below the far-infrared radiation plate (16). A heating element (17) which holds and holds an electric resistance heating element is arranged.

The far-infrared radiation plate (16) is a far-infrared ray such as a metal oxide such as silicon oxide, oxynitride, aluminum oxide, sodium oxide, and titanium oxide, and a rare earth oxide on the lower surface of a metal substrate (20) made of an aluminum alloy. Radiant material particles are coated with a sodium silicate or the like as a binder using a spraying method to form a far-infrared radiation surface (21), and the radiation surface is heated by near-infrared rays and convection from the heat source irradiated on the radiation surface ( 21) is heated and far infrared rays are emitted from the same surface (21).

In particular, since the far infrared radiation plate (16) is made of an aluminum alloy having a high heat transfer coefficient for the metal substrate (20), the temperature distribution of the radiation plate (16) is made uniform, and each part in the furnace (1) is It emits far-infrared rays of uniform wavelength and intensity.

For the coating of the far-infrared radiation material, a method such as enameling can be used, and the point is that the same material is attached to the surface of the metal substrate so as to withstand high temperature.
However, in order to promote the scattering of radiated far infrared rays and make the far infrared intensity in the furnace uniform, it is desirable that the radiating surface is a rough surface. From this point, in the present embodiment, the radiating surface is a rough surface. It employs a thermal spraying method that finishes with.

The far-infrared ray used here excites the rotational vibration of the dough raw material molecules to heat the bread dough itself, and the longer the wavelength, the less the midway attenuation and the greater the reach distance to the inside of the dough. is there.

And this wavelength and intensity can be adjusted by controlling the radiation surface temperature of the radiation plate.

Particularly, in the present invention, a temperature sensor (S) for detecting the temperature of the far-infrared radiation plate (16) is arranged in the center of the back surface of the far-infrared radiation plate (16), and a signal from the sensor (S) Four
It is input to the control device (C) shown in the block diagram of the figure.

The control device (C) includes an A / D converter (7), a microcomputer (8), a memory (12), a clock (18), an amplifier (19) and a power relay (14), and the microcomputer (8) Is a function of differentiating the temperature (T) of the far-infrared radiation plate (16) detected by the sensor (S) with respect to time, and the temperature rise rate (dT / dt) previously input to the memory (12) ( K) and the same temperature (T) and the firing temperature (T) previously input to the memory (12).
It has a function to compare with 1), and the analog signal from the temperature sensor (S) is A / D converted and input to the microcomputer (8), and the same computer (8) of FIG. The process shown in the flowchart is performed.

This flowchart will be described below according to the progress of firing.

That is, the relationship between the temperature (T) of the far-infrared radiation plate (16) and the time (t) is as shown in FIG. 6, in which the object to be fired (10) is inserted into the oven (A) which has reached the preheating temperature. Then, when heating is started, the temperature (T) once lowered due to opening and closing of the door body (4) rises rapidly and reaches the firing temperature (T1). The temperature (T) of the far-infrared radiation plate (16) gradually rises as the temperature inside the article to be fired (10) rises, and at the same time when the inside of the article to be fired (10) completely passes through the same temperature ( T)
Rises sharply. Until this temperature rises rapidly, the temperature sensor (S) continues to input the temperature (T) of the far-infrared radiation plate (16) into the microcomputer (8). When (T) reaches the firing temperature (T1) previously input to the memory (12), calculation of the differential (dT / dt) with respect to time of the temperature (T) is started. Then, when the temperature (T) rapidly increases, that is, the differential value (dT / dt) becomes larger than the temperature increase rate (K) input in advance, that is, the temperature of the far infrared radiation plate (16). When (T) is higher than the firing temperature (T1) and the differential value (dT / dt) of the same temperature (T) with respect to time becomes larger than the temperature increase rate (K), the heating element (17). The power is turned off and the lamp or buzzer provided in the display / control unit (2) is turned on and blown to notify the operator of this fact.

As described above, the fire passage inside the object to be fired (10) is detected by the rapid rise in the temperature (T) of the far infrared radiation plate (16), and the door body (4) is opened and closed. Without
Can be reliably detected from outside the oven (A),
It is possible to surely pass through the fire, not to overfire, and to easily fire a uniformly fired product.

[Brief description of drawings]

FIG. 1 is an overall front view of an oven having a fire detection device for an object to be fired according to the present invention. FIG. 2 is a sectional view taken along the line II of FIG. 1. FIG. 3 is a partial sectional view of a far-infrared radiation plate. Fig. 4 is a block diagram of the control device. Fig. 5 is a flow chart. Fig. 6 is a graph showing the relationship between the temperature of the far infrared radiation plate and time (A): oven (K): temperature rise rate (R). : Far infrared radiator (T): Temperature (T1): Firing temperature (dT / dt): Differential value (10): Firing object

Claims (1)

(57) [Claims] 1. A far-infrared radiator (R) is provided inside,
In the oven (A) configured to heat the object to be fired (10) by the radiator (R), means for measuring the temperature (T) of the far infrared radiator (R), and the same temperature (T) A means for comparing with a preset firing temperature (T1), a means for calculating a differential value (dT / dt) of the same temperature (T) with respect to time, and a differential value (dT / dt) and a preset temperature rise A means for comparing with the rate (K) is provided to stop the heating of the far infrared radiator (R) when the differential value (dT / dt) becomes larger than the temperature increase rate (K). A device for detecting the fire flow of an object to be fired in an oven, which is configured to output the control signal of.