JPH0434890A - High frequency heater - Google Patents

Abstract

PURPOSE:To properly self-control the heating time of a material to be heated regardless of a heating starting mode, or a continuously using mode in use by calculating and mutually comparing the variation grades of a temperature function determined by the temperature of the air flowing in and out of a heating chamber so as to control high frequency power. CONSTITUTION:A surface temperature T1 and an exhaust temperature T2 of a high frequency oscillating tube 4 are calculated by a high frequency oscillating tube surface temperature sensor 15 and an exhaust temperature sensor 12 at a certain time interval after heating is started. If a variation grade C of a temperature function B to be determined is smaller than a preset value, high frequency power is increased, and if a variation grade Cn of the temperature function B at a certain sampling time is greater than the grade Cn-1 of the previous sampling time by one timing, an optimal heating time t2 from a time t1 when this variation grade Cng is reached, after the start of the heating is calculated, and after the time t2 passes by, the supply of high frequency power is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-frequency heating device, and particularly to a high-frequency heating device that automatically controls its optimum heating time.

[Prior Art] FIG. 6 is a schematic diagram of a conventional high-frequency heating device disclosed in Japanese Patent Application Laid-Open No. 53-50545. In the figure,
(1) is the heating chamber, (2) is the saucer placed in the heating chamber, (
3) is the object to be heated placed on the saucer (2), (4) is a high frequency oscillation tube that supplies high frequency waves into the heating chamber (1), (5) is the door of the heating chamber (1), and (6) is the (7) is the heating room ventilation fan, (8) is the intake port of the high-frequency heating device, (
8a) is the exhaust port of the high-frequency heating device, and (9) is the heating chamber (1
), (10) is the exhaust port of heating chamber (1), and (11) is the exhaust port of heating chamber (1).
) is the intake temperature sensor, (12) is the exhaust temperature sensor,
(13) is a control device for the high frequency heating device.

Next, this heating operation will be explained. High frequency oscillator tube (
4) is driven by the power supply device (6) to oscillate and heat the object to be heated (3) placed on the saucer (2) in the heating chamber (1). During the heating period, the heating chamber ventilation fan (7) operates, and as a result, the outside air entering from the intake port (8) of the high-frequency heating device is transferred from the air intake port (9) of the heating chamber (1) to the heating chamber (
1) enters the interior, passes around the object to be heated (3), flows out of the heating chamber (1) from the exhaust port (10) of the heating chamber (1), and further passes through the ventilation fan (7). and flows out from the exhaust port (8a) of the high-frequency heating device. In this case, the heating chamber (1
) The intake temperature sensor (11
), the temperature of the air discharged from the heating chamber (1) is detected by the exhaust temperature sensor (12), and the temperature difference between the two is determined to detect the increase in exhaust temperature during the heating period. next,
This detection signal is applied to the control device (13), and when the exhaust temperature rise value reaches a preset value, the control device (13)
13) cuts off the output of the power supply device (6) and stops the oscillation of the high frequency oscillation tube (4).

[Problems to be Solved by the Invention] However, in the conventional high-frequency heating device having the above configuration,
If there is a temperature difference between intake air and exhaust air at the start of heating, or if a high frequency heating device is used continuously, a large control error will occur.

For example, if the same object is heated three times in a row, the exhaust gas temperature at the start of heating will gradually become higher each time the heating is repeated.

This is because the temperature of the top, wall, bottom, etc. of the saucer (2) and heating chamber (1) has increased due to the previous heating, and the temperature of the object to be heated (3) has increased.
) is trapped inside the heating chamber (1). On the other hand, the intake air temperature remains almost constant even when used continuously. Therefore, each time the device is used continuously, the temperature difference between the intake air and exhaust gas at the start of heating increases, and as a result, the temperature difference between the intake air and exhaust gas at the end of each heating operation gradually increases. Therefore, if you set the heating to stop when the temperature difference between the intake and exhaust reaches a preset value, the second heating will turn off early, and the third heating will cause the intake and exhaust to change even before heating. There have been cases where the temperature difference has become larger than a preset constant value and the heating has stopped and the workpiece has not been heated.

The present invention has been made to solve the above-mentioned problems, and even when there is a temperature difference between intake air and exhaust air at the start of heating, or when a high-frequency heating device is used continuously, the heating time of the object to be heated is The purpose of this study is to obtain a high-frequency heating device that can appropriately control automatically.

[Means for Solving the Problems] The high-frequency heating device according to the present invention heats the object by supplying high-frequency power into the heating chamber housing the object to be heated. or a first temperature detection means for detecting the temperature T1 of a portion corresponding to this, and a second temperature detection means for detecting the temperature T2 of the air inside the heating chamber or the air flowing out from the heating chamber, at the same time. Temperatures T and T2 at the same time are sampled at predetermined intervals, and the temperature function B B-axT2-71 determined by the unique constant a that is the ratio of the temperature T at the same time to the temperature T1 and the temperatures T1 and T2 at the same time is calculated. Calculate the change gradient C, and if this change gradient C is smaller than the preset value, increase the high frequency power,
The change gradient C at a certain sampling time of temperature function B is the change gradient C at the time of sampling one time before this sampling time.
When the temperature becomes larger than n- again, calculate the optimum heating time t2 of the workpiece from the time t1 from the start of heating until the time when the change gradient C is reached, and stop the supply of high-frequency power after the heating time t2 has elapsed. A control means is provided.

[Function] The high-frequency heating device according to the present invention uses the first temperature detection means and the second temperature means to detect the temperature T1 of the air flowing into the heating chamber or a corresponding portion thereof at the same time, and the temperature of the air or air inside the heating chamber at the same time. The temperature T2 of the air flowing out from the heating chamber is sampled at predetermined intervals.

Then, the control means controls these sampled temperatures T
Calculate the change gradient position C of the temperature function B determined from do.

Further, the control means compares a change gradient C at a certain sampling time of the temperature function B with a change gradient C at a sampling time immediately before this sampling time, and determines that the change gradient C is larger than the change gradient C n n -1, the optimum heating time t2 of the object to be heated from the time t1 from the start of heating until the time when the change gradient Cn is reached.
is calculated, and high frequency power is supplied via the power supply device to perform heating until this time t2 has elapsed.

[Example] FIG. 1 is a schematic configuration diagram of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the first temperature detection means according to the present invention, and FIG. FIG. 2 is a configuration diagram showing an embodiment of a second temperature detection means according to the present invention. In the figure, the same reference numerals as in FIG. 6 indicate the same or corresponding parts. (13a)
is a control device that performs a heating control operation according to the present invention, (14)
(15) is a high frequency oscillation tube surface temperature sensor that detects the surface temperature of the high frequency oscillation tube (4) corresponding to the air flowing into the heating chamber (1), (16) is the electric chamber (14). It is a cooling fan. In the above embodiment, the high frequency oscillation tube (
4), etc., force outside air into the electrical room (14), and part of this air flows into the heating room (1) from the air intake port (9) of the heating room (1). I'm letting you do it. Also,
(17) is a DC power source for driving the temperature sensors (12) and (15), and (18) and (19) are load resistances.

Here, the temperature function will be explained.

Temperature T2 of the air in the heating chamber (1) or the air flowing out from the heating chamber (1) after a certain time in seconds has elapsed from the start of heating
(t) is the surface temperature T1(t) of the high frequency oscillation tube (4), which corresponds to the temperature of the air flowing into the heating chamber (1), and the heated target on the saucer (2) in the heating chamber (1). Temperature increase △T of the exhaust port (10) of the heating chamber (1) due to the temperature rise of the object (3)
It can be expressed as a function of (t).

'r2(t)-('r, (t)/at ten(b+△T(t)l)...(1) Here, a is the air in the heating chamber (1) or the heating chamber ( The ratio of the temperature T2 of the air flowing out from 1) to the temperature T1 of the air flowing into the heating chamber (1) or a corresponding portion thereof at the same time,
Size of heating chamber (1), intake port (9) of heating chamber (1)
Although it varies depending on the shape of the exhaust port (lO) of the heating chamber (1), the responsiveness of temperature detection at the same time to the actual intake and exhaust temperatures, etc., it can be easily determined by experiment.

Moreover, b varies depending on the temperatures T and T2 at the start of heating, and (1) the temperature difference, and is not easily determined because it is a function that changes with time. Therefore, by transforming equation (1), a (△T (t) + b) = a X T 2
(t)-'r, (t)... (2) and further, let B be the left side of equation (2), then B = a
x T2 (t) ”1 (t) ・・・・・・(
3), and this will be called the temperature function. FIG. 4 shows the contact time t. High frequency oscillation tube surface temperature sensor (1
5) The temperature T1 measured in step 5) and the exhaust temperature sensor (12)
It is a graph showing temperature function B calculated from temperature T2 measured in .

According to FIG. 4, as heating begins, the temperature function B approaches a certain constant value, and its change gradient C becomes smaller.

However, the workpiece (3) on the saucer (2) in the heating chamber (1)
As the temperature rises and begins to affect the exhaust temperature sensor (12), the change gradient C becomes large again. This is true even if the temperatures of the intake air and exhaust air are different before heating, or even when they are heated continuously. However, if the change gradient C of the temperature function B is smaller than the predetermined set value, the object to be heated (3) is difficult to heat or the temperature thereof is sufficiently low. The effect is less likely to appear on the exhaust temperature sensor (12).

Next, the heating operation of the high-frequency heating apparatus of the above embodiment equipped with the control device (1(a)) utilizing the above will be explained.

Figure 5 shows heating control in the high frequency heating device of Figure 1.
It is a flowchart.

First, when heating is started, in step S1 - fixed time t
. At the time of the nth (n is a positive integer including 0) sampling every second (n X to seconds), the high frequency oscillation tube surface temperature sensor (15) and the exhaust temperature sensor (12
) detects the respective temperature detection voltages V1n and v2n.

Next, in step S2, the temperature detection voltages V1n and v
The surface temperature T1n of the high frequency oscillation tube (4) and the exhaust temperature T2n are calculated from 2n.

Next, in step S3, the temperature function B at this nth
is calculated by B -aXT2n-Tln.

Next, in step S4, the change gradient C of the temperature function B is
C-(B-B)/lo by n
Calculate n n n-1. n here is an integer greater than or equal to 1, and Bn-1 is ((n-1) x t at the n-1st sampling time.

It is a temperature function when

Next, in step S5, it is determined whether the change gradient C calculated this time is larger than the change gradient Cn-1 calculated one time before. If it is larger, the process goes to step S6; if it is smaller, the process returns to step S1. .

Next, in step S6, the time t1 from the start of heating to this nth sampling time is measured □.

Next, in step S7, the time t1 measured in step S6 is
From this, the remaining heating time t2 until the heated object (3) in the heating chamber (1) reaches the appropriate temperature is calculated using the following formula.

・ ・ ・ ・ (4) Here, d = e + ta is the size of the heating chamber (1) of the high-frequency heating device and the intake port (9) of the heating chamber (1).
), is a unique constant determined by the shape of the exhaust port (10) of the heating chamber (1), etc., and is determined by experiment.

Next, in step S8, time t2 is counted down,
When it becomes 0, it acts on the power supply device (6) to stop the supply of high frequency power.

Also, although not shown in the flowchart, step S4
If the gradient of change C calculated is smaller than the preset value, the power supply device (6) is operated to increase the high frequency power and continue heating.

Note that in the above embodiment, the predetermined time interval t. every temperature T
Although sampling of temperatures T1 and T2 was performed, changes in temperature T2 may be captured and sampling of temperatures T1 and T2 may be performed at predetermined temperature intervals.

Further, in the above embodiment, the surface temperature of the high frequency oscillation tube (4) is detected, but the air itself flowing into the heating chamber (1) may also be detected.

Further, in the above embodiment, the temperature of the air discharged from the heating chamber (1) is detected, but the temperature of the air inside the heating chamber (1) may also be detected. In this case, the temperature sensor is used by shielding it from high frequencies with a radio wave shield.

In addition, in the case of a mechanism that simply forces outside air into the heating chamber (1) or a mechanism that forces the air inside the heating chamber (1) to flow out, the temperature T and It is also possible to detect T2.

According to the above embodiment, even if there is a temperature difference between the intake and exhaust air before heating, or even when heating is performed continuously, highly accurate heating control can be performed, and the surface temperature of the high frequency oscillation tube (4) can be controlled. Since it is directly detected, abnormal temperature rises in the high frequency oscillator tube (4) can also be detected.

[Effects of the Invention] As described above, according to the present invention, the temperature T1 of the air flowing into the heating chamber or a corresponding portion thereof at the same time, and the temperature T2 of the air inside the heating chamber or the air flowing out from the heating chamber at the same time.
is sampled at a predetermined interval, and the gradient of change C of temperature function B determined from these is calculated. If this gradient of variation C is smaller than a preset value, the high frequency power is increased, and When the change gradient C at the time of sampling becomes larger than the change gradient C at the time of sifting one time before this sampling time, the optimum heating time from the time t1 from the start of heating to the time when this change gradient C is reached. Since we provided a means for calculating t2 and stopping the supply of high-frequency power after the elapse of time t2, we simply calculated the temperature T1.
Compared to the case where heating is controlled based on the difference between A high frequency heating device capable of heating can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of a first temperature detection means according to the present invention, and FIG. A configuration diagram showing an example of the second temperature detection means, FIG. 4 shows the temperature function B.
FIG. 5 is a flowchart of heating control in the high-frequency heating device of FIG. 1, and FIG. 6 is a schematic diagram of the conventional high-frequency heating device. In the figure, (1) is the heating chamber, (3) is the object to be heated, and (4) is the heating chamber.
) is a high-frequency oscillation tube, (6) is a power supply device, (9) is an intake port of the heating chamber (1), (10) is an exhaust port of the heating chamber, (12)
(13a) is a control device for the high-frequency heating device; (15) is a high-frequency oscillation tube surface temperature sensor. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a high-frequency heating device that heats an object by supplying high-frequency power into a heating chamber housing an object to be heated, the temperature T_1 of the air flowing into the heating chamber or a corresponding portion thereof is detected. comprising a first temperature detection means and a second temperature detection means for detecting the temperature T_2 of the air in the heating chamber or the air flowing out from the heating chamber, and the temperature T_1 and T_2 at the same time are detected at predetermined intervals. A temperature function BB=a×T_2 determined by a unique constant a that is the ratio of the temperature T_2 to the temperature T_1 at the same time and the temperatures T_1 and T_2 at the same time.
- Calculate the gradient C of change of T_1, and if the gradient C is smaller than a preset value, increase the high frequency power, and the gradient C_n of temperature function B at a certain sampling time will be lower than that at the sampling time. Change gradient C_n_- at the time of previous sampling
When the temperature exceeds _1, calculate the optimum heating time t_2 of the object to be heated from the time t_1 from the start of heating until the time when the change gradient C_n is reached, and after the heating time t_2 elapses, supply the high-frequency power. A high-frequency heating device characterized by comprising a control means for stopping the heating.