JP2001017024A - Temperature-controlling device for aquarium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the production cost of a temperature-controlling device inexpensive. SOLUTION: This temperature-controlling device is provided by constituting an abnormality-detecting sensor 31 with a commonly used joined diode impressed with a reverse directional electric voltage by a direct electric current source 32 and using a reverse leak electric current of the abnormality-detecting sensor 31, which increases accompanying with the temperature elevation, so as to detect the abnormal state such as an electricity passing through air, etc. There, since the commonly used joined diode is inexpensive, the production cost of the device 11 becomes inexpensive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for controlling the temperature of water in a water tank for rearing ornamental fish.

[0002]

2. Description of the Related Art The present applicant controls the temperature of water in an aquarium to a set temperature suitable for breeding ornamental fish, and cuts off the power supply to the heating element when the heating element is exposed to the air when the power is supplied. A water tank temperature control device capable of preventing a fire or the like has been proposed in Japanese Patent Application Laid-Open No. 9-308408.

[0003] This is a heating element that generates heat by energization to heat water in a water tank, a water temperature detection sensor that detects the temperature of water in the water tank, and a heating element based on a detection signal from the water temperature detection sensor. A control unit that controls the water temperature to a set temperature by controlling energization; and an abnormality detection sensor that detects an abnormal state when the water element is heated to an abnormal temperature. Is detected, the control unit cuts off the power supply to the heating element based on the signal from the abnormality detection sensor.The abnormality detection sensor is controlled by a thermistor whose resistance value decreases with increasing temperature. It is composed.

[0004]

However, in such a water tank temperature control device, since an expensive thermistor is used as an abnormality detection sensor, there is a problem that the entire control device becomes expensive. is there.

[0005] It is an object of the present invention to provide a temperature control device for a water tank that can reduce the manufacturing cost.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a heating element that generates heat when energized to heat water in a water tank, a water temperature detection sensor that detects the temperature of the water in the water tank, and a water temperature detection sensor. A control unit that controls the water temperature to a set temperature by controlling energization of the heating element based on the detection signal,
When the heating element is heated to an abnormal temperature, an abnormality detection sensor that detects an abnormal state is provided, and when the abnormality detection sensor detects an abnormal state, the control unit performs the operation based on a signal from the abnormality detection sensor. In the water tank temperature control device configured to cut off the current supply to the heating element, the abnormality detection sensor is configured by a junction diode to which a reverse voltage is applied, and the abnormality is detected by using a reverse leakage current that increases with a rise in temperature. This can be achieved by detecting the condition.

When the heating element is energized and is exposed to the air, the surroundings of the heating element are surrounded by air having an adiabatic effect, so that the heating element heats the abnormality detection sensor and the temperature rises. Since the abnormality detection sensor is formed of a junction diode, the value of the reverse leakage current increases.
Then, when the abnormality detection sensor is heated to an abnormal temperature,
When the value of the reverse leakage current becomes a predetermined value and an abnormal state is detected, at this time, the control unit cuts off the power supply to the heating element to prevent a fire or the like from occurring. Here, since the abnormality detection sensor is composed of an inexpensive general-purpose junction diode,
The manufacturing cost of the control device can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 11 denotes a water temperature control device for controlling the temperature of water in a water tank for rearing ornamental fish to a set temperature. The water temperature control device 11 is made of quartz glass immersed in the water in the water tank. An outer tube 12 is provided.
Is sealed by fitting a rubber cap 13 at the base end. The outer tube 12 and the rubber cap 13 described above constitute a sealed case 14 as a whole. The inside of the outer tube 12 is partitioned by a partition plate 15 disposed at the center thereof, and a separator 16 extending in the axial direction on the tip side from the partition plate 15 and a heating element turned back at a tip of the separator 16 as a heating element. The heating wire 17 is housed. The heating wire 17 is made of, for example, a nichrome wire or an iron chrome wire, and generates heat when energized to heat water in the water tank.

On the other hand, a water temperature detection sensor 21 is disposed in the outer tube 12 near the rubber cap 13 far from the heating wire 17 at the base end side of the partition plate 15, and the water temperature detection sensor 21 is Is composed of an NTC thermistor which is in close contact with the inner surface. Then, the water temperature detection sensor 21 detects the temperature of water (in some cases, surrounding air) in the water tank via the outer pipe 12, and outputs a detection result as a detection signal. Further, a control unit 23 is housed in the outer tube 12 closer to the base end than the partition plate 15, and the control unit 23 has a thyristor 24 as a control circuit connected in series to the heating wire 17.

Reference numeral 25 denotes a comparator as a comparison circuit. The comparator 25 includes a water temperature detection sensor 21 and a resistor 26.
Is input as a detection signal from the water temperature detection sensor 21, and the partial pressure between the resistors 27 and 28 is input as a setting signal for setting the water temperature. And this comparator 25
Compares the input detection signal with the setting signal, and when the water temperature is lower than the setting temperature and the detection signal is higher than the setting signal, the output signal of “HIGH” (hereinafter, referred to as “H”) is output. Is higher than the set temperature and the detection signal is smaller than the set signal, the inverted “LOW” (hereinafter, referred to as “low”)
(Referred to as “L”).

Here, the output signal from the comparator 25 is input to the gate of the thyristor 24. At this time, when the output signal is "H", the thyristor 24 permits the energization of the heating wire 17 On the other hand, the output signal is "L".
In this case, the power supply to the heating wire 17 is cut off. Thus, the thyristor 24 controls the temperature of the water in the water tank to the set temperature by controlling the energization of the heating wire 17 based on the comparison result of the comparator 25. When changing the set temperature, the values of the resistors 27 and 28 may be changed to adjust the value of the set signal.

An abnormality detecting sensor 31 is disposed in the outer tube 12 near the heating wire 17, and the abnormality detecting sensor 31 is heated by the heating wire 17. The abnormality detection sensor 31 is composed of a general-purpose junction diode to which a voltage is applied by a DC power supply 32, and the applied voltage is a reverse voltage in which a negative voltage is applied to an anode and a positive voltage is applied to a cathode. As a result, the current flowing through the abnormality detection sensor 31 becomes a weak reverse leakage current. Here, it is widely known that the reverse leakage current increases with an increase in the temperature of the abnormality detection sensor 31 itself, and more specifically, increases by a factor of 10 every time the temperature doubles. When the detection sensor 31 is heated to an abnormal temperature, the abnormal reverse state is detected using the increased reverse leakage current.

As described above, in this embodiment, since the abnormality detection sensor 31 is formed of an inexpensive general-purpose junction diode, the manufacturing cost of the water temperature control device 11 can be reduced. Then, the reverse leakage current flowing through the abnormality detection sensor 31 is amplified by the amplification transistor 33 connected to the abnormality detection sensor 31.

Reference numeral 36 denotes a comparator serving as a determination circuit. The comparator 36 uses the divided voltage of the resistors 37 and 38 as a detection signal from the abnormality detection sensor 31 and the divided voltage of the resistors 39 and 40. Is input as an abnormality setting signal. The comparator 36 compares the detection signal from the abnormality detection sensor 31 with the abnormality setting signal. When the temperature of the abnormality detection sensor 31 itself is lower than the abnormal temperature and the detection signal is higher than the abnormality setting signal, “HIGH” (Hereafter, "H"
On the other hand, when the temperature of the abnormality detection sensor 31 itself becomes higher than the abnormal temperature (abnormal state) and the reverse leakage current increases significantly, the detection signal (abnormal signal) becomes smaller than the abnormal setting signal. , And outputs an inverted output signal of “LOW” (hereinafter “L”).

Here, the output signal from the comparator 36 is also input to the gate of the thyristor 24. At this time, when the output signal is "H", the thyristor 24 permits the energization of the heating wire 17 On the other hand, the output signal is "L".
In this case, the power supply to the heating wire 17 is cut off. Thus, when the abnormality detection sensor 31 is heated to an abnormal temperature by the heating wire 17, the comparator 36 determines that the heating wire 17 is in an abnormal state based on the abnormality signal (detection signal) from the abnormality detection sensor 31. Then, an output signal is output to the thyristor 24 to cut off the current supply to the heating wire 17. When changing the abnormal temperature, the values of the resistors 39 and 40 may be changed to adjust the value of the abnormal setting signal.

The aforementioned thyristor 24, comparator 25,
The comparator 36 constitutes the control unit 23 as a whole, and the control unit 23 controls the energization to the heating wire 17 based on the detection signal from the water temperature detection sensor 21 as described above, thereby controlling the temperature of the water in the water tank. To the set temperature,
When the abnormality detection sensor 31 detects an abnormal state, the power supply to the heating wire 17 is cut off based on a signal from the abnormality detection sensor 31.

Reference numeral 44 denotes a plug. The plug 44 and the heating wire 17 are connected through a cord 45. Reference numeral 46 denotes a thermal fuse connected in series to the heating wire 17. The thermal fuse 46 is housed in the outer tube 12 near the abnormality detection sensor 31. When the thermal fuse 46 is heated to a fusing temperature higher than the abnormal temperature by the heating wire 17, the thermal fuse 46 is blown and forcibly cuts off the power supply to the heating wire 17.

Reference numeral 50 denotes a diode as a holding circuit,
This diode 50 is connected in parallel with the comparator 36,
That is, the anode of the diode 50 is connected to the detection signal side input terminal of the comparator 36, while the cathode is connected to the output terminal. As a result, the diode 50 is heated by the abnormality detection sensor 31 to an abnormal temperature,
When the output from 36 is inverted from "H" to "L" at least once, all the voltage applied to the input terminal of comparator 36 flows to the output terminal side of comparator 36, and the output from comparator 36 is detected as abnormal. Even if the temperature of the sensor 31 falls below the abnormal temperature, it is maintained at "L", that is, the comparator 36
Hold the abnormal state judgment of. Here, the holding of the abnormal state determination by the diode 50 is performed, when the return operation is performed, here, the plug 44 is pulled out from the outlet of the commercial power supply, and the power supply to the control unit 23 is stopped. After a few seconds, when the plug 44 is plugged into the outlet and power supply is started, the power is released.

Next, the operation of the embodiment of the present invention will be described. Now, it is assumed that the plug 44 is inserted into an outlet of a commercial power supply, and the sealed case 14 is immersed in the water of the aquarium. At this time, the water temperature detection sensor 21 detects the water temperature of the water tank, and outputs a detection signal to the comparator 25. At this time, the comparator 25 compares the input detection signal with the setting signal, and outputs an “H” output signal to drive the thyristor 24 when the water temperature is lower than the setting temperature and the detection signal is higher than the setting signal. Then, the heating wire 17 is energized. Thereby, the heating wire 17 generates heat, and the water in the water tank is heated.

On the other hand, the abnormality detection sensor 31 also detects the water temperature. However, since this water temperature is considerably lower than the abnormality temperature, only a very weak reverse leakage current flows through the abnormality detection sensor 31, and as a result, the comparator 36 The input detection signal is larger than the abnormality setting signal. For this reason, the same “H” output signal as described above is output from the comparator 36 to the thyristor 24.

Next, when the temperature of the water in the water tank becomes equal to or higher than the set temperature due to the heating as described above, the detection signal from the water temperature detection sensor 21 becomes smaller than the set signal. At this time, since the output signal from the comparator 25 is inverted from “H” to “L”, the thyristor 24 cuts off the power supply to the heating wire 17,
Thus, heating of the heating wire 17 is temporarily stopped. By controlling the power supply to the heating wire 17 in this manner, the water temperature in the water tank is controlled to the set temperature, and an environment suitable for breeding ornamental fish is provided.

Next, for example, when water in the water tank flows out and the sealed case 14 is exposed to the air while the power is being supplied, the water temperature detection sensor 21
Detects the temperature of the air. If the temperature of the air is lower than the set temperature, the comparator 25 outputs a signal “H” to the thyristor 24. As a result, heating wire 17
However, at this time, since the outer tube 12 is surrounded by air having a heat insulating effect, the heat from the heating wire 17 is less likely to be radiated. Heated by the heating wire 17, the temperature rises,
The value of the reverse leakage current increases.

When the abnormality detection sensor 31 is heated to an abnormal temperature (to an abnormal state), the value of the reverse leakage current increases to a predetermined value. At this time, a detection signal (abnormal signal ) Is smaller than the abnormality setting signal, the comparator 36 determines that the state is abnormal, outputs the inverted signal “L” to the thyristor 24, and cuts off the power supply to the heating wire 17. As a result, even if the temperature (air temperature) detected by the water temperature detection sensor 21 is lower than the set temperature, energization to the heating wire 17 is stopped, and the heating wire 17 becomes idle and a fire occurs. Is prevented.

When the output from the comparator 36 is inverted from "H" to "L" even once as described above, the diode 50 changes the voltage applied to the input terminal of the comparator 36 to the output terminal of the comparator 36. And keeps the output from the comparator 36 at "L" even if the temperature of the abnormality detection sensor 31 falls below the abnormal temperature, that is, keeps the abnormality state judgment of the comparator 36. This prevents the power from being turned on again to the heating wire 17 and improves safety. Next, after the plug 44 is unplugged from the outlet of the commercial power supply and then inserted again into the outlet, that is, when the return operation is performed, the holding is released.

In the above embodiment, the control unit
Although 23 is housed in the sealed case 14, in the present invention, it may be taken out of the sealed case 14 and housed in the control case installed on the cord 45 located outside the water tank. In the above-described embodiment,
Although the thyristor 24 is used as the control circuit, a triac may be used in the present invention.

[0026]

As described above, according to the present invention, the manufacturing cost of the temperature control device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view showing an embodiment of the present invention.

FIG. 2 is a circuit diagram thereof.

[Explanation of symbols]

 11 ... temperature control device 17 ... heating element 21 ... water temperature detection sensor 23 ... control unit 31 ... abnormality detection sensor

Claims (1)

[Claims] 1. A heating element that generates heat by energization to heat water in a water tank, a water temperature detection sensor that detects a temperature of water in the water tank, and energizes the heating element based on a detection signal from the water temperature detection sensor. A control unit that controls the water temperature to a set temperature, and an abnormality detection sensor that detects an abnormal state when the heating element is heated to an abnormal temperature, wherein the abnormality detection sensor detects the abnormal state Then, in the temperature control device of the water tank configured to cut off the current to the heating element by the control unit based on the signal from the abnormality detection sensor, the abnormality detection sensor, from the junction diode to which a reverse voltage is applied A temperature control device for an aquarium, wherein the abnormal condition is detected using a reverse leakage current that increases with an increase in temperature.