JPH09172905A - Heating device for water vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device for a water vessel not abruptly changing the water temperature in the water vessel, and dissolving a trouble where the water temperature becomes widely different from a set temperature. SOLUTION: This heating device for a water vessel is provided by installing a heater 2 for heating the water in the water vessel and a temperature detecting element 4 for detecting the water temperature, turning on an electric current to the heater 2 when the water temperature detected by the temperature detecting element 4 in the water vessel is lower than the prescribed temperature, turning off the electric current to the heater 2 when the water temperature detected by the temperature detecting element 4 is higher than the prescribed temperature. In this case, when the detected water temperature is in the prescribed temperature range, the electric current is intermittently turned on and off to the heater 2 according to the water temperature detected by the temperature detecting element 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for an aquarium, and more particularly to an aquarium heating device for heating water in an aquarium for breeding appreciation fish and small aquatic animals, or for growing aquatic plants.

[0002]

2. Description of the Related Art A conventional water tank heating device includes a heater for heating water in a water tank in which a nichrome wire is disposed in a watertight state in a cylindrical body, and a temperature detecting element including a thermistor for detecting the water temperature of the water tank. When the water temperature of the water tank detected by the temperature detection element is lower than the target temperature, the heater is energized from the commercial power supply to heat the water in the water tank, and the water temperature in the water tank detected by the temperature detection element is set to the target temperature. When the temperature is higher than the temperature, the power supply to the heater is stopped to maintain the water temperature in the water tank at the target temperature.

[0003]

However, in this conventional water tank heating device, when the water temperature of the water tank is lower than the target temperature, the power is continuously supplied from the commercial power source, and when the water temperature of the water tank is higher than the target temperature. However, since the power supply from the commercial power source is immediately stopped, the water temperature in the water tank changes abruptly, and the water temperature slightly differs from the target temperature.

[0004] The present invention has been made in view of such problems of the conventional apparatus, and a heating apparatus for a water tank in which the water temperature of the water tank does not suddenly change to become a water temperature far from the target temperature. The purpose is to provide.

[0005]

In order to achieve the above object, a water tank heating apparatus according to the present invention is provided with a heater for heating water in the water tank and a temperature detecting element for detecting the water temperature of the water tank. , Energize the heater when the water temperature in the water tank detected by this temperature detecting element is below a predetermined temperature, and stop energizing the heater when the water temperature detected by this temperature detecting element is above a predetermined temperature In the water tank heating device, when the water temperature detected by the temperature detection element is within the predetermined temperature range, the heater is intermittently energized according to the water temperature detected by the temperature detection element.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an electric circuit diagram showing an embodiment of a water tank warming apparatus according to the present invention. 1 is an AC power supply composed of a commercial power supply or the like, 2 is a heater, 3 is a rectifying circuit, 4 is a thermistor or the like. A temperature detection element, 5 is a water detection circuit, 6 is a control circuit, and 7 is a heater drive circuit.

The heater 2 is composed of a heater in which a nichrome wire or the like is sealed in a watertight state in a cylindrical body, or a ceramic heater in which a heating wire made of molybdenum or the like is embedded in a ceramic body. The heater 2 is connected to the AC power supply 1 via the heater driving circuit 7.

The rectifying circuit 3 includes a diode D ₁ , a capacitor C ₁ , a resistor R ₁ , a Zener diode ZD ₁ and a transformer T ₁ .
_It consists of ₁ etc. and rectifies AC power supply 1 to make DC power supply.
The LED ₁ in the rectifier circuit 3 is a light emitting diode that indicates the state when AC power is supplied.

[0009] Temperature sensing element 4, the resistance through the R ₈ are connected to the rectifier circuit 3, a comparator IC resistor R ₈ and the temperature sensing element 4 controls the voltage determined by the voltage dividing resistors between themselves circuit 6 Enter in ₃ .

The water detection circuit 5 comprises a water detection electrode S ₁ , a transformer T ₁ , bridge type diodes D _{2 to} D ₅ , a comparator IC _{1 and the} like, and determines whether water exists between the water detection electrodes S _1. Detect. The water detection circuit 5 is configured by providing a water detection electrode S ₁ between the AC power source 1 transformed by the transformer T ₁ and the rectifying circuit composed of the diodes D _{2 to} D _5. AC voltage is constantly applied to S ₁ . When the water detection electrode S ₁ is in water, the current flowing through the resistance of the water is rectified through the diodes D _{2 to} D _{5 and} obtained as a DC voltage corresponding to the rectified value.

On the other hand, the comparator IC ₁ has a voltage dividing resistor R
₂ , the reference voltage provided by R ₃ and the water sensing electrode S ₁
The voltage (water detection voltage) obtained from the above is compared to determine whether the water detection electrode S ₁ is in water or in air. When the water detection electrode S ₁ is underwater, a water detection voltage equal to or higher than the reference voltage is input to the comparator IC ₁ , so that it can be determined as underwater. Further, when it is in the air, the water detection voltage exceeding the reference voltage cannot be obtained, so that it is determined to be in the air. When a water detection voltage higher than the reference voltage is obtained, the comparator IC
_By outputting from ₁ , and keeping the base potential of the transistor Q _{1 at} a predetermined potential, the heater 2 can be energized. If the water detection voltage above the reference voltage cannot be obtained, there is no output from the comparator IC ₁ and the transistor Q ₁
The base potential of the is not lowered and the heater 2 is not energized.

The control circuit 6 includes operational amplifiers IC _{2 to} IC ₆
And a transistor Q ₁ etc.
The heater drive circuit 7 is operated based on the water temperature of the water tank detected in step S6.

The heater drive circuit 7 includes a photo coupler P.
The heater 7 is driven based on a signal generated by the control circuit 6, which is composed of C ₁ , TRIAC TR _{1, and the} like. In addition,
The LED ₂ in the heater driving circuit 7 is a light emitting diode that displays the state when the heater 2 is energized. LED that indicates the status of connection to AC power supply 1
LED indicating that the heater 2 is energized separately from _1.
By providing ₂ , it is possible to separately display whether or not the AC power supply 1 is connected and whether or not the heater 2 is energized, and even if the connection with the AC power supply 1 is accidentally disconnected The state can be recognized.

Next, the operation of the heating device constructed as described above will be described. First, the output of the rectifier circuit 3 is divided by the resistor R ₈ and the temperature detection element 4 to form a thermistor voltage, and this thermistor voltage is input to the + terminal of the operational amplifier IC ₃ . The comparator IC ₂ forms a reference voltage, and the comparator I
The thermistor voltage is amplified by C ₃ . In this case, the amplification factor is determined by the comparator IC ₂ and the resistors R _{12 to} R ₁₄ . This is to facilitate comparison with the reference voltage.

Next, in the operational amplifier IC ₄ , the resistance R ₁₅ ,
The reference voltages determined by the variable resistors VR ₁ and R ₁₆ , R ₁₉ and R ₂₀ are added and amplified. This is because the thermistor voltage is fluctuated in a pseudo manner by adding the reference voltage, and the thermistor voltage is moved in parallel to the voltage range for duty control.

On the other hand, the operational amplifier IC ₅ , the resistor R ₂₃ ,
A triangular wave is generated by R ₂₄ , R ₂₇ and capacitor C ₆ . The time constant of this triangular wave is determined by the resistors R ₂₇ and R ₃₀ and the capacitor C ₆ . This triangular wave serves as a reference voltage for performing duty control, as shown in FIG. Duty control can be performed by comparing and synthesizing the reference triangular wave and the thermistor voltage T _V amplified and translated as described above.

Assuming that the thermistor voltage T _V is at a low voltage point of the reference triangular wave, as shown on the left side of FIG. 2A, if the thermistor voltage T _V and the reference triangular wave are compared and synthesized, the reference triangular wave becomes 1 When viewed in a cycle, the voltage on the triangular wave side is high for a long time and the thermistor voltage T _V is low for a short time. Therefore, as shown in FIG. 2B, the output comparatively synthesized by the operational amplifier IC ₆ has the transistor Q ₁ turned on for a long time and turned off for a short time. On the other hand, when the thermistor voltage T _V rises as shown on the right side of FIG. 2A, the transistor Q ₁ has a short ON time and a long OFF time as shown on the right side of FIG. 2B. As described above, the on-time of the transistor Q ₁ becomes longer or shorter depending on the magnitude of the thermistor voltage T _V.

As shown in FIG. 1, the transistor Q ₁ is connected to the photocoupler PC ₁ of the heater driving circuit 7 via the resistor R _31.
The photocoupler PC ₁ is made conductive when the transistor Q ₁ is turned on, thereby triggering the triac TR ₁ and applying the AC voltage 1 to the heater 2. As a result, the heater 2 is fed back by the thermistor voltage, and the temperature is controlled to be as close as possible to the target temperature set by the variable resistor VR ₁ . The target temperature set by the variable resistor VR ₁ is slightly lower than the highest point of the reference triangular wave.

When the thermistor voltage T _V is lower than the lowest point O _{L of the} reference triangular wave for a certain period, the operational amplifier IC
The output of ₆ is turned on, the transistor Q ₁ is turned on for the entire period, and the heater 2 is continuously energized. Further, when the thermistor voltage T _V is higher predetermined period than the highest point O _H of reference triangular wave, the output of the operational amplifier IC ₆ is turned off, the transistor Q ₁ is power supply to the heater 2 is turned off all the time is stopped completely . Therefore, in the aquarium heating device according to the present invention, the temperature detected by the temperature detecting element 4 causes
The heater 2 is driven in three modes: a mode in which the heater 2 is continuously energized, a mode in which the heater 2 is not energized at all, and a mode in which the heater 2 is intermittently energized. That is, when the thermistor voltage is lower than the predetermined temperature which is the lowest point O _L of the reference triangular wave, the heater 2 is continuously energized,
Is lower than the predetermined temperature is the highest point O _H of the reference triangular wave is not at all energized to the heater 2, the lowest point of the reference triangular wave O _L
And when the range of the predetermined temperature is between the highest point O _H, it is intermittently operated in accordance with the thermistor voltage T _V.

As shown in FIG. 1, when the temperature detecting element 4 is connected to the AC power source 1 through the transformer T ₁ , the temperature detecting element 4 portion used by being immersed in water is high even if the insulating resin deteriorates. It is safe with no danger of electric shock from voltage.

[0021]

As described above, according to the aquarium heating device of the present invention, when the water temperature detected by the temperature detecting element is within the predetermined temperature range, the water temperature detected by the temperature detecting element is set to the water temperature detected by the temperature detecting element. Accordingly, since the heater is intermittently energized, the heater can be accurately driven so as to approach the target temperature according to the water temperature of the water tank, and it is possible to prevent the water temperature of the water tank from abruptly changing. Can be controlled very strictly so as to reach the target temperature.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a water tank heating device according to the present invention.

FIG. 2 is a diagram showing a relationship between a set temperature, a detected temperature, and a heater driving time of the water tank heating device according to the present invention.

[Explanation of symbols]

1 ... AC power source, 2 ... Heater, 3 ... Rectifier circuit, 4 ... Temperature detection element, 6 ... Control circuit, 7 ...
・ Heater drive circuit

Claims (2)

[Claims] 1. A heater for heating water in a water tank and a temperature detecting element for detecting a water temperature in the water tank are provided, and when the water temperature in the water tank detected by the temperature detecting element is equal to or lower than a predetermined temperature, the heater is provided. In a water tank heating device that energizes and stops energizing the heater when the water temperature detected by the temperature detection element is equal to or higher than a predetermined temperature, the water temperature detected by the temperature detection element is within the predetermined temperature range. When inside, the water tank heating device is characterized in that the heater is intermittently energized according to the water temperature detected by the temperature detecting element. 2. The water tank warming device according to claim 1, wherein the temperature detecting element is connected to an AC power source for energizing the heater through a transformer.