JPS5938553A - Temperature controller for water boiler - Google Patents

Abstract

PURPOSE:To give no discomfort feeling to a user by varying a temperature of hot water even if the titled boiler is used intermittently, by so constituting that even if an electric power source of a control circuit is interrupted an integrated quantity of integrating capacitor is being stored. CONSTITUTION:A voltage drop is generated and a transistor 26 is electrified through divided voltage of resistors 24 and 25 as an electric current of an excitation coil 19 is being applied to resistor 18 under a state that a hot water tap is opened and electric power source switch 10 is closed. Then, a transistor 23 is electrified through existence of base resistor 27 and a switching device is turned into a closed state. As the resistor 18, however, is not electrified when the hot water tap is closed and the electric power source switch 10 is opened, the transistor 26 is not electrified causing that the transistor 23 is turned into an OFF state and the switching device is turned into an open state. As for a temperature control circuit which is obtained by providing the switching device in a discharge channel of an integrating capacitor 20 like this, a temperature of hot water hardly vary even if hot water supply is started again from a state where the hot water supply is suspended by closing the hot water tap as an integrated quantity of the integrating capacitor 20 hardly vary through interruption of the electric power source switch.

Description

[Detailed description of the invention] The present invention relates to a temperature control device for a water heater.

FIG. 1 is a schematic diagram of a water heater using a gas proportional valve that proportionally controls the amount of gas supplied to a burner in accordance with the current level. In other words, the water heater includes a gas burner 2 to which C gas is supplied through a gas pipe 1, heated by the combustion heat of this gas burner 2, and exchanges heat with water that is integrated with a water pipe 5 and flows in from the water pipe 3. A heat exchanger 4, a temperature sensing element 5 such as a negative characteristic thermistor for detecting the hot water temperature, which is attached to the heat exchanger outlet side of the water pipe 5, and a signal from this temperature sensing element 5 and a signal from a temperature setting device are inputted. The temperature side FM [position 6] is controlled by the output signal of this temperature control device 6, basically consists of a gas proportional valve 7 provided in the gas pipe 1, and the signal detected by the temperature sensing element 5. Accordingly, the C gas proportional valve operates, which controls the amount of gas supplied to the gas burner 2 and maintains the temperature of the hot water coming out of the C faucet 8 at a predetermined temperature. A switch 70 is attached to the water pipe 3, and the flow switch 9 is used to open and close the power supply to the temperature control device B for purposes such as power saving.

As described above, a conventional temperature control device that adjusts the temperature of hot water by controlling the amount of gas burned in a gas burner using a gas proportional valve has a circuit configuration as shown in FIG. 2, for example. 10 is a power switch for opening and closing the DC power supply connected to the circuit, and 70 is attached to the water pipe.
- It is operated by switch 9 and closes when there is water flow in the water pipe. 11 is a temperature sensing element such as a negative characteristic thermistor that detects the water temperature, 12 is a temperature setting device consisting of a variable resistor etc. connected to the temperature sensing element 1, and 3 is a resistor that divides the power supply voltage. 14 is an operational amplifier 2 that detects the difference between the hot water temperature and the set temperature.
a detector consisting of a temperature sensing element 11 and a temperature setting device 1;
2 is connected to its negative input terminal, and the reference voltage 13 is connected to its positive input terminal. This detector 14 outputs a signal that is lower than the reference voltage 13 when the temperature detected by the thermosensing element is lower than the set temperature, and when the detected temperature is higher than the set temperature, the output signal is set to the medium voltage. 13, and when the detected temperature matches the set temperature, the output signal operates to match the reference voltage 13. 15 is an operational amplifier, and the detector 1
The output signal of No. 4 is connected to its negative input terminal through a resistor 16, and the base pressure 16 is connected to its positive input terminal.

Reference numeral 17 denotes a control transistor controlled by the output signal of the operational amplifier 15. Its emitter side is connected to ground via a resistor 18 for coil current detection, and its collector side is connected to the ground via the excitation coil 19 of the gas proportional valve 8. It is connected to the DC power supply and controls the current flowing through the exciting coil 19. Twenty capacitors are connected between the negative input terminal of the operational amplifier 15 and the emitter of the control transistor 17, and the operational amplifier 15, the resistor 16, and the control transistor 17 constitute a Miller integrator. 21
is a diode that serves to absorb the back electromotive force generated in the exciting coil 19. Due to the presence of the integral circuit, the temperature control circuit configured in this way can take out hot water at a stable temperature as long as the water heater is used in a steady state. However, in general, water heaters are often used intermittently at a predetermined set temperature, and in that case, the conventional temperature control circuit is not able to restart the hot water supply from the state where the hot water faucet was turned off and hot water supply stopped, as shown in Figure 6. Immediately after starting hot water supply, the temperature of the hot water immediately drops and cools down, causing discomfort to the user. This phenomenon occurs for the following reasons.

In other words, when the hot water supply is stopped, the power switch 10 is opened by the operation of the flow switch 9, and the power supply voltage is not supplied. is discharged through the resistor 1. In this state, when the flow switch operates again and the power switch 10 is closed, the control transistor 17 is discharged until the integrating capacitor 20 is charged with a predetermined charge. flows to [W,
Since the flow becomes smaller, the amount of gas supplied to the burner 2 is lowered, and as a result, the temperature of the hot water is lowered. After the integral capacitor 20 is charged with a predetermined charge c, the water temperature recovers to the predetermined set temperature.

The present invention provides a temperature control device for a water heater that eliminates the disadvantages of conventional temperature control circuits and can always supply hot water at a stable temperature even during frequent and intermittent use. The gist of this is that even if the power to the control circuit is cut off, the integrating capacitor of the integrating circuit remembers the value of the integrator.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 4, C1 numerals 10 to 21 are the same as the configuration of the conventional example described in FIG. 22 is a switching means provided in the discharge path of the integrating capacitor 20, which operates in synchronization with the power switch 10. When the hot water faucet is closed and hot water supply is stopped, the switching means 22 is opened at the same time as the power switch 10, and when hot water supply is started, the switching means 22 is closed. Such a switching means 22 may be integrated with a 70-switch so as to be interlocked with the power switch 10, or may be constituted by a separate relay, but a more practical one is shown in FIG. A circuit configuration like this is adopted. That is, a transistor 23 is connected in series to the discharge path of the integrating capacitor 20, and a transistor 26 is provided which is operated by a voltage obtained by dividing the voltage across the coil current detection resistor 18 by a voltage dividing resistor 24.25. It is connected to the base circuit of the transistor 23 via a base resistor 27. The switching means configured in this manner operates as follows. The hot water faucet is opened (power switch 10)
When C is closed, the current of the excitation coil 19 flows through the resistor 18, causing a voltage drop, and the divided voltage of the resistors 24 and 25 causes the C transistor 26 to conduct. Due to the presence of the base resistor 27, the transistor 23 becomes conductive and the switching means is closed.However, when the hot water tap is closed and the °C power switch 10 is opened, no current flows through the resistor 18.
Transistor 26 is not conducting and as a result transistor 23 is also non-conducting and the switching means is open.

In this way, the temperature control circuit provided with a switching means in the discharge path of the integral capacitor does not change the integral amount of the integral capacitor 20 even if the power switch is turned off. Even if you start picking up the hot water again from the state where you stopped the humming bath, the temperature of the hot water will hardly change.

Although the temperature control circuit for the water heater of the present invention is configured as shown in μ, it is not necessarily limited to the one actually used in the above example, and the order and v can be modified. For example, the integrating circuit may be a Miller integrator (not limited to C) as described above, but may also be an integrator with other circuit configuration buttons.The point is that when the power switch of the control circuit is cut off, the charge of the integrating capacitor is Any structure that allows discharge will suffice.

Furthermore, a proportional apposition differentiating circuit may be added to the above-mentioned integrating circuit if necessary.

As explained above, the water heater temperature control device of the present invention is configured such that when the power to the control circuit is cut off, the integral capacitor stores the integral amount of "C", so even if the water heater is used intermittently, It has the excellent effect of not causing discomfort to the user due to changes in the temperature of the hot water.

[Brief explanation of drawings]

Figure 1 is a system diagram explaining the temperature control of a water heater, Figure 2C is a conventional temperature control circuit diagram, Figure 3 is a diagram showing the resulting change in water temperature, and Figure 4 is a diagram of the invention. FIG. 5 is a circuit diagram of the switching means used therein, and FIG. 6 is a diagram showing changes in hot water temperature by the temperature control circuit of the present invention. 10...Power switch, 11...Temperature sensing element, 12...Temperature setting device, 13...Basic α pressure, 14... Detector, 15...Operation amplifier, 16-18...Resistor, 17...
...Control transistor, 19...Exciting coil, 20...-- Integrating capacitor, 21...
da f ode, 22...Switching means. Patent Applicant Co., Ltd. Yanagisawa Seisakusho Co., Ltd. Figure 1 Figure 2 Figure 0 Figure 3 Figure 4/D

Claims (1)

[Claims] By CO heat exchanger] 3. The output signal from the detector that detects the difference between the heated water temperature and the set temperature causes the NOS proportional valve to be activated via a control circuit including at least an integrating circuit. In the temperature control device for a water heater, the integral capacitor of the integral circuit stores the integral amount even if the power to the control circuit is cut off. Control device. (2) By providing switching means that operates in synchronization with the power switch of the control circuit in the discharge path of the integrating capacitor, even if the control circuit α, 2. A temperature control device for a water heater according to claim 1, wherein the integral amount is stored by itself.