JPS6235578B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to hot water temperature control for water heaters using gas, oil, electricity, etc. as heat sources, and eliminates the drawback of conventional installations such as not being able to obtain the set hot water temperature when overloaded. The purpose is to provide a new control device that allows you to obtain the desired hot water temperature.

The explanation will be given below using a gas water heater as an example.

FIG. 5 is a block diagram of a conventional gas water heater, in which combustion heat in a burner 1 and water are exchanged in a heat exchanger 2 to provide hot water. The temperature controller 3 receives the signal TW from the hot water temperature detector 4 and the signal from the temperature setting device 5.
TWR is input, a predetermined combustion amount is determined from the difference TER between the TW and TWR, and a control signal is output to the supply heat amount controller 6 to control the hot water temperature. Here, as the outlet hot water temperature detector 4, for example, a thermistor is often used, and as the temperature controller 3, a PiD controller or the like is often used.

FIG. 4 is a diagram showing the relationship between the hot water output amount Fw of the gas water heater and the temperature rise ΔT. The solid line represents the characteristics at the maximum combustion amount. In other words, the maximum combustion amount Qg
max, temperature rise ΔT, and flow rate Fw are as follows, where η is the combustion efficiency, η・Qg max=Fw・ΔT (1), and ΔT=η・Qg max/Fw (2). Therefore, the temperature rise Δ above that indicated by the solid line
T does not exist. For example, if the hot water output amount is Fw ₁ when the maximum combustion amount Qg max is reached, the temperature rise ΔT becomes ΔT ₁ as shown in the figure. The temperature controller 3 mentioned above controls the amount of hot water Fw when the temperature rise is ΔT=ΔT ₁ .
It works effectively when Fw is ₁ or less. If Fw>
At Fw ₁ , control becomes impossible and the hot water temperature TW cannot reach the set temperature.

In this way, the amount of hot water Fw that can control the hot water temperature is limited by the maximum combustion amount Qg max. This phenomenon is not limited to gas water heaters, but also applies to water heaters using other fuels.

The present invention provides a temperature control device that eliminates the drawbacks seen in the hot water temperature control of the conventional water heater mentioned above.
TW is what you get.

FIG. 1 is a block diagram of a gas water heater according to the present invention.
Devices with the same numbers as in FIG. 5 are devices having the same functions. In the water flow controller 7, the hot water temperature detector 4
signal TW from and signal from temperature setting device 5
TWR and the output of the temperature controller 3 are input, the flow rate to be changed is calculated from the difference TER between the signals TW and TWR, and a signal is output for a predetermined period of time to control the amount of water supplied to maintain the flow rate. Controls the control device 8. When starting to use a gas water heater, the maximum flow rate Fw
The supply water amount control device 8 is initialized to obtain the maximum value, and when the water temperature control reaches a steady state, the amount of heat supplied to the water heater is the maximum, and the temperature deviation TER is greater than a predetermined value, the deviation The value of TER and
The water flow rate controller 7 calculates the amount of hot water that should be changed based on the characteristics showing the relationship between the hot water flow rate and temperature rise shown in Figure 4, and the supply water flow rate control device 8 is operated to achieve that hot water flow rate until the TER reaches zero. Control the amount of water to get closer. When the above hot water temperature control reaches a steady state,
This is a particularly important problem in systems with large process delays, and can be determined using timer elements. In addition, if the amount of heat supplied is not the maximum in steady state and the amount of water supplied is not Fw max,
The supplied water amount control device 8 is operated to increase the supplied water amount so that the set hot water temperature can be obtained at the maximum flow rate by operation at the hot water supply point.

FIG. 2 shows the driving means of the water flow control device 8 of the present invention. The horizontal axis represents the output time and the vertical axis represents the flow rate, and it can be seen that the flow rate changes in proportion to the driving time. In other words, the flow rate change range Fw max ~ Fw
Within min, the same changing flow rate ΔFw can be obtained no matter what the flow rate is if it is output for a certain predetermined time. Thereby, it is only necessary to calculate the flow rate to be throttled from the steady state deviation TER in accordance with the capacity characteristics shown in FIG. 4, and to drive the water amount control device 8 for a predetermined time determined from the result.

Although the case where the output time and the flow rate change are in a proportional relationship is shown here, it is of course possible to select the output time accordingly if there is a fixed relationship, even if it is not a proportional relationship.

FIG. 3 shows a specific example of the present invention. here,
An example is given in which the microcomputer 9 is used for various calculations and sequence control, and in particular, water flow control, which is the center of the present invention, is specifically described.
4, 5, 6, and 8 indicate a thermistor as a hot water temperature detector, a temperature setting device, a supply heat amount controller, and a supply water amount control device, as described above.

First, we will explain how to capture the deviation TER. The set temperature TWR is input to the operational amplifier 12 via a resistor 11 as a partial voltage V _TER between the variable resistor of the temperature setting device 5 and a resistor 10 connected in series. Further, the tapped water temperature TW is applied as a partial voltage V _TWO between the thermistor 4 and the resistor 13 connected in series through the resistor 14 to the same input section as the TWR potential of the operational amplifier 12 described above. This operational amplifier 12 forms a so-called adder, the reference potential of which is determined by the voltage division of resistors 15 and 16, and the difference between V _TWO and V _TWR appears as an output by the resistor 17 that determines the amplification factor. This is the inverting input of Comparative Example 18. This comparator 18 A/D converts the value of TER, that is, the potential-converted _VTER , and outputs it as the input _P1 of the microcomputer 9 mentioned above.The reference input side is controlled by the microcomputer output section _P2 . This is the output of the D/A converter 19. In this way, the deviation
The microcomputer is importing TER.

In this example, the output to the supply heat amount control device calculated from the above-mentioned deviation TER according to the PiD control calculation method, for example, is output from the D/A converter 19 via the analog switch 20 and the drive section 21 to control the supply heat amount. The signal is transmitted to the device 6. Microcomputer output P ₃
The analog switch 20 controlled by D/
This is provided to share the A converter for input and output.

Furthermore, in the water flow control of the present invention, an output signal is issued to drive the water supply flow control device for a predetermined time calculated from the TER, and when reducing the flow rate, the microcomputer output _P4 is set to LOW level, and the resistor 22 , 23 to turn on the transistor 24, drive the relay Ry ₁ of 25, and make the relay contact 27 conductive in order to energize the motor coil 26 that controls the flow rate in the throttle direction. The rotation angle of the motor is determined by this conduction time, and the supplied water amount control device 8 is driven via a mechanism section 28 such as a transmission. The combination of 28 and 8 is provided, for example, to obtain the characteristics shown in FIG. When increasing the flow rate using similar operating means, resistors 29, 30, transistor 31, relay Ry ₂ 3
In order to energize the motor coil 33 via 2,
This closes the relay contact 34. A portion 35 surrounded by a thin line in this figure includes the temperature controller 3 and the water amount controller 7.

As described above, according to the water heater control device of the present invention, the hot water output amount Fw is always limited to a range where the hot water temperature can be controlled, so an excellent effect can be obtained in that hot water at a desired temperature can be obtained at any time. In addition, since the drive time of the water supply flow rate control device and the water supply flow rate variable characteristics are in a simple proportional relationship, the configuration itself does not need to be complicated, and the water flow rate controller is calculated based on the performance characteristics of the predetermined water heater. This can be controlled simply by managing your time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a control device for a gas water heater showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between output time and flow rate change showing the driving means of the present invention, and FIG. A circuit diagram of one embodiment, FIG. 4 is a characteristic diagram showing the relationship between hot water output amount and temperature rise of a gas water heater, and FIG. 5 is a configuration diagram of a conventional gas water heater. 3... Temperature controller, 4... Hot water temperature detector, 5
... Temperature setting device, 6 ... Supply heat amount controller, 7 ...
Water flow rate controller, 8... Supply water flow rate control device.

Claims (1)

[Claims] 1 Water heater outlet temperature detector, temperature setting device,
a temperature controller that outputs a signal for controlling the amount of heat supplied to the water heater depending on a deviation (TER) between a signal of the hot water temperature detector and a signal of the temperature setter; and a temperature controller that is responsive to the output of the temperature controller. A water heater supply heat amount controller, a water amount controller that calculates a flow rate to be changed from the temperature deviation (TER) and outputs a signal for a predetermined period of time to control the supplied water amount to maintain the flow rate, and an output of the water amount controller. A water heater control device comprising: a water supply amount control device that controls the amount of water supplied to the water heater in proportion to time.