JPH059704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to water heaters, and particularly to hot water temperature control in instantaneous water heaters.

Conventional configuration and its problems Conventionally, this type of control device corrects the operation signal for controlling the gas amount to the heating burner according to the water temperature and flow rate detected by the inlet side temperature sensor and flow sensor. It has a feed forward circuit for processing the flow rate detected from the flow sensor, in particular, proportionally and differentially processing it. In this configuration,
Since the feed forward circuit section does not involve the signal from the hot water temperature setting device, the accuracy of presetting the gas amount is poor. Furthermore, since the flow rate signal is subjected to differential processing, the feedforward circuit is constantly activated due to slight fluctuations in the flow rate or fluctuations in the response performance of the flow sensor. For this reason, there have been problems in that the time for the tap water temperature to converge to the set temperature becomes long and the hot water temperature fluctuates.

Purpose of the Invention The present invention solves such conventional problems by presetting the amount of heat supplied to the burner from the signals of a temperature setting device, a flow rate detector, and an inlet water temperature detector, and also presetting the amount of heat to be supplied to a burner from the signals of a temperature setting device, a flow rate detector, and an inlet water temperature detector. When the signal of the device changes by more than a predetermined amount, the adjustment section is activated.
It is an object of the present invention to provide a control device for a water heater that improves the performance of hot water outlet temperature control, eliminates fluctuations in hot water temperature during a steady state, and shortens the convergence time during a transient state.

Composition of the Invention In order to achieve this object, the present invention provides a water heater having a heat quantity controller, which includes a flow rate detector and an inlet water temperature detector that detect the flow rate and temperature of supplied water, and a water inlet temperature detector that sets the outlet temperature. and a hot water temperature detector, the heat quantity controller is driven from the set temperature signal of the temperature setter and the flow rate and temperature of water detected by the flow rate detector and the incoming water temperature detector. A heat amount comprising an adjustment section that adjusts the signal, and a correction section that corrects the operation signal of the heat amount controller by performing calculations such as proportionality, integration, differentiation, etc. on the deviation between the signal of the temperature setting device and the signal of the outlet temperature sensor. It has a calculation operation section of a controller, and the adjustment section is provided with a control device that is activated when the signal from the flow rate detector changes by a predetermined amount or more.

With this configuration, the preset temperature signal is involved in the amount of heat supplied by feedforward control, and the adjustment unit is activated when the flow rate of water changes by more than a predetermined amount. It has the effect of

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described using a gas water heater as an example.

FIG. 1 is a schematic configuration diagram showing a control device for a water heater according to the present invention. 1 is a heat exchanger, 2 is a burner, 3
is a heat quantity controller (for example, a gas proportional control valve that proportionally controls the gas quantity). The water circuit is provided with a flow rate detector 4 and an inlet water temperature detector 5 on the inlet side, and an outlet hot water temperature detector 6 on the outlet side, and these detection signals are used for calculation operations together with the signal from the temperature setting device 7. After being taken into the unit 8 and subjected to predetermined calculations, a signal is outputted to operate the heat amount controller.

FIG. 2 is a control block diagram showing the operation of the arithmetic operation section of the control device of the present invention. Components with the same numbers as in FIG. 1 are components having the same function. The calculation operation section 8 includes an adjustment section 9 and a correction section 10. The adjustment unit 9 is a part that calculates a preset value of the amount of heat supplied by feedforward control, and it calculates the deviation Te1 between the signal Ts of the temperature setting device 7 and the signal Ti of the inlet water temperature detector 5, and the signal Qw of the flow rate detector 4. Intake,
Calculate the predetermined amount of heat Qg1.

Qg1=k×Qw×Te1 (1) k is a constant that takes into consideration the heat exchange efficiency of the water heater. It can be seen that Qg1 calculated by the above equation (1) is a preset value and depends on the set temperature, water input temperature, and water flow rate.

Further, the correction unit 10 corrects the output of the hot water temperature detector 6 by
The deviation Te2 between To and the signal Ts of the temperature setting device is taken in, and the control by the adjustment section is corrected. In other words, normal proportional, integral, and differential control (PID suppression) is applied to Te2 to bring the hot water temperature closer to the set value.

The relationship between the above adjustment section and correction section is shown in Fig. 2.
Although it is shown that the signal from the correction unit 10 is used to correct the calculation result of the adjustment unit 9, the result of the adjustment unit may be given as the initial value of the integral calculation term of PID control, or another calculation may be performed. May be treated as a term.
In other words, there are cases where the portion due to feed forward control is used as the initial integral value for calculation. and,
If the temperature setting value or the flow rate changes during control, calculation may be performed according to equation (1) above and replaced with the integral term during control. This operation
This is easy if you use DDC, which has become popular these days.

11 is a process showing the action of a heat exchanger.

By the way, a signal from a flow rate detector that measures the flow of water in a pipe does not necessarily indicate a predetermined value even if the flow rate is the same. This is because the flow of water is turbulent, and the structure of the flow rate detector itself may cause variations and fluctuations. For example, there are flow rate detectors that open and close a magnetic field with the rotation of a propeller and output pulses with a frequency corresponding to the amount of water, and those that use Karman vortices to detect the amount of water with an ultrasonic sensor. teeth,
An example of the former output is shown. In this figure, t _{1 and} t ₂ are the periods between pulses, but even if the flow rate is the same, t ₁ ≠
The t ₂ condition may occur for the reasons mentioned above. If the amount of water must be detected and determined using several pulses, the difference between t ₁ and t ₂ will occur as a difference between the preset flow rate values calculated using equation (1). However, using the adjustment section to change the amount of heat due to this fluctuation tends to produce the results shown in FIG. 4. That is, due to the integral term operation, an overshoot occurs at t _a and an undershoot occurs at t _b . Of course, the overshoot and undershoot corrections are performed by the correction section 10 shown in FIG.

Therefore, in the present invention, the fluctuation of the signal of the flow rate sensor as described above can be directly corrected without using heat amount control.
It is used for arithmetic control in the adjustment section only when the signal changes by a predetermined value or more, which is larger than the variation width of the fluctuation. The same applies to the water temperature, and when a signal exceeding a predetermined amount of change is detected by the incoming water temperature detector, the adjustment section processes the signal. The determination as to whether or not these predetermined amounts are exceeded is carried out within the arithmetic operation section.

Effects of the Invention As described above, the water heater control device of the present invention provides the following effects.

(1) Since the heat amount preset value in feedforward control is calculated from the signals of the temperature setting device, inlet water temperature detector, and flow rate detector, the time to reach the set temperature is short.

(2) Considering variations in the configuration of the flow rate detector itself and fluctuations in the flow rate detector's signal due to fluctuations in water pressure, etc., feed forward control is activated when the signal changes by a predetermined amount or more. , it is possible to realize stable control of the hot water temperature.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the water heater control device of the present invention, FIG. 2 is a block diagram showing the arithmetic operation section of the control device of the present invention, FIG. 3 is a diagram showing the output signal of the flow rate detector, and FIG. FIG. 4 is a diagram showing the temperature change of the hot water. 1... Heat exchanger, 2... Burner, 3... Heat quantity controller, 4... Flow rate detector, 5... Incoming water temperature detector, 6... Outgoing water temperature detector, 7... Temperature setting device,
8... Arithmetic operation section, 9... Adjustment section, 10... Correction section.

Claims (1)

[Claims] 1. A heat exchanger, a burner that heats the heat exchanger, a heat amount controller that controls the amount of heat to the burner, and a flow rate detector that detects the flow rate and temperature of water supplied to the water heater. and an incoming water temperature detector, a temperature setting device for setting an outgoing water temperature, and an outgoing hot water temperature detector, and the setting temperature signal of the temperature setting device and the water detected by the flow rate detector and incoming water temperature detector are provided. an adjustment unit that adjusts the operation signal of the heat quantity controller based on the flow rate and temperature of the heat quantity controller; It has an arithmetic operation section of a heat quantity controller consisting of a correction section that corrects the operation signal,
A control device for a water heater, wherein the adjustment section operates when the signal from the flow rate detector changes by a predetermined amount or more. 2. The water heater control device according to claim 1, wherein the adjustment section is activated when the signal of the incoming water temperature sensor changes by a predetermined amount or more.