JPH0416690B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a hot water mixing control device for a water heater, etc., and in particular, a hot water mixing control device for a water heater, etc. that has improved usability when the amount of hot water output is reduced. Regarding.

(Prior Art) FIG. 1 is a configuration diagram showing the configuration of a hot water mixing control device such as a mixing type water heater.

In Figure 1, 1 is a water inlet thermistor, 2 is a water flow sensor, 3 is a heat exchanger, 4 is a burner, 5 is a proportional control valve, 6 is a gas solenoid valve, 7 is a bypass waterway, 8
9 is a hot water mixing unit, 9 is a hot water mixing valve opening detection means (limit switch), 10 is a mixing thermistor,
Reference numeral 11 represents an operation section, and reference numeral 12 represents a control device.

Conventionally, in this type of hot water mixing control device,
In the control device 12, as shown in FIG. 4, the hot water side hot water outlet temperature T _H is set at a constant high temperature (high temperature fixing setting method) in order to ensure sufficient hot water outlet capacity of the appliance. After the gas amount is calculated by feedforward control based on the deviation between the set temperature TS' and the water inlet temperature TC and the hot water flow rate Q _H (F9), hot water mixing is performed depending on whether limit switch 9 is activated or not. It is determined whether or not the hot water mixing part 8 has reached the limit of the control range (F10), and if the hot water mixing part 8 has reached the limit of the control range, the hot water mixing valve is stopped (F11), and if it is within the control range. Feedback control of the hot water mixing section 8 is performed based on the deviation between the mixed tap water temperature T _M and the set temperature TS (F12 to F15).

(Problem to be solved by the invention) However, in the above conventional method, when the user throttles down the amount of mixed hot water with a stopper, a hot water mixing valve is used to control the amount of hot water at the same time or only the amount of hot water. With appliances that use a hot water mixing valve that only controls water flow, the hot water mixing valve may stop working due to a drop below the specified minimum operating water flow before the hot water output capacity of the appliance reaches its minimum. Beyond the control range, the mixing ratio Q _M /Q _H cannot be kept large, and an offset may occur where the mixed hot water temperature T _M becomes higher than the predetermined set temperature TS.

For example, in a device that uses a hot water mixing valve that controls the amount of hot water at the same time or only the amount of hot water, the hot water outlet temperature T _H is 80°C, the set temperature TS is 40°C, and the incoming water temperature is 15°C, and the burner is activated. Minimum operating water flow
Q _H (min) is 2.0/min, minimum burner capacity is 3.0
Assuming that it is of the same issue, the minimum amount of hot water at this time is
Q _M (min) is 5.2l/min, heating capacity is 5.2,
It is not possible to use the burner to its minimum capacity, and it is not possible to reduce the amount of hot water Q _M below this level.

The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a hot water mixing control device for a water heater or the like that has improved usability when the amount of hot water dispensed is reduced.

(Means for solving the problem) The hot water mixing control device for a water heater or the like according to the present invention has the following features:
In order to achieve the above object, a hot water supply circuit including a heating path passing through a heat exchanger and a bypass path parallel to the heat exchanger; A capacity control device that controls the calorific value, a hot water temperature detection means that detects the mixed hot water temperature, a hot water mixing section that controls the ratio between the amount of water and the amount of hot water, and a control section that operates the capacity control device and the hot water mixing section. and a valve opening detection means for detecting the valve opening of the hot water mixing section, and the control section determines whether the hot water mixing section has reached the limit of the control range based on the output of the valve opening detection means. A discrimination circuit, a hot water mixture ratio control unit that fixes the hot water mixture ratio of the hot water mixing section when the answer of this discrimination circuit is affirmative, and a water inlet temperature and hot water side setting when the answer of the discrimination circuit is affirmative. It is characterized by comprising a hot water side temperature control section that performs feed forward fuel control based on temperature and hot water side flow rate, and feedback fuel control based on mixed hot water temperature, set temperature, and hot water side flow rate.

(Function) According to the above configuration, when the hot water mixing section has reached the limit of the control range, the feedback control of the hot water mixing section is not performed, and the feed based on the incoming water temperature, hot water side set temperature, and hot water side flow rate is controlled. Forward fuel control and feedback fuel control based on the mixed hot water temperature, set temperature, and hot water side flow rate are performed, and if the hot water mixing section is within the control range, feedback fuel control is performed based on the deviation between the mixed hot water temperature and the set temperature. Instead, feedback control of the hot water mixing section is performed based on the deviation between the mixed tap water temperature and the set temperature. As a result, the entire range of the appliance's hot water tapping capacity can be effectively utilized, making it easier to use.

(Example) Hereinafter, a detailed explanation will be given based on an example of a diagram.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a block circuit diagram of the control device, and FIG. 3 is a flow diagram showing the main part of the operation flow of the control device. be.

In FIG. 1, 1 is an inlet thermistor (inlet water temperature detection means) that detects the temperature of incoming water, 2 is a water flow sensor (hot water side flow rate detection means) that detects the heating path flow rate,
3 is a heat exchanger, 4 is a burner (heating device), 5 is a proportional control valve (capacity control device), 6 is a gas electromagnetic on-off valve,
Reference numeral 7 indicates a bypass path parallel to the heat exchanger 3, 8 indicates a hot water mixing section provided at the meeting point of the heating path 17 and the bypass path 7, and 9 indicates whether or not the hot water mixing section has reached the limit of the control range. The detection limit switch (hot water mixing valve opening detection means) 10 is a mixing thermistor (outlet hot water temperature detection means), 11 is an operation section (outlet temperature setting means), and 12 is a control section.

This control unit 12 includes a hot water side outlet temperature setting means,
It includes a hot water side temperature control section 14 and a hot water mixing ratio control section 15. The hot water side temperature control section 14 controls the gas electromagnetic on-off valve 6 and proportional control based on inputs from the inlet water temperature detection means 1, the hot water side flow rate detection means 2, and the hot water side temperature setting means 13 that sets the hot water side set temperature TS'. It is configured to control the hot water side outlet temperature T _H by controlling the valve 5 . The hot water mixing ratio control section 15 controls the hot water mixing section 8 based on the output of the hot water mixing valve opening detection means 9.
If the answer of this judgment circuit 15a is affirmative, the hot water mixing ratio of the hot water mixing unit 8 is fixed, and if the answer is negative, the hot water mixing ratio is fixed. Hot water temperature setting means 1
1 and a feedback control circuit 15b that performs feedback control on the hot water mixture ratio of the hot water mixing section 8 so as to change the hot water mixture ratio in the direction of making the mixed hot water temperature match the set temperature based on the input from the hot water tapping temperature detection means 10. We are prepared.

The hot water side temperature control section 14 includes a gas amount calculation section 1
4a, and this gas amount calculation section 14a receives the outputs of the inlet water temperature detection means 1, the hot water side flow rate detection means 2, and the hot water side temperature setting means, as well as the hot water mixture ratio control section 1.
5, the outputs of the discriminating circuit 15a, the hot water temperature setting means 11, and the hot water temperature detecting means 10 are input, and when the hot water mixing part 8 has reached the limit of the control range, Feedforward fuel control amount G _FF = based on side flow rate Q _H
(TS′−TC)・Q _H , mixed hot water temperature T _M , and set temperature
Feedback fuel control amount G _FB =∫(TS- _TM )・Q _H dt based on TS and hot water side flow rate Q _H is calculated, and the fuel amount G = G _FF + G _FB is calculated, and the hot water mixing unit 8 is controlled. When within the range, the inlet water temperature TC, hot water side set temperature
It is configured to calculate the feed forward fuel control amount G _FF = (fuel amount G = G _FF consisting of TS' - TC·Q _H ) based on TS' and the hot water side flow rate Q _H.

According to the above configuration, when the hot water mixing section 8 has reached the limit of the control range, F1, the hot water mixing section 8
Without feedback control, the inlet water temperature TC,
Feedforward fuel control based on the hot water side set temperature TS' and hot water side flow rate _QH , and feedback fuel control based on the mixed hot water temperature T _M , set temperature TS and hot water side flow rate _QH are performed (F2), and the hot water is mixed. The hot water mixture ratio in section 8 is fixed (F3). In addition, hot water mixing section 8
is within the control range, feedback fuel control based on the mixed outlet temperature T _M , set temperature TS, and hot water side flow rate Q _H is not performed, but is based on the inlet water temperature TC, hot water side set temperature TS', and hot water side flow rate Q _H. Feedforward fuel control (F4) and feedback control (F5 to F7, F3) of the hot water mixing section 8 based on the deviation between the mixed outlet temperature T _M and the set temperature TS are performed. As a result, the full range of appliance hot water supply capacity can be utilized effectively,
Usability can be improved.

In short, when the bypass path 7 side of the hot water mixing section 8 is fully opened and the water side is fully open, exceeding the control range of the hot water mixing section 8, the control device of the present invention does not operate the mixing valve of the mixing section any further and opens the mixing valve fully. The capacity control device consisting of a one-way proportional control valve is controlled by feedforward fuel control and feedback fuel control to reduce the hot water outlet temperature on the hot water side by throttling the gas amount, and as a result, the mixed outlet temperature is reduced. The temperature is set as per the set temperature.

In this embodiment, when the hot water mixing section 8 is within the control range, the hot water side outlet temperature T _H is controlled by feed forward fuel, but the hot water side outlet temperature T _H is detected. It is also possible to use feedback fuel control so that T _H =TS'. or,
The set temperature TS′ on the hot water side is shown as being fixed at a high temperature (80℃), but this can be changed, for example, by changing the set temperature.
It may be automatically set as a function of TS (TS′=(TS), where TS′>TS).

(Effects of the Invention) As explained above, according to the present invention, when the hot water mixing section reaches the limit of the control range, feed forward fuel control and mixing based on the inlet water temperature, hot water side set temperature, and hot water side flow rate are performed. Feedback fuel control is performed based on the hot water outlet temperature, set temperature, and hot water side flow rate, and when the hot water mixing section is within the limit of the control range, feedback control of the hot water mixing section is performed based on the mixed hot water outlet temperature and the set temperature as in the past. be exposed. That is, within the control range of the mixing valve, the hot water output range is expanded by mixing hot water, and outside the control range of the mixing valve, the hot water output range is expanded by restricting the amount of gas. Therefore, it was possible to obtain a hot water mixing control device that is easy to use and can effectively use the entire range of the hot water tapping capacity of the appliance.

In addition, feedback fuel control is not performed when the hot water mixing section is within the control range limit.
Control is not complicated.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a block circuit diagram of the control device, and FIG. 3 is a flow diagram showing the main part of the operation flow of the control device. be. FIG. 4 is a flow diagram showing the operation of the conventional example. 3... Heat exchanger, 4... Heating device, 5... Capacity control device, 7... Bypass path, 8... Hot water mixing section, 9... Valve opening detection means, 10... Hot water temperature detection means, 12... Control section, 14... Hot water side temperature control section, 15... Hot water mixture ratio control section, 15a... Discrimination circuit, 17... Heating path.

Claims (1)

[Claims] 1. A hot water supply circuit configured with a heating path passing through a heat exchanger and a bypass path parallel to the heat exchanger;
A heating device that heats a heat exchanger, a capacity control device that controls the calorific value of the heating device, a hot water temperature detection means that detects the temperature of mixed hot water, a hot water mixing section that controls the ratio between the amount of water and the amount of hot water, and the ability The controller includes a control unit that operates the control device and a hot water mixing unit, and a valve opening detection means that detects a valve opening of the hot water mixing unit, and the control unit operates the hot water mixing unit based on the output of the valve opening detection unit. a discriminating circuit that determines whether or not has reached the limit of the control range; a hot water mixing ratio control unit that fixes the hot water mixing ratio of the hot water mixing section when the answer of this determining circuit is affirmative; If the answer is an affirmative circuit, the hot water side temperature control unit performs feed forward fuel control based on the inlet water temperature, hot water side set temperature, and hot water side flow rate, and feedback fuel control based on the mixed hot water exit temperature, set temperature, and hot water side flow rate. A hot water mixing control device comprising: