JPH07104040B2 - Hot water heating system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hot water heating apparatus having a proportional control type combustion device.

(Prior Art) Conventionally, in the case of adopting a proportional control type combustion device in a hot water heating device, as shown in Fig. 4, the hot water temperature at the outlet of the heat exchanger is fed back to the gas amount. However, at the start-up, as shown in FIG. 5, overshoot occurs due to the accumulation of the integrated amount after the outlet heated water temperature reaches the set temperature. As measures against this overshoot, for example, as shown in Japanese Patent Laid-Open No. 57-31722, a judgment circuit for judging the occurrence of overshoot is provided, and the input level of the integration circuit is shifted by the output of the judgment circuit. .

(Problems to be solved by the invention) However, unlike a water heater, hot water is circulated in the hot water heater, and the temperature of water entering the heat exchanger is also affected by the heating amount, so that the occurrence of overshoot is detected. At that time, the temperature of the incoming water was also rising, and it was not so much that the amount of integration was shifted.

An object of the present invention is to eliminate overshoot at the time of rising.

(Means for Solving the Problems) The present invention is characterized by the following configurations in order to achieve the above object. That is, a circulation circuit having a circulation pump for circulating hot water between the heat exchanger and the radiator, a temperature sensor for detecting the hot water temperature at the outlet of the heat exchanger, a burner for heating the heat exchanger, and a burner. A proportional valve that controls the combustion amount of
Forced combustion circuit that sets the output data to the proportional valve to the maximum until the outlet heated water temperature reaches a predetermined temperature lower than the set temperature, and outputs the maximum amount of gas to the proportional valve, and outputs when the outlet heated water temperature reaches the predetermined temperature. A subtraction circuit that reduces the data by a predetermined amount, and from the time when the output data is subtracted to a predetermined value
When the PID control is started, it has a proportional control circuit.

(Operation) According to the present invention, the output data to the proportional valve is maximized by the forced combustion circuit at the time of rising, and the proportional valve is set to the maximum opening degree, so that the heating is performed with the maximum capacity, so that the temperature rises to the predetermined temperature. Is sudden. Since the output data is reduced by the subtraction circuit after reaching the predetermined temperature, the amount of gas decreases and the rising speed of the tapping temperature slows down. When the reduced output data reaches a predetermined value, PID control is started from there. At this point, the hot water outlet temperature is close to the set temperature, and no large overshoot occurs.

(Embodiment) FIG. 1 is an overall outline view of an embodiment of a hot water heating apparatus according to the present invention, and FIG. 2 is a circuit diagram of a main part of its control means.

(1) is a heat exchanger, which forms a circulation circuit for circulating hot water with a radiator (not shown), (2) is a high-temperature forward pipe,
(3) is a return pipe. An expansion tank (4) and a circulation pump (5) are provided in the return pipe (3), and a negative to low temperature forward pipe (6) at the outlet of the circulation pump (5) and the inlet of the heat exchanger (1) is not shown. It is connected to a low temperature radiator.
The return pipe from the low temperature radiator is connected to the same return pipe (3) as the high temperature side outside the device. (7) is a temperature sensor that detects the temperature of the hot water discharged from the outlet of the heat exchanger (1).
(8) is a burner for heating the heat exchanger (1), and (9) is a proportional valve for controlling the combustion amount of the burner (8). (10) is a bypass pipe that bypasses the radiator when the load is low.
Reference numeral (11) is a proportional control circuit which receives the output of the temperature sensor (7) and controls the proportional valve (9) by PID control. (1
2) is forced combustion in which the output data to the proportional valve is set to the maximum and the opening is maximized until the hot water temperature detected by the temperature sensor reaches a predetermined temperature that is lower than the set temperature, and the maximum amount of gas is flowed to the proportional valve. Circuit. (13) is a subtraction circuit for decreasing the output data by a predetermined amount from the time when the hot water discharge temperature reaches a predetermined temperature. The proportional control circuit (11), the forced combustion circuit (12), and the subtraction circuit (13) are composed of a microphone computer.

Next, the operation of the above configuration will be described with reference to FIGS. 3 and 6. First, at the start-up, forced combustion circuit (12)
Is activated, the maximum output data is set so that the proportional valve (9) has the maximum opening (S1), and the burner (8) heats the heat exchanger (i) with maximum capacity. Therefore, the tap water temperature rises with the maximum gradient. When the tap water temperature rises to a predetermined temperature (for example, 75 ° C) lower than the set temperature (for example, 80 ° C), the subtraction circuit (1
3) operates and the output data of the gas amount output to the proportional valve (9) is reduced by a predetermined amount (S4). At this point, the incoming water temperature is also rising, and the gradient becomes steeper with the combustion capacity as it is. In this embodiment, unlike the conventional example, the output data of the gas amount is reduced instead of the integrated amount, so that the response is fast and the reduced gas amount is large. Therefore, the gradient of tapping temperature becomes gentle. The subtraction amount at this time is appropriately calculated according to the hot water outlet temperature or calculated according to the forced combustion time. When the subtraction is repeated and the reduced output data reaches a predetermined value, the value of this output data is replaced as the integration initial value of PID control (S7), and PID control is started (S8). This value is the most PI determined by experiment.
The value is set so that the transition to D control is prompt. At this point, the hot water outlet temperature is almost at the set temperature, and a large amount of integration has not been accumulated. Therefore, a large overshoot does not occur and the set temperature is reached quickly and smoothly. It should be noted that the output data of the predetermined minimum value of the gas amount was used as the integrated initial value of the PID control so that the gas amount at the time of the transition was not changed drastically, and the inflection point of the hot water temperature was changed. The output data that is detected and prepared in advance may be appropriately selected and substituted according to the tapping temperature.

(Effect of the invention) As described above, according to the present invention, the forced combustion is performed with the maximum capacity at the initial stage of rising, and the output data is gradually reduced when the outlet heated water temperature becomes the predetermined temperature lower than the set temperature, and the predetermined output data is obtained. Since the PID control is performed at that point, the temperature can be quickly raised to the set temperature, and the set temperature can be smoothly reached without causing a large overshoot.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of an embodiment of a hot water heating apparatus according to the present invention, FIG. 2 is a circuit diagram of a main part of its control means, and FIG. 3 is a characteristic diagram of the hot water temperature and gas amount. Is. FIG. 4 is a circuit diagram of a main part of the control means of the control means of the conventional example, FIG. 5 is a characteristic diagram of the hot water temperature and the amount of gas, and FIG. 6 is a control flow chart according to the present invention. (1) …… Heat exchanger (2) …… High temperature forward pipe (3) …… Return pipe (7) …… Temperature sensor (8) …… Burner (9) …… Proportional valve (11) …… Proportional control Circuit (12) …… Forced combustion circuit (13) …… Subtraction circuit

Claims (1)

[Claims] 1. A circulation circuit having a circulation pump for circulating hot water between a heat exchanger and a radiator, a temperature sensor for detecting a hot water temperature at the outlet of the heat exchanger, and a burner for heating the heat exchanger. And a proportional valve for controlling the combustion amount of the burner, and a forced combustion circuit for maximizing the output data to the proportional valve and flowing the maximum amount of gas through the proportional valve until the hot water temperature reaches a predetermined temperature lower than the set temperature. And a subtraction circuit that decreases the output data by a predetermined amount from the time when the outlet heated water temperature reaches a predetermined temperature, and a proportional control circuit that starts PID control from the time when the output data is reduced to a predetermined value. Characteristic hot water heating system.