JPS6314193Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention consists of an air gas mixing device, a zero governor that automatically adjusts the gas supply amount according to the adjustment of the air supply amount, and a blower for supplying air based on the temperature detected by the hot water temperature sensor. The present invention relates to a combustion control device for a water heater that is provided with a mechanism that controls the rotation speed so that the water temperature is maintained at a set temperature.

Conventional combustion control devices for this type of water heater were configured to adjust the air supply amount, that is, the input, only by changing the rotation speed of the blower. When a large sudden decrease occurs, the fan rotation speed is controlled to be lowered based on the detected hot water temperature that has increased due to the decrease in hot water output. Because the temperature did not drop quickly, that is, the blower's followability was poor, this led to excessive input, and as a result, there was a risk that the hot water temperature would greatly overshoot.

The purpose of the present invention is to overcome these conventional drawbacks.

The combustion control device for a water heater according to the present invention is
A mechanism capable of switching the air supply amount into two stages, large and small, by changing the passage area of the air supply path, and a mechanism capable of switching the gas supply amount into two stages, large and small, by changing the passage area of the gas supply path, and the above-mentioned The present invention is characterized in that a mechanism is provided that automatically and reversibly switches the switching mechanism to a small supply amount state when the temperature detected by the hot water temperature detector rises above a certain level with respect to the set temperature.

The function of the device of the present invention, which has such a characteristic configuration, is that under normal operating conditions when the water temperature does not deviate significantly from the set temperature, the fan speed is changed steplessly based on the detection result of the water temperature. However, when the amount of hot water suddenly decreases and the hot water temperature rises above a certain level with respect to the set temperature, not only does the rotational speed of the blower decrease based on the detection of the hot water temperature, but also the switching mechanism Both automatically switch to a small supply amount state, and the input can be quickly reduced regardless of the blower's poor follow-up performance.As a result, during normal operation, the blower's stepless It is possible to control the hot water temperature with high accuracy by controlling the rotation speed, and also to prevent overshoot of the hot water temperature when the amount of hot water is drastically reduced, or to minimize the overshoot even if there is an overshoot. This has resulted in the effect of improving the safety of using water heaters.

Hereinafter, embodiments of the present invention will be described based on the drawings.

1 is a blower that can forcibly supply air to a burner 3 for heating the hot water heat exchanger 2, and the amount of air supplied can be changed by changing its rotation speed; 4, This is an air-gas mixing device that suctions and mixes gas into an air supply path 7 as air is supplied by an air orifice 5 and a gas orifice 6. 8 is a device for adjusting the load pressure PL, which changes as the air supply amount is adjusted. This is a zero governor that automatically adjusts the gas supply amount according to the adjustment of the air supply amount so that the air-fuel ratio becomes the set value. 9 is a thermistor for detecting the temperature of hot water; 10 is a water flow detection switch that is turned ON when a water flow is generated as the hot water tap 11 is opened; 12 is an igniter; 13 is a flame rod; and 14 is a main interposed in the gas supply path 15. The solenoid valve 16 is a mixing orifice. 17 is a mechanism that can switch the air supply amount into two stages, large and small, by changing the passage area of the air supply path 7;
It is a mechanism that can switch the gas supply amount into two stages, large and small, by changing the passage area of the gas supply path 15, and 19
2 is a pressure switch that detects the pressure generated as the blower 1 rotates, and 20 is a combustion controller.

The air supply amount switching mechanism 17
There is a damper 17A that can be freely switched between a fully open position and a closed position, and this damper 17A is
Solenoid 17B that reversibly switches the
It is composed of.

The gas supply amount switching mechanism 18 is connected to the gas supply path 1
Bypass path 1 with orifice 18c connected to 5
8A, an electromagnetic valve 18B that can reversibly close the bypass passage 18A by energization is interposed therebetween.

The combustion controller 20, as shown in FIG.
a sequence control circuit A; a control circuit B that controls the rotation speed of the blower 1 and the switching of the two supply amount switches 17 and 18 so that the hot water temperature is maintained at a set temperature based on the detected hot water temperature; When the detected hot water temperature rises above a certain level with respect to the set temperature, both supply rate switching mechanisms 17 and 18 are automatically set to the small supply rate side;
and a reversibly switching circuit C.

The sequence control circuit A rotates the blower 1 at full speed and after completion of pre-purge for a certain period of time, relay _R1 is energized to open the main solenoid valve 14 and ignite combustion.

The control circuit B is a P1D circuit that outputs a proportional control voltage based on a deviation detected by a bridge composed of a thermistor 9, a variable resistor VR for setting hot water temperature, and resistors R ₁ , R ₂ , R ₃ , and R ₄ . 21, a conduction angle control circuit 22 that controls the rotation speed of the blower 1 via a pulse transformer according to the output (hereinafter referred to as PID output), and a PID output as shown in FIG. , the first input IP
When the value has decreased to a value corresponding to set value 1 _p1 , relay _R2 is excited to energize the solenoid 17B and solenoid valve 18B, and the PID output changes to the second input IP as shown in FIG. Setting value 1 _p2
When solenoid 1 rises to a value corresponding to
7B and a comparator OP that cuts off power to the solenoid valve 18B. Therefore, as shown in FIG. 3, even though the range of input IP change is large and the load pressure PL is made small at the time of a large input, both supply amount switching mechanisms 17 and 18 are set to a small supply amount at a small input. By switching to the state, the load pressure PL at the minimum input,
The value can be set to a value that is sufficient for the operation of the zero governor 8.

The switching mechanism C detects whether or not the detected hot water temperature is higher than the set temperature by a certain Δt or more by comparing the potential in A and the potential in B, and when detected,
It is equipped with a comparator OP' that sets the PID output to a value equivalent to the minimum input. Therefore, when the detected hot water temperature rises above a certain Δt relative to the set temperature ta,
Not only is the solenoid 17B and the electromagnetic valve 18B energized, but the rotational speed of the blower 1 is controlled to the minimum value.

According to the configuration of the above embodiment, for example, at point t ₁ in FIGS. 4 and 5, the amount of hot water coming out is suddenly reduced, and the hot water temperature detected by the detector 9 becomes equal to or higher than a certain Δt with respect to the set temperature ta. When the supply amount increases, both supply amount switching mechanisms 17 and 18 switch to the small supply amount state, and the input IP decreases as shown by a→a' and b→b' in FIG. The IP decreases instantaneously as shown by the solid line in FIG. 4, and therefore the hot water temperature does not rise too much as shown by the solid line in FIG. 5, thereby avoiding overshoot of the hot water temperature. Incidentally, in the conventional device that adjusts the input IP only by controlling the rotation speed of the blower 1, the input change when the hot water output is suddenly reduced is as shown by the dotted line in Fig. 4. As shown by the dotted line in Figure 5, the water temperature rises significantly, resulting in so-called overshoot.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of a water heater, Figure 2 is a control circuit diagram, Figure 3 is a graph showing the relationship between input and load pressure, Figure 4 is a graph showing an example of input change over time, and Figure 5. is a graph corresponding to FIG. 4 showing an example of a change in water temperature over time. 4... Air gas mixing device, 8... Zero governor,
9... Hot water temperature detector, 1... Blower, B... Control mechanism, 7... Air supply path, 17... Air supply amount switching mechanism, 15... Gas supply path, 18... Gas supply amount, switching Mechanism, C...Switching mechanism, 17A...Damper, 17B...Solenoid, 18A...Bypass path, 18B...Solenoid valve.

Claims (1)

[Scope of claim for utility model registration] Air gas mixing device 4 and zero governor 8 that automatically adjusts the gas supply amount according to the adjustment of the air supply amount
and a mechanism B for controlling the rotation speed of the air supply blower 1 based on the temperature detected by the water temperature detector 9 so that the water temperature is maintained at a set temperature. , a mechanism 17 that can switch the air supply amount into two stages, large and small, by changing the passage area of the air supply path 7; and a mechanism 18, which can switch the gas supply amount into two stages, large and small, by changing the passage area of the gas supply path 15. and a mechanism C that automatically and reversibly switches the switching mechanisms 17 and 18 to a small supply amount state when the temperature detected by the hot water temperature detector 9 rises above a certain level with respect to the set temperature. A combustion control device for hot water supply, characterized by being provided with. The air amount switching mechanism 17 is composed of a damper 17A that can swing between a fully open position and a closed position for the air supply path 7, and a solenoid 17B that switches and operates the damper 17A. A combustion control device for a water heater according to Scope 1. The gas amount switching mechanism 18 is connected to the gas supply path 15
The combustion control device for a water heater according to claim 1 or 2, which is constructed by interposing a solenoid valve 18B that can open and close the bypass passage 18A connected to the bypass passage 18A.