JPH0627574B2 - Blower fan controller for water heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for controlling the rotational speed of a blower fan that supplies combustion air to a combustor (burner) of a water heater.

(Background Art) In a conventional water heater, a proportional valve is provided in the gas passage, and the opening of the proportional valve is changed according to the current value of the proportional valve, thereby controlling the amount of gas supplied to the combustor. ing. On the other hand, the blower fan that supplies combustion air to the combustor detects the proportional valve current and controls the fan speed in proportion to the proportional valve current. That is, when the fan speed is N, the proportional valve current is i, and the proportional constant is β, the fan speed is determined by the relationship of N = β × i.

However, the combustion capacity of the combustor may also vary when the proportional valve is fully opened due to various reasons such as the difference in calories of the gas supplied to the gas passage and fluctuations in the gas pressure. At times, the combustor may overpower.

Therefore, the proportional valve current has the maximum value (the maximum opening of the proportional valve)
In a normal operating state where the temperature has not reached the maximum, even if the fan speed may be controlled according to the OA line in FIG. 4,
It is necessary to consider the output over at the time of full opening of the proportional valve and design it so that the air volume has a margin. For this reason,
When the proportional valve current has the maximum value, the fan rotation speed is set to a point B which is larger than the point A, and the fan rotation speed is controlled according to the OB line even in the normal operating state.

Thus, in the conventional case, when the proportional valve is not fully opened, the fan rotation speed shown by the OA line may be used, but the control is performed by the OB line having a larger rotation speed than that. Therefore, there is a problem that the operating energy of the blower fan is wasted, the efficiency is low, and the noise is large.

Therefore, the applicant of the present application previously detected in Japanese Patent Application No. 1-15140 (Japanese Utility Model Application No. 2-106540) that the proportional valve reached the maximum opening degree, and detected from the temperature detecting means and the water amount detecting means. The actual output of the combustor is calculated based on the signal, this actual output is compared with the specified output, and if the actual output is greater than the specified output when the proportional valve reaches the maximum opening, the fan rotation speed of the blower fan I have proposed what increases.

(Problems to be Solved by the Invention) However, if the number of rotations of the fan is increased to a position corresponding to the actual output, the efficiency of the heat exchanger changes,
In some cases, the actual output dropped and fell below the specified output. And the rotation speed of the fan decreases and returns to the OA line,
When it returns, the efficiency will rise again, the actual output will exceed the specified output, and the number of rotations will increase,
The rotation speed of the blower fan caused hunting.

(Means for Solving the Problem) Therefore, the blower fan control device of the water heater according to the present invention includes a heat exchanger, a water amount detecting unit that detects a flow rate of a water passage that is continuous with the heat exchanger, and an incoming water temperature of the heat exchanger. And a temperature detecting means for detecting the hot water temperature, a combustor for heating the heat exchanger, a proportional valve provided in a gas passage connected to the combustor, a blower fan for supplying combustion air to the combustor, and the temperature. The actual output of the combustor is obtained based on the detection means and the detection means from the water amount detection means, and this actual output is compared with the designated output that is stored after the actual output is calculated in advance. If it is larger, the controller is provided with a controller for sequentially increasing the fan rotation speed of the blower fan step by step by a timer.

(Operation) In the present invention, if the actual output is larger than the specified output that is stored after the actual output is calculated in advance, the fan rotation speed is shifted in a stepwise manner at regular intervals by the timer. Therefore, even if the efficiency of the heat exchanger changes, the amount of change is small and the actual output does not become less than the specified output.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a heat exchanger 1 is provided in the water channel 2, and a water thermistor 4 for detecting the temperature of the water and a water amount sensor for detecting the water flow rate are provided on the water inlet side of the water channel 2. 3, a hot water outlet thermistor 5 for detecting the temperature of the hot water and a water amount servo valve 1 are provided on the hot water outlet side of the water channel 2.
7 is provided.

The combustor 6 for heating the heat exchanger 1 is provided with a blower fan 9 for supplying combustion air to the combustor 6.
A rotation speed sensor 20 for detecting the rotation speed of the blower fan 9 is attached to the blower fan 9. In the gas passage 7 for supplying gas to the combustor 6, a proportional valve 8
And a pair of solenoid valves 15 and 16 are provided.

This water heater is controlled by a controller 10 using a microcomputer, and the controller 10 has a structure as shown in FIG. 2, for example. The detection signals from the water amount sensor 3, the incoming water thermistor 4, and the hot water thermistor 5 are input to the arithmetic and control unit 13 (microcomputer), and here the flow rate W of the water channel 2 and the hot water temperature T before and after the heat exchanger 1 are input. A temperature difference t between _H and the incoming water temperature T _C is detected. The arithmetic control unit 13 then outputs the actual output of the combustor 6. And a comparison / judgment function for comparing the actual output with a designated output stored in advance and stored. The valve drive unit 19 drives the water amount servo valve 17 to control the amount of water flowing through the water channel 2. The arithmetic control unit 13 controls the valve drive unit 19 by an input signal from a switch panel (not shown) or the like. The signal is output. The valve drive unit 18 controls the opening / closing of the solenoid valves 15 and 16 and controls the current value of the proportional valve 8 to change the opening degree (gas amount) of the proportional valve 8. The control signal is output to the drive unit 18. The proportional valve current that controls the opening of the proportional valve 8 is detected by the proportional valve current detection unit 11, and the fan rotation speed control unit 12 outputs the proportional valve current i by the signal from the arithmetic control unit 13 in the normal operation state. The blower fan 9 is operated at the fan rotation speed N proportional to (that is, N = α × i: α is a proportional constant). Further, the fan rotation speed control unit 12 can shift to an operating state at the time of output over by a signal from the arithmetic control unit 13, and in a steady state of this operation state, the fan rotation number α × when the proportional valve current is maximum. _K of i _{0 0} (> 1) times the fan speed _{K 0 (α} × _{i 0)} next, it is possible to operate the blowing fan 9 at high fan speed. The constant K is gradually increased when shifting to the operating state when the output is over. That is, the first constant K ₁ is K
₁ = (K ₀ +1) / 2, and the next constant K ₂ is K ₂ =
(K ₁ +1) / 2, the nth constant K _n is K _n = K
_{It is set to n-1} +1) / 2. Further, the signal from the rotation speed sensor 20 is input to the arithmetic control unit 13, and the fan rotation speed is feedback-controlled by the controller 10. The arithmetic control unit 13 determines that the proportional valve current has the maximum value i based on the signal from the proportional valve current detection unit 11.
It is determined whether or not ₀ has been reached, and when the proportional valve current reaches the maximum value i ₀ and a preset fixed time has elapsed, a rotation speed change command is output to the fan rotation speed control unit 12.

The calculation control unit 13 of the timer 14 is the fan rotation speed control unit 1
It is set when the rotation speed change command is output to 2, and the time counting time is a time in consideration of the delay from the change in the rotation speed until the efficiency is affected. Does not output a new rotation speed change command.

The timer 14 is set when the actual output calculated by the arithmetic control unit 13 exceeds the designated output.

Then, in the normal operation state where the proportional valve current does not reach the maximum value, the blower fan 9 is controlled according to N = α × i and according to the OA line in FIG.

On the other hand, the controller 10 detects whether the output of the combustor 6 is over, according to the flowchart as shown in FIG. 3, and if it is over output, changes the control mode so as to increase the fan rotation speed. That is, it is determined whether or not the proportional valve current has reached the maximum value i ₀ , and if not, it is determined whether or not the normal operation state is continued and the proportional valve current has reached the maximum value again. If the proportional valve current reaches the maximum value i ₀ (point A in FIG. 4), the arithmetic control unit 13 compares the actual output with the designated output, and when the proportional valve 8 is fully opened, the combustor 6 outputs too much. Judge if not.
If the actual output is less than or equal to the specified output, the fan speed N
Continues to be in the normal operating state with α × i ₀ . If the actual output signal is larger than the designated output, the set signal is output to the timer 14. The set timer 14 performs a time counting operation, and if the actual output signal becomes equal to or less than the designated output signal by the time when a preset fixed time elapses, the arithmetic control unit 1
It is reset by the reset signal from 3. This timer is provided to discriminate between the apparent output over-state and the actual output over-state. Then, after a certain period of time has passed, the calculation control unit 1 is started from the timer 14.
When the count-up signal is input to 3, it is determined that the output is actually over, and the fan speed N is K.
It is doubled to N = Kα × i ₀ , and the air flow rate increases. At this time, if the number of rotation speed changes is the first, K = (K ₀ +1) / 2. At the same time when the rotation speed is changed, the timer 14 is set. When the number of rotations changes and the amount of blown air increases, the efficiency of the heat exchanger 1 decreases, the outlet heated water temperature decreases, and the actual output decreases. However, since there is a delay until the hot water discharge thermistor 5 detects the hot water discharge temperature after the amount of blown air changes and it takes time for the state to stabilize, the rotation speed is not changed anew while the timer 14 is counting. In the first increase in the number of revolutions, the amount of increase is half that in the steady state, so the efficiency does not decrease significantly, and even if the actual output decreases, it does not fall below the specified output. When the state stabilizes after the first increase, the fan speed is increased K times again. At this time, since it is the second rotation, the constant K becomes K = (K ₁ +1) / 2, which is an intermediate rotation speed between the first rotation speed and the steady-state rotation speed. Then, like the first time, after the time of the timer 14 is up, the number of revolutions is increased to the next number. Then, repeat this operation multiple times, K
When n becomes sufficiently close to Ko, k = Ko is set, and the rotational speed is stable when the output is over. As a result, the water heater shifts to the state of point B in FIG. 4, becomes a stable steady state, and there is a margin in combustion.

Incidentally, when the after actual output comes down, the Ko Kn, or K _n and K _n-1, may be lowering the fan speed.

Further, if the proportional valve current drops from the maximum value io after this, the fan rotation speed may be controlled again along the OA line, or after the fan rotation speed once shifts to the point B, the OB line is changed. The fan rotation speed may be controlled accordingly.

(Effect of the Invention) According to the present invention, when the proportional valve is fully opened and the output is over, the fan rotation speed is gradually increased stepwise by the timer at a certain time to increase, so that the transitional period is not increased. The actual output does not fall below the specified output, fan hunting is eliminated, and it is now possible to quickly reach the rotational speed that corresponds to the actual output when the output is over. Then, when the output is over, a larger air flow than in the normal operating state can be sent to the combustor. On the other hand, if the proportional valve has not reached the maximum opening or if the output has not actually exceeded even if it has reached the maximum opening, the blower fan can be operated at a low fan rotation speed. It is possible to reduce the noise caused by, and to improve the blowing efficiency by operating the blowing fan at an appropriate fan rotation speed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the same controller, FIG. 3 is a flowchart showing a control method of the same, and FIG. 4 is a blower fan of the same. 3 is a graph showing the relationship between the number of revolutions and the combustion ability of the combustor. FIG. 5 is a time chart showing a transition state at the time of output over in the same as above. FIG. 6 is a time chart of the transition state when the output is over in the related art. 1 ... Heat exchanger 2 ... Water channel 3 ... Water amount sensor 4 ... Inlet thermistor 5 ... Outflow thermistor 6 ... Combustor 7 ... Gas channel 8 ... Proportional valve 9 ... Blower fan 10 ... Controller

Claims (1)

[Claims] 1. A heat exchanger, a water amount detecting means for detecting a flow rate of a water channel connected to the heat exchanger, a temperature detecting means for detecting an incoming water temperature and a hot water temperature of the heat exchanger, and a combustion for heating the heat exchanger. , A proportional valve provided in a gas passage connected to the combustor, a blower fan for supplying combustion air to the combustor, and an actual output of the combustor based on detection signals from the temperature detection means and the water amount detection means This actual output is compared with a designated output that is stored after calculating the actual output in advance, and if the actual output is larger than the designated output, the fan rotation speed of the blower fan is sequentially stepped by a timer at regular intervals. And a controller for increasing the volume of the fan.