JPS5969614A - Control device for water heater - Google Patents

Abstract

PURPOSE:To prevent a sudden rise in the temperature of hot water even when the quantity of the hot water is suddenly reduced by a method wherein when an overshoot is detected, a brake means operates immediately so as to reduce the number of revolutions of a fan motor to a predetermined lowest value. CONSTITUTION:A switching element 21 (for example, a triac) is provided between a fan motor 5 and an AC power source 20 and a trigger signal (e) from a phase control circuit 22 is inputted to the switching element. Further, an overshoot detecting circuit 24 is provided in a PID control circuit 23 and a detecting signal is outputted to a brake control circuit 25. The fan motor 5 is provided with a r.p.m. detector 26 whose output is applied to a r.p.m. discriminating circuit 28 which is adopted to detect the lowest r.p.m. of the fan motor 5 and outputs the detected r.p.m. to the brake control circuit 25. The brake control circuit 25 operates such that when it receives a lowest r.p.m. discrimination signal, the brake means 27 is stopped to thereby return the number of revolutions of the fan motor to the original condition.

Description

[Detailed description of the invention]

(1) Field of the Invention This invention calculates a predetermined control amount from the deviation between the hot water outlet temperature and the target temperature by PrD calculation, controls the combustion state in the burner according to the outlet 'aω, and controls the operating temperature and water wetness. It relates to a tlltllll device for a water heater that operates to maintain the water temperature at a target temperature regardless of changes, and particularly relates to improvements in technology for suppressing overflow]-1 which occurs when changing the amount of hot water etc. (2) ) Problems with the prior art FIG.
A thermistor 2 that detects the hot water temperature of the heat exchanger 1, a temperature setting device 3 that sets the temperature, and a burner 4.
(supplies combustion air to the
A control circuit 6 is installed in the gas supply path to the burner 1, and controls the rotation speed of the fan motor 5 based on the deviation of the temperature and humidity detection signal from the target temperature setting signal of the target temperature setting device 3. The valve opening changes according to the blowing air pressure of the fan motor 5, and the valve operates so that the gas pressure supplied to the burner 4 is proportional to the air pressure! It has a pressure equalizing valve 7 as shown in the figure. At the water inlet leading to the heat exchanger 1, there is a Morrow switch 8 that detects the water flow passing through the heat exchanger 1 and inputs it to the control circuit 6 as a starter.

In the gas supply path leading to the pressure equalizing valve 7, a source valve 9 for turning on and off the supply of gas and a gas governor 10 are provided. igniter 1 that generates an ignition spark in connection with the Ishi-C burner 4;
First, a flame detector 12 is installed to detect whether the ignition is normally ignited by the ignition operation, and a wind pressure switch 13 is installed to check the operation of the motor 5. is the exhaustion performed by the control circuit 6.
This is a conceptual diagram showing IO operation, and this control system is configured by a feedback loop. Basic f according to Figure 2 below.
Explain l+ work. First, when the flow switch 8 detects the water flow in the heat exchanger 1, the control circuit 6
At the same time, the igniter 11 is turned on and the fan motor 5 is driven. Fan motor 5 feed 1!1f
As il increases toward a predetermined value, the opening degree of the pressure equalizing valve 7 increases in proportion to the air pressure (a), and gas combustion in the burner 4 grows toward a predetermined state. Next, when the thermistor 2 detects the -1-point of the hot water 111Hα from the heat exchanger 1, the control circuit i 6 t;L performs the operation shown in FIG. 2. That is, the deviation C between this i-edition detection signal a and the target temperature signal S is determined, and a predetermined control md is created by performing all PID calculations on this deviation C. Next, the phase angle of the rotating magnetic field that drives the rotor of the fan motor 5 is calculated and determined based on this control component 11, and the drive current of the fan motor 5 is thereby triggered (Fi The switching element controls the phase of the drive current of the motor 5 with the conduction angle determined by the trigger signal c, and under the rotating magnetic field of a predetermined phase caused by this, the switching element outputs a signal e. , I. The predetermined number of rotations increases.As a result, a predetermined air pressure f is transmitted to the pressure equalizing valve 7.As a result, the valve opening m of the pressure equalizing valve 7 becomes a predetermined opening degree, and the gas supplied to the burner 4 is adjusted appropriately. Become something,
Hot water temperature L:I: Controlled to be 4'i with the set humidity. The above operations are repeated to maintain the output IF temperature at the set temperature, and burner/ItJ: continues combustion with the predetermined gas m. If there is a change in the set temperature or outlet 1ffi, the change in outlet temperature is fed back, and -1
- The output i temperature is corrected by the control operation described above. By the way, as is well known, there is a response delay in starting and stopping the fan motor due to TM characteristics and the like. Diagram M3 shows this. When η is increased and the power supply is increased by A, the rotation speed of the fan motor increases with a rising time constant T1 and approaches a constant value. Furthermore, when the power supply is turned on (A), the rotational speed decreases from the constant value with a falling time constant T2. The time constants TI and T2 are generally about 6 seconds, but J causes the following Δ-basicote problem. It should be noted that although an under-shield 1--1.b occurs, this does not pose any practical problem and will be omitted from the above explanation. In Figure 4, if the hot water temperature is stably moving at 111 and the amount of hot water that comes out is suddenly decreased at time Ta, this is the hot water temperature that is 111. appears as P, 1, then l-'+t1'r
As described above, feedback control is performed to reduce the rotational speed of the motor. However, the Noan motor decreases the rotation speed by the falling time constant -r2.
. Then, the valve opening degree of the pressure equalizing valve follows the change of lp r, etc., and the gas m supplied to the burner corresponds to the high-output boiling point of No.3L change history nII at time Tb, J:, As a result, the hot water temperature reaches an all-time high. After time Tb, the valve opening of the 11 valves is reduced and the amount of waste supplied to the burner is suppressed, so this output fA
The temperature of 2m degrees decreases toward a constant temperature in the latter stage. This j; transient sudden rise in eel water temperature is over]-1. If the duration of this overshoot is short, the temperature of the hot water dispensed from the faucet will be only 10 I/r due to the reduction effect of the piping from the heat exchanger to the tap [1]. However, if the duration is longer than a few seconds, the peak level of the heat is high, so the piping reduction effect [) is insufficient, and the temperature measurement taken from the snake 1] reaches a considerable temperature. In some cases, hot water is poured out,
It's extremely dangerous. Therefore, in the past, an overshoot detection circuit was installed, and when the hot water temperature marked 1 rose from the set humidity to a predetermined hot stone level, it was judged as an overshoot, and at this time, the drive current of the fan motor was turned on and off. This problem was dealt with by performing phase calculations to minimize the conduction angle of the switching element -r and quickly reduce the rotational speed of the 7-arm motor. However, this results in a certain amount of A-Bachut Gel,
Although it can be reduced, the culm of this overshoot varies depending on the amount of decrease in the amount of hot water, etc., and the above-mentioned measure 1 is insufficient, and an effective countermeasure is desperately needed. (3) Object 1 of the Invention An object of the present invention is to provide a water heater control device that can effectively reduce overshoot regardless of its size. (4) Structure and effect of the invention In order to achieve the above object, the present invention includes 14 overshoot detection circuits for detecting an overshoot of 32°C.
A braking means that operates to act on the output shaft of the fan motor to prevent shaft rotation, and detects the rotation speed of the fan motor and discriminates when the rotation speed has become lower than a predetermined minimum rotation speed. a rotational speed detection means; and a braking control means for operating the braking means in response to a detection signal from the overshoot detection circuit and stopping operation of the braking means in response to a detection signal from the rotational speed detection means. It is characterized by having the following. According to this configuration, when an overshoot is detected, the braking means is immediately activated and the fan motor reaches a predetermined minimum rotation speed, so the overshoot is quickly suppressed and its peak level is extremely low. You can get it back. Therefore, even if the tapped hot water n1 is suddenly changed to a lower value, there is no sudden temperature rise of the tapped hot water. In addition, the duration of the overshoot is short<<K, and the predetermined amount of hot water of 1 g is delivered in a short time after changing the hot water supply, so that a water heater that is easy to use can be provided. 5〉Explanation of Embodiment FIG. 5 is a schematic diagram showing a control device according to the present invention, focusing on a drive circuit for a fan motor. In the figure, a switching element 21 (for example, a triac) is provided between the fan motor 5 and the AC power source 20, and the trigger signal e is inputted to the switching element 21 from the phase control circuit 22. The phase control circuit 22 is a circuit that performs the above-mentioned phase calculation,
Further, the PIDIII11 circuit 23 is a circuit that performs the above-mentioned PID calculation. This P I l) control circuit 23 is provided with the above-mentioned overshoot detection circuit 24, and this overshoot detection circuit 24 sends a detection signal to the braking control circuit 2.
Output to 5. 9-Fan [-A rotation speed detector 26 and a braking means 27
The detected value of the rotation speed detector 26 is given to the rotation speed discrimination circuit 28. The rotation speed discrimination circuit 28 discriminates the lowest rotation speed of the fan motor 5 and sends it to the braking control circuit 25. This braking control circuit 25 operates the braking means 27 upon receiving the overshoot detection signal, and stops the operation of the braking means 27 upon receiving the lowest rotational speed discrimination signal. In Fig. 6, the rotation speed detector 26 includes a rotary plate 31 fixed to the rotation shaft 5a of the fan motor 5 and a rotary sensor 32.The rotary plate 31 has a plurality of blades 31a arranged at equal intervals. A kind of impeller with 318.31 blades each.
A light transmitting portion 31b is formed between the portions a. The photosensor 32 includes a light emitting element 32a and a light receiving element 32b that transmit and receive light through the light transmitting section 31b. In FIG. 7, the braking means 27 is composed of a solenoid 35 and a brake belt 36. The solenoid 35 is
The coil 35a is excited and demagnetized by the output of the braking control circuit 25, and one end of the coil 35a is biased by a spring 35G, and the coil 35a is excited and demagnetized so as to freely move against the coil 35a. A movable iron core 35b that moves tJJl-d is provided. The brake belt 36 straddles the rotating shaft 5a of the fan motor 5, one end is fixed to a pin 37 erected on the side of the motor body 5b, and the other end is connected to a movable iron core 351 via a connecting rod 38. ) is connected to the other end. Next, the overshoot suppressing operation of the device of this embodiment will be explained with reference to FIG. First, when the hot water temperature is stable at a certain amount of hot water, the braking means 27 is not activated. In other words,
One end of the d-dynamic iron core 35b is biased by a spring 335C, and the other end pushes up the other end of the brake belt 36, so that the brake belt 36 is in contact with the rotating shaft 5a and is floating. Therefore, the Noan 5 rotates at a predetermined rotational speed in the direction of the arrow shown in the figure, and supplies a stable wind fik to the burner 4. Then, when the outlet hot water temperature is suddenly decreased at time Ta, the above-mentioned J: sea urchin hot water temperature starts to rise and eventually exceeds the overshoot detection circuit T, and the overshoot detection circuit 24 outputs a detection signal. In response to this overshoot detection circuit, the brake control circuit 25 supplies an exciting current to the coil 35a, so one end of the movable iron core 3511 overcomes the biasing force of the spring 35C and is attracted into the coil 35a, and the other The end strongly pulls the other end of the brake belt 36. As a result, the brake belt 36 comes into strong pressure contact with the rotating shaft 5a of the fan motor 5, and due to the frictional force, the rotation of the rotating shaft 5a is impaired and the number of revolutions rapidly decreases. Therefore, the air volume decreases without any time delay, and accordingly, the amount of gas supplied to the burner 4 decreases, and the combustion state shifts to low combustion. As a result, the stomach humidity of the water temperature rapidly declines, reaching a low peak temperature quickly, and A5 begins to decline. During this period, the rotation speed of the fan motor 5 is inputted to the rotation speed discrimination circuit 28 via the rotation speed detector 26, and the rotation speed discrimination circuit 28 detects that the rotation speed of the fan motor 5 is a predetermined minimum rotation speed (appropriate speed that does not lead to stopping). When the number of rotations exceeds the maximum number of rotations), a brake release signal is output. Upon receiving this brake release signal, the brake control circuit cuts off the excitation current supplied to the coil 35a. As a result, the braking means 27 operates as described above.
Rotation m +) - stops working. Therefore, after the braking time TO of the fan has elapsed, the rotational speed of the fan turns upward, and the air volume and supply gas level also start to increase. By this time, the hot water temperature has fallen below the overshoot detection mark T, and after that, the normal hot water temperature adjustment is performed for the changed output 1ffi by the PTD# mode operation and phase control operation described above. So, here we go! The peak level of the overshoot is low and its duration is short, and most of the time the temperature drops further due to the above-mentioned reduction effect of the piping, and the waFJt of the lagoon that actually comes out of the faucet is lower than the setting. It will not be much different from the temperature.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the warm water type that this invention targets, Fig. 2 is a conceptual diagram showing the hot water adjustment control system, Fig. 3 is a schematic diagram showing the inertial operation of the fan motor, and Fig. 4 is a schematic diagram showing the inertial operation of the fan motor. Figure 5 is an explanatory diagram of the overshoot generation process, Figure 5 is a schematic block diagram of an embodiment of the present invention with a focus on the driving circuit of the engine, and Figure 6 is a schematic diagram of the rotation. 7 is a schematic diagram showing an embodiment of the braking means; FIG. 8 is a schematic diagram illustrating the overshoe 1 to suppressing operation of the embodiment device of the present invention. It is a diagram. 1... Heat exchanger 2... Warm stone detector 3... tfA degree setting device 4... Burner 5...Fan motor 5a... Rotating shaft 6... Control circuit 24... Overshoot detection circuit 25...
... Brake control circuit 26 ... Rotation speed detector 27 ... Braking means 28 ... Rotation speed discriminator 35 ... Solenoid 35a ... Coil 35b ...Movable iron core 14-3G... Prem: 1. Belt/Special V1 Applicant: Tateishi Electric Co., Ltd. 15- 67- Range 5 Figure 5 68- Broom 6 Figure 2 Figure 7

Claims (2)

[Claims] (1) A temperature detector that detects the humidity of hot water coming out of the heat exchanger, a temperature setting device that sets the target temperature, a fan motor that supplies combustion air to the burner, a detection signal of the temperature detector, and the temperature setting device A control circuit that controls the rotation speed of the fan motor according to the deviation from the target thirst determination signal, and a valve opening that changes according to the air pressure of the fan motor to adjust the amount of fuel supplied to the burner. The control device is equipped with an overshoot detection circuit that detects an overshoot of the hot water temperature, and an overshoot detection circuit that acts on the output shaft of the fan motor. a braking means that operates to prevent the shaft from rotating; a rotational speed detection means that detects the rotational speed of the fan motor and determines when the rotational speed has fallen below a predetermined minimum rotational speed; The braking means is operated in response to a detection signal from the chute detection circuit, and the operation of the braking means is stopped in response to a detection signal from the rotation speed detection means. A control device for a water heater, characterized in that it is equipped with one stage of braking control. (2) The braking means includes a solenoid that is energized and demagnetized by J, .) in the braking control means, and a brake that is energized by this solenoid and presses against the output shaft of the fan motor when the solenoid is energized. A water heater control device according to claim 1, characterized in that the water boiler control device has a belt.