JPH03260552A - Controller of water heater - Google Patents

Abstract

PURPOSE:To reduce a change in the temperature of hot water and to supply the hot water at a stable temperature by a method wherein a flow rate being suitable for heating by a heating means is calculated from a water temperature and a set temperature and determined as a target flow rate for the set temperature and a flow rate adjusting means is controlled so that this target flow rate can be obtained. CONSTITUTION:A target flow rate W0 being suitable for heating to a set temperature Tset is calculated on the basis of the heat exchange rate of a heat exchanger 16 and the heating capacity of a burner so that it corresponds to a temperature difference from a water temperature Tin. When the target flow rate W0 is set and when there are neither alteration of the set temperature Tset nor change in the water temperature Tin thereafter and consequently the target flow rate W0 is not altered, a detected flow rate W by a flow sensor 17 is compared with the target flow rate W0. When the detected flow rate W is smaller than the target flow rate W0, a normal rotation operation of a geared motor of a water quantity control device 19 being driven for normal rotation is made as an operation for increasing a flow rate, and when the detected flow rate W is larger than the target flow rate W0, a reverse rotation operation of the geared motor of the water quantity control device 19 being driven for reverse rotation is made as an operation for reducing the flow rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention controls the flow rate passing through a heat exchanger using a water flow control device so as to supply as much hot water as possible according to a set temperature. The present invention relates to a control device for a water heater.

[Prior Art] In water heaters, the maximum heating capacity that can be obtained by gas burners, etc. for heating the water passing through the heat exchanger is limited, so the water circuit including the heat exchanger is equipped with a valve body using a geared motor. The heat exchanger is equipped with a water flow control device that controls the flow rate by driving the heat exchanger, and limits the flow rate of water passing through the heat exchanger so that the temperature of the outflowing water reaches a set temperature.

In this case, in addition to simply restricting the flow rate, in order to obtain as much flow rate as possible for the set temperature, it is necessary to adjust the set temperature and the temperature of water entering the heat exchanger to match the maximum heating capacity of the gas burner, etc. Calculate the maximum hot water supply amount,
The water amount IVIIIw device is controlled so that the maximum amount of hot water is obtained.

At this time, the water flow control device is controlled based on the detected flow rate of the flow rate sensor that detects the flow rate of water passing through the heat exchanger,
Since the geared motor is stopped when the detected flow rate reaches the calculated maximum hot water supply amount, the geared motor drives the valve body relatively slowly.

[Problem to be solved by the invention] As described above, in the past, the geared motor was driven smoothly because the water flow control device had to be stopped when the predetermined maximum flow rate was detected. However, it takes time to change the opening degree using the water flow rate device, and the desired flow rate cannot be obtained quickly.

Therefore, in order to quickly obtain the desired flow rate, it is possible to increase the rotational speed of the geared motor, but in this case, the control to stop the geared motor must be performed after detecting that the detected flow rate has reached the target value. However, because the geared motor operates at high speed, the valve body of the water flow control device does not stop immediately, making it difficult to stop it correctly at the target opening, and causing the valve to change the opening beyond the target value. As a result, so-called hunting occurs in which the opening degree increases or decreases around the target opening degree, causing problems such as the flow rate being unstable and the tapping temperature becoming unstable.

The present invention provides a water heater that adjusts the amount of hot water supplied by a water flow control device, which can quickly obtain a flow rate that maximizes the heating capacity of the water heater, and can supply hot water at a stable temperature with little change in the hot water temperature. The purpose is to provide a control device that can perform the following steps.

[Means for Solving Eight Problems] The present invention provides a temperature setting means for setting the temperature of hot water flowing out from a water circuit including a heat exchanger heated by a heating means, and a temperature setting means for setting the temperature of water flowing into the water circuit. The temperature difference between the temperature set by the temperature setting means and the temperature detected by the water inflow temperature detection means is provided. In the water heater control device, the water heater control device controls a flow rate adjusting means that adjusts the flow rate of hot water passing through the water circuit based on the detected flow rate of the flow rate detecting means, the flow rate adjusting means controlling the flow rate according to the flow rate change. small first
and a second operation with a larger change in flow rate than the first operation, and the control device includes target flow rate determining means for determining a target flow rate based on the set temperature and the detected temperature; a storage means for storing information that the operation has been performed, the flow rate adjustment means is driven so that the flow rate detected by the flow rate detection means becomes the target flow rate, and the second operation is performed at the time of the driving. The technical means is to perform the second operation if the device has not been used, and to perform the first operation if the second operation has been performed.

[Function] In the present invention, the flow rate that can be heated by the heating means is calculated from the incoming water temperature and the set temperature with respect to the set temperature set by the temperature setting means, and determined as the target flow rate, and this target flow rate is obtained. The flow rate adjustment means is controlled so that the

When controlling the flow rate adjusting means, if the storage means does not store that the second operation with a large change in flow rate has been performed, the second operation is performed to quickly change the flow rate.

In this case, even if the drive of the flow rate adjustment means is stopped when the flow rate detection means detects that the target flow rate has been reached, the speed of change of the valve body, etc. of the flow rate adjustment means is fast, so it must be stopped at an appropriate position. As a result, the flow rate is changed excessively, and if the flow rate is initially driven to increase, the flow rate is decreased, and if the flow rate is initially driven to decrease, the flow rate is changed. , that is, in a direction opposite to the initial driving direction.

When driving in the first direction again after being driven in the opposite direction, it is remembered that the second operation with a large flow rate change was performed, so the first speed with a smaller change rate than the second operation is used. The flow rate adjusting means is driven and when the target flow rate is reached, the drive is stopped.

[Effects of the Invention] According to the present invention, when the flow rate adjusting means is driven for the first time after the target flow rate is determined, it is driven in the second operation with a large flow rate change, so that the target flow rate can be quickly approached. .

In addition, after the flow rate approaches the target flow rate, the flow rate is driven by the first operation with a small change in flow rate, so the flow rate adjustment means can be appropriately stopped when the detected flow rate reaches the target flow rate. This prevents the flow rate from becoming unstable due to hunting or the like after it approaches the target flow rate.

Therefore, changes in the flow rate are reduced and the temperature of the tapped water is quickly stabilized.

Further, since the maximum flow rate is determined based on the set temperature and the water inlet temperature according to the heating capacity of the heating means, many possible flow rates can be obtained for the set temperature.

[Example] Next, the present invention will be explained based on examples.

In a gas water heater 1 whose outline is shown in FIG. 2, a burner plate 11 made of ceramics is disposed inside a water heater case 10.
The combustor is divided into a combustion chamber 10a and a mixing chamber 10b, and a blower 12 is provided below the water heater case 10 for supplying combustion air.

The blower 12 includes an impeller 12b inside a scroll casing 12a, and is driven by a DC motor (not shown).
2b is rotated. The scroll casing 12a is provided with a nozzle 13 for ejecting fuel gas.

A large number of flame ports 11a are formed on the burner plate 11,
The water heater case 10 and the burner plate 11 form a total air burner that burns only with primary air supplied by the blower 12, and combustion exhaust gas is discharged to the outside of the water heater case 10 from an exhaust port (not shown). In addition, mixing chamber 10
A rectifier plate 10c provided with a large number of holes is disposed within b in order to equalize the air-fuel mixture supplied by the blower 12 to the burner plate 11.

In the combustion chamber 10a, an ignition electrode 14 for performing spark discharge and a thermocouple 15 for detecting the temperature of the burner plate 11 are provided near the burner plate 11.

A heat exchanger 16 is disposed within the combustion chamber 10a, and a water supply pipe 16 upstream of the heat exchanger 16 is connected to a water supply source (not shown).
A is equipped with a flow rate sensor 17 that detects the amount of incoming water by rotating an impeller with the water flow, an incoming water temperature thermistor 18 that detects the temperature of the incoming water, and a water amount control device 19 that adjusts the amount of incoming water, and is connected to the hot water tap 20. A hot water outlet pipe 16b downstream of the heat exchanger 16 is provided with a hot water outlet temperature thermistor 21 for detecting the temperature of heated hot water.

The water amount control unit 219 is a flow rate adjusting means that adjusts the flow rate using a valve body driven by a geared motor.

On the other hand, in the fuel pipe 25 that guides the fuel gas to the nozzle 13, there are solenoid valves 26.2 and 26.
7, and a governor proportional valve 28 that adjusts the pressure on the downstream side of the fuel gas according to the current value.

The gas water heater 1 having the above-mentioned tank bottom has a control unit f40 centered on a microcomputer that performs necessary control operations according to a pre-installed program.
controlled by

As shown in FIG. 3, the control device 40 includes a temperature control section 41.
, a combustion control section 42, a water flow control section 43, and a sequence control section 44 that controls the entire sequence such as ignition control, and is externally equipped with a controller 50 for setting a target hot water temperature. ing.

The functions of each front section will be explained below.

The temperature control unit 41 calculates a feedforward control amount (as the combustion amount of the burner) from the inlet water temperature detected by the hot water supply start water temperature thermistor 18, the set temperature set by the controller 50, and the flow rate detected by the flow rate sensor 17. The combustion amount Q is finally determined by calculating the FF control amount>Q22 and adding the feedback control amount (FB control amount>Q□) based on the exit hot water temperature detected by the exit hot water temperature thermistor 21.

In this case, the determined combustion amount Q is determined by comprehensively determining the maximum combustion amount Q based on the shape and volume of the water heater case 10, the size and flame port of the burner plate 11, the diameter of the nozzle 13, the characteristics of the governor proportional valve 28, etc. laX and minimum combustion amount QlaX
is determined, and the combustion amount Q is determined within that range.

The combustion control section 42 controls the voltage applied to the DC motor of the blower 12 according to the combustion amount Q determined by the temperature control section 41 .

Further, the rotation speed detection unit 42a detects the rotation speed of the motor of the blower 12, and controls the current value to the governor proportional valve 28 in accordance with the detected rotation speed.

Note that the blower 12 does not operate until a predetermined period of time has elapsed after ignition.
In order to supply more fuel gas than the supply amount corresponding to the rotation speed, the current value to the governor proportional valve 28 is increased.

After the predetermined time has elapsed, based on the output voltage of the thermocouple 15, the fuel supply amount for air-fuel ratio correction is calculated based on the excess or deficiency of the combustion temperature with respect to the rotation speed of the blower 12.
A corrected current value corresponding to the corrected fuel gas is applied.

In this case, in order to eliminate sudden changes in the air-fuel ratio,
The current value is changed gradually over a period of, for example, about 10 seconds.

The water flow control unit 43 adjusts the flow rate of water passing through the heat exchanger 16 using the water flow control device 19, and opens the water flow control device 19 according to the outlet temperature so that as much flow as possible can be obtained for the set temperature. Controls the degree change.

Here, the set temperature Tset by the controller 50 and the inlet water temperature Ti detected by the inlet water temperature thermistor 18 are
n, the flow rate that can be heated in the gas water heater 1 is calculated in advance and set as the target flow rate W0, and the water flow control device 19 is controlled so that the target flow rate W0 is achieved.

In this case, the water flow control device 19 rotates forward or reverse by changing the direction of the voltage applied to the geared motor to increase or decrease the flow rate, and also changes the magnitude of the applied voltage for each direction of rotation. By doing so, it is possible to perform a first operation of driving at a low speed and a second operation of driving at a high speed.

Below, an outline of flow rate control by the water amount control device 19 will be explained with reference to FIG. 1.

In the flow rate control, as described above, once the set temperature T set is determined by the controller 50, the target flow rate W0 that can be heated to the set temperature T Set according to the temperature difference from the inlet water temperature Tin is determined by the heat exchange rate of the heat exchanger 16. It is calculated based on the heating rate and the heating capacity of the burner (Step 1).

After the target flow rate W0 is determined, if the target flow rate W0 is not changed because there is no change in the set temperature Tset or inlet water temperature Tin (NO in step 2), the flow rate W detected by the flow rate sensor 17 is compared with the target flow rate W0. be done.

If the detected flow rate W is less than the target flow rate W0 (step 3
In "<"), as an operation to increase the flow rate,
A forward rotation operation is performed in which the geared motor of the water flow control device 19 is driven forward (step 4), and the detected flow rate W is changed to the target flow rate W.
If the amount is greater than 0 (“〉” in step 3), a reverse operation in which the geared motor of the water flow control device 19 is driven in reverse is performed as an operation to reduce the flow rate (step 5) in steps 4 and 5, respectively. After the water flow control device f19 is controlled, the process moves to step 1, and if the detected flow rate W is the target flow rate W0 (r-'' in step 3), the water flow control device 19 is not driven and the process moves to step 1. do.

Thereafter, that state is maintained unless the target flow rate W0 is changed.

On the other hand, if the target flow rate W0 is changed due to a change in the set temperature TSet or the inlet water temperature Tin (step 2
(YES in Step 4 or Step 5) - The memory of the second operation described later in Step 4 or Step 5 is cleared (Step 6>, the initial state in which the second forward rotation operation or the second reverse rotation operation is not performed in Step 4 or Step 5) Control is performed as follows.

Next, the forward rotation operation in step 4 will be explained with reference to FIG. 4.

In the normal rotation operation, it is determined whether or not a second normal rotation operation has been performed in which the geared motor of the water flow control device 19 is rotated in the normal direction at high speed. ), performs the second normal rotation operation (step 1
2).

When the second forward rotation operation is performed, it is stored in the storage device of the microcomputer.

The second normal rotation operation occurs when the detected flow rate W is less than the target flow rate W0 (No in step 13), and when the detected flow rate W becomes the target flow rate W0 (YES in step 13)
, the power supply to the geared motor is stopped and the water control device 19
When the drive is completed, step 14) ends the flow rate increasing operation.

When performing forward rotation operation, if it is stored that the second forward rotation operation has been performed (YES in step 11)
, the geared motor performs a first normal rotation operation in which the rotational speed of the geared motor is lower than that of the second normal rotation operation (step 15).

Similarly to the second normal rotation operation, the first normal rotation operation occurs when the detected flow rate W is less than the target flow rate W0 (No in step 16), and when the detected flow rate W reaches the target flow rate W0 (YES in step 16). , the power supply to the geared motor is stopped and the driving of the water flow control device 19 is terminated.Step 1
4) Finish the flow increase operation.

Next, the reversal operation in step 5 will be explained.

In the reverse rotation operation, as shown in FIG. 5, only the direction of the voltage applied to the geared motor is reversed, and the control operation is exactly the same as the normal rotation operation.

In reverse operation, water flow control device! It is determined whether or not a second reverse operation has been performed to reverse the gad motor No. 19 at high speed. If the second reverse operation has not been performed (NO in step 21), the second reverse operation is performed (step 22). 〉.

When the second reversal operation is performed, it is stored in the memory device of the microcomputer.

The second reverse operation occurs when the detected flow rate W is less than the target flow rate W0 (No in step 23>, YES in step 23 when the detected flow rate W becomes the target flow rate W0)
, the power supply to the geared motor is stopped and the water flow control device 19
When the drive is completed, step 24) ends the flow rate reduction operation.

When performing a reversal operation, if it is stored that the second reversal operation has been performed (YES in step 21)
, a first reverse operation is performed in which the geared motor has a lower rotational speed than the second reverse operation (step 25).

Similarly to the second reverse operation, the first reverse operation occurs when the detected flow rate W is less than the target flow rate W0 (NO in step 26), and when the detected flow rate W reaches the target flow rate W0 (YES in step 26), the geared motor Step 24
〉, the flow rate reduction operation ends.

The sequence control unit 44 performs ignition control in a predetermined sequence when the flow rate sensor 17 detects the inflow of water into the heat exchanger 16, and performs extinguishing control when the stoppage of the inflow is detected.

Further, ignition is detected by a thermocouple 15, and if a misfire occurs, the supply of fuel gas is stopped for safety.

Next, the operation of the gas water heater 1 of this embodiment having the tank bottom described above will be explained with reference to FIG. 6, focusing on water flow control.

When the user operates the hot water faucet 20 to start hot water supply and the flow of water is detected by the flow rate sensor 17, ignition control is performed in a predetermined sequence, the solenoid valves 26 and 27 are opened, and the ignition is started. A spark discharge occurs at the electrode 14 to ignite.

At this time, the water flow control device 19 is maintained at the same opening as when it was used last time, and water flows through the heat exchanger 16 at a flow rate determined according to the opening of the hot water tap 20 and the pressure of the water supply source such as the water supply. pass.

During this ignition control, the temperature control section 41 controls the blower 1112 and the governor proportional valve 28 by setting the feedforward control amount (FF control l) Q□ to the combustion amount Q as an initial control.

Further, a target flow rate W0 as the maximum amount of hot water that can be heated is calculated from the set temperature TSet and the incoming water temperature Tin, and the flow rate W detected by the flow rate sensor 17 is the target flow rate W. As if to shout,
The water amount control device 19 is driven.

At this time, for example, the set temperature T
When the target flow rate W0 is changed by lowering Set and becomes higher than the previous time, a forward rotation operation is performed to increase the flow rate.

In this case, since the memory of the second normal rotation operation is cleared by changing the target flow rate W0, the second normal rotation operation with a large flow rate change is initially performed.

The operation continues until the detected flow rate W reaches the target flow rate W0, and when the target flow rate W0 is detected, the water flow rate control device 1
9 is stopped. Therefore, the flow rate quickly approaches the target flow rate W0.

However, since the geared motor of the water flow control device 19 is driven at high speed, the target flow rate W is low. Even if the current is immediately stopped after detection, the valve body of the water flow control device 19 continues to change, and the flow rate becomes the dotted flow rate, which is higher than the target flow rate W0, as shown by the solid line in Fig. 6. Put it away.

Therefore, a reverse operation is performed to reduce the flow rate.

In this case as well, since the second reversal operation is not stored,
The second reverse operation is performed to reduce the flow rate, but the target flow rate W
Even if 0 is detected and the water flow control device 19 is stopped, as shown at point M, the flow rate is reduced too much and the water flow control device 19 is stopped.

After that, the normal rotation operation is performed again to increase the flow rate, but at this time, since the second normal rotation operation is stored, the geared motor of the water flow control unit f19 is driven in the normal rotation at a low speed fixed rotation. be done. Therefore, as shown by the arrow N, the flow rate can be gradually changed and gradually increased, and the target flow rate W0
If the drive is stopped when detecting the
can be set to an appropriate opening degree to obtain the target flow rate W0.

In addition, when the detected flow rate W is larger than the target flow rate W0, as shown by the broken line in FIG. 6, the flow rate is adjusted to the target flow rate W0 by an operation opposite to that described above.

After that, a feedback control amount (FB control amount) Qo including the temperature detected by the hot water temperature thermistor 21 is added to the combustion amount Q.
is determined.

As described above, in this embodiment, by giving the water flow control device two types of operation, it is possible to quickly obtain an appropriate flow rate corresponding to the set temperature Tset and the water input temperature Tin, and to maximize the hot water supply capacity of the water heater. It can be utilized to the maximum extent possible.

Further, since hunting does not occur near the target flow rate WO, the temperature of the hot water quickly stabilizes, so it can be used with peace of mind.

In this embodiment, all of the water supplied from the water supply pipe passes through the heat exchanger, but by connecting the water supply pipe and the hot water outlet pipe with a bypass pipe, some of the water supplied from the water supply pipe is connected. A water heater may also have a water circuit with a bypass pipe that prevents the water from passing through the heat exchanger.

In this embodiment, the controller allows the temperature of hot water to be freely set, but the set temperature may be fixed.

Although this embodiment shows a combustor with a ceramic burner plate arranged inside the casing, the burner plate may be made of metal, or may be a sheet metal burner or a cast burner other than the burner plate.

In this embodiment, a gas water heater is shown, but the heating source is not limited to gas, and may be an oil burner or an electric water heater.

[Brief explanation of drawings]

Fig. 1 is a flowchart for explaining the operation of the control device of this embodiment, Fig. 2 is a schematic diagram of the tank bottom of a gas water heater according to this embodiment of the present invention, and Fig. 3 is a flowchart for explaining the operation of the control device of this embodiment. FIG. 4 and FIG. 5 are flowcharts for explaining the operation of the control device, and FIG. 6 is a flow chart for explaining the operation of the gas water heater of this embodiment. In the figure, 11... burner plate (heating means), 16...
...Heat exchanger, 17...Flow rate sensor (flow rate detection means)
, 18... Inlet water temperature thermistor (inlet water temperature detection means),
19...Water flow rate control device (flow rate adjustment means), 40...
Control device (target flow rate determination means, storage means), 50...
Controller (temperature setting means).

Claims (1)

[Scope of Claims] 1) Temperature setting means for setting the temperature of hot water flowing out from a water circuit including a heat exchanger heated by a heating means, and incoming water temperature detection means for detecting the temperature of water flowing into the water circuit. , comprising a flow rate detection means for detecting the flow rate passing through the water circuit, and controlling the heating means based on a temperature difference between a temperature set by the temperature setting means and a temperature detected by the water input temperature detection means. , a control device for a water heater that controls a flow rate adjustment means that adjusts the flow rate of hot water passing through the water circuit based on the flow rate detected by the flow rate detection means, wherein the flow rate adjustment means performs a first operation with a small change in flow rate. , and a second operation in which the flow rate change is larger than the first operation, and the control device includes a target flow rate determining means for determining a target flow rate based on the set temperature and the detected temperature, and a second operation in which the second operation is performed. and a storage means for storing information on the flow rate adjustment means, the flow rate adjustment means being driven such that the flow rate detected by the flow rate detection means becomes the target flow rate, and the second operation is not being performed at the time of the driving. In this case, the second
A control device for a water heater, characterized in that the control device performs an operation, and performs the first operation if the second operation is performed.