JPH0456217B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a fuel supply system that automatically adjusts the amount of fuel supplied by calculating the required amount of heat based on the temperature difference between the set temperature and the incoming water temperature and the amount of incoming water. This invention relates to a water heater that employs eid-forward control.

[Prior Art] Conventionally, a water heater control device calculates the target combustion capacity of a burner based on the temperature difference between the set temperature and the incoming water temperature and the amount of incoming water, and adjusts the feed rate based on the target combustion capacity. When performing word control, the target combustion capacity can be output as is, or the amount of fuel supplied can be automatically adjusted so that the burner burns with the output of a component proportional to the target combustion capacity until a certain period of time has elapsed as an initial setting value. I was adjusting.

[Problems to be Solved by the Invention] However, in the conventional water heater control device, regardless of whether the initial value of the hot water temperature is high or constant, feedforward control is performed using at least the combustion capacity based on feedforward calculation. As a result, there was a problem that the burner's combustion ability was too strong when the hot water temperature was high during intermittent use. Therefore, there was a problem that the hot water temperature did not approach the set temperature.

An object of the present invention is to provide a water heater that corrects the required amount of heat of a burner based on the hot water temperature even during feed forward control, so that the hot water temperature quickly approaches the set temperature.

[Means for Solving the Problems] The present invention provides: a burner that burns fuel; a fuel supply amount control means that controls the combustion capacity of the burner by adjusting the amount of fuel supplied to the burner; a heat exchanger that heats the water by exchanging heat between the water passing through the burner and the combustion heat of the burner; and an inlet that is provided upstream of the heat exchanger and detects the temperature of water flowing into the heat exchanger. water temperature detection means; inflow water amount detection means for detecting the inflow amount of water passing through the heat exchanger; outlet hot water temperature detection means for detecting the outlet temperature of water flowing out from the heat exchanger; a temperature setting means for setting a preset temperature; a first calculation value that is a required amount of heat based on the temperature difference between the preset temperature and the incoming water temperature and the amount of incoming water; Calculate a second calculated value based on the amount of water input, and based on the comparison result between the first calculated value and the second calculated value, calculate a slow rate that produces an output that has approximately the same amount of heat as the required amount of heat. One of three areas consisting of a heating area, a rapid heating area that produces an output with a larger amount of heat than the required amount of heat, and a residual heat purge area that produces an output with an amount of less heat than the required amount of heat, is set to the set temperature and the hot water is tapped. control means that performs feedforward control that automatically adjusts the amount of fuel supplied in accordance with the selected slow heating region, rapid heating region, and residual heat purge region; adopted technical means with

[Function] The present invention calculates the first calculated value of the required heat amount based on the temperature difference between the set temperature and the incoming water temperature and the amount of incoming water during feedforward control, and calculates the first calculated value of the required heat amount based on the temperature difference between the set temperature and the incoming water temperature and the amount of incoming water. A second calculated value is calculated based on the temperature difference and the amount of water entering. Furthermore, by comparing the first calculated value and the second calculated value, one of the three areas consisting of the slow heating area, rapid heating area, and residual heat purge area is determined to be the set temperature and the outlet temperature. Select according to the current deviation of. Since the amount of fuel supplied to the burner is automatically adjusted according to the selected slow heating area, rapid heating area, or residual heat purge area, the combustion capacity of the burner is controlled based on the deviation between the set temperature and the hot water temperature. be done.

[Effects of the Invention] Even during feedforward control, the amount of fuel supplied to the burner can be corrected based on the deviation between the set temperature and the hot water temperature. Therefore, the combustion capacity of the burner does not become too strong when the hot water temperature is high due to intermittent use, so that the hot water temperature can quickly approach the set temperature.

[Example] An example of the water heater of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing a gas-fueled water heater that uses fuel gas as fuel.

Inside the water heater case 2 of the gas combustion water heater 1,
A combustor case 10 is provided, and a double gas burner 11 consisting of a first burner 11a and a second burner 11b that combusts fuel gas supplied through a gas supply pipe 20 is further provided inside the combustor case 10. . In addition, the combustor case 10 is equipped with a combustor that controls the amount of combustion air supplied to the gas burner 11 (hereinafter abbreviated as air amount), and is a fuel supply amount control means using a three-phase Y-connected brushless DC motor. A gas burner 11 is provided.
is a forced-air combustor that burns the combustion air supplied by the combustion fan 12 and the fuel gas supplied from the gas supply pipe 20 at a predetermined air-fuel ratio. The combustion gas is exhausted to the outside through the exhaust port 3.

Above the combustor case 10 is a water supply pipe 30.
A heat exchanger 13 is provided, and water passing through the heat exchanger 13 is heated by the flame generated by the gas burner 11 and the heat of the combustion gas. Further, in the vicinity of the burner 11 in the combustor case 10, a sparker 14 as an additive device and a flame rod 15 as a flame detection means are provided.

The gas supply pipe 20 includes a source solenoid valve 21, a main solenoid valve 22, which allows fuel gas to pass through when energized from the upstream side.
A governor-type gas proportional valve (hereinafter referred to as governor proportional valve) 23, which is a fuel supply amount control means that adjusts the amount of fuel gas supplied (hereinafter referred to as gas amount) by controlling the supply pressure, goes to the second burner 11b. a switching solenoid valve (hereinafter abbreviated as switching valve) 24 which is a fuel supply amount control means that shuts off fuel gas according to usage conditions;
are provided respectively, and supply fuel gas to the gas burner 11 described above.

A water filter 31 is installed at the most upstream part of the water supply pipe 30.
A water drain valve 32 is provided downstream thereof, and a water volume proportional adjustment valve 33 operated by a geared motor that adjusts the amount of water flowing into the heat exchanger 13 is provided. A potentiometer 34 is provided to detect the opening degree.

The water whose amount of water has been adjusted by the water amount proportional adjustment valve 33 has the temperature of the water flowing into the heat exchanger 13 detected by an incoming water temperature thermistor 35, which is an incoming water temperature detection means provided immediately downstream. Further, the amount of water flowing into the heat exchanger 13 is detected by a water amount sensor 36, which is water amount detection means downstream thereof, and is sent to the heat exchanger 13 through the water supply pipe 30.

The water supply pipe 30 on the downstream side of the heat exchanger 13 is provided with a hot water outlet temperature thermistor 38, which is a hot water temperature detection means for detecting the outlet temperature of the water heated by the heat exchanger 13. A location-mounted hot water tap (not shown) is provided.

In addition, 39 is a boiling prevention switch.

The water heater 1 having the above configuration has a control device 50
controlled by

As shown in FIG. 2, the control device 50 connects a control circuit 60 connected to a power cord 51 connected to a wiring outlet, and a main controller 54 and a sub-controller 54a for remotely controlling the water heater 1. It is equipped with a terminal.

The main controller 54 and the sub-controller 54a are temperature setting means set by the user. In this embodiment, the main controller 54 is provided close to the water heater 1, and the sub-controller 54a is installed in a hot water supply place such as a bathroom. It is provided. In addition, the main controller 54 and the sub-controller 54a are operated by respective operation switches 56, 5.
6a, and water temperature setting switches 57, 57a for setting the hot water temperature to a desired set temperature.

The control circuit 60 includes a microcomputer (hereinafter referred to as CPU) 70, a sparker circuit 71, a fan drive circuit 72, and a proportional valve control circuit 7.
3. Geared motor drive circuit 74, position detection circuit 7
5. There is a water amount detection circuit 76, and these circuits
Predetermined control is performed by the CPU 70.

The fan drive circuit 72 rotates the combustion fan 12 according to the required amount of heat, detects its rotation speed using a Hall IC provided in a three-phase Y-connected brushless DC motor, and sends a detection signal to the CPU 70.

The proportional valve control circuit 73 controls the amount of electricity supplied to the governor proportional valve 23 according to the characteristics of the governor proportional valve 23 (which differs depending on the type of gas) in order to adjust the amount of gas so that combustion in the gas burner 11 is performed at a desired air-fuel ratio. This circuit performs control based on corresponding control constants.
The proportional valve control circuit 73 is a semi-fixed circuit that proportionally controls the maximum value of the proportional valve current of the governor proportional valve 23 in order to correct errors due to variations in the water heater 1 and pressure loss due to gas type to obtain an appropriate amount of gas. It has a volume.

The geared motor drive circuit 74 is a circuit that drives the geared motor of the water volume proportional adjustment valve 33 for adjusting the amount of water flowing into the heat exchanger 13.
In the OFF state, it does not operate, but in the power ON state, the operation switch 56 of the sub-controller 54a
Regardless of whether a is ON or OFF, it is set to the position of the previous set temperature, and from that position it is initially set to a position corresponding to the reference temperature.

The position detection circuit 75 is a circuit for analyzing a signal from the potentiometer 34 provided in the water volume proportional adjustment valve 33 to detect its opening degree.

The water amount detection circuit 76 detects the amount of water flowing into the heat exchanger 13 based on the rotational speed signal of the water amount sensor 36.

The CPU 70 has a memory function that stores a reference temperature that is set in advance at the shipping stage when the water heater 1 is assembled and the type of fuel gas to be used, and a discrimination function that discriminates between the main controller 54 and the sub-controller 54a. Sequence control that controls the operating order and timing of each of the above circuits, Feedforward control (hereinafter referred to as FF control) that controls the combustion amount and water input amount based on the input water temperature and setting degree as combustion capacity control, and hot water output control. Feedback control (hereinafter referred to as PI control) performs proportional integral control (hereinafter referred to as PI control) of the combustion capacity and water input amount of the gas burner 11, such as automatic adjustment of the gas amount based on temperature, ON/OFF of the switching valve 24, and air volume adjustment of the combustion fan 12. (called FB control) and switching control that switches between FF control and FB control, and also has safety functions.

The determination function is a part that analyzes pulse signals in order to perform control according to the respective setting states of the main controller 54 and sub-controller 54a connected to the terminals 61 and 62 of the control circuit 60, respectively. The terminal 62 is a wire-saving terminal that can supply electricity to the main controller 54 and sub-controller 54a.
It is a wire terminal.

In the sequence control, when the user opens the hot water tap and a water flow signal based on the water flow sensor 36 is obtained, the combustion fan 12 is activated, and after pre-purging is performed for a predetermined period of time, ignition is performed. In the ignition operation, the main solenoid valve 21, the main solenoid valve 22, the governor proportional valve 23, and the sparker 14 are energized at the same time, and after ignition is detected, the combustion capacity is calculated and combustion starts according to the set amount. .

On the other hand, when a water flow signal is detected based on the water flow sensor 36, the combustion amount calculation starts simultaneously based on the inlet water temperature thermistor 35, but if the water temperature when water is not flowing through the water supply pipe 30 is read, the water temperature is correct. Therefore, in this embodiment, the water temperature is read by the inlet water temperature thermistor 35 after the water flow signal is detected, and the water temperature at that time is used as the water temperature data.

Combustion capacity control includes FF control that corrects the required amount of heat according to the comparison result between the first calculated value and the second calculated value, which will be described later, and the combustion capacity of the gas burner 11 that corrects the required heat amount according to the deviation between the hot water temperature and the set temperature. FB to correct
(PI) control is performed.

FF control uses the first calculated value (required amount of heat) calculated from the temperature difference between the set temperature and incoming water temperature and the amount of incoming water.
The most efficient combustion capacity is calculated from the comparison result between Q and the second calculated value q calculated from the temperature difference between the outlet water temperature and the inlet water temperature and the amount of water inlet, and the combustion fan 12 and the governor proportional valve 23 are , the switching valve 24, and the water amount proportional adjustment valve 33, respectively, to automatically adjust the amount of air, gas, and water input.

In addition, FF control uses the first calculated value (required heat amount)
Based on the comparison result between Q and the second calculated value q, the eighth
As shown in the graph showing the relationship between the required heat amount and gas amount, the slow heating heat amount (Q ×
1.0), which is controlled by proportional control during slow heating, and a rapid heating area, which is controlled by proportional control during rapid heating, which outputs a rapid heating amount (Q+α) larger than the required amount of heat Q. B, and a residual heat purge area C that is controlled by proportional control during residual heat purging that outputs a residual heat purge heat amount (Q-β) smaller than the required heat amount Q. The combustion fan 12, the governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 33 are controlled based on the current deviation from the air flow rate, and the air volume, gas volume, and water intake volume are automatically adjusted. Therefore, during FF control, the combustion capacity of the gas burner 11 is controlled according to the deviation between the set temperature and the hot water temperature.

Further, the rapid heating region B is equal to or lower than the maximum value of the half-open capacity control region I controlled by the control of the governor proportional valve 23 during half-open capacity operation with combustion of only the first burner 11a, and It is limited to an overlapping control area which is an overlapping area with the minimum value or more of the full-open capacity control area controlled by the governor proportional valve 23 during full-open capacity operation due to simultaneous combustion of the second burner 11b.

By FB (PI) control, when the gas proportional control reaches the vicinity of the maximum range of the half-open capacity control range, the switching valve 24 is turned on (opened) while performing slow ignition control to switch to the full-open capacity range. Further, by FB (PI) control, when the gas proportional control reaches the vicinity of the minimum range of the full-open capacity control range, the switching valve 24 is turned OFF (closed) and switched to the half-open capacity control range.

Therefore, even during the switching control between the half-open capacity control area and the full-open capacity control area, a safe combustion state is maintained, and smooth switching control between the half-open capacity control area and the full-open capacity control area is performed.

In switching control from FF control to FB (PI) control,
When the deviation between the set temperature and the hot water temperature reaches a predetermined temperature difference, FF control is switched to FB (PI) control. Alternatively, even if the deviation between the set temperature and the hot water temperature does not reach the predetermined temperature difference, the predetermined time τ ₁ =
a/w [seconds] and a predetermined time τ ₂ =b−bw [seconds], and if the outlet hot water temperature does not approach the set temperature even after the predetermined time τ ₁ and τ ₂ elapse, the FF control FB
By switching to (PI) control, even if the deviation between the set temperature and the hot water temperature does not reach the predetermined temperature difference due to a load error such as insufficient gas volume due to variations in appliances, the FF control can be switched to the (PI) control. FB(PI)
Switch to control. (w = amount of water entering) As a safety function, if the temperature of the outlet water reaches boiling temperature or higher and continues for t8 (for example, 1 to 10) seconds, continuous combustion will continue for a predetermined period of time t7 (for example, 40 to 120).
If the flame continues for several minutes or if no flame is detected, each solenoid valve will be closed and operation will be stopped.

The operation of the control device 50 of the water heater 1 of this embodiment will be explained based on the operation flowcharts shown in FIGS. 3 to 7.

When installing the water heater 1, check the gas type of the fuel gas set by the gas company or the distributor of the water heater 1, and also check the standard temperature (40°C in this example).
℃) settings (S1). The selection of the fuel gas type and the setting of the reference temperature are not performed by the user of the water heater, and are stored in the memory function of the CPU 70, so they are stored in the CPU 70 regardless of whether the power is turned on or off. However, when the set temperature is input by the user, the CPU 70 gives priority to the set temperature over the reference temperature and controls the water heater 1 so that the hot water temperature approaches the set temperature.

To use the water heater 1, connect the power cord 51 to a wiring outlet and turn on the power (S2).

The water volume proportional adjustment valve 33 is set at a reference temperature (in this embodiment,
It is determined whether the opening degree is initially set to allow the maximum amount of water inflow, which is the amount of water inflow corresponding to the temperature (40°C) (S3).

Here, the water volume proportional adjustment valve 33 is set to a predetermined opening of the set temperature (or reference temperature) when the fully open water heater 1 is used, regardless of whether the sub-controller 54a is ON or OFF. However, with the geared motor that changes the opening degree of the water volume proportional adjustment valve 33, if you try to adjust the opening degree after inputting the set temperature, the movement time will be several seconds, which may eat into the combustion control time. Control is delayed. In order to prevent this, in this embodiment, the water amount proportional adjustment valve 33 is moved in advance before starting combustion.

Therefore, the adjustment time of the water volume proportional adjustment valve 33 from the opening degree at the initial setting of the water volume proportional adjustment valve 33 until it moves to the opening degree according to the set temperature during FF control described later is shortened. During control, the hot water temperature can be quickly set to the set temperature.

When the opening of the gas burner 11 is set to allow the maximum amount of water to enter, the geared motor is
Turn off (S4). If the opening is not set to allow the maximum amount of water to enter, turn on the geared motor (S5).

Normally, the driving time of the water volume proportional adjustment valve 33 is about a few seconds even if the water volume proportional adjustment valve 33 is displaced to its maximum extent, but in the event of freezing or foreign matter, the water volume proportional adjustment valve 33 is locked, so the geared motor drive circuit 7
In some cases, the water volume proportional adjustment valve 33 does not move despite being energized from 4, which increases the energization time and risks combustion due to heating of the motor and geared motor drive circuit 74. In this embodiment, in order to prevent equipment failure even in such a case, the energization time by the geared motor drive circuit 74 is adjusted.
The geared motor is turned off in _t1 (5 to 30) seconds (S6).

Next, the operation switches 56, 56a of the main controller 54 or sub-controller 54a are activated.
It is determined whether or not it is turned on (S7), and S7 is repeated until it is turned on. When it is ON, it is determined whether or not the hot water temperature is set by the water temperature setting switches 57, 57a (S8).

Further, if the hot water temperature is not set even after the predetermined time (t2 seconds) has elapsed (S9), the set temperature is set to the reference temperature of 40°C (S10). Next, when the user opens the hot water tap (S11), the amount of water entering is detected by the water amount sensor 36 (S12).

Here, the way in which the inflowing water amount change signal is accepted is that a minute change not detected by the water amount detection circuit 76 is not accepted, but it is accepted when the amount of change in the inflowing water amount is equal to or greater than a predetermined value compared to the current inflowing water amount (steady flow). .

If the signal from the water flow sensor 36 is read by the water flow detection circuit 76, and the signal is higher than a predetermined voltage, it is detected as a water flow signal. In this example, a hysteresis characteristic is provided to prevent chattering and reduce the amount of water.
When it is 2.5/min or more, it is detected as a water flow signal, and 2.0
When there is a minute change of less than /min, it is not detected as a water flow signal.

Normally, water inflow data is updated every sampling time, but taking into consideration the response delay of the water flow sensor 36, even if the cumulative value within a certain time exceeds a predetermined value, it is considered as a change in water inflow. Accept.

Therefore, it is possible to detect not only an instantaneous change in the amount of water inflow, but also a change in the amount of water inflow within a certain period of time, and it is possible to adjust the gas amount in response to a wide range of changes in the amount of water inflow.

After a predetermined time (t3 seconds) has elapsed after detecting the amount of water entering (S13), the temperature of the entering water is detected by the entering water temperature thermistor 35 (S14). Then, it is determined whether the incoming water temperature is 55°C or higher (S15), and when the temperature is 55°C or higher, the user closes the hot water tap (S16) and turns off the operation switches 56, 56a of the main controller 54 and sub-controller 54a. (S17).
When the temperature is lower than 55℃, it is determined whether the inlet water temperature is below the set temperature (S18), and when it is higher than the set temperature, S12
Repeat the following operation and turn on the combustion fan 12 when the temperature is below the set temperature (S19).

The Hall IC detects the rotation speed of the combustion fan 12 (S20), and determines whether the rotation speed is equal to or higher than a predetermined rotation speed (S21). When the rotation speed is lower than the predetermined rotation speed, the rotation speed corresponding to the combustion capacity cannot be obtained, so the main solenoid valve 21, the main solenoid valve 22, and the switching valve 2
4. All the governor proportional valve 23 and combustion fan 12
OFF (S22-S26), the user closes the hot water tap (S27), and then the operation switches 56, 5 of the main controller 54 and sub-controller 54a
6a is turned OFF (S28).

When the rotation speed is higher than the specified rotation speed, t4 (for example, 0.5
~10) Perform a pre-purge for seconds (S29) and remove the sparker 14, original solenoid valve 21, main solenoid valve 22, and switching valve 2.
Turn on all 4 (S30 to S33), and turn on the cabana proportional valve 23.
Supplies slow ignition current to (S34).

The proportional valve current to the governor proportional valve 23 is controlled based on the rotational speed of the combustion fan 12, that is, the air volume, and the gas type Kp, except at the time of ignition. In this embodiment, in particular, the amount of gas for slow ignition during ignition is made to be a constant ratio to the maximum value of the proportional valve current to the governor proportional valve 23 adjusted by the semi-fixed volume of the proportional valve control circuit 73. This makes it possible to supply an appropriate amount of slow ignition gas at the time of ignition.

Further, after t5 (for example, 5 to 20) seconds have elapsed after turning on the sparker 14 (S35), the sparker 14 is turned off (S36). Then, the combustion flame is detected by the flame rod 15, and the flame rod 1
5, it is determined whether a current greater than IA is being input (S37). When a current higher than IA is not input, the operation of S22 and below is repeated as an ignition error. When a current of more than IA is input,
A slow ignition timer for t6 (for example, 0.1 to 10) seconds is performed (S38), and the outlet hot water temperature is detected by the outlet hot water temperature thermistor 38 (S39).

Next, the combustion capacity control shown in the operation flowcharts of FIGS. 6 and 7 is performed (S40), and the following safety function control is performed.

It is determined whether the rotation speed of the combustion fan 12 is equal to or higher than a predetermined rotation speed (S41). When the rotation speed is lower than a predetermined rotation speed, the operation in S22 or lower is performed, and when the rotation speed is higher than a predetermined rotation speed, it is determined whether or not a current of IA or higher is being input by the frame rod 15 (S42). When a current higher than IA is input, continuous combustion continues for t7 (e.g. 40 to 120) minutes (S43), or the temperature of the hot water reaches boiling temperature or higher (S44), and it continues for t8 (e.g. 1 to 10) seconds. If it continues (S45), repeat the operations from S22 onwards. If the continuous combustion is within t7 minutes and the hot water temperature does not reach the boiling temperature, the set temperature is input again (S46), and the operations from S39 onwards are repeated. S46 is for dealing with the case where the user changes the set temperature.

When a current higher than IA is not input, it is detected as a misfire such as blowing out, and a misfire during combustion is detected as one.
It is determined whether or not it is the first time (S47), and when the first fire is the second time,
Repeat the operations from S22 onwards. When the pre-fire is first fired, the main solenoid valve 21, main solenoid valve 22, and switching valve 24 are
Turn OFF (S48 to S50) and then repeat the operations from S19 onwards.

Combustion capacity control will be explained based on the operation flowcharts shown in FIGS. 6 and 7.

First, the required amount of heat required for the combustion capacity of the gas burner 11 is calculated based on the following formula (S100), (S101).

First calculated value Q = (Test - THin) x w = Required heat amount Second calculated value q = (THout - THin) x w Tset: Set temperature THin: Incoming water temperature THout: Outgoing water temperature w: Incoming water amount FF control Determine whether it has been done (S102), and FF
If control is being performed, FB (PI) control is performed, and if FF control is not being performed, it is determined whether t9 seconds have elapsed since the initial setting of the water volume proportional adjustment valve 33 (S103 ), when t9 seconds have elapsed, it is determined whether Q≧qx (S104). Note that x is a coefficient that satisfies x>1.0.

When Q≧qx is not satisfied, it is determined whether Q<q or not (S105).

When Q<q is not satisfied, in order to bring the hot water temperature closer to the set temperature, the amount of heat for slow heating in slow heating area A (Q×
Gas burner 11 so as to produce an output of 1.0)
control the combustion power of. That is, combustion fan 1
2 and the cabana proportional valve 23, and further controls the water amount proportional adjustment valve 3 according to the combustion capacity of the gas burner 11.
3, and switches from the FF control described above to FB (PI) control based on the operation flowchart shown in FIG. 7 (S106).

When Q<q, the outlet hot water temperature is higher than the set temperature, so in order to bring the outlet hot water temperature closer to the set temperature, the residual heat purge heat amount (Q
-β) The combustion capacity of the gas burner 11 is controlled to produce the output (minimum combustion capacity). That is, the combustion fan 12 and the governor proportional valve 23 are controlled, and the water amount proportional adjustment valve 33 is further controlled according to the combustion capacity of the gas burner 11 (S107).

Next, τ ₁ = a/w [seconds] is calculated (S108), and FF
After the predetermined time (τ ₁ second) for switching from control to FB (PI) control has elapsed (S109), residual heat purge area C
so that the residual heat purge heat amount (Q-β) approaches the output that is the slow heating heat amount (Q x 1.0) of the slow heating area A.
The combustion fan 12 and the ganava proportional valve 23 are controlled, the water amount proportional adjustment valve 33 is controlled, and the above-mentioned FF
The control is switched to FB (PI) control based on the operation flowchart shown in FIG. 7 (S110).

Here, when τ ₁ second has not elapsed, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is |
Determine whether it is within dt | °C {= predetermined temperature difference ± y °C} (S111). If the deviation is within |dt | °C, perform S110; if the deviation is not within |dt | °C, repeat
Perform S109.

In addition, since there may be errors due to variations in water heaters or insufficient gas volume where the gas pressure is lower than the standard value, the water volume proportional adjustment valve 33 is moved to the initial setting position and t9 seconds have elapsed (S103). , when the detected temperature of the outlet hot water temperature thermistor 38 is not the set temperature Q≧qx, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is |dt|°C{=predetermined temperature difference ±
y℃} (S112), and determines whether the deviation is within |
When the deviation is within |dt|℃, perform S106, and when the deviation is not within |dt|℃, the rapid heating heat amount (Q+
The combustion capacity of the gas burner 11 is controlled so as to produce the output α). That is, combustion fan 1
2, the governor proportional valve 23, and the switching valve 24, and further controls the water amount proportional adjustment valve 33 according to the combustion capacity of the gas burner 11 (S113).

However, due to changes in the amount of water, the calculated value of the required heat amount is updated, and if the combustion capacity of the gas burner 11 is controlled at this time, the changes in the amount of air and gas will interfere with the changes in the amount of water input, and the temperature of the hot water being discharged will be affected. Therefore, when changing the opening degree of the water volume proportional adjustment valve 33 by maintaining maximum capacity combustion, the air volume and gas volume are not adjusted by controlling the combustion fan 12 and the governor proportional valve 23.

Here, it is determined whether or not the switching valve 24 is turned on (S114), and when the switching valve 24 is turned on,
That is, the first burner 11a and the second burner 11
During full-open capacity operation with simultaneous combustion of b, it is determined whether or not the maximum value of the half-open capacity control area I (capacity of 1/2 of the full-open capacity control area) is below (S115). The governor proportional valve 23 is controlled proportionally with the output of , and the switching valve 24 is turned ON or
Turn off (S116).

When the switching valve 24 is not turned on, that is, the first
During half-open capacity operation with combustion of only the burner 11a, it is determined whether or not the capacity is equal to or higher than the minimum value of the full-open capacity control area (1/4 capacity of the full-open capacity control area) (S117);
When the value is greater than or equal to the minimum value, perform S116.

Therefore, the rapid heating heat amount (Q+
The judgment level for α) is less than or equal to the maximum value of the half-open capacity control area {= maximum value of the half-open capacity control area ÷ (Q + α)}
, and is limited to multiple control areas that are overlapping areas that are greater than or equal to the minimum value of the full-open capacity control area (fixed value). As a result, it is possible to prevent the chattering between fully open and half open the gas burner 11 that occurs when the switching valve 24 is turned on and off, and it is possible to both expand the temperature control range and speed up the control of the maximum combustion capacity, which is the amount of heat that is rapidly heated.

Next, calculate τ ₂ = b - cw [seconds] (S118), and calculate FF
After the predetermined time (τ ₂ seconds) for switching from control to FB (PI) control has elapsed (S119), residual heat purge area C
The combustion capacity of the gas burner 11 is controlled so that an output equal to the amount of residual heat purge heat (Q-β) is generated. That is, the combustion fan 12 and the governor proportional valve 2
3, and further controls the water quantity proportional adjustment valve 33 according to the combustion capacity of the gas burner 11.
Switch from FF control to FB (PI) control (S120).

Here, when τ ₂ seconds have not elapsed, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is |
Determine whether or not the deviation is within dt｜℃｜{=predetermined temperature difference ±y℃} (S121). If the deviation is within |dt|℃, perform S120; if the deviation is not within |dt|℃, the predetermined temperature difference At time Δt, it is determined whether or not there is a change in the outlet hot water temperature that is less than or equal to the temperature difference Δy in the outlet hot water temperature. (S122). When there is a change in the outlet hot water temperature by Δy/Δt or less, S120 is performed, and when there is no change in the outlet hot water temperature by Δy/Δt or less, the operations from S119 onwards are repeated.

As described above, the control device 50 of the water heater 1
During FF control, the first calculated value Q and the second calculated value q
As shown in the graph showing the relationship between the required amount of heat and the amount of gas in FIG. and a slow heating region A in which the water volume proportional adjustment valve 33 is proportionally controlled, and a rapid heating region B in which the governor proportional valve 23 and the water volume proportional adjustment valve 33 are proportionally controlled with an output that provides a rapid heating amount (Q + α) larger than the required heat amount Q. , a residual heat purge region C is selected in which the governor proportional valve 23 and the water quantity proportional adjustment valve 33 are proportionally controlled at an output that provides a residual heat purge heat amount (Q-β: minimum combustion capacity) smaller than the required heat amount Q. Then, the selected slow heating area A, rapid heating area B,
The air amount, gas amount, and water inflow amount are corrected according to the residual heat purge area C.

Therefore, even during FF control, the amount of gas supplied to the gas burner 11 can be corrected according to the current deviation between the set temperature and the hot water temperature. Therefore, the combustion ability of the gas burner 11 will not be too weak when the temperature of the hot water being tapped is low, nor will the combustion ability of the gas burner 11 be too strong when the hot water temperature is high, such as when the water heater 1 is continuously used. Therefore, even during FF control, the hot water temperature can be quickly brought close to the set temperature.

In FB (PI) control, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is the predetermined temperature difference (+y℃)
(S123), and if the deviation is +y℃ or more, the residual heat purge heat amount (Q
-β) so that the gas burner 11
control the combustion capacity of That is, the combustion fan 12 and the governor proportional valve 23 are controlled, and the water amount proportional adjustment valve 33 is further controlled according to the combustion capacity of the gas burner 11 (S124). Then, after t10 seconds have elapsed (S125), the above-mentioned safety control is performed. Also,
If t10 seconds have not elapsed, repeat the operations from S123 onwards.

When the deviation is not greater than +y°C, the integral time is calculated from the composite function of the temperature deviation function and the water input amount function (S127).

Temperature deviation: e = Set temperature - Output water temperature ∴F(e) + (K ₁ - e) x k ₁ K, k are constants Incoming water amount w is a known quantity detected by the water amount sensor 36 ∴G(W) = (K ₂ −e) × k ₂ ∴ Integral time: T = K ₃ × {F(e) + G(w)} = PI control output time Therefore, the larger the deviation between the set temperature and the hot water temperature, the longer the integral time The shorter [seconds] or the larger the amount of water entering, the shorter the integral time [seconds], and the shorter the output time to the governor proportional valve 23 or the water amount proportional adjustment valve 33.

After that, after T time has passed (S128), it is determined whether the temperature deviation e≦1 (S129), and when e≦1,
When the above-mentioned safety control is performed and e≦1 is not satisfied, the gas type Kp of the fuel gas is input (S130), and the following PI control output is updated so as to switch to the control constant according to the gas type Kp. After outputting the control constant of the PI control output to the governor proportional valve 23 or water volume proportional adjustment valve 33 as a temperature deviation function (S131),
Perform safety control.

PI control output: PN=PN-1+e×Kp PI control output variation: ΔVS=e×Kp PN-1=Q+α: Current PI control output ∴PI control output PN=PN-1+ΔVs However, if the water input is less than the specified flow rate When ,
The rapid heating heat amount (Q+α) in the rapid heating region B is brought close to the slow heating heat amount (Q×1.0) in the slow heating region A to improve stability at minute flow rates.

Therefore, by switching the control constants according to the load such as gas type Kp, gas amount, and water inflow amount, the gas amount can be increased or decreased (not a fixed value but a variable), allowing a wide range of flexible FBs. (PI) control can be performed. Further, it is possible to perform FB (PI) control that is compatible with the characteristics of the governor proportional valve 23 (which differs depending on the type of gas). Furthermore, the integration time T and
From the PI control output, the hot water temperature can be quickly brought close to the set temperature.

[Modification] In this embodiment, gaseous fuel such as fuel gas is used as the fuel, but liquid fuel such as petroleum may also be used.

In this embodiment, the governor proportional valve 23 and the water volume proportional adjustment valve 33 were comparatively controlled; however, the governor proportional valve 23
It is also possible to perform proportional control only. Alternatively, the combustion capacity of the gas burner 11 may be controlled by proportionally controlling the combustion fan 12.

Further, only the governor proportional valve 23 or the switching valve 24 may be used as the fuel supply amount control means.

[Brief explanation of the drawing]

1 to 8 show one embodiment of the present invention. Fig. 1 is a schematic diagram showing the water heater, Fig. 2 is a block diagram showing the water heater control device, Figs. 3 to 7 are operational flowcharts of the water heater control device, and Fig. 8 is a necessary diagram. It is a graph showing the relationship between the amount of heat and the amount of gas. In the diagram, 1...Water heater, 11...Gas burner, 1
3...Heat exchanger, 23...Governor proportional valve (fuel supply amount control means), 35...Incoming water temperature thermistor (incoming water temperature detection means), 36...Water flow sensor (incoming water amount detection means), 38...Hot water output Temperature thermistor (outlet hot water temperature detection means), 54... main controller (temperature setting means), 54a... sub-controller (temperature setting means), 70... CPU (controlling means).

Claims (1)

[Scope of Claims] 1 (a) a burner that burns fuel; (b) fuel supply amount control means that controls the combustion capacity of the burner by adjusting the amount of fuel supplied to the burner; (c ) a heat exchanger that heats the water by exchanging heat with water passing through the interior and the combustion heat of the burner; and (d) an inlet temperature of water provided upstream of the heat exchanger and flowing into the heat exchanger. (e) an inflow water amount detection means for detecting the amount of water passing through the heat exchanger; (f) a hot water outlet that detects the outlet temperature of water flowing out from the heat exchanger; (g) temperature setting means for setting the outlet water temperature to a desired set temperature; and (h) a first calculation of the required amount of heat based on the temperature difference between the set temperature and the incoming water temperature and the amount of incoming water. and calculate a second calculated value based on the temperature difference between the outlet hot water temperature and the inlet water temperature and the amount of water input, and based on the comparison result between the first calculated value and the second calculated value. a slow heating region that produces an output that is approximately the same amount of heat as the required amount of heat; a rapid heating region that produces an output that is greater than the required amount of heat; and a residual heat purge region that produces an output that is less than the required amount of heat. One of the three regions consisting of is selected according to the current deviation between the set temperature and the tapped water temperature, and fuel is A water heater equipped with a control means that performs feed forward control to automatically adjust the amount of water supplied.