JPH01118067A - Hot water supplying device - Google Patents

Abstract

PURPOSE:To enable a combustion capability to be selected in response to an output hot water by a method wherein a gradual heating capability range producing an approximate same output as a combustion capability, a rapid heating capability range producing a larger output than the combustion capability and a surplus heat purge capability range producing a lower output than a combustion capability are selected and an amount of supplied fuel is automatically adjusted in response to a control range. CONSTITUTION:A feed-forward control(FF control) may select a gradual heating capability range in which a control is carried out through a proportional control of a fan 12, a governor proportional valve 23 and a changing-over valve 24 in case of a gradual heating for producing an output acting as the same capability as the combustion capability Q under a comparison between a first calculated value Q and a second calculated value (q); a rapid heating range in which a control is carried out through a proportional control of the fan 12, governor proportional valve 23 and changing-over valve 24 in case of a rapid heating operation for producing an output acting as a larger capability than the combustion capability; and a surplus purge capability range in which a control is carried out through a proportional control of the fan 12, governor proportional valve 23 and changing-over valve 24 in case of performing a surplus heat purge for producing an output acting as a smaller capability than the combustion capability. An amount of fed fuel gas is automatically adjusted in response to these control ranges.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention employs feedforward control that automatically adjusts the amount of fuel supplied by calculating the required capacity based on the deviation between the set temperature and the inlet water temperature. Regarding water heaters.

[Prior Art] Traditionally, water heaters calculate the combustion capacity based on the deviation between the set temperature and the inlet water temperature, and when performing feedforward control based on the calculated value of the combustion capacity, the combustion capacity is calculated. The fuel supply amount was automatically adjusted by outputting the calculated value as is, or by setting the initial setting value to a power that was greater than the combustion capacity for a certain period of time.

[Problems to be solved by the invention] However, in conventional water heaters, the initial value of the hot water temperature is high;
Since feedforward control is performed using the same combustion capacity regardless of the low temperature, there is a problem that the combustion capacity is too weak when the hot water temperature is low, and the combustion capacity is too strong when the hot water temperature is high.

An object of the present invention is to provide a water heater whose combustion capacity can be selected depending on the hot water temperature.

[Means for Solving the Problems] The water heater of the present invention includes a combustor case, a burner provided in the case, and a burner provided in the case that heats water passing through the case. a heat exchanger; an inlet water temperature detection means provided upstream of the heat exchanger for detecting the inlet temperature of water flowing into the heat exchanger; and an outlet temperature for detecting the outlet temperature of water flowing out from the heat exchanger. temperature detection means; temperature setting means for setting the outlet water temperature to a desired set temperature; A first calculated value of the combustion capacity is calculated based on the hot water temperature, and a second calculated value is calculated based on the hot water temperature, and the combustion capacity is calculated by comparing the first calculated value and the second calculated value. A slow heating capacity range that produces an output that is almost the same as the combustion capacity, a rapid heating capacity range that produces an output that is larger than the combustion capacity, and a residual heat purge capacity range that produces an output that is smaller than the combustion capacity. The configuration includes a control 0 circuit that performs feedforward control that automatically adjusts the fuel supply amount according to these W control ranges.

[Actions and Effects of the Invention] The water heater of the present invention has the following actions and effects due to the above configuration.

A first calculated value of the combustion capacity is calculated based on the deviation between the set temperature and the incoming water temperature, and a second calculated value is calculated based on the outlet water temperature, and the first calculated value and the second calculated value are calculated. By comparing with By selecting the purge capacity range and automatically adjusting the fuel supply amount according to these control ranges, the gas volume control means can be controlled in accordance with the outlet hot water temperature. For this reason, it is possible to prevent problems in which the combustion capacity is too weak when the outlet temperature is low and the combustion capacity is too strong when the outlet temperature is high.

[Embodiment] In the present invention, an embodiment of a gas combustion type water heater using gas as fuel will be explained based on the drawings.

FIG. 1 shows a gas combustion type water heater employing an embodiment of the present invention.

A combustor case 10 is provided inside the water heater case 2 of the gas combustion type water heater 1, and a gas supply pipe 2 is further provided inside the combustor case 10.
A 62-speed gas burner 11 consisting of a first burner 11a and a second burner 11b that burns fuel gas supplied by a gas burner 11 is provided.

In addition, the combustor case 10 includes a three-phase Y-connection brush "'"
,, D C Yo-ya. A combustion fan 12 is provided as a fuel supply amount control means, and the gas burner 11 controls the combustion air supplied by the fan 12 and the fuel gas supplied from the gas supply pipe 20 at a predetermined air-fuel ratio. It is a forced air type combustor that burns, and the combustion gas generated by combustion is exhausted to the outside from the exhaust port 3.

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

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

A drain plug 32 equipped with a water filter 31 is provided at the most upstream portion of the water supply pipe 30, and a heat exchanger 13 is provided downstream of the drain plug 32.
A water volume proportional adjustment valve 33 operated by a geared motor is provided to adjust the amount of water entering the interior, and this water volume proportional/circumference adjustment valve 33 is provided with a potentiometer 34 for detecting its opening degree.

The temperature of the water whose inflow amount has been adjusted by the water amount proportional adjustment valve 33 is detected by an inlet water temperature thermistor 35 which is an inlet water temperature detection means provided immediately downstream, and further downstream a water amount sensor 36 which is a large water amount detection means. The amount of water entering is detected and 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 temperature thermistor 38, which is a hot water temperature detection means for detecting the temperature of heated water. A stopper (not shown) is provided.

The water heater 1 having the above configuration is controlled by a control Il device 50.

As shown in FIG. 2, the water control device 50 includes 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. A terminal for connection is provided.

Main controller 54 and sub controller 54a
is temperature setting means set by the user; in this embodiment, a main controller 54 is provided close to the water heater 1, and a sub-controller 54a is provided at a hot water supply location such as a bathroom. In addition, the main controller 54 and the sub-controller 54a are connected to each operation switch 5.
6.56a and a water temperature setting switch 57 for setting the hot water temperature
．． 57a are provided.

The control circuit 60 includes a microcomputer (hereinafter referred to as CPU).
There are a sparker circuit 71, a fan drive circuit 72, a proportional valve control circuit 73, a geared motor drive circuit 74, a position detection circuit 75, and a water amount detection circuit 76, centered around the CPU 70. Control ■ will be carried out.

The fan drive circuit 72 rotates the fan 12 according to the combustion capacity such as the set temperature, detects the 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. send to

The proportional valve control circuit 73 controls the amount of electricity supplied to the governor proportional valve 23 in order to adjust the amount of fuel gas supplied so that combustion in the gas burner 11 is performed at a desired air-fuel ratio. ) is a circuit that performs control based on a proportional control constant corresponding to The proportional valve control circuit 73 is a semi-fixed volume that proportionally controls the maximum value of the current to 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 gas output. It is equipped with

The geared motor drive circuit 74 is a circuit that drives the geared motor of the water volume proportional adjustment valve 33 for regulating the amount of water flowing into the heat exchanger 13, and does not operate when the power is OFF, but when the power is ON, the subcontroller 54a Regardless of whether the operation switch 56a 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 m proportional adjustment valve 33 to detect its opening degree.

The water amount detection circuit 76 detects the amount of water entering 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 warmer 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, and Feedforward control that controls the amount of combustion and water input based on the input water temperature and set temperature as combustion capacity control.
1 (hereinafter referred to as FF control), automatic adjustment of the gas amount based on the hot water temperature, ON/OFF of the switching valve 24, air volume adjustment of the fan 12, etc. Proportional integral control of the combustion l and water input amount! 10(
Feedback control (hereinafter referred to as F
FF! 11111 and FB! 1111
performs FF-FB (PI) switching control to switch between
In addition, they also have 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 the sub-controller 54a connected to the terminals 61 and 62 of the control circuit 60, respectively.
1 and terminal 62 are wire-saving two-wire terminals that can supply electricity to the main controller 54 and sub-controller 54a.

In the sequence control, when the user opens the hot water faucet and a water flow signal based on the water flow sensor 36 is obtained, the fan 12 is activated, and after pre-purging is performed for a predetermined period of time, the ignition operation 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 amount capacity is calculated and combustion is performed according to the setting position. It begins.

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.

The combustion capacity dividing section performs FF control and an FB (PI) subsection that detects the hot water temperature and corrects the combustion amount and water input amount.

FF! 1110 is a first calculation value Q of the combustion capacity calculated from the temperature set by the main controller 54 and the sub-controller 54a, incoming water temperature and incoming water amount, and a second calculated value Q which is calculated from the incoming water temperature, incoming water amount and outlet hot water temperature. Calculated value q
Calculate the most efficient combustion capacity from
, governor proportional valve 23, switching valve 24, water volume proportional adjustment valve 33
The amount of gas and water input are automatically adjusted by controlling each of them.

In addition, the FF control is based on the first calculation fl (combustion capacity) Q and the second
By comparison with the calculated value q, as shown in the graph showing the relationship between combustion capacity and gas amount in FIG.
Proportional control of the fan 12, governor proportional valve 23, and switching valve 24 during rapid heating that produces an output with a capacity greater than the combustion capacity to a slow heating capacity range controlled by proportional control of the governor proportional valve 23 and switching valve 24. Fan 12 and governor proportional valve 2 during residual heat purging that produces an output with a capacity smaller than the rapid heating capacity range B1 combustion capacity controlled by
3. Select the residual heat purge capacity range C established by proportional control of the switching valve 24, and automatically adjust the amount of fuel gas supplied according to these control ranges.

FFIIIt[l is controlled by the rapid heating capacity range (Q+α) controlled by the gas proportional control during rapid heating which outputs a capacity larger than the required capacity Q, and the gas proportional control during residual heat purge which outputs a capacity smaller than the required capacity Q. The fan 12, the governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 33 are controlled in accordance with the remaining heat purge capacity range (Q-β) to adjust the gas amount and the water inflow amount to vJ.

In addition, the rapid heating capacity range (Q+α) corresponds to the governor proportional valve 2 during half-open capacity operation due to combustion of only the first burner 11a.
The maximum range during half-open capacity operation is controlled by the control of 3, and the full-open capacity control is controlled by the control of the governor proportional valve 23 during full-open capacity operation by simultaneous combustion of the first burner 11a and the second burner 1N). Overlapping control with the minimum area of the m area is limited to the I area.

When the gas proportional control reaches the vicinity of the maximum range of the half-open capacity control range I by FBIIIIO, the switching valve 24 is turned ON (opened) while performing the slow ignition division section, and the full-open capacity control 1 [I[
Switch to. According to the FB control, when the gas proportional control reaches the vicinity of the minimum range of the fully open capacity control mt range ■, the switching valve 24 is turned to O.
By switching to FF (valve closed) and half-open capacity control in area I, a safe combustion condition and smooth half-open capacity control in area M and full-open capacity control +111ii! Performs switching control with II.

In FF-+FB (PI) switching control, when the deviation between the set temperature and the hot water temperature reaches a predetermined temperature difference, the PI is switched from FF control to
Switch to control+. Alternatively, even if the deviation between the set temperature and the outlet hot water temperature does not reach the predetermined temperature difference, the predetermined time τ+=a/W [seconds], which is a function of the water input amount, and the predetermined time τ2=b−
bw [seconds] is calculated, and if the starting temperature does not approach the set temperature even after a predetermined period of time, even if a load error occurs such as a lack of gas volume due to variations in the equipment, the PI is set from the FF control. Switch control. (W - water input amount) As a safety function, if the temperature of the outlet water exceeds the boiling temperature, then t8
(for example, 1 to 10) seconds, when continuous combustion continues for a predetermined time t7 (for example, 40 to 120) minutes, or when no flame is detected, each solenoid valve is closed.
Stop driving.

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 fuel gas to be used depending on the gas company or the distributor of the water heater 1, and set the reference temperature (40°C in this example) (Sl);
The selection of the fuel gas type and the setting of the reference temperature are as follows:
The user of the water heater does not do this, and since it is stored in the memory function of the CPU 70, it is 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.

In order to use the water heater 1, the 'ri source cord 51 is connected to a wiring outlet and the power is turned on (S2).

Moisture proportional control valve 33 sets the reference temperature (40°C in this example)
It is determined whether or not the opening degree is initially set to allow the maximum water inflow m, which is the amount of water inflow according to (S3).

Here, the water volume proportional control valve 33 is controlled by the sub-controller 54.
Regardless of whether a is ON or OFF, the opening is set to the predetermined opening of the set temperature (or reference temperature) when the water heater 1 was used last time. However, with the geared motor that changes the opening degree of the moisture 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, water is moved through the proportional adjustment valve 33 before starting combustion.

Therefore, the adjustment time of the water volume proportional adjustment valve 33 from the initial setting opening degree to the opening degree corresponding to the set temperature during FF control (described later) is shortened, so that the outlet water temperature can be quickly adjusted to the set temperature during FF control. Can be set to .

When the opening degree is set to allow maximum water entry m for the combustion capacity, the geared motor is turned off (S4).

When the opening degree is not set to allow maximum water entry m, the geared motor is turned on (S5).

Normally, the driving time of the water proportional adjustment valve 33 is about a few seconds even if the maximum displacement occurs, but in the event of freezing or foreign matter, the water proportional adjustment valve 33 is locked, so the geared motor drive The water volume proportional adjustment valve 33 may not be displaced despite being energized from the circuit 74, which increases the energization time and risks burnout due to heating of the motor and geared motor drive circuit 14. 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 set to tl (5 to 3
0) The geared motor is turned off in seconds (S
6).

Next, determine whether or not the operation switch 56.56a of the main controller 54 or sub-controller 54a is turned on (S7), and repeat step 87 until it is turned on.
Go back. When turned on, the water temperature setting switch 57
．． 57a, it is determined whether or not the hot water temperature has been set (S8).

In addition, if the hot water temperature is not set even after the predetermined time (t2 seconds) has elapsed (S9), the set temperature is set to 40°C, which is the reference temperature.
(810). Next, when the user opens the hot water tap (
S11), the amount of water entering is detected by the water amount sensor 36 (8
12).

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

Water amount detection circuit 76 that reads the signal from the water amount sensor 36
If the signal exceeds a predetermined voltage, it is detected as a water flow signal, but reading errors will occur in the water flow detection circuit 76 due to undulations in the water flow, and chattering will occur if the set voltage is kept constant. In the example, chattering is prevented by providing a hysteresis characteristic, and when the water amount is 2.5 Jl 1 minute or more, it is detected as a water flow signal,
2. Oj! When there is a minute change of less than /min, it is not detected as a water flow signal.

Normally, the water inflow data is updated every sampling time, but taking into account the response delay of the water inflow sensor 36, the water inflow may also change if the cumulative value within a certain time exceeds a predetermined value. accepted as

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, making it possible to adjust the gas flow in response to a wide range of changes in the amount of water inflow.

After detecting the amount of water entering, after a predetermined time (t3 seconds) has elapsed (8
13) The incoming water temperature is detected by the incoming water temperature thermistor 35 (814). Then, it is determined whether or not 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 (816), and the operation switch 56.56a of the main controller 54 and sub-controller 54a
is turned off (S17). When the temperature is lower than 55° C., it is determined whether the inlet water temperature is below the set humidity (818), and when the temperature is higher than the set temperature, the operation at 812 and below is repeated, and when the temperature is below the set temperature, the fan 12 is turned on (S19).

The number of rotations of the fan 12 is detected by the Hall IC.
), and determines whether the rotation speed is greater than or equal to a predetermined rotation speed ( S
21"). 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, main solenoid valve 22, switching valve 24, governor proportional valve 23, fan 1
2 to 0FFL (822-26), the user closes the hot water tap (S27), and then the operation switch 56.56a of the main controller 54 and sub-controller 54a
is turned off (828).

When the rotational speed is equal to or higher than a predetermined rotational speed, t4 (for example, 0.
Perform pre-purge for 5-10 seconds (S29), turn on the sparker 14, main solenoid valve '21, main solenoid valve 22, and switching valve 24 (830-33), and supply slow ignition current to the governor proportional valve 23. (834).

The amount of current applied to the governor proportional valve 23 is controlled based on the rotational speed of the fan 12, that is, the air volume, and the gas type Kp, except when igniting. 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 current to the governor proportional valve 23 adjusted by a 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 turning the sparker 14 ONL, after t5 (for example, 5 to 20) seconds have elapsed (S35), the sparker 14
is turned off (836). And frame rod 15
The combustion flame is detected by the flame rod 15, and the IA is detected by the flame rod 15.
Determine whether or not a current greater than or equal to the current value is input (837
). When a current of IA or more is not input, the operation of 822 and below is repeated as an ignition error.

When a current of IA or higher is input, t6 (for example, 0
．． A slow ignition timer is activated for 1 to 10 seconds (838), and the output temperature is detected by the output AWm thermistor 38 (S
39).

Next, the combustion capacity control shown in the operation flowcharts of FIGS. 6 and 7 is performed (840), and the following safety function control is performed.

Determine whether the rotation speed of the fan 12 is equal to or higher than a predetermined rotation speed (
841). When the rotation speed is lower than a predetermined rotation speed, the operation 322 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 inputted by the frame rod 15 (842). When a current of more than IA is input, continuous combustion may continue for tl (for example, 40 to 120) minutes (S43), or the temperature of the outlet water may exceed the boiling temperature (S44).
), if this continues for t8 (for example, 1 to 10) seconds (S45), the operations from 822 onwards are repeated. If the continuous combustion is within t7 minutes and the output temperature does not reach the boiling temperature, after inputting the set temperature again (846),
Repeat steps 9 and below. 346 deals 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 it is difficult to determine whether or not this is the first misfire during combustion (547), and when it is the second misfire, the operations from 822 onwards are repeated. When a misfire occurs for the first time, the original solenoid valve 21, main solenoid valve 22, and switching valve 24 are set to 0FFL.

(S48-50), and then repeats the operations from 819 onwards.

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

First, combustion capacity is calculated based on the following formula (3100), (S101).

First calculated value Q-(Tset-THin) xw=
Combustion capacity second calculated value q= (THout −THin) xw
Tset: Setting fA THin: Inlet water temperature THout: Output 1m W: Incoming water amount FFi11wJ, whether or not to go forward L (S102),
When performing FF ill Ill, FB(P
I) Perform control and FF! II! [When not doing I,
Determine whether t9 seconds have elapsed after initial setting (3103)
, after t9 seconds have elapsed, determine whether Q≧qx (
S104).

When Q≧qx, determine whether Q<Q (S
105).

In this way, by comparing the first calculated value (combustion capacity) Q and the second calculated value q, it is found that the combustion capacity Q is almost the same as shown in the graph showing the relationship between combustion capacity and gas amount in Figure 8. A slow heating capacity range A controlled by proportional control of the fan 12, governor proportional valve 23, and switching valve 24 during slow heating to produce an output with a capacity of Rapid heating capacity range B controlled by proportional control of fan 12, governor proportional valve 23, and switching valve 24, and fan 12 and governor proportional valve 2 during residual heat purge that produces an output with a capacity smaller than combustion capacity.
3. Select residual heat purge capacity range C controlled by proportional control of the switching valve 24, and perform <FF control based on the operation flowchart below to automatically adjust the fuel gas supply amount according to these controls iI1wt. .

When Q<q does not exist, in order to bring the outlet hot water temperature close to the set temperature, the fan 12, governor proportional valve 23,
The switching valve 24 and the water volume proportional adjustment valve 33 are controlled, and the above-mentioned F
Based on the operation flowchart shown in FIG. 7 from F control, <P
Switch to IIIIO (8106).

When Q<q, the hot water temperature is higher than the set temperature, so in order to bring the hot water temperature closer to the set temperature, burn at the minimum combustion capacity (residual heat purge capacity) in the residual heat purge capacity range. Fan 12, governor proportional valve 23, switching valve 24
, controls the water volume proportional adjustment valve 33 (S107). r
+-a/W [seconds] (8108), and after the predetermined time (11 seconds) for switching from FF control to PIlltIIID has elapsed (3109), the residual heat purge capacity range ((Q+α)
FFIII
PI sub-control is switched based on the operation flowchart shown in FIG. 7 (3110).

Here, if τ1 second has not elapsed, the set temperature (T
The deviation 1 dtl between the temperature (Set) and the output temperature (THout) is ±
Determine whether it is within y℃ (Sllll) and calculate the deviation 1dt1
is within ±y℃, perform 5110, and the deviation 1d [1 is ±
If the temperature is not within y°C, perform step 5109 again.

Since there may be errors due to variations in the water heater or insufficient gas volume where the gas pressure is lower than the standard value, the detected temperature of the outlet hot water temperature thermistor 38 is set when t9 seconds have elapsed (S103) after moving to the initial setting position. Q≧q that does not result in temperature
At the time of x, the set temperature (Tset) and hot water temperature (THou
It is determined whether the deviation 1 dtl from t) is within ±y”0 (3112), and when the deviation 1 dtl is within ±y°C, 5
106, and when the deviation l dt l is not within ±y°C, the fan 12, governor proportional valve 23, switching valve 24, The water amount proportional adjustment valve 33 is controlled (S113).

However, due to changes in water volume, the combustion capacity calculation value is updated, and if combustion control is activated at this time, the change in gas volume and the change in water input amount will interfere and affect the hot water temperature, so it is necessary to maintain maximum combustion capacity. When changing the opening degree of the water volume proportional adjustment valve 33, the gas volume is not adjusted by controlling the fan 12 and the governor proportional valve 23.

Here, it is determined whether or not the switching valve 24 is turned on (5114). When the switching valve 24 is turned on, that is, when the first burner 11a and the second burner 11b are operated at full capacity by simultaneous combustion, It is determined whether the output is below the maximum range of the half-open capacity control tll1gI (1/2 capacity of the full-open capacity control range l range ■) (5115), and if it is not below the maximum range, the governor proportional valve is activated with the output within the overlap control range m. 23 is subjected to gas proportional control (S116).

When the switching valve 24 is not turned on, that is, during half-open capacity operation with combustion of only the first burner 11a, it is determined whether or not the capacity is equal to or higher than the minimum range of the full-open capacity control area (■) (the capacity of 174 of the full-open capacity control area ■). 5117), and when it is not greater than the minimum range, perform 8116.

Therefore, the judgment level for the rapid heating capacity (Q0α) is: below the maximum range of half-open capacity control area 11 engineering = maximum range of half-open capacity control ll area engineering ÷ ((Q+α)/Q), and full-open capacity control The overlap control is limited to 1lTiA■ which is greater than or equal to the minimum area of area ■ (fixed value). As a result, the switching valve 24 is turned ON.
, it is possible to prevent chattering between fully open and half open the gas burner 11 that occurs when the gas burner 11 is turned off, and it is possible to both expand the temperature control range and speed up the control of the rapid heating capacity.

Next, calculate τ2-b-cw [seconds] 3118),
Predetermined time for switching from FF control to PI sub-control (12 seconds)
After the elapsed time (3119), the residual heat purge capacity area ((Q-
The fan 12, the governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 33 are controlled so that combustion occurs with the residual heat purge capacity of β)/Q), and the FF control described above is switched to the PI sub-control (S120).

Here, if τ2 seconds have not elapsed, the set temperature (T
1 dt deviation between set ) and hot water m (THout)
Determine whether l is within a predetermined temperature difference ±y°C (S 1
21) When the deviation 1dtl is within ±y℃, perform 5120, and when the deviation 1dtl is not within ±y℃, check whether there is a change in the outlet WA temperature that is less than or equal to the temperature difference Δy in the outlet water temperature in a predetermined time Δt. (S122). When there is a change in the outlet hot water temperature equal to or less than Δy/Δ, step 8120 is performed, and when there is no change in the outlet hot water temperature equal to or less than Δy/Δ, the operations from 8119 onwards are repeated.

The PI sub-control controls the set temperature (rset) and hot water temperature (THo).
ut) is greater than or equal to +y°C (S12
3), When the deviation is +y℃ or more, the residual heat purge capacity range ((Q
- β)/Q) The fan 12, governor proportional valve 23, switching valve 24, and water volume proportional adjustment valve 33 should be controlled so that the combustion occurs with the residual heat purge capacity of β)/Q). Performs safety control. Also, t10
If the seconds have not elapsed, the operations from 8123 onwards are repeated.

When the deviation is not greater than +y℃, calculate the integral time from the composite function of the temperature deviation function and the large water flow function (S127
).

Temperature deviation: 20 general constant temperature: hot water temperature, ', F (e) = (K+-e)
G (W) = (K2-e) The shorter the integral time [seconds] is, or the greater the amount of water entering, the shorter the integral time is.
The output time to the governor proportional valve 23 or the water volume proportional adjustment valve 33 becomes shorter.

After that, after 1 hour (8128), temperature deviation e≦
1 or not 5129), when e≦1, perform the above-mentioned safety control, and when e≦1, input the gas type Kp of the fuel gas 8130), and perform the proportional control according to the gas type Kp. The following P111tll output was updated so as to switch to the control constant, and the proportional control constant of the PI control output to the governor proportional valve 23 or water volume proportional adjustment valve 33 was output as a temperature deviation function (8131) l, safety control I do.

PI proportional control force PM = PN-1+exKp proportional output change: Δ■5=eX) (p pH-1-Q+α: current PI proportional control output, ", PI
Proportional IJt [l Output PH = PN-1 + Δ■S However, when the amount of water entering is less than the specified flow rate, the maximum value of the output should be brought closer to (Q + α) / Q to QX 1.0 to improve stability at minute flow rates. ing.

Therefore, by switching to a proportional control constant according to the load such as gas type Kp1 gas darkness and water inflow amount, the gas amount can be increased or decreased (not a fixed value but a variable), and a wide range and free PI control can be performed. be able to. In addition, it is possible to perform PIIIlm that is compatible with the characteristics of the governor proportional valve 23 (which differs depending on the gas type).Furthermore, the integral time T
and P■ proportional control output, the hot water temperature can be quickly brought close to the set temperature.

In this embodiment, gas is used as the fuel, but liquid fuel such as oil may also be used.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a water heater employing an embodiment of the present invention, Fig. 2 is a block diagram showing a water heater employing an embodiment of the present invention, and Figs. 3 to 7 are a schematic diagram showing a water heater employing an embodiment of the present invention. FIG. 8 is a graph showing the relationship between the combustion capacity and the amount of gas in the water heater according to the embodiment of the present invention. In the diagram

Claims (1)

[Scope of Claims] A combustor case, a burner provided in the case, a heat exchanger provided in the case for heating water passing through the case with the burner, and an upstream part of the heat exchanger. an inlet water temperature detection means for detecting an inlet temperature of water flowing into the heat exchanger; an outlet water temperature detection means for detecting an outlet temperature of water flowing out from the heat exchanger; a temperature setting means for setting the temperature to a set temperature; a fuel supply amount control means for controlling the amount of fuel supplied to the burner; and a first calculated value of the combustion capacity based on the deviation between the set temperature and the inlet water temperature. , and calculates a second calculated value based on the outlet hot water temperature, and by comparing the first calculated value and the second calculated value, a slow heating capacity that produces an output that is almost the same as the combustion capacity. a rapid heating capacity range that produces an output that is larger than the combustion capacity, and a residual heat purge capacity range that produces an output that is smaller than the combustion capacity, and supplies fuel according to these control ranges. A water heater equipped with a control circuit that performs feed forward control to automatically adjust the amount.