JPH0456218B2 - - Google Patents

Description

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

[Prior Art] Japanese Utility Model Publication No. 60-16843 discloses a first burner connected to a fuel supply passage through a proportional valve, and a second burner connected to the proportional valve through a switching solenoid valve. a half-open capacity control region controlled by proportional control of a proportional valve during half-open capacity operation by combustion of only the first burner;
overlap between the full-open capacity control range controlled by the proportional control of the proportional valve during full-open capacity operation due to simultaneous combustion of the burner and the second burner, the maximum range of the half-open capacity control range, and the minimum range of the full-open capacity control range A water heater having a control area is disclosed.

[Problems to be Solved by the Invention] However, in the water heater having the above configuration, when the proportional control of the proportional valve reaches the maximum range of the half-open capacity control range and the full-open switching signal is output, the switching solenoid valve is opened immediately. When the valve is suddenly switched from the half-open capacity control area to the full-open capacity control area, or when the proportional control of the proportional valve reaches the minimum range of the full-open capacity control area and a full-open switching signal is output, the switching solenoid valve is immediately activated. The valve closes and suddenly switches from the full-open capacity control area to the half-open capacity control area.

In this way, when the full-open switching signal and the half-open switching signal are captured as instantaneous values, the switching solenoid valve opens and closes frequently in items with large heat capacity such as water heaters, or items with delayed response. There was a risk that a repeated chattering phenomenon would occur.

Furthermore, since the combustion fan has a large inertia force and a response delay, switching control between the half-open capacity control range and the full-open capacity control range cannot be performed smoothly.

Therefore, there has been a problem in that poor control of the water heater occurs during switching control between the half-open capacity control area and the full-open capacity control area.

SUMMARY OF THE INVENTION An object of the present invention is to provide a water heater that can prevent the chattering phenomenon of a switching solenoid valve from occurring, and can smoothly perform switching control between a half-open capacity control area and a full-open capacity control area, thereby preventing poor control.

[Means for Solving the Problems] The present invention provides a first burner connected to a fuel supply path through a proportional valve that adjusts the amount of fuel supplied, and a first burner connected to a fuel supply path through a proportional valve and a switching solenoid valve. A burner consisting of a second burner connected to a fuel supply path, a combustion fan that changes the volume of combustion air supplied to the burner, and a combustion fan that is provided above the burner and that connects water passing through the burner and the burner. a heat exchanger for heating water by exchanging heat with the combustion heat; a hot water outlet temperature detecting means provided downstream of the heat exchanger for detecting the outlet temperature of water flowing out from the heat exchanger; temperature setting means for setting the outlet temperature of water flowing out from the exchanger to a desired set temperature; a half-open capacity control region controlled by proportional control of the proportional valve; and controlled by proportional control of the proportional valve. full-open capacity control area,
An overlapping control range between the maximum range of the half-open capacity control range and the minimum range of the full-open capacity control range is selected based on the deviation between the set temperature and the hot water temperature, and the switching solenoid valve is controlled according to these control ranges. and a control circuit that performs feedback control that automatically adjusts the amount of fuel supplied to the burner and the amount of combustion air, wherein the control circuit is configured to switch the proportioning valve so that the proportional control valve is half-open. Only when the maximum capacity control area is reached and a full-open switching signal to the full-open capacity control area is output for a certain period of time, or only when the full-open capacity control area is near the minimum area and a half-open switching signal to the half-open capacity control area is output. The switching solenoid valve is switched only when the switching solenoid valve is outputted for a certain period of time, and the proportional valve and the Adopted technical means to control combustion fans.

In the present invention, 1/4 half-open includes not only 1/2 of full opening but also other partial openings.

[Function] The present invention is capable of controlling the proportional valve only when the proportional control of the proportional valve during feedback control reaches the maximum range of the half-open capacity control range and outputs a full-open switching signal to the full-open capacity control range for a certain period of time, or when the proportional control valve is controlled during feedback control. By switching the switching solenoid valve only when the proportional control of the proportional valve reaches near the minimum range of the full-open capacity control range and outputs a half-open switching signal to the half-open capacity control range for a certain period of time, the full-open switching signal or half-open switching signal is output. Switching control between the half-open capacity control area and the full-open capacity control area is performed only when the switching signal is output for a certain period of time.

At this time, the amount of combustion air sent to the burner by the combustion fan and the amount of fuel supplied by the proportional valve are:
Each corresponds to the optimum value, and is constant regardless of whether the burner is fully opened or half-open.As the combustion fan has a large inertia force and a response delay, the amount of combustion air sent to the burner by the combustion fan and the proportional valve The amount of fuel supplied is not changed. Therefore, the air-fuel ratio is stabilized and a safe combustion state is obtained, and smooth switching control between the half-open capacity control range and the full-open capacity control range is performed.

[Effect of the invention] Even in water heaters with a large heat capacity or a response delay, the switching solenoid valve is frequently opened and closed during switching control between the half-open capacity control area and the full-open capacity control area. It is possible to prevent repeated occurrence of chattering phenomenon. In addition, since the air-fuel ratio is stabilized, a safe combustion state can be obtained, and smooth switching control between the half-open capacity control area and the full-open capacity control area can be performed. It is possible to prevent poor control of the water heater during switching control.

[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 combustion water heater using fuel gas as fuel.

Inside the water heater case 2 of the gas combustion water heater 1,
A combustor case 10 is provided, and inside the combustor case 10 is 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 serving as a fuel supply path. is provided. The combustor case 10 is also equipped with a combustion fan 12 using a three-phase Y-connected brushless DC motor, and the two-barrel gas burner 11 uses combustion air supplied by the combustion fan 12. The combustor is a forced-air combustor that burns with fuel gas supplied from a gas supply pipe 20, and the combustion gas generated by combustion is exhausted to the outside from an exhaust port 3.

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

The gas supply pipe 20, which has a gas supply path formed inside, includes a source solenoid valve 21 and a main solenoid valve 22, which allow fuel gas to pass through when energized from the upstream side, and a supply pressure that determines the supply amount of fuel gas (hereinafter abbreviated as gas amount). a governor-type gas proportional valve (hereinafter referred to as governor proportional valve) 23, which is a fuel supply amount control means that adjusts by controlling the
A switching solenoid valve (hereinafter abbreviated as switching valve) that shuts off fuel gas to the second burner 11b depending on usage conditions
24 are provided respectively, and supply fuel gas to the above-mentioned double gas burner 11.

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 of the drain valve 32, and a water volume proportional adjustment valve 33 using a geared motor that adjusts the amount of water entering the heat exchanger 13 is provided downstream thereof. A potentiometer 34 is provided for detecting the opening degree.

The temperature of the water whose inflow amount is adjusted by the water amount proportional adjustment valve 33 is detected by an incoming water temperature thermistor 35, which is an incoming water temperature detection means provided immediately downstream.
Furthermore, the amount of water entering is detected by a water amount sensor 36 which is a water amount detecting means downstream of the water entering water, 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 temperature thermistor 38, which is a hot water temperature detection means for detecting the temperature of heated water. Stopper (not shown)
is provided. 39 is a boil 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. and a gas type changeover switch 55 for setting the type of fuel gas. Types of fuel include LP gas, city gas 1
The gas type switching switch 55 selectively switches between gaseous fuels such as 3A and city gas 6C.

The main controller 54 and the sub-controller 54a are temperature setting means operated 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. Note that 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 combustion capacity such as the set temperature, and
A Hall IC provided in a three-phase Y-connected brushless DC motor detects its rotational speed and sends a detection signal to the CPU 70.

The proportional valve control circuit 73 is connected to the dual gas burner 1.
In order to adjust the gas amount so that the combustion in step 1 is performed at a desired air-fuel ratio, the amount of current applied to the governor proportional valve 23 is based on a proportional-integral control constant according to the characteristics of the governor proportional valve 23 (which varies depending on the type of gas). This is a circuit that controls the The proportional valve control circuit 73 has a semi-fixed volume that proportionally controls the proportional valve 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 amount of gas. We are prepared.

The geared motor drive circuit 74 includes a water amount proportional adjustment valve 3 for adjusting the amount of water flowing into the heat exchanger 13.
The power is turned off in the circuit that drives gear motor 3.
It does not operate when the power is on, but when the power is on,
The operation switch 56a of the sub-controller 54a is
Regardless of whether it is ON or OFF, it is set at the fully open set temperature position, and from that position it is initially set to a position according to the reference temperature.

The position detection circuit 75 is a circuit for analyzing the signal from the potentiometer 34 provided in the water volume proportional adjustment valve 33 to detect its opening degree. Accurate control is achieved by using only the electrically effective portion of the entire rotation angle in which a change in rotation appears as a change in resistance value, and by reading the detected resistance value directly as the rotation angle.

The water amount detection circuit 76 detects the amount of water entering based on the rotational speed signal of the water amount sensor 36. In this embodiment, the water amount detection circuit 76 detects the amount of water entering the water based on the rotation speed signal of the water amount sensor 36.
By obtaining two new pulse signals, the pulse repetition period is shortened and the pulse width is increased to reduce errors in F/V conversion.

The CPU 70 has a memory function that stores the reference temperature that is set in advance when the water heater 1 is assembled or shipped, and the gas type of the fuel gas that is set with the gas type changeover switch 55, and the main controller 54.
and the sub-controller 54a, a sequence control function that controls the operating order and timing of each of the above circuits, and a feed forward control (controlling the combustion amount and water input amount based on the input water temperature and set temperature). (hereinafter referred to as FF control), automatically adjusts the gas amount based on the hot water temperature, turns on the switching valve 24,
OFF, feedback control (hereinafter referred to as FB control) that performs proportional-integral control (hereinafter referred to as PI control) of the combustion amount and water inflow amount such as air volume adjustment of the combustion fan 12, and switching control that switches between FF control and FB control. It also has a combustion capacity control function and other 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 function, when the user opens the hot water tap and a water flow signal is obtained based on the water flow sensor 36, the combustion fan 12 is activated, and after pre-purging is performed for a predetermined time, the ignition operation is performed. . Ignition operation is performed by the original 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 capacity for combustion is calculated, and combustion begins according to the set amount.

The operation of the sparker 14 is not limited to the time of starting use.
In the following cases where there is a possibility of misfire even during use, i.e. when the double gas burner 11
When the switching valve 24 is placed in the open state due to capacity control associated with the use of This is also done in some cases, and each operates for a predetermined period of time.

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. is not obtained. Therefore, in this embodiment, the water temperature is read by the incoming 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 control function includes FF control and FB (PI) that detects the hot water temperature and corrects the combustion amount and water input amount.
control is performed.

The FF control uses a calculated value Q of the required capacity calculated from the set temperature, incoming water temperature, and incoming water amount by the main controller 54 and sub-controller 54a.
The most efficient combustion capacity is calculated from the calculated value q of the necessary capacity calculated from the incoming water temperature, incoming water amount, and outgoing hot water temperature, and the combustion fan 12, governor proportional valve 23, switching valve 24, and water volume proportional adjustment are calculated. Each valve 33 is controlled to automatically adjust the amount of gas and the amount of water entering.

FF control has a rapid heating capacity range that is controlled by gas proportional control during rapid heating, which outputs a rapid heating capacity (Q + α) that is larger than the required capacity Q, and a residual heat purge capacity (Q - β) that is smaller than the required capacity Q. Combustion fan 12, governor proportional valve 23, switching valve 24, water volume proportional adjustment valve 3 according to the residual heat purge capacity range controlled by gas proportional control when outputting residual heat purge.
3 to automatically adjust the amount of gas and water input.

Moreover, the rapid heating capability range is the maximum range of the half-open capability control region controlled by the control of the governor proportional valve 23 during half-open capability operation with combustion of only the first burner 11a, and 2
It is limited to an overlapping control range in which the minimum range of the full open capacity control range controlled by the governor proportional valve 23 during full open capacity operation due to simultaneous combustion of the burner 11b overlaps.

In particular, in this embodiment, as shown in the graph of FIG. 9 showing the relationship between the degree of opening of the governor proportional valve 23 and the full opening capacity, a half open capacity control area, a full open capacity control area, and an overlapping control area are set. ing.

In addition, in the case of the water heater 1 having the governor proportional valve 23 that can throttle the opening to 1/4 of the full opening degree, the half-open capacity control range is the half-open capacity control range when the switching valve 24 is in the closed state, and the first burner 11a only has the full open capacity. This is a control range that performs gas proportional control of 1/8 to 1/2. The full-open capacity control range is a control range in which when the switching valve 24 is in the open state, the first burner 11a and the second burner 11b perform gas proportional control of 1/4 to 1 of the full-open capacity. The duplicate control area is
A control area that performs gas proportional control when the maximum value of the half-open capacity control area is below and the minimum value of the full-open capacity control area, and the maximum range of the half-open capacity control area (1/2 of the full-open capacity) and the full-open capacity This is a control area that overlaps with the minimum control area (1/4 of full open capacity).

By FB control, when the proportional-integral control of the governor proportional valve 23 has reached near the maximum range of the half-open capacity control range and the full-open switching signal to the full-open capacity control range is output for a certain period of time, slow ignition control is performed. While doing so, the switching valve 24 is turned on (opened) to switch from the half-open capacity control area to the full-open capacity control area. In addition, by FB control, when the proportional integral control of the governor proportional valve 23 has reached the vicinity of the minimum range of the full-open capacity control range and the half-open switching signal to the half-open capacity control range is output for a certain period of time, switching is performed. valve 24
Turn OFF (close the valve) and switch from the full open capacity control area to the half open capacity control area. Then, during the switching control between the half-open capacity control area and the full-open capacity control area in the FB control, the air volume of the combustion fan 12 and the proportional valve current of the governor proportional valve 23 are not changed,
Smooth switching control between the half-open capacity control area and the full-open capacity control area is performed.

As a safety function, if the temperature of the hot water reaches boiling point or higher and continues for a predetermined time of t8 (e.g. 1 to 10) seconds, or if continuous combustion continues for t7 (e.g. 40 to 120) minutes, no flame will be detected. At times, each solenoid valve is closed and operation is 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 8.

When installing the water heater 1, the combustion gas is checked using the gas type changeover switch 55, and the reference temperature (40° C. in this embodiment) is set (S1). The user of the water heater does not select the type of fuel gas and set the reference temperature, and since they are stored in the memory function of the CPU 70, the CPU
It is stored in 70. 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 water heater 1 was used last time, 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, from the initial setting opening degree, the FF described later
Since the adjustment time of the water volume proportional adjustment valve 33 until it moves to the opening degree according to the set temperature during control is shortened, the outlet hot water temperature can be quickly set to the set temperature during FF control.

When the opening is set to allow the maximum amount of water to enter in accordance with the combustion capacity, the geared motor is turned 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, and as a result, the energization time becomes longer and there is a risk of burnout due to heating of the motor or 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 (for example, 2 to 30) seconds (S6).

Next, the operation switches 56, 56a of the main controller 54 or sub-controller 54a are activated.
Determine whether it is turned on (S7) and repeat S7 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).

In addition, if the hot water temperature is not set even after the predetermined time t2 seconds has passed (S9), the set temperature will be changed to 40°C, which is the reference temperature.
(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 detecting the amount of water entering, after t3 seconds have elapsed (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 on the operation switches 56, 56 on the main controller 54 and sub-controller 54.
Turn a off (S17). When the temperature is lower than 55℃, it is determined whether the inlet water temperature is below the set temperature (S18), and when the temperature is higher than the set temperature, the operation below S12 is repeated, and when the temperature is below the set temperature, the combustion fan 12 is turned on.
(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, the switching valve 24,
Governor proportional valve 23 and combustion fan 12 all
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 governor proportional valve 23.
Supplies slow ignition current to (S34).

As shown in FIG. 10, the amount of current applied 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 of the governor proportional valve 23 adjusted by the semi-fixed volume of the proportional valve control circuit 73. can be,
Thereby, an appropriate amount of slow ignition gas can be supplied at the time of ignition.

Furthermore, after turning on the sparker 14, after t5 (for example, 5 to 20) seconds have elapsed (S35), the sparker 1
4 is turned OFF (S36). Then, the combustion flame is detected by the flame rod 15, and the flame rod 15
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 higher than IA is input, t6
A slow ignition timer is set for (for example, 0.1 to 10) seconds (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 to 8 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 second misfire (S47).
Repeat the operations from S22 onwards. When a misfire occurs for the first time, close the main solenoid valve 21, main solenoid valve 22, and switching valve 24.
Turn OFF (S48 to S50) and then repeat the operations from S19 onwards.

The combustion capacity control will be explained based on the operation flowcharts shown in FIGS. 6 to 8.

First, the required capacity for combustion capacity control is calculated based on the following formula (S100), (S101).

Equation 1... Calculated value Q = (Test - THin) x w Equation 2... Calculated value q = (THout - THin) x w Tset: Set temperature THin: Inlet water temperature THout: Outlet water temperature w: Inlet water amount Was FF control performed? Determine whether or not (S102), FF
When controlling, the FB shown in Figure 7
(PI) control is performed and FF control is not performed, it is determined whether a predetermined time t9 seconds has elapsed after the initial setting of the water volume proportional adjustment valve 33 (S103), and after t9 seconds have elapsed, Q≧qx It is determined whether or not (S104).

When Q≧qx is not satisfied, it is determined whether Q<q or not (S105), and when Q<q is not satisfied, combustion is performed at a slow heating capacity (Q×1.0) in order to bring the outlet hot water temperature close to the set temperature. Then, the combustion fan 12, governor proportional valve 23, switching valve 24, and water volume proportional adjustment valve 33 are controlled (S106).

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, the remaining heat purge capacity (Q-β: minimum combustion capacity) is used to burn the hot water. Combustion fan 12, governor proportional valve 23, switching valve 24, water volume proportional adjustment valve 33
(S107). τ ₁ = a/w [seconds] is calculated (S108), and after τ ₁ second has elapsed (S109), combustion is performed with a combustion capacity that brings the rapid heating capacity (Q + α) closer to the slow heating capacity (Q × 1.0). , combustion fan 1
2. Control the governor proportional valve 23, switching valve 24, and water volume proportional adjustment valve 33 (S110), and perform FB (PI) control.

Here, when τ ₁ second has not elapsed, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is |dt
It is determined whether the deviation is within |dt| (S111).
When the deviation is within |dt|, S110 is performed, and when the deviation is not within |dt|, S109 is performed again.

There may be errors due to variations in water heaters or cases where the gas pressure is lower than the standard value and the gas volume is insufficient.
After the water volume proportional adjustment valve 33 moves to the initial setting position, t9
When seconds have elapsed (S103), the detected temperature of the hot water temperature thermistor 38 does not reach the set temperature Q≧qx
At the time of , the set temperature (Tset) and hot water temperature (THout)
Determine whether the deviation is within |dt| (S112), and if the deviation is within |dt|, perform S106,
When the deviation is not within |dt|, the rapid heating capacity (Q+
α), the combustion fan 12, the governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 33.
(S113).

At this time, for example, the water volume proportional adjustment valve 33 is
The data input to the CPU 70 is read and the opening degree is quickly narrowed down to the deviation |dt| between the set temperature (Tset) and the outlet hot water temperature (THout).

However, due to a change in water volume, the calculated value of the required capacity for combustion capacity control is updated, and if combustion capacity control is activated at this time, the change in gas volume and the change in water input will interfere, and the temperature of the hot water will be affected, so rapid heating is not possible. When changing the opening degree of the water volume proportional adjustment valve 33 by maintaining the capacity (maximum capacity), the gas volume is 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,
In other words, the switching valve 24 is open and the first burner 1
During full-open capacity operation with simultaneous combustion of burner 1a and second burner 11b, it is determined whether the maximum value of the half-open capacity control area (capacity of 1/2 of the full-open capacity control area) or less is determined (S115), and the half-open capacity control area is set. is less than the maximum value, the governor proportional valve 23 is controlled gas proportionally with an output within the overlapping control range (S116).

When the switching valve 24 is not turned on, that is, when the switching valve 24 is closed and only the first burner 11a is in combustion at half-open capacity, the minimum value of the full-open capacity control range (1/4 of the full-open capacity control range) (S117), and if it is greater than or equal to the minimum value of the full-open capacity control range, S116 is performed.

Therefore, the determination level of the rapid heating ability (Q+α) is below the maximum value of the half-open capacity control area {=maximum value of the half-open capacity control area ÷ (Q+α)}, and above the minimum value of the full-open capacity control area. Limited to the overlap control area, which is an overlap area (fixed value). This results in
It is possible to prevent the occurrence of a chattering phenomenon in which the gas burner 11 is repeatedly fully opened and half-opened due to ON and OFF of the switching valve 24, and it is possible to both expand the temperature control range and speed up the control of the rapid heating capacity.

Next, calculate τ ₂ = (b-cw) [seconds] (S118),
After τ ₂ seconds (S119), residual heat purge capacity (Q
−β), the combustion fan 12, the governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 3.
3 (S120), and performs FB (PI) control.

Here, when τ ₂ seconds have not elapsed, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is |dt
It is determined whether the deviation is within |dt| (S121).
If the deviation is within |dt|, S120 is performed, and if the deviation is not within |dt|, 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 water temperature in a predetermined time Δt (S122).
When there is a change in outlet hot water temperature less than Δy/Δt, S120
is carried out, and when there is no change in the outlet hot water temperature less than Δy/Δt, the operations from S119 onwards are repeated.

In FB (PI) control, it is determined whether the deviation between the set temperature (Tset) and the hot water outlet temperature (THout) is greater than or equal to +y℃ (S123), and when the deviation is greater than or equal to +y℃, the residual heat purge capacity (Q- The combustion fan 12, the governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 33 are controlled so as to cause combustion at β) (S124), and after t10 seconds have elapsed (S125), the above-mentioned safety control is performed. Also,
If t10 seconds have not elapsed, the operations from S123 onwards are repeated.

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 function (S127).

Temperature deviation: e = set temperature - hot water temperature ∴F(e) = (K ₁ - e) x k ₁ K, k are constants Incoming water volume w is a known quantity detected by the water flow sensor ∴G(w) = (K ₂ −e)×k ₂ ∴Integral time: T=K ₃ ] is shorter or the amount of water entering is larger, the integration time is shorter, and the output time to the governor proportional valve 23 or the water amount proportional adjustment valve 33 is shorter.

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, input the gas type Kp of the fuel gas (S130), and update the PI control output below to switch to the proportional integral control constant according to the gas type Kp. After that, the proportional control constant of the PI control output to the governor proportional valve 23 or the water volume proportional adjustment valve 33 is output as a temperature deviation function (S131), and then safety control is performed.

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, from the specified flow rate When the amount of water entering is small,
The maximum output value brings the rapid heating capacity (Q+α) closer to the slow heating capacity (Q×1.0) to improve stability at minute flow rates.

Therefore, by switching to the proportional-integral control constant according to the load such as gas type Kp, gas amount, and water input amount, the gas amount can be increased or decreased (not a fixed value but a variable), and can be used over a wide range and freely. PI control can be performed. In addition, the governor proportional valve 23
It is possible to perform PI control that matches the characteristics of the gas (varies depending on the gas type). Furthermore, the integration time T and
From the PI control output, the hot water temperature can be quickly brought close to the set temperature.

In addition, when the gas passage in the gas supply pipe 20 has a large load, for example, when a gas type Kp (low vomit gas) that is subject to a large resistance force of passage resistance is adopted, switching between the half-open capacity control area and the full-open capacity control area is possible. , even if the opening area ratio (nozzle diameter x number) of the two-bar gas burner 11 changes, the gas supply pipe 20
Due to the pressure loss, it may not be possible to obtain a predetermined amount of gas according to the air volume control of the combustion fan 12.

In this case, in this embodiment, the proportional valve current supplied to the governor proportional valve 23 is changed from A ₁ to the minimum value of the proportional valve current during full open capacity operation according to the gas type Kp, as shown in the graph of FIG. A ₂ is brought close to the maximum value, and the maximum value of the proportional valve current is set during half-open capacity operation.
The minimum value from B ₁ to B ₂ is made to be close to wavy. Therefore, it is possible to control the air volume of the combustion fan 12 or to perform gas proportional control to obtain a predetermined gas amount according to the gas type Kp.

In addition, by switching between the half-open capacity control range and the full-open capacity control range, even if the opening area ratio of the dual gas burner 11 changes, the proportional valve current of the governor proportional valve 23 can be controlled to reduce the load per unit gas burner 11. can be set to a predetermined amount corresponding to the air volume control of the combustion fan 12, so the air-fuel ratio is stabilized,
Safe combustion can be performed.

Here, when the following state is reached by the FB (PI) control, the half-open capacity control area and the full-open capacity control area are switched based on the operation flowchart shown in FIG.

At the time of PN-1 proportional control output, the switching valve 24
is ON (S200), and when the switching valve 24 is not ON, that is, the switching valve 24
When the first burner 11a is closed and only the first burner 11a is in operation at a half-open capacity, the proportional valve current of the governor proportional valve 23 is controlled by gas proportional control in the half-open capacity control region to automatically adjust the gas amount ( S201).

At this time, it is determined whether the gas proportional control has reached near the maximum range of the half-open capacity control range (S202), and if it has not reached near the maximum range, the process returns to (S202).

Further, when reaching near the maximum range, a full open switching signal is output (S203). The full open switching signal uses a limit on the supply voltage to the combustion fan 12 or the current value to the governor proportional valve 23.

It is determined whether a certain period of time t11 (for example, 5 to 30) seconds has elapsed since the full-open switching signal was output (S204), and if the certain period of time t11 seconds has not elapsed, the full-open switching signal is continued. It is determined whether or not it is being output (S205). When the full-open switching signal is not being output continuously, the process returns to (S202), and when the full-open switching signal is being continuously output, the process returns to (S204).

When the full open switching signal is continuously output for a certain period of time t11 (for example, 5 to 30 seconds), a gentle ignition current is supplied to the governor proportional valve 23 (S206), and the switching valve 24
is turned ON (S207) to switch to a full-open capacity control region with simultaneous combustion of the first burner 11a and the second burner 11b. Then, the process returns to (S200).

When the switching valve 24 is turned on, that is, when the switching valve 24 is closed and the first burner 11a and the second burner 11b are in full-open capacity operation with simultaneous combustion, gas proportional control in the full-open capacity control range is performed. Then, the proportional valve current of the governor proportional valve 23 is controlled to automatically adjust the gas amount (S208).

At this time, it is determined whether the gas proportional control has reached near the minimum range of the full-open capacity control range (S209), and if it has not reached near the minimum range, the process returns to (S209).

Furthermore, when reaching near the minimum range, a half-open switching signal is output (S210). The half-open switching signal uses a limit on the supply voltage to the combustion fan 12 or the current value to the governor proportional valve 23.

It is determined whether a certain period of time t12 (for example, 5 to 30) seconds has elapsed since the output of the half-open switching signal (S211), and if the certain period of time t12 seconds has not elapsed, the half-open switching signal is continued. It is determined whether or not it is being output (S212). When the half-open switching signal is not being output continuously, the process returns to (S209), and when the half-open switching signal is being continuously output, the process returns to (S211).

When the full open switching signal is continuously output for a certain period of time t12 (for example, 5 to 30 seconds), the switching valve 24 is turned OFF.
(S213), and switches to a half-open capacity control region where only the first burner 11a burns. and,
Return to (S200).

At this time, the air volume of the combustion fan 12 and the proportional valve current of the governor proportional valve 23 each correspond to their optimum values, and are constant regardless of whether the dual gas burner 11 is fully opened or half-open. 12 is
Since the inertial force is large and there is a delay in response, the air volume of the combustion fan 12 and the proportional valve current of the governor proportional valve 23 are not changed. Therefore, two-bar gas burner 1
1, the combustion air volume and gas volume never deviate from the optimum values. Therefore, by stabilizing the air-fuel ratio and achieving safe combustion conditions,
Smooth switching control from the half-open capacity control area to the full-open capacity control area or from the full-open capacity control area to the half-open capacity control area can be performed.

Furthermore, each of the first burner 11a and the second burner 11b has a capacity limit, and if the other burner can cover the limit value, the control range may be expanded by switching the switching valve 24. However, the method of detecting the switching signal as an instantaneous value is not suitable for water heaters 1 that have a large heat capacity and a delayed response, when controlling the switching valve 24 between the half-open capacity control area and the full-open capacity control area. A chattering phenomenon occurs in which the opening and closing of the valves are frequently repeated, resulting in poor control.

However, as in this embodiment, the governor proportional valve 23
A water heater 1 that switches to the control region when the proportional control of is stopped in the switching region (overlapping control region) for a certain period of time.
This can prevent the chattering phenomenon caused by frequent repetition of ON (open) and OFF (closed) of the switching valve 24, so hot water supply during switching control between the half-open capacity control area and the full-open capacity control area can be prevented. Control defects of the device 1 can be prevented.

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

In this embodiment, the present invention is used for feedback control, but the present invention may be similarly applied to a component of feedback control in a water heater that controls a combination of feedback control and feedback control.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing a gas combustion type water heater, Figure 2
The figure is a block diagram showing a gas combustion type water heater, Figures 3 to 8 are operational flowcharts for the gas combustion type water heater, and Figure 9 is the opening degree and fuel of the governor proportional valve for the gas combustion type water heater. FIG. 10 is a graph showing the relationship between the amount of gas supplied and the current flowing to the governor proportional valve of the gas combustion water heater. In the figure, 1... Gas combustion water heater, 11... Dual gas burner, 11a... First burner, 11
b...Second burner, 12...Combustion fan, 1
3... Heat exchanger, 20... Gas supply pipe, 23...
Governor proportional valve (governor type gas proportional valve), 24...
Switching valve (switching solenoid valve), 30...Water supply pipe, 3
8... Outlet hot water temperature thermistor (outlet hot water temperature detection means), 5
4... Main controller (temperature setting means), 5
4a...Sub controller (temperature setting means), 6
0...Control circuit.

Claims (1)

[Claims] 1 (a) A first burner connected to the fuel supply passage through a proportional valve that adjusts the amount of fuel supplied, and a first burner connected to the fuel supply passage through the proportional valve and a switching solenoid valve. (b) a combustion fan that changes the volume of combustion air supplied to the burner; (c) a burner that is provided above the burner and that passes through the burner; a heat exchanger that heats water by exchanging heat with the combustion heat of the burner; (d) a hot water temperature detection device that is provided downstream of the heat exchanger and detects the hot water temperature of the water flowing out from the heat exchanger; (e) temperature setting means for setting the outlet temperature of water flowing out of the heat exchanger to a desired set temperature; (f) a half-open capacity control region controlled by proportional control of the proportional valve; , a full-open capacity control range controlled by proportional control of the proportional valve, and an overlapping control range of the maximum range of the half-open capacity control range and the minimum range of the full-open capacity control range, are determined by the set temperature and the hot water temperature. a control circuit that performs feedback control that selects based on the deviation, switches the switching solenoid valve according to these control ranges, and automatically adjusts the amount of fuel supplied to the burner and the amount of combustion air. In the water heater equipped with the above, the control circuit outputs a full-open switching signal to the full-open capacity control range for a certain period of time only when the proportional control of the proportional valve reaches near the maximum range of the half-open capacity control range, or when the proportional control valve outputs a full-open switching signal to the full-open capacity control range for a certain period of time The switching solenoid valve is switched only when the control range reaches near the minimum range and a half-open switching signal to the half-open capacity control range is output for a certain period of time. A water heater characterized in that the proportional valve and the combustion fan are controlled so as not to change the supply amount and the combustion air volume.