JPH0478898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water heater that employs feedback control that automatically adjusts the amount of fuel supplied based on the deviation between a set temperature and a hot water temperature.

[Conventional technology]

Utility Model Publication No. 60-16843 discloses a burner comprising a first burner connected to a fuel supply path through a proportional valve, and a second burner connected to the proportional valve through a switching solenoid valve. , a half-open capacity control range in which the gas amount is controlled by proportional control of the proportional valve current during half-open capacity operation with combustion of only the first burner, and a full-open capacity control area with simultaneous combustion of the first burner and the second burner. a fully open capacity control region in which the gas amount is controlled by proportional control of the proportional valve current during operation;
A water heater is disclosed that has an overlapping control range of a maximum half-open capacity control range and a minimum full-open capacity control range.

[Problem that the invention seeks to solve]

However, in the water heater configured as described above, when the outlet temperature is lower than the set temperature and the combustion capacity is increased from the half-open capacity control range to the full-open capacity control range, the half-open capacity operation is suddenly switched to the full-open capacity operation. Furthermore, when the outlet temperature is higher than the set temperature and the combustion capacity is reduced from the full-open capacity control range to the half-open capacity control range, the full-open capacity operation is suddenly switched to the half-open capacity operation.

Therefore, there was a problem in that smooth switching control between half-open capacity operation and full-open capacity operation could not be performed while maintaining a safe combustion state.

An object of the present invention is to provide a water heater that can perform smooth switching control between half-open capacity operation and full-open capacity operation while maintaining a safe combustion state.

[Means for solving problems]

The water heater of the present invention includes: a fuel supply amount control means for adjusting the amount of fuel supplied; a first burner connected to a fuel supply path via the fuel supply amount control means; and a first burner connected to the fuel supply amount control means. a burner consisting of a second burner connected via a switching solenoid valve; a heat exchanger provided above the burner to heat water passing through the burner; and a heat exchanger provided downstream of the heat exchanger; a hot water outlet temperature detection means for detecting the outlet temperature of the water flowing out from the heat exchanger; a temperature setting means for setting the outlet temperature of the water flowing out from the heat exchanger to a desired set temperature; and only the first burner. The switching solenoid valve is closed during half-open capacity operation due to combustion of the first burner and the second burner, and the switching solenoid valve is opened during full-open capacity operation due to simultaneous combustion of the first burner and the second burner.
A half-open capacity control range that proportionally controls the control state of the fuel supply amount control means according to the deviation between the set temperature and the hot water temperature during the half-open capacity operation; A control circuit that performs feedback control having a full-open capacity control area that proportionally controls the control state of the fuel supply amount control means, and an overlapping control area that includes a maximum area of the half-open capacity control area and a minimum area of the full-open force control area. In the water heater, the control circuit opens the switching solenoid valve while performing slow ignition control when the proportional control reaches near the maximum range of the half-open capacity control range by feedback control during half-open capacity operation. A technical means is adopted in which the switch is switched to full-open capacity operation, and when the proportional control reaches near the minimum range of the full-open capacity control range by feedback control during full-open capacity operation, the switching solenoid valve is closed and switched to half-open capacity operation. .

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

[Effect]

During half-open capacity operation, when the proportional control of the control state of the fuel supply amount control means reaches near the maximum range of the half-open capacity control range based on the deviation between the set temperature and the hot water temperature, the switching electromagnetic switch is activated while performing slow ignition control. By opening the valve and switching to full-open capacity operation, the first
burner and the second burner are fired simultaneously.

In addition, when the proportional control of the control state of the fuel supply amount control means reaches near the minimum range of the full open capacity control range based on the deviation between the set temperature and the hot water temperature during full open capacity operation, the switching solenoid valve is closed. By switching the valve to half-open capacity operation, only the first burner is burned.

〔Effect of the invention〕

The water heater of the present invention can perform smooth switching control between half-open capacity operation and full-open capacity operation while maintaining a safe combustion state.

〔Example〕

Next, an example of a gas combustion type water heater using fuel gas as fuel will be described based on the drawings.

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

Inside the water heater case 2 of the gas combustion water heater 1,
A combustor case 10 is provided, and a double gas burner 11 consisting of a first burner 11a and a second burner 11b that combusts fuel gas supplied through a gas supply pipe 20 is further provided inside the combustor case 10. . In addition, the combustor case 10 includes a three-phase Y
A combustion fan 12 is provided that uses a wire-connected brush DC motor and adjusts the amount of combustion air (fan air volume) sent to the gas burner 11 according to the rotation speed.

The gas burner 11 is a forced-air combustor that burns using combustion air supplied by a combustion fan 12 and fuel gas supplied from a gas supply pipe 20, and is a forced-air combustor that burns the combustion air generated by combustion. The gas is exhausted to the outside through the exhaust port 3.

Above the combustor case 10 is a water supply pipe 30.
A heat exchanger 13 is provided, and water passing through the heat exchanger 13 is heated by the flame generated by the gas burner 11 and the heat of the combustion gas. Further, in the vicinity of the gas burner 11 in 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, a main solenoid valve 22, which allows fuel gas to pass through when energized from the upstream side.
A governor-type gas proportional valve (hereinafter referred to as governor proportional valve) 23, which is a fuel supply amount control means that adjusts the amount of fuel gas supplied (hereinafter referred to as gas amount) by controlling the supply pressure, goes to the second burner 11b. A switching electromagnetic valve (hereinafter abbreviated as a switching valve) 24 is provided to cut off the fuel gas depending on the usage state, and supplies the fuel gas to the gas burner 11 described above.

A water filter 31 is installed at the most upstream part of the water supply pipe 30.
A water drain valve 32 is provided downstream 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 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.
Further, the amount of water entering is detected by a water amount sensor 36 which is a water amount detecting means downstream thereof, and is sent to the heat exchanger 13 through the water supply pipe 30.

The water supply pipe 30 on the downstream side of the heat exchanger 13 is equipped with a hot water temperature thermistor 38 which is a hot water temperature detecting means for detecting the temperature of heated water, and a boiling prevention switch that is turned on when the hot water temperature exceeds the boiling temperature. 39, and a hot water tap (not shown) attached to a hot water supply location is provided at the most downstream end.

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 that is set according to the type of fuel gas.

Types of fuel include LP gas, city gas13
A, gas type switch 55 for city gas 6C, etc.
Selectively switch by.

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 set in.
In addition, the main controller 54 and the sub-controller 54a have respective operation switches 56,
56a, and outlet hot water temperature setting switches 57, 57a for setting the outlet 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 installed in a three-phase Y-connected brushless DC motor detects the rotation speed and sends a detection signal to the CPU 70. In this embodiment, the rotation speed signal is detected from all three phases of the motor. ,
The detection cycle is shortened.

The proportional valve control circuit 73 controls the amount of electricity supplied to the governor proportional valve 23 based on the characteristics of the governor proportional valve 23 (depending on the type of gas) 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. This is a circuit that performs control based on a proportional control constant depending on the The proportional valve control circuit 73 is connected to the water heater 1
In order to obtain a proper gas amount by correcting errors due to variations in the gas and pressure loss due to the type of gas, a semi-circular regulator is provided to proportionally control the maximum value of the current to the governor proportional valve 23.

The geared motor drive circuit 74 includes a water amount proportional adjustment valve 33 for adjusting the amount of water flowing into the heat exchanger 13.
The power is turned off in the circuit that drives the geared motor.
In this state, it does not operate, but in the power ON state, the operation switch 56a of the sub-controller 54a is activated.
Regardless of whether it 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 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 a reference temperature that is set in advance at the time of assembling the water heater 1 or at the shipping stage and the type of fuel gas to be used, and a discrimination control that discriminates between the main controller 54 and the sub-controller 54a. , sequence control for controlling the operating order and timing of each of the above circuits;
Combustion capacity control includes feed forward control (hereinafter referred to as FF control) that controls the combustion amount and water amount based on the incoming water temperature and set temperature, and automatically adjusts the gas amount based on the outlet hot water temperature and turns the switching valve 24 ON and 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 input amount such as air volume adjustment of the combustion fan 12;
It performs switching control to switch between FF control and FB control, and also has safety control.

The discrimination control 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. The terminal 62 is a wire-saving terminal that can supply electricity to the main controller 54 and sub-controller 54a.
It is a wire terminal.

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

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 opened due to capacity control associated with the use of the combustion fan 12, the set temperature is changed and the current flowing to the governor valve 23 is reduced by, for example, 50% due to a change in the rotational speed of the combustion fan 12. It also 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. Therefore, in this embodiment, the water temperature is read by the inlet water temperature thermistor 35 after the water flow signal is detected, and the water temperature at that time is used as the water temperature data.

Combustion capacity control includes FF control that detects the set temperature and incoming water temperature to set the combustion amount (air amount and gas amount) and incoming water amount, and FF control that detects the set temperature and hot water temperature and sets the combustion amount (air amount and gas amount). ) and correct for water inflow.
FB (PI) control is performed.

The FF control is based on the first calculated value (required capacity) Q calculated from the temperature difference between the set temperature and the inlet water temperature and the amount of water input by the main controller 54 and sub-controller 54a, and the temperature difference between the inlet water temperature and the outlet temperature and the amount of water input. The most efficient capacity is calculated from the second calculated value q calculated from the combustion fan 1.
2. The governor proportional valve 23, the switching valve 24, and the water volume proportional adjustment valve 33 are controlled to automatically adjust the air volume, gas volume, and water intake volume.

FF control has the same capacity as the required capacity Q (Q x 1.0)
A slow heating capacity range that outputs a capacity of
(Q-β)/Q} depending on the residual heat purge capacity range, the combustion fan 12 and governor proportional valve 2
3. The switching valve 24 and the water volume proportional adjustment valve 33 are controlled to automatically adjust the amount of air, gas, and water input.

In addition, in this embodiment, the governor proportional valve 2 in FIG.
As shown in the graph showing the relationship between the opening degree and the full opening capacity in No. 3, in the case of the water heater 1 having the governor proportional valve 23 that can be throttled to 1/4 of the full opening degree, when the switching valve 24 is in the closed state, the first There is a half-open capacity control range in which the gas amount and air amount are proportionally controlled from 1/8 to 1/2 of the full-open capacity using only the burner 11a, and when the switching valve 24 is in the open state, the first
The maximum value of the full-open capacity control range (1/2 of the full-open capacity) and the half-open capacity control range in which the burner 11a and the second burner 11b perform proportional control of the gas amount and air amount from 1/4 to 1 of the full-open capacity. An overlapping control range is set between the minimum value of the full open capacity control range (1/4 of the full open capacity).

When the proportional control of the gas amount and air amount by FB control reaches near the maximum range of the half-open capacity control area (for example, the maximum value of the half-open capacity control area), the capacity is made equal to the maximum value of the half-open capacity control area, for example. Therefore, turn on the switching valve 24 (open the valve) while performing slow ignition control.
and switch to full capacity operation.

When the proportional control of the gas amount and air amount by FB control reaches around the minimum range of the full-open capacity control range (for example, the minimum value of the full-open capacity control range), combustion fan 1
By turning off (closing) the switching valve 24 and switching to half-open capacity operation without changing the rotation speed of 2 and the current of the governor proportional valve 23, smooth half-open capacity operation can be achieved while maintaining a safe combustion state. Controls switching between and full capacity operation.

As a safety control, if the hot water temperature reaches the boiling temperature or higher and continues for a predetermined time (t8 seconds: e.g. 1 to 10 seconds), continuous combustion will continue for a predetermined time (t7 minutes:
For example, if the flame continues for 40 to 120 minutes, or if no flame is detected, each solenoid valve is closed and the operation is stopped.

The operation of the control device 50 of the water heater 1 of this embodiment will be explained based on the flowcharts shown in FIGS. 3 to 8 and the graphs shown in FIGS. 9 and 10. Note that FIGS. 3 to 5 are flowcharts showing sequence control (ignition operation), combustion capacity control, safety control, etc.

When installing the water heater 1, the type of fuel gas used by the gas company or the distributor of the water heater 1 is confirmed, and a reference temperature (40° C. in this embodiment) is set (S1). The user of the water heater does not set the fuel gas type and reference temperature.
Further, the fuel gas type and reference temperature settings are stored in the memory capacity of the CPU 70 regardless of whether the power is turned on or off. However, when the set temperature is input by the user, the CPU 70 gives priority to the set temperature over the reference temperature and controls the water heater 1 so that the hot water temperature approaches the set temperature.

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

It is determined whether the opening degree of the water volume proportional adjustment valve 33 is initially set to the maximum opening degree that allows for the maximum amount of water input, which is the amount of water input according to the reference temperature (40° C. in this embodiment) (S3).

Here, the water volume proportional adjustment valve 33 is set to an opening degree corresponding to the set temperature (or reference temperature) when the water heater 1 was last used, regardless of whether the sub-controller 54a is ON or OFF. However, with the geared motor that changes the opening degree of the water volume proportional adjustment valve 33, if you try to adjust the opening degree after inputting the set temperature,
Since the travel time requires several seconds, there is a risk that it will cut into the combustion capacity control time and the combustion capacity control will be delayed.In order to prevent this, in this embodiment, before starting the combustion capacity control (FF control), The water volume proportional adjustment valve 33 is moved prior to the above.

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

When the opening degree is set to the maximum that allows the maximum amount of water to enter for the combustion capacity, the geared motor is turned OFF (S4). If the opening is not set to the maximum that allows 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 approximately several seconds even when the maximum displacement occurs, but when freezing or foreign matter is mixed in, the water volume proportional adjustment valve 33
Because the water volume proportional adjustment valve 33 is locked, the water volume proportional adjustment valve 33 is closed despite the power supply from the geared motor drive circuit 74.
may not be displaced, and as a result, the normal operating time of the geared motor becomes longer and there is a risk of burnout due to heating of the motor or geared motor drive circuit 74. In this embodiment, the geared motor drive circuit 74 is designed to prevent equipment failure even in such a case.
When the predetermined energization time (t1 seconds: e.g. 5 to 30 seconds) has elapsed (S6), the geared motor is
I try to turn it off.

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 outlet temperature is set to a desired set temperature by the hot water outlet temperature setting switches 57, 57a (S8).

Further, if the outlet hot water temperature is not detected after a predetermined period of time (t2 seconds: for example, 1 second) has elapsed (S9), the set temperature is set to the reference temperature of 40° C. (S10). Next, when the user opens the hot water tap (S11), the amount of water entering is detected by the water amount sensor 36 (S12).

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

If the signal input to the water amount detection circuit 76 that reads the signal from the water amount sensor 36 is higher than a predetermined voltage, it is detected as a water flow signal, but reading errors occur in the water amount detection circuit 76 due to undulations of the water flow, etc., and the set voltage is kept constant. If this is done, chattering will occur, so in this example, chattering is prevented by providing a hysteresis characteristic.
When the water flow rate is 2.5/min or more, it is detected as a water flow signal, and when there is a minute change such as 20/min or less, it is not detected as a water flow signal.

Normally, data on the amount of water entering is updated every sampling time, but taking into consideration the response delay of the water amount sensor 36, the amount of water entering may 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, 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 a predetermined time (t3 seconds: for example 10 seconds) has elapsed (S13), the entering water temperature thermistor 3
5, the incoming water temperature is detected (S14). and,
The user determines whether or not the incoming water temperature is 55°C or higher (S16), closes the hot water tap when the incoming water temperature is 55°C or higher (S16), and turns on the operation switches 56, 56a of the main controller 54 and sub-controller 54a.
Turn off (S17). When the inlet water temperature is lower than 55℃, determine whether the inlet water temperature is below the set temperature (S18),
When the temperature is higher than the set temperature, the operations in S12 and below are repeated, and when the temperature is lower than the set temperature, the combustion fan 12 is turned on as shown in FIG. 4 (S19).

The Hall IC detects the rotation speed of the combustion fan 12 (S20), and determines whether the rotation speed of the combustion fan 12 is equal to or higher than a predetermined rotation speed (S21). When the rotation speed of the combustion fan 12 is lower than the predetermined rotation speed, the rotation speed corresponding to the combustion capacity cannot be obtained.
The main solenoid valve 21, main solenoid valve 22, switching valve 24, combustion fan 12, and governor proportional valve 23 are all turned off (S22 to S26), the user closes the hot water tap (S27), and then the main controller 54 and Operation switches 56, 56a of the sub-controller 54a
Turn off (S28).

When the rotation speed of the combustion fan 12 is higher than a predetermined rotation speed, a predetermined period of time (t4 seconds: e.g. 0.5 to 10 seconds)
Perform pre-purging (S29) and remove all sparker 14, original solenoid valve 21, main solenoid valve 22, and switching valve 24.
It is turned ON (S30 to S33), and a slow ignition current is supplied to the governor proportional valve 23 (S34).

The current applied to the governor proportional valve 23 is controlled at the time of ignition based on the rotational speed of the combustion fan 12, that is, the air volume, and the type of gas Kp, as shown in FIG.
In this example, especially when igniting, the amount of gas for slow ignition is
It is set to be a constant ratio (initial value) to the maximum value of the current flowing to the governor proportional valve 23, which is adjusted by the semi-fixed volume of the proportional valve control circuit 73.
Thereby, an appropriate amount of slow ignition gas can be supplied at the time of ignition.

Further, after turning on the sparker 14, after a predetermined time (t5 seconds: for example, 5 to 20 seconds) has elapsed (S35), the sparker 14 is turned off (S36). and,
The combustion flame is detected by the flame rod 15, and it is determined whether a current greater than IA is inputted by the flame rod 15 (S37). When a current higher than IA is not input, S22 is detected as an ignition error.
Repeat the following actions. When a current of IA or more is input, the specified time (t6 seconds: e.g. 0.1 to 10
A slow ignition timer (seconds) is activated (S38), and the outlet hot water temperature is detected by the outlet hot water temperature thermistor 38 (S39), as shown in the flowchart of FIG.

Next, after the combustion capacity control shown in the flowcharts of FIGS. 6 to 8 is performed (S40), safety control from S41 onwards 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 rotational speed of the combustion fan 12 is lower than the predetermined rotational speed, an operation of S22 or lower is performed, and when the rotational speed of the combustion fan 12 is higher than the predetermined rotational speed, is a current of IA or higher being input by the flame rod 15? It is determined whether or not (S42). When a current of IA or more is input, continuous combustion will continue for a specified time (t7 minutes: e.g. 40 to 120 minutes)
(S43), the temperature of the hot water reaches the boiling temperature or higher (S44), and the water temperature continues to rise for a predetermined period of time (t8 seconds: e.g. 1 to 10 seconds).
(seconds) 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. The operation of S46 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 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.

FIG. 6 mainly shows a flowchart of FF control among combustion capacity controls.

After performing the operation of S39 in FIG. 5, the required amount of heat is calculated based on the following formula (S100), (S101).

Equation 1...First calculated value Q = (Tset - THin) x W = Required capacity (required heat amount) Equation 2... Second calculated value q = (THout - THin) x W = Current capacity Tset in the transition period : Set temperature THin : Incoming water temperature THout : Outgoing water temperature W : Incoming water amount After calculating the first calculated value Q and the second calculated value q, it is determined whether FF control has been performed (S102),
If FF control is being performed, FB (PI) control from S123 onwards shown in the flowchart of FIG. 7 is performed.

In addition, it is determined whether a predetermined time (t9 seconds: for example, 1 second) has elapsed after the initial setting of the water volume proportional adjustment valve 33 (S103), and after t9 seconds have passed, Q≧
qx or not (S104). Here, x is a coefficient satisfying, for example, 1.5, and a cold start of the water heater 1 is determined based on the comparison result between the first calculated value Q and the second calculated value q.

When Q≧qx is not the case, it is determined whether Q<q or not (S105), and when Q<q is not the case, that is, when the hot water temperature (THout) is slightly lower than the set temperature (Tset),
Switching valve 24 according to the required capacity Q calculated in S100.
is controlled (on: full-open capacity operation, or off: half-open capacity operation). And the hot water temperature (THout)
In order to bring the temperature close to the set temperature (Tset), the control target value of the governor proportional valve 23 is set so as to output the same slow heating capacity (Q x 1.0) as the required capacity Q, and the fan drive circuit 72 and the proportional valve Control circuit 73 and geared motor drive circuit 74 are controlled (S106). Note that 1.0 of (Q×1.0) is a coefficient.

That is, in the operation of S106, the current applied to the governor proportional valve 23 is adjusted by proportional control, with the opening degree (gas amount) that provides the slow heating capacity (Q x 1.0) as the control target value. Furthermore, the rotational speed of the combustion fan 12 and the opening degree of the water volume proportional adjustment valve 33 are also controlled.

When Q<q, that is, when the hot water temperature is higher than the set temperature, the switching valve 24 is controlled according to the required capacity Q calculated in S100 (ON: full open capacity operation, or OFF: half open capacity operation). ) to be done.
In order to bring the hot water temperature closer to the set temperature,
A control target value for the governor proportional valve 23 is set so as to output a minimum capacity smaller than the required capacity Q, and the fan drive circuit 72, proportional valve control circuit 73, and geared motor drive circuit 74 are controlled (S107).

In other words, when the switching valve 24 is turned off (half-open capacity operation) according to the required capacity Q calculated in S100, the opening degree (gas amount) that provides the minimum capacity in the half-open capacity control region is set as the control target value. As a result, the current flowing to the governor proportional valve 23 is adjusted by proportional control.

In addition, when the switching valve 24 is turned on (full open capacity operation) according to the required capacity Q calculated in S100, the opening degree (gas amount) is adjusted so that the minimum value of the capacity in the full open capacity control area is obtained. The current applied to the governor proportional valve 23 is adjusted. Furthermore, the rotational speed of the combustion fan 12 and the opening degree of the water volume proportional adjustment valve 33 are also controlled.

Then, calculate τ ₁ = a/w [seconds] {a is a coefficient, for example, when the heat capacity of the heat exchanger 13 is 500 c.c., the amount of water entering w is (10/s), and τ ₁ is 3 seconds}. (S108), and after the predetermined time τ ₁ second has passed (S109), the same slow heating capacity (Q x 1.0) as the required capacity Q is output.
The fan drive circuit 72, proportional valve control circuit 73, and geared motor drive circuit 74 are controlled (S110).
Note that 1.0 of (Q×1.0) is a coefficient.

In other words, the same slow heating capacity as the required capacity Q (Q×
The current supplied to the governor proportional valve 23 is adjusted by proportional control using the required opening degree that yields 1.0) as the control target value. Furthermore, the rotational speed of the combustion fan 12 and the opening degree of the water volume proportional adjustment valve 33 are also controlled.

After that, as shown in the flowchart of Figure 7,
Performs FB (PI) control for S123 and below.

Here, when τ ₁ second has not elapsed, the deviation between the set temperature (Tset) and the outlet hot water temperature (THout) is |dt
Determine whether it is within |℃ (=±y℃C: For example, 5℃) (S111), and if the deviation is within |dt|℃, S110
If the deviation is not within |dt|℃, continue to perform S109. When Q≧qx, that is, when the hot water temperature does not reach the set temperature, the deviation between the set temperature (Tset) and the hot water temperature (THout) is |dt|
(=+y: For example, 5 degrees Celsius) It is determined whether or not it is within degrees Celsius (S112), and when the deviation is within |dt| degrees Celsius, S106 is performed.

When the deviation is not within |dt|°C, the switching valve 24 is controlled (ON: full open capacity operation, or OFF: half open capacity operation) according to the required capacity Q calculated in S100. Then, the fan drive circuit 72, proportional valve control circuit 73, and geared motor drive circuit 74 are controlled to output a maximum capacity {rapid heating capacity: Q×(Q+α)/Q} larger than the required capacity Q (S113). After that, the operations from S112 onwards are performed.
In addition, (Q + α)/Q is a coefficient, for example α is Q × 3/4
When expressed as kcal, it is 1.75.

In other words, the maximum capacity {Q
The current supplied to the governor proportional valve 23 is adjusted by proportional control as a control target value so that the target opening degree is obtained by x(Q+α)/Q}. Furthermore, the rotational speed of the combustion fan 12 and the opening degree of the water volume proportional adjustment valve 33 are also controlled.

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 according to the deviation between the set temperature (Tset) and the outlet hot water temperature (THout).

However, due to a change in the amount of water input, the first calculated value Q, which is the required capacity, is updated, and if the governor proportional valve 23 is activated at this time, the change in the gas amount and the change in the amount of water input will interfere, and the temperature of the hot water being discharged will be affected. Therefore, when changing the opening degree (inflow amount) of the water volume proportional adjustment valve 33, proportional control of the capacity by the governor proportional valve 23 is not performed.

FIG. 7 shows a flowchart of FB (PI) control.

It is determined whether the deviation between the set temperature (Tset) and the outlet temperature (THout) is more than +y℃ (for example, 5℃) (S123), and when the deviation is more than +y℃, the residual heat purge capacity is smaller than the required capacity Q. {Q×(Q-β)/Q}
The fan drive circuit 72, proportional valve control circuit 73, and geared motor drive circuit 74 are controlled so as to output (S124). Note that (Q-β)/Q is a coefficient, for example, 0.6 when β is Q×1/4 kcal.

That is, first, the governor proportional valve 23 is throttled to a target opening that provides a minimum capacity {Q×(Q-β)/Q} smaller than the required capacity Q. and,
Switching valve 24 according to the required capacity Q calculated in S100.
is controlled (on: full-open capacity operation, or off: half-open capacity operation). Furthermore, the combustion fan 12
The rotation speed and the opening degree of the water volume proportional adjustment valve 33 are also controlled.

Then, for a predetermined period of time (t10 seconds: for example, 30 seconds)
After the time has elapsed (S125), safety control from S41 shown in the flowchart of FIG. 5 is performed. Furthermore, if t10 seconds have not elapsed, the operations from S123 onwards are repeated.

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

The temperature deviation function is: ∴F(e) = (K ₁ − e) × k ₁ K ₁ , k ₁ is a constant Temperature deviation: e = set temperature - outlet hot water temperature The water input amount function is, ∴G(w) = (K ₂ − w)×k ₂ K ₂ , k ₂ is a constant Integral time is ∴T={F(e)+G(w)} = {(155−e)×1/8+(80−w)×1/ 8 = Output time of PI control Therefore, the greater the deviation between the set temperature and the outlet temperature, the shorter the integral time (seconds), or the greater the amount of water input, the shorter the integral time. output time becomes shorter.

Then, the integration time (T time: e.g. 150 seconds)
has elapsed (S128), it is determined whether the temperature deviation e≦1 (S129), and when e≦1, the safety control from S41 in the flowchart shown in Fig. 5 is performed, and e
When it is not ≦1, input the gas type Kp of the fuel gas (S130), update the PI control output below so as to switch to the proportional control constant according to the gas type Kp,
After outputting the proportional control constant of the PI control output to the governor proportional valve 23 or water volume proportional adjustment valve 33 as a temperature deviation function and performing switching control of the gas burner 11 shown in the flowchart of FIG. 7 (S131), The safety control from S41 shown in the flowchart of Fig. 5 is carried out.

PI control output: PN=PN-1+e×Kp PI control output variation: △VS=e×Kp Current PI control output: PN-1=Q+α ∴PI control output: PN=PN-1+△VS However, given flow rate When the amount of water entering is smaller,
The maximum value of the control output {Q×(Q+α)/Q} is brought close to the slow heating capacity (Q×1.0), which is the same as the required capacity Q, to improve stability at minute flow rates.

Therefore, by switching to a proportional 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 (variable rather than fixed value), and can be used over a wide range and freely. PI control can be performed. In addition, PI control that is compatible with the characteristics of the gas proportional valve 23 (which differs depending on the type of gas) can be performed. Furthermore, from the integral time T and the PI control output, the outlet hot water temperature can be quickly brought close to the set temperature.

Further, a predetermined amount of gas may not be obtained due to the gas type Kp of the fuel gas or the pressure loss of the gas supply pipe 20. In this case, the current flowing to the governor proportional valve 23 is changed from A ₁ to A ₂ for the minimum current during full-open capacity operation, and from B 1 to B for the maximum current during half-open capacity operation, as shown in the graph of Fig. ₁₀ . ₂ , proportional control is performed to obtain a predetermined amount of gas.

Here, as shown in the flowchart of Figure 7,
When the PI control output is updated in G131, switching control is performed to switch the dual gas burner 11 between half-open capacity operation and full-open capacity operation based on the flowchart shown in FIG.

At the time of updating the PI control output in S131 shown in the flowchart of FIG. 7, it is determined whether the switching valve 24 is turned on (S200). The switching valve 24
When not turned on, that is, the first burner 11a
In half-open capacity operation with only combustion, the supply voltage to the combustion fan 12 is proportionally controlled based on the deviation between the set temperature and the hot water temperature to automatically adjust the amount of air, and the current flowing to the governor proportional valve 23 is controlled proportionally. Automatically adjust the gas amount using proportional control (S201).

At this time, the proportional control of the voltage supplied to the combustion fan 12 and the current applied to the governor proportional valve 23 has reached approximately the maximum range of the half-open capacity control range (overlapping control range: for example, the maximum value of the half-open capacity control range). It is determined whether or not (S202), and when the half-open capacity control range reaches near the maximum range, a full-open switching signal is output (S203).
The full open switching signal uses a limit on the voltage supplied to the combustion fan 12 or the current applied to the governor proportional valve 23.

A certain period of time (t11:
For example, for 5 to 30 seconds), the combustion fan 1
The proportional control of the supply voltage to the governor proportional valve 23 and the current flowing to the governor proportional valve 23 remains near the maximum range of the half-open capacity control range (duplicate control range: for example, the maximum value of the half-open capacity control range) (S204). S205), for example, in order to equalize the capacity to the maximum value of the half-open capacity control, a gentle ignition current is supplied to the governor proportional valve 23 (S206), and the switching valve 24 is turned ON (S207), and the first burner 11a and The amount of air and gas are automatically adjusted by operating at full capacity with simultaneous combustion of the second burner 11b.

When the switching valve 24 is turned on, that is, when the first burner 11a and the second burner 11b are operating at full capacity with simultaneous combustion, the supply voltage to the combustion fan 12 is controlled to automatically adjust the air amount. At the same time, the current applied to the governor proportional valve 23 is controlled to automatically adjust the gas amount. (S208).

At this time, whether the proportional control of the voltage supplied to the combustion fan 12 and the current applied to the governor proportional valve 23 has reached the vicinity of the minimum range of the full-open capacity control range (overlapping control range: for example, the minimum value of the full-open capacity control range). (S209), and when it reaches near the minimum range of the full-open capacity control range, a half-open switching signal is output (S210). The half-open switching signal uses a limit on the voltage supplied to the combustion fan 12 or the current applied to the governor proportional valve 23.

A certain period of time (t12:
For example, for 5 to 30 seconds), the combustion fan 1
The proportional control of the supply voltage to the governor proportional valve 23 and the current flowing to the governor proportional valve 23 remains near the minimum range of the full-open capacity control range (overlapping control range: for example, the minimum value of the full-open capacity control range) (S211). S212), the switching valve 24 is turned OFF without changing the supply voltage to the combustion fan 12 and the current flowing to the governor proportional valve 23 (S213), and the air is blown at half-open capacity by combustion only in the first burner 11a. Automatically adjusts volume and gas amount.

At this time, the voltage supplied to the combustion fan 12 and the current supplied to the governor proportional valve 23 each correspond to their optimum values, and are constant regardless of whether the gas burner 11 is operated at full or half open capacity. Since the combustion fan 12 has a large inertial force and a response delay, the voltage supplied to the combustion fan 12 and the current applied to the governor proportional valve 23 are not changed. Then,
Smooth switching control from half-open capacity operation to full-open capacity operation or from full-open capacity operation to half-open capacity operation can be performed while maintaining a safe combustion state.

Furthermore, each of the first burner 11a and the second burner 11b has a capacity limit, and if the limit value can be covered by another burner, the control range may be expanded by switching the switching valve 24. However, the method of detecting the switching signal as an instantaneous value can cause chattering of the switching valve 24 in water heaters with large heat capacity or delayed response, such as the water heater 1, which may cause the control of the water heater 1 to become difficult. This was a cause of defects. However, as in this embodiment, half-open capacity operation and full-open capacity operation occur when staying in the switching region {near the overlapping control area (for example, the maximum value of the half-open capacity control area or the maximum value of the full-open capacity control area)} for a certain period of time. The switching valve 24 can prevent chattering of the switching valve 24 due to repeated ON and OFF switching of the switching valve 24.

[Modified example]

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 agricultural fuel.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a gas combustion water heater according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a control device for a gas combustion water heater according to an embodiment of the invention. 3 to 5 show sequence control, combustion capacity control, and combustion capacity control according to an embodiment of the present invention.
Flowchart of safety control, FIG. 6 is a flowchart mainly of FF control according to an embodiment of the present invention,
FIG. 7 is a flowchart of FB control according to an embodiment of the present invention, FIG. 8 is a flowchart of gas burner switching control, and FIG. 9 is a flowchart of governor proportional valve opening and gas according to an embodiment of the present invention. FIG. 10 is a graph showing the relationship between the current to the governor proportional valve and the gas amount according to an embodiment of the present invention. In the figure 1... Gas combustion water heater, 11... Gas burner, 11a... First burner, 11b... Second burner, 13... Heat exchanger, 20... Gas supply pipe (fuel supply path), 23... Governor proportional valve (Fuel supply amount control means), 24... Solenoid valve for switching, 38... Outlet hot water temperature thermistor (Outlet hot water temperature detection means), 50... Control device, 54
...Main controller (temperature setting means), 54a
...Subcontroller (temperature setting means), 60...Control circuit.

Claims (1)

[Scope of Claims] 1 (a) a fuel supply amount control means for adjusting the amount of fuel supplied; (b) a first burner connected to the fuel supply passage via the fuel supply amount control means; a burner consisting of a second burner connected to the fuel supply amount control means via a switching solenoid valve; (c) a heat exchanger provided above the burner and heating water passing through the burner; d) a hot water outlet temperature detection means provided downstream of the heat exchanger for detecting the outlet temperature of the water flowing out from the heat exchanger; and (e) a desired setting of the outlet temperature of the water flowing out from the heat exchanger. temperature setting means for setting the temperature; (f) closing the switching solenoid valve during half-open capacity operation with combustion of only the first burner;
The switching solenoid valve is opened during full-open capacity operation due to simultaneous combustion of the second burner and the second burner, and the fuel supply amount control means is controlled in accordance with the deviation between the set temperature and the hot water temperature during the half-open capacity operation. a half-open capacity control range that proportionally controls the state, a full-open capacity control range that proportionally controls the control state of the fuel supply amount control means according to the deviation between the set temperature and the hot water temperature during the full-open capacity operation, and a maximum of the half-open capacity control range. In a water heater equipped with a control circuit that performs feedback control having an overlapping control range between a range and a minimum range of a full-open capacity control range, the control circuit performs proportional control by feedback control during half-open capacity operation to change to half-open capacity control. When reaching near the maximum range of the range, the switching solenoid valve is opened while performing slow ignition control to switch to full-open capacity operation, and during full-open capacity operation, proportional control is controlled by feedback control to the minimum of the full-open capacity control range. The water heater is characterized in that when the temperature reaches near the range, the switching solenoid valve is closed and the operation is switched to half-open capacity operation.