JPH0450499B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a gas water heater in which the outlet temperature immediately follows even when the set temperature is rapidly increased.

《Prior art and its problems》 Traditionally, temperature control in general gas water heaters
For example, to correct the deviation between the set temperature set by the temperature setting device and the hot water temperature detected by the hot water tap temperature detector while the opening degree of the water flow adjustment valve remains fixed.
It performs PID calculations, etc., and uses the results of these calculations to control the opening degree of the gas flow rate adjustment valve.

However, with this type of temperature control method, if the set temperature is suddenly increased, the control system is unable to quickly follow this, and it takes a long time before the hot water temperature actually reaches the set temperature. This method takes time and has problems such as being difficult to use when, for example, you are washing dishes at 40°C and suddenly need hot water at about 80°C.

Therefore, the applicant has developed (unpublished) a gas water heater that solves this problem and has high temperature followability. Instead of the conventional temperature control method by adjusting the gas flow rate, a proactive control method is now used in which the gas flow rate is fixed at the maximum and the water flow is conversely throttled to rapidly raise the temperature of the hot water.

In addition, as a result of using a microcomputer as a temperature control device, whether or not the set temperature has risen sharply can be determined by comparing the set value read at regular time intervals with the previous set value, and by comparing these deviations from the reference value. It is determined whether or not it has been exceeded.

However, when trying to determine a sudden change in the set temperature by comparing each previous reading value and the latest reading value, if the set temperature happens to change during the reading timing, each previous reading value A simple comparison shows that the deviation in either case does not exceed the reference value, and therefore, even if there is a sudden change in the set temperature, there is a problem in that it cannot be detected accurately.

<Object of the Invention> The object of the invention is to reliably detect a sudden change in the set value of the temperature setting device in the novel gas water heater temperature control device described above.
The objective is to quickly switch from temperature control based on gas flow rate control to advance control that maximizes gas flow rate and throttles water flow.

<Structure and Effects of the Invention> In order to achieve the above object, the present invention reads the set value of the temperature setting device at regular intervals, and reads the latest multiple readings of the read set values. is stored, and the difference between the latest reading value and each reading value among the stored reading values is calculated, and if any of these differences exceeds a reference value, it is determined that there is a sudden change in setting. That is.

According to such a configuration, even if the set value suddenly changes at any reading point, the difference between the readings before and after that is compared with the reference value, so the temperature setting may change suddenly at any reading point. Even if there is a sudden change in the settings of the device, by comparing the readings before and after the change, the above-mentioned detection error can be prevented and the sudden change in settings can be reliably detected.

<<Description of Embodiments>> FIG. 1 is a diagram showing a system configuration of a gas water heater according to an embodiment of the present invention.

In the figure, a furnace pair 1 is formed in a vertical cylindrical shape, a burner 2 is disposed at the bottom thereof, a heat exchanger 3 is disposed above the burner 2, and a heat exchanger 3 is disposed above the burner 2. An exhaust fan 5 driven by a motor M is attached to the exhaust port 4 .

A water supply pipe 6 is connected to the inlet side of the heat exchanger 3, and a hot water supply pipe 7 is connected to the outlet side, and this hot water supply pipe 7 is branched into three pipes at the tip side, and each branch pipe Curtains 8a, 8b, 8c are attached to the channels 7a, 7b, 7c, respectively.

On the water supply pipe 6 near the inlet side of the heat exchanger 3,
A water flow adjustment valve 9, a water flow switch 10, and an inlet water temperature detector 11 are installed in this order.

The water volume adjustment valve 9 is composed of, for example, a motor-driven servo valve whose opening degree can be continuously adjusted from a fully closed state to a fully open state, and its current opening degree is determined by a potentiometer installed in the water volume adjustment valve 9. It is sent to the controller 12 side via a meter or the like.

The water flow switch 10 is a switch that detects and turns on when either of the switches 8a, 8c is opened and a water flow of a certain value or more is generated in the water supply pipe 6.

The incoming water temperature detector 11 is composed of a temperature sensing element such as a thermistor, for example, and is connected to a processing circuit within the controller 12 to output an analog voltage corresponding to the incoming water temperature.

On the hot water supply pipe 7 near the outlet side of the heat exchanger 3,
A hot water temperature detector 13 is attached. This detector 13 is also composed of a temperature sensing element such as a thermistor, for example, and is connected to a processing circuit within the controller 12, and outputs an analog voltage corresponding to the tapped water temperature.

A gas cutoff valve 15, a gas governor 16, and a gas flow rate adjustment valve 17 are installed in this order on a gas supply pipe line 14 that supplies fuel gas to the burner 2.

The cutoff valve 15 is constituted by an electromagnetic valve that can take two states: a fully closed state and a fully open state, and is controlled to open and close based on a signal from the controller 12.

The gas governor 16 has a function of keeping the pressure of fuel gas constant.

The flow rate adjustment valve 17 is composed of, for example, a motor-driven servo valve whose opening degree can be continuously adjusted from a fully closed state to a fully open state, and its current opening degree is determined by a potentiometer or the like installed in the flow rate adjustment valve 17. It is sent to the controller 12 side via.

The igniter 18 emits a spark in response to a command from the controller 12 to ignite the fuel gas ejected from the burner 2 .

The fire detector 19 is located close to the spark emitted from the burner 2 and converts the fire into an electrical signal using the flame current and its rectifying action, and after suitably amplifying this signal, converts it into an electrical signal with a relatively large time constant. The output is smoothed by a smoothing circuit, and then binarized using a reference level, and the output is used to drive a relay via a driver to output a contact signal.

The controller 12 is composed of a sequence circuit that controls sequence operations from starting combustion to stopping combustion, and a temperature control circuit that maintains the hot water temperature at a set temperature, and these circuits are implemented by a microcomputer.

Next, FIG. 2 is a flowchart showing the control procedure executed by the microcomputer, and the overall operation of the water heater will be briefly explained according to this flowchart.

First, in step 1, the state of the water flow switch 10 is read, and if there is water flow, the process moves to combustion start processing.

In the combustion start process, a pre-purge is first performed in step 3, and when the pre-purge time has elapsed, the process proceeds to step 4 and then proceeds to a slow ignition process.

In the slow ignition process 5, the gas cutoff valve 15 is fully opened, the gas flow rate adjustment valve 17 is slightly opened, and while fuel gas is slightly spouted from the burner 2, the igniter 18 is driven to attempt ignition over the safety switch time. .

If the burner does not ignite after the safety switch time has elapsed, proceed to step 6 followed by step 7.
Execute and perform some error handling.

If ignition is confirmed before the safety switch time elapses, then the hot water temperature control process according to the present invention is repeatedly performed in step 9 until fire breakage and no water flow are detected in steps 10 and 11, respectively.

In addition, if a fire breakage is detected during hot water temperature control processing,
Following step 10, the process returns to step 3 and the pre-purge process is performed again.

On the other hand, if no water flow is detected during the hot water temperature control process, step 12 is executed following step 11 to perform an after-purge process.

Also, if the presence of water flow is detected again during the afterpurge process, step 13 is followed by step 5.
Go back to step 14 and execute the slow ignition process, and when the afterpurge process has elapsed for a predetermined period of time, proceed to step 14.
Subsequently, the process returns to step 1, the wait-for-use process.

Next, details of the hot water temperature control process performed in step 9 will be explained based on FIGS. 3 to 5.

FIG. 3 is a flowchart showing the control procedure executed by the microcomputer in response to the hot water temperature control process according to the present invention, FIG. 5
The figure is a flowchart showing the details of the sudden change confirmation process of the set temperature according to the present invention, FIG. 6 is an explanatory diagram showing the sudden change confirmation process when the number of times the reading value is stored is the latest three, and FIG. 7 is the reading value memory. It is an explanatory view showing sudden change confirmation processing when the number of times is set to 6 times.

In Fig. 3, when hot water temperature control is started, the output of each detector and setting device is read in step 100, and then the water volume correction mode and advance control mode (described later) are confirmed in steps 101 and 102. .

Here, if it does not correspond to any of the modes, proceed to step 103 and check whether there is a sudden change in the set temperature.

At this point, if there is no sudden change in the set temperature, the step
In step 104, the water flow rate adjustment valve 9 is fully opened, and in step 105, the required gas flow rate is calculated.

This calculation is performed based on the outlet hot water temperature MP detected by the outlet hot water temperature detector 13 and the set temperature SP set by the temperature setting device 20, and the required gas flow rate necessary to correct these deviations is determined.

Next, in step 106, the opening degree of the gas flow rate adjustment valve 17 is determined in accordance with the determined gas flow rate, and the fuel adjustment servo system is controlled to match the opening degree. The above series of operations is referred to as normal mode operation.

Next, when a sudden change in the set temperature is detected in step 103 during the above normal mode operation, step 103 is performed.
Step 107 is executed following step 103, and the opening degree of the gas flow rate regulating valve 17 is fixed to be fully open.

Next, in step 108, the amount of inflow water Qa required to make the outlet temperature MP match the set temperature SP is determined based on the set temperature SP at the relevant time, the inlet water temperature WP, and the maximum calorific value FUmax corresponding to the fully open gas flow rate adjustment valve. is determined by advance calculation.

Next, in step 109, the opening degree of the water amount regulating valve 9 corresponding to this inflow water amount is outputted, and the servo system is driven to match this opening degree.

Next, in step 110, the advance control mode flag is set, and thereafter step 111 is repeated until the tapping temperature MP becomes stable. The above series of operations is referred to as advance control mode.

Next, in the advance control mode described above, when stability of the outlet hot water temperature is detected in step 111, in step 112, the corrected water amount Qb necessary to correct the deviation between the outlet hot water temperature MP and the set temperature SP is determined.

Next, in step 113, the required opening degree of the water amount regulating valve is determined in accordance with the corrected water amount Qb obtained by the above-mentioned required water amount correction calculation.

Based on this determined opening degree, the servo system is driven, and the opening degree of the water amount regulating valve 9 is controlled to open or close.

Next, in step 114, the water amount correction mode flag is set, and the operation in the water amount correction mode continues thereafter. In addition, various methods can be considered in order to return to the normal mode from the water amount correction mode.For example, there is no deviation between the outlet temperature MP and the set temperature SP, or a certain period of time has passed after the set temperature suddenly changed. It can be done with etc.

According to the above control, if there is a sudden change in the temperature setting device as shown by the dotted line in the figure during normal mode operation up to time _t1 as shown in Fig. 4,
From t ₁ to t ₂ , the advance control mode is operated, and as a result, the water flow is throttled in the maximum combustion state, and the temperature of the hot water rises rapidly.

Next, when the hot water temperature is stabilized, the water flow correction mode is operated from time _t2 onwards, and the deviation between the stable value of the hot water tap temperature in the advance control mode and the hot water tap temperature setting value shown by the dotted line in the figure is corrected. , gas water heaters with high temperature responsiveness can be manufactured.

Next, with reference to the flowchart of FIG. 5, the process for confirming a sudden change in set temperature according to the present invention performed in step 103 will be described.

In this process, within the working area of the microcomputer, three storage areas SP, SP, and
SP ₁ and SP ₂ are provided.

First, in step 200, a predetermined initial flag is referenced. This initial flag is set during initial processing after power is turned on.

Therefore, if it is the first time, it is determined in step 200 that it is the first time, and in the following step 201, the set value of the temperature setting device is read, and this read set value is transferred to the area.
At the same time, the storage contents of this area SP are simultaneously transferred to areas SP ₁ and SP ₂ , respectively.

Next, in step 202, the first time flag is reset and a timer for setting the reading time interval is started.

From then on, in the second and subsequent processing, the step
Steps 201 and 202 are skipped, and step 203 waits for the timer to expire.

Next, when the timer times up, a new setting value is read and stored in the area SP in step 204, and after starting the timer again in step 205, a sudden change determination process is performed.

First, in step 206, it is determined whether the deviation between the latest reading value SP and the previous reading value _SP1 exceeds the reference value h, and in step 207, the difference between the latest reading value and the previous reading value _SP2 is determined. It is determined whether the deviation exceeds the reference value h.

Here, if any of the determination results is NO, it is assumed that there is no sudden change, and the contents of each area are shifted in step 209, and then the process moves to the above-mentioned step 104 and subsequent steps.

On the other hand, if the determination result is YES in either step 206 or 207, the process advances to step 208.
After the contents of each area SP, SP ₁ and SP ₂ are shifted to the previous area and the previous previous area, it is determined that there is a sudden change and the process moves to step 107 and subsequent steps.

Thus, in this example, not only is the latest reading compared to the previous reading, but the latest reading is also compared to the previous reading.
For example, as shown in Figure 6a, not only when the set value suddenly changes by 10°C or more from the reference value between each reading time, but also when the reading time tn is shown in Figure 6b.
Even if a setting change occurs by chance, by looking at the deviation of the reading values at the reading times tn+ ₁ and tn- ₁ before and after the change, it is possible to confirm that the setting value has been changed during that time. It becomes possible to detect

In this example, the presence or absence of a sudden change was determined by storing the past three readings and comparing these with the latest reading. For example, as shown in FIG. Increase the latest reading time tn and the past five reading times tn− ₁ , tTn− ₂ ,
By taking the deviation from Tn- ₃ , Tn- ₄ , and Tn- ₅ , a more reliable sudden setting change confirmation process can be performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the system configuration of a gas water heater to which the present invention is applied, FIG. 2 is a flowchart schematically showing the entire control procedure of the gas water heater, and FIG.
The figure is a flowchart showing the details of the hot water temperature control process.
Fig. 4 is a graph showing the relationship between the set temperature and the outlet temperature, which are the control results of the present invention, Fig. 5 is a flowchart showing details of the process for confirming a sudden change in the set temperature, and Fig. 6 is a graph showing the set value and the point of sudden change in the set temperature. A graph showing the relationship in FIG. 7 is similar to FIG. 6 when the number of times of storage is varied. 2...Burner, 3...Heat exchanger, 6...Water absorption pipe, 7...Hot water supply pipe, 9...Water flow adjustment valve, 11...
...Inlet water temperature detector, 12...Controller, 13
... Outlet hot water temperature detector, 14 ... Gas supply pipe, 1
7...Gas flow rate adjustment valve, 20...Temperature setting device.

Claims (1)

[Claims] 1. With the opening degree of the water volume adjustment valve fixed,
a first temperature control means for controlling the opening degree of the gas flow rate regulating valve in order to correct the deviation between the set temperature set by the temperature setting device and the outlet temperature detected by the outlet hot water temperature detector; With the opening degree fixed at the maximum, the required amount of water inlet is calculated in advance based on the inlet water temperature at the start of control, the set hot water outlet temperature, and the calorific value in the maximum combustion state, and the amount of water is calculated in accordance with the amount of water inlet. a second temperature control means for fixing the opening degree of the regulating valve; a sudden setting change detection means for detecting that a sudden change in the set temperature has been detected in the temperature setting device; , a switching control means for switching control from the first temperature control means to the second temperature control means when a sudden change in the set temperature is detected; reading control means for reading the set values at regular intervals; storage means for storing the most recent reading values among the read setting values; 1. A temperature control device for a gas water heater, characterized in that the device comprises a determining means for determining the difference between each read value and determining that there is a sudden change in setting when any of these differences exceeds a reference value.