JP3244995B2 - Gas water heater with combustion abnormality detection function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas heater in which a heat exchanger is heated by a gas burner to obtain tap water. More specifically, the fins of the heat exchanger are made of metal oxide or the like. The present invention relates to a gas heater with a combustion abnormality detection function that detects a combustion abnormality caused by blockage and safely stops combustion.

[0002]

2. Description of the Related Art Conventionally, this type of gas water heater is, as is well known, when a combustion gas by a gas burner passes between heat collecting fins of a heat exchanger in which a large number of heat collecting fins are arranged. Then, the gas combustion heat is collected by the heat collecting fins, and the water transmitted through the heat exchanger is heated by the heat transmitted through the heat collecting fins, so that tap water is obtained.

[0003]

However, in this type of gas water heater, a drain containing combustion products and the like adheres to the heat collecting fins of the heat exchanger due to long-term use.
Oxidation of the heat collecting fin is promoted by the adhesion of the drain, and the gap between the fins is gradually (gradually) closed by the oxide. With the blockage between the heat collecting fins, the heat transfer of the heat collecting fins gradually deteriorates, and the thermal efficiency decreases.

[0004] Further, since the gap between the heat collecting fins is narrowed due to the blockage between the heat collecting fins, the ventilation resistance when the combustion gas of the gas burner passes between the heat collecting fins of the heat exchanger increases. Then, the amount of air supplied to the gas burner decreases with the increase of the ventilation resistance, and the combustion of the gas is not sufficiently performed, which promotes incomplete combustion,
After all, there was a problem that the thermal efficiency was reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to safely stop the combustion of a gas burner when the heat efficiency is reduced due to clogging of fins in a heat exchanger. An object of the present invention is to provide a gas water heater. The second object of the present invention is to pay attention to the fact that the input value of the gas burner at the maximum hot water volume increases when the thermal efficiency decreases due to the fin clogging of the heat exchanger, and the combustion of the gas burner can be safely performed by determining the input value. An object of the present invention is to provide a gas water heater that is stopped. In each case, the safety in using the gas water heater is to be ensured.

[0006]

In order to achieve this object, a gas water heater according to the present invention comprises a heat exchanger provided with an inlet pipe and an outlet pipe, and a gas burner for heating the heat exchanger. In a gas water heater, a hot water temperature detecting means for detecting a temperature of hot water flowing through a hot water pipe, an incoming water temperature detecting means for detecting a temperature of water flowing in a hot water pipe, and the hot water pipe or the hot water pipe.
Maximum hot water limiting means provided in the water pipe to limit the flow rate
When a gas quantity detecting means for detecting the amount of gas supplied to the gas burner, the water temperature detecting means, input water temperature detected hand stage, the detection signal and the maximum amount of hot water limit means from gas amount detecting means
Thermal efficiency calculating means for calculating the thermal efficiency based on the maximum amount of hot water which is more limited, and a thermal efficiency determining means for comparing the thermal efficiency calculated by the thermal efficiency calculating means with the reference thermal efficiency to determine whether it is lower than this, The gist of the invention is that the combustion of the gas burner is stopped when the thermal efficiency determining means determines that the calculated thermal efficiency is lower than the reference thermal efficiency. In this case, the value of the reference thermal efficiency used for the determination by the thermal efficiency determining means may be a calculated value at the time of initial use.

The second aspect of the gas water heater according to the present invention is a gas water heater having a heat exchanger provided with an inlet pipe and a tap pipe, and a gas burner for heating the heat exchanger.
A water temperature detecting means for detecting the temperature of the hot water flowing through the hot water pipe, and inlet water temperature detecting means for detecting the temperature of the water flowing through the water inlet pipe, before
It is installed in the tap water pipe or the inlet pipe and controls the flow rate.
The maximum amount of hot water limiting means limited to, the gas amount detecting means for detecting the amount of gas supplied to the gas burner, on the basis of the detection signal from the gas amount detecting means, the maximum amount of hot water limiting means
Input value calculating means for calculating the input value of the gas burner when the maximum hot water amount is limited, and comparing the input value calculated by the input value calculating means with the appropriate maximum gas amount to determine whether the input value is lower than this. Input value determining means, wherein the combustion of the gas burner is stopped when the calculated input value is determined to be higher than the appropriate maximum gas amount by the input value determining means. . The appropriate maximum gas amount is a value obtained by dividing the gas heat amount (maximum output value) when the amount of hot water flowing through the tapping pipe is maximum by the thermal efficiency in a normal state.

[0008]

According to the gas water heater of the present invention having the above structure, the water supplied to the heat exchanger via the water inlet pipe is heated by the gas burner and obtained as hot water from the hot water pipe. However, in the combustion state of the gas burner,
The temperature of the hot water flowing through the tap pipe and the temperature of the water flowing through the inlet pipe
If, the amount of gas supplied to the gas Subana and are detected, it is limited by these detection signals and the maximum amount of hot water limiting means
The thermal efficiency is calculated based on the maximum hot water amount . Then, when it is determined that the calculated thermal efficiency is lower than the reference thermal efficiency, the combustion of the gas burner is stopped. In this case, if the value of the reference thermal efficiency is used as the calculated value at the time of the first use, the difference between the appliances generated due to the difference in gas calorific value, sensor error, input difference, etc. is canceled, the abnormality detection level rises, and the incomplete combustion occurs. When it occurs, it is quickly discovered and convenient.

According to the gas water heater according to the second invention, the water supplied to the heat exchanger via the water inlet pipe is heated by the gas burner and obtained as hot water from the hot water outlet pipe. , In the combustion state of the gas burner,
Amount of gas hot water is supplied to the maximum time moth Subana flowing is <br/> detected, input values of the gas burner at maximum hot water is obtained by calculation on the basis of the detection signal. If the calculated input value of the gas burner is determined to be higher than the appropriate maximum gas amount, combustion of the gas burner is stopped.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a gas water heater to which the present invention is applied. In the gas water heater 10 shown in FIG. 1, a heat exchanger 16 provided with a water supply pipe 12 and a tapping pipe 14 is provided in a casing 18 and the heat exchanger 16 The gas burner 20 which heats is provided.

The gas pipe 22 of the gas burner 20 is provided with a gas proportional valve 24, and the water supply pipe 12 is provided with a water flow switch 26 for detecting the flow of water and a water temperature sensor for detecting the temperature of the water (water temperature sensor). ) 27 and a water governor 28 for regulating the flow of the water. On the other hand, the tapping pipe 14 is provided with a tapping temperature thermistor (a tapping temperature sensor) 30 for detecting tapping temperature, and a tap (faucet) 32 is provided at a tapping outlet of the tapping pipe 14.

The input side of a burner controller 34 for controlling the operation of the gas water heater is connected to the water amount switch 26, the input water temperature sensor 27, the outlet water temperature sensor 30, and the like. Is connected to a gas proportional valve 24 and the like.

The gas water heater 10 includes a faucet (faucet) 32.
, The water flow switch 26 is turned on, the gas burner 20 is ignited, the heat exchanger 16 is heated, and the water inlet pipe 1 is opened.
The water supplied from 2 is heated, and tap water is obtained from tap pipe 14. At this time, a command is given from the burner controller 34 to the gas proportional valve 24 based on the detection signal from the tapping water temperature sensor 30, and the opening degree is adjusted by controlling the proportional valve current value of the gas proportional valve 24, and the tapping temperature reaches the set temperature. Operation is controlled to be maintained.

Thus, according to the present invention, the outlet temperature of the heat exchanger 16 is detected and the gas proportional valve 2 of the gas burner 20 is detected.
In an instantaneous gas water heater or the like that controls the gas amount while adjusting the opening degree of the heat exchanger 4, the heat efficiency is calculated for each use of the gas water heater and compared with the normal heat efficiency. The present invention proposes a constant flow valve type as one of the methods for estimating the fin blockage and safely stopping the combustion.

This constant flow valve type is an instantaneous gas water heater that controls the gas amount by detecting the temperature of the hot water, and has a hot water temperature thermistor 30 as hot water temperature detecting means provided at the hot water outlet of the heat exchanger. And a water inlet temperature thermistor 27 as a water supply temperature detecting means provided in the water supply passage portion, and provided at any position of the water passage (in this embodiment,
A water governor 28 as a maximum hot water limiter (provided on the water supply pipe 12) and a detection signal from a current value measuring circuit or the like of the gas proportional valve 24 as gas amount detection means,

Measured heat efficiency = measured output / measured input is calculated, and normal heat efficiency stored in advance in the burner controller 34 is compared. If measured heat efficiency <normal heat efficiency, the heat collecting fins of the heat exchanger 16 are measured. Is assumed to be closed by a drain such as a combustion product, and the combustion by the gas burner 20 is safely stopped.

This will be described in detail below. That is, in the above-described formula of measured thermal efficiency = measured output / measured input, the measured output and the measured input are represented by the following formulas 1 and 2.

[0018]

(Equation 1)

[0019]

(Equation 2)

Here, in Equation 2, the Q gas (gas input flow rate at the time of measurement) is obtained by the following Equation 3.

[0021]

(Equation 3)

On the other hand, normal thermal efficiency, the instrument difference: nozzle diameter, the gas nozzle pressure, the performance of the heat exchanger, the variation of the combustion air-fuel ratio, thermistors, variations in bar bacon. Difference due to calorific value of used gas Difference due to usage environment: Temperature, humidity, atmospheric pressure Depth of hot water, output of hot water, difference due to heat exchanger performance Considering a decrease in thermal efficiency in the range where normal combustion is possible due to aging And is determined. The normal thermal efficiency is obtained according to the following equation (4).

[0023]

(Equation 4)

For example, if the thermal efficiency (η reference) and coefficient (k 1) of the initial performance in the equation (4) are set as in the following equation (5), the normal thermal efficiency (η normal) becomes Become like

[0025]

(Equation 5)

[0026]

(Equation 6)

As the η normal value, (I) it may be set for each gas type and selected and set by a gas type connector or the like. (II) The setting may be stored for each of the hot water temperature, the hot water amount and the incoming water temperature. In the above equation (1), for the incoming water temperature (T water), the lowest daily temperature is detected by the outlet temperature thermistor 30 on the outlet side of the heat exchanger 16, and this value may be substituted. Good. In that case, the incoming water temperature thermistor 27 is not required in the configuration.

Further, if the initial measured thermal efficiency is obtained in the initial state in the field, the value is used as the initial value of η, and the normal value of η is obtained by the following equation (7), the abnormality detection level is further increased. The setting of the η normal value including the learning function is also effective.

[0029]

(Equation 7)

However, when correcting the η normal value by the learning function, it is of course necessary to clarify the output and input of the gas burner by actually measuring the amount of hot water at the time of correction.

Next, a second embodiment of the present invention will be described. In the second embodiment, the configuration of each detecting means (outlet water temperature thermistor 30, incoming water temperature thermistor 27, gas proportional valve 24), maximum hot water amount limiter (water governor 28), etc.
This is the same as in the first embodiment.

In the second embodiment, the maximum flow capacity of the constant flow valve (water governor 28) is set to a value which is cut in a low temperature region of, for example, 45 ° C. or less. Is stored in advance in the burner controller 34, and if the calculated gas burner measurement input value exceeds the appropriate maximum gas amount, the combustion is stopped.

For example, FIG. 2 shows the relationship between the amount (Q) of hot water and the temperature (T) of tapping water of the gas water heater. The maximum capacity line (solid curve "A") of No. 20 shown in FIG. ), A constant flow valve (water governor 2)
8. When the maximum water amount regulated in 8) is, for example, a water temperature of 0 ° C.
If the outlet temperature is controlled at 4 liters / min and the tapping temperature at the time when the gas burner 20 is fully opened is 53 ° C., at a lower temperature (for example, 45 ° C. or lower), the constant flow valve (water governor 28) is used. The appropriate maximum gas amount is determined by the value obtained by cutting the maximum water amount in ()), and if the actual measured input value exceeds this appropriate maximum gas amount, it is determined that incomplete combustion has occurred and the combustion of the gas burner is stopped. It is. Now, the measured gas input flow rate of the gas burner is as shown in the above equation (3), and the appropriate maximum gas amount is as shown in the following equation (8).

[0034]

(Equation 8)

In the equation (8), since the normal value of η is determined in advance, only the measurement input is calculated.
Combustion abnormality is determined by comparing with the appropriate maximum gas amount. It should be noted that the present invention is not limited to the above-mentioned embodiment at all, and it is needless to say that various design changes or improvements can be made without departing from the spirit of the present invention.

[0036]

As is apparent from the above description, according to the gas water heater with the combustion abnormality detecting function of the present invention, a decrease in thermal efficiency due to clogging of the fins of the heat exchanger, etc., is quickly detected, and the gas burner is detected. Since the combustion of the gas is stopped, safety in using the gas appliance is ensured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire gas water heater to which the present invention is applied.

FIG. 2 is a diagram illustrating a relationship between a hot water amount (Q) and a tapping temperature (T) in the gas water heater shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas water heater 12 Water supply pipe (inlet pipe) 14 Outlet pipe 16 Heat exchanger 20 Gas burner 24 Gas proportional valve 27 Inlet temperature sensor (inlet temperature thermistor) 28 Constant flow valve (water governor) 30 Outlet temperature sensor (outlet temperature thermistor) ) 34 Burner controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F23N 5/02 350 F24H 1/10 302 F24H 1/10 303 F24H 5/24 104

Claims (3)

(57) [Claims] In a gas water heater provided with a heat exchanger provided with a water inlet pipe and a hot water pipe, and a gas burner for heating the heat exchanger, a hot water temperature detecting means for detecting a temperature of hot water flowing through the hot water pipe. And an inlet water temperature detecting means for detecting a temperature of water flowing through the inlet pipe, and provided on the tapping pipe or the inlet pipe, and the flow rate thereof is
The maximum amount of hot water limiting means limiting for the gas quantity detecting means for detecting the amount of gas supplied to the gas burner, the water temperature detecting means, input water temperature detected hand stage, the detection signal and the maximum amount of hot water limit from gas amount detecting means Limited by means
Thermal efficiency calculating means for calculating the thermal efficiency based on the maximum amount of hot water to be obtained, and thermal efficiency determining means for comparing the thermal efficiency calculated by the thermal efficiency calculating means with a reference thermal efficiency to determine whether the thermal efficiency is lower than the reference thermal efficiency. A gas heater with a combustion abnormality detection function, wherein the combustion of the gas burner is stopped when it is determined by the means that the calculated thermal efficiency is lower than the reference thermal efficiency. 2. The gas water heater with a combustion abnormality detecting function according to claim 1, wherein the value of the reference thermal efficiency used for the determination by the thermal efficiency determining means is a calculated value at the time of initial use. 3. A hot water temperature detecting means for detecting a temperature of hot water flowing through a hot water pipe in a gas water heater including a heat exchanger provided with a water inlet pipe and a hot water pipe, and a gas burner for heating the heat exchanger. And an inlet water temperature detecting means for detecting a temperature of water flowing through the inlet pipe, and provided on the tapping pipe or the inlet pipe, and the flow rate thereof is
The maximum amount of hot water limiting means limiting for the gas quantity detecting means for detecting the amount of gas supplied to the gas burner, on the basis of the detection signal from the gas amount detecting means, the outermost
An input value calculating means for calculating an input value of the gas burner at the maximum hot water amount limited by the large hot water amount limiting means; and comparing the input value calculated by the input value calculating means with an appropriate maximum gas amount. Input value determining means for determining whether the calculated value is lower than this, and when the calculated input value is determined to be higher than the appropriate maximum gas amount, the combustion of the gas burner is stopped. A gas water heater with a combustion abnormality detection function.