JPH10160252A - Hot water supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the error of regulation work of the electric input to a proportional valve and a gas pressure from having an effect on the decision of output drop by deciding an output drop state based on a calculated hot water supply capacity and a set heating capacity. SOLUTION: When decision starting conditions are satisfied during steady combustion at a heating section, a decision is made whether a set gas pressure at a gas pressure setting section 25 is higher than a predetermined level. When it is higher than the predetermined level and the ration between a hot water supply capacity calculated at a hot water supply capacity calculating section 28 and a set heating capacity at a heating capacity setting section 23 is lower than a reference level, a decision is made that the unit is defective, e.g. a fin of a heat-exchanger is choked. The decision is not made when the gas pressure is lower than the predetermined level. According to the arrangement, decision making in a region having high possibility of making an erroneous decision due to the effect of error can be avoided even when the actual gas pressure is lower than a set gas pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply apparatus which detects a deterioration of a device such as a fin blockage of a heat exchanger by a decrease in output and takes safety measures.

[0002]

2. Description of the Related Art In a hot water supply apparatus having a heat exchanger in which a large number of fins for absorbing heat are arranged side by side, combustion products adhere to the fins or corrosion occurs with the fins due to long-term use. The gap may be closed, in such cases,
Since the supply / exhaust resistance increases, the combustion state deteriorates, and harmful gas may be generated due to incomplete combustion.

In order to prevent such a situation, the tapping capacity is calculated based on the tapping temperature, the inlet temperature, and the flow rate, and a drop in the output is detected based on the ratio of the tapping capacity to the set value of the heating capacity. It is known that a safety operation such as forcibly stopping the combustion is performed when the decrease is equal to or higher than a reference level.

For example, in Japanese Patent Application Laid-Open No. 6-257856, when a decrease in output is detected and ignition detection is continued for a predetermined time or more,
The safety operation is performed assuming that the fin is closed, so that a decrease in output due to misfiring or misfire of the heating unit is not mistaken for fin occlusion.

[0005]

In the above-described conventional hot water supply apparatus, if the fins are clogged, the heat exchange efficiency is deteriorated, and the output is reduced. On the other hand, when the actual value of the heating capacity is low, the output similarly decreases. That is, even if the heat exchange efficiency is in the normal range, when the actual value of the heating capacity is lower than the set value, the tapping capacity naturally becomes low. As in the case of the blockage, a safe operation such as stopping the combustion is performed.

[0006] When the actual value of the heating capacity is lower than the set value due to the failure or deterioration of the heating unit, there is no particular inconvenience in performing the safe operation as in the case of the fin blockage. If the actual value of the heating capacity is low due to the deviation, and even if there is no practical inconvenience in that state, the output may be detected and a safety operation may be reached, and there is room for improvement in this point. is there.

More specifically, in a hot water supply apparatus, generally, a heating capacity is varied by adjusting a gas pressure of a fuel gas supplied to a heating unit by using a proportional valve. In many cases, the heating capacity is switched by switching the number of combustion tubes for supplying gas to a large number of combustion tubes.

In such a water heater, when the set value of the heating capacity is set, the number of combustion and the gas pressure are set in accordance with the set value, and an electric input corresponding to the gas pressure is given to the proportional valve. It is supposed to be. Therefore, in such a hot water supply device, it is necessary to previously match the electric input given by the proportional valve with the gas pressure controlled by the proportional valve, and for example, it is described in Japanese Patent Publication No. 3-60015. As described above, an adjustment operation is performed to match the specified maximum gas pressure and minimum gas pressure of the hot water supply device with the electric input to the proportional valve.

If an error occurs in this adjustment operation, the gas pressure controlled by the proportional valve will cause an error with respect to the set gas pressure, and as a result, an error will occur in the heating capacity. Such a hot water supply apparatus generally employs a so-called feedback control that detects the tapping temperature and corrects the setting of the heating capacity according to the deviation between the set temperature and the tapping temperature. Therefore, there is no practical problem with a certain degree of error.

However, when a decrease in output is detected based on the ratio between the tapping capacity and the set value of the heating capacity, if an error occurs so that the actual value of the heating capacity becomes lower than the set value, the feedback control is performed as described above. Thus, even if the tapping temperature is made to match the set temperature and the intended tapping capacity is obtained, the setting value of the heating capacity is corrected in a direction to increase, so that it is finally determined that the output is reduced, and the combustion is stopped. Safety operation.

The present invention solves such a problem and suppresses an error in the adjustment operation between the electric input to the proportional valve and the gas pressure from affecting the determination of the output decrease, and there is no practical problem. It is an object of the present invention to provide a hot water supply device that does not sometimes stop burning.

[0012]

The hot water supply apparatus of the present invention has the following structure to solve the above-mentioned problems.
That is, the hot water supply apparatus according to the first aspect of the invention controls the heat exchanger connected to the water inlet pipe and the hot water pipe, a heating unit for heating the heat exchanger, and a gas pressure of the fuel gas supplied to the heating unit. A proportional valve, a capacity setting means for setting a heating capacity of the heating unit, a gas pressure setting means for setting a gas pressure according to the set heating capacity, and a tapping water temperature, an incoming water temperature, and a flow rate of water. Tapping capacity calculating means for calculating tapping capacity; determining means for determining a reduced output state based on the calculated tapping capacity and the set heating capacity; and stopping the operation of the heating section based on the determination result of the determining means. And a forced stopping means for causing the determination means not to perform the determination when the set gas pressure is less than a predetermined value.

[0013] A hot water supply apparatus according to a second aspect of the present invention includes a heat exchanger connected to the water inlet pipe and the hot water pipe, a heating unit for heating the heat exchanger, and a gaseous fuel gas supplied to the heating unit. Proportional valve for controlling the pressure, capacity setting means for setting the heating capacity of the heating section, gas pressure setting means for setting the gas pressure according to the set heating capacity, tapping temperature, incoming water temperature, water flow rate and Tapping capacity calculating means for calculating tapping capacity based on the temperature, judging means for judging a power reduction state by comparing a ratio of the calculated tapping capacity to the set heating capacity with a reference value, and a judgment result of judging means And a forcible stopping means for stopping the operation of the heating section based on the reference value, and the judging means varies the reference value in accordance with the set gas pressure.

In the hot water supply apparatus according to the first aspect of the present invention, when the set gas pressure is equal to or higher than a predetermined value, a decrease in output is determined based on the set values of the tapping capacity and the heating capacity, for example, by the ratio between the two. I do. When adjusting the electrical input of the proportional valve and the gas pressure, it is expected that the same level of error (gas pressure) will occur in both the adjustment of the maximum gas pressure and the adjustment of the minimum gas pressure. Gas pressure set accordingly,
A substantially constant amount of error may exist between the proportional gas and the actual gas pressure on the secondary side regardless of the set gas pressure. Assuming that the error is substantially constant, the smaller the set gas pressure, the greater the effect of the error, and the greater the rate of decrease or increase in the heating capacity due to the gas pressure error.

If there is an error in the direction in which the actual gas pressure becomes lower than the set gas pressure, and if the set gas pressure is small, the actual value of the heating capacity becomes less than the set value. On the other hand, the ratio is considerably low, and as a result, when the ratio between the tapping capacity and the set value of the heating capacity is obtained, the ratio becomes low.

In the hot water supply apparatus according to the first aspect of the present invention, when the set gas pressure is a small value less than the predetermined value, the determination of the output reduction based on the ratio of the tapping capacity and the set value of the heating capacity is not performed. Therefore, the forced stop means does not work when the output decreases due to a gas pressure error.

In the hot water supply apparatus according to the second aspect of the present invention, a reduction in output is determined by comparing the ratio of the set value of the tapping capacity and the set value of the heating capacity to a reference value regardless of the set gas pressure. However, this reference value is varied according to the set gas pressure. When the set gas pressure is low,
The reference value is set low in consideration of the possibility that the ratio may decrease due to a gas pressure error. As a result, the forced stop means does not operate only by the output decrease caused by the gas pressure error.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram showing an embodiment of a hot water supply apparatus according to the present invention. Reference numeral 1 denotes a heating unit formed by arranging a number of combustion tubes in parallel. A first combustion tube group 11, a second combustion tube group 12, and a third combustion tube group 13. The gas supply path 2 to the heating unit 1 is located downstream of the original solenoid valve 3 and the proportional valve 4. At the first to third
Switching solenoid valves 14 and 15 for connecting and disconnecting the gas supply passages to the second and third combustion pipe groups 12 and 13 respectively.
In the present embodiment, each of the combustion tube groups 11, 12, and 13 is assumed to be composed of two combustion tubes.

Reference numeral 5 denotes a heat exchanger having a large number of fins, which are connected to a water inlet pipe 6 and a hot water outlet pipe 7. The water inlet pipe 6 is provided with a flow rate sensor 8 for detecting a water flow rate Q and a water inlet temperature sensor 9 for detecting a water inlet temperature Tc.
Is provided with a tapping temperature sensor 10 for detecting a tapping temperature Th.

Reference numeral 16 denotes an ignition device, 17 denotes an ignition sensor such as a frame rod, and 18 denotes a fan motor for supplying combustion air. Reference numeral 19 denotes a remote controller including a means for setting a set temperature Ts of hot water supply, and reference numeral 20 denotes a control device that controls various functions of the hot water supply device.

FIG. 2 is a block diagram of a main part of the control device 20, which is shown together with the proportional valve 4 and the switching solenoid valves 14 and 15.

Reference numeral 21 denotes a set temperature Ts set by the remote controller 19, an incoming water temperature Tc detected by the incoming water temperature sensor 9, and a water flow rate Q detected by the flow rate sensor 8.
And calculates the required number G _FF by inputting the required number _GFF, and calculates the heating capacity required for tapping the hot water at the set temperature Ts by a well-known feedforward calculation.
Reference numeral 22 denotes a correction number calculating unit which inputs the set temperature Ts, the tapping temperature Th detected by the tapping temperature sensor 10, and the flow rate Q, and calculates the correction number G _FB.
Is calculated by a well-known PID operation or PI operation or the like to increase or decrease the heating capacity to make the temperature equal to the set temperature Ts.

Reference numeral 23 denotes a combination of the required number G _FF calculated by the required number calculation unit 21 and the correction number G _FB calculated by the correction number calculation unit 22 to set a heating capacity set value G _IN. 24 is a heating capacity setting section for setting the number H of used combustion tubes of the heating section 1 according to the heating capacity setting value G _IN , and 25 is a heating capacity setting value G
A gas pressure setting unit that sets the gas pressure P controlled by the proportional valve 4 according to _IN and the set number H of combustion.

Reference numeral 26 denotes a switching solenoid valve control unit for controlling the switching solenoid valves 14 and 15 in accordance with the number of combustions H set by the combustion number setting unit 24, and 27 denotes a gas pressure set by the gas pressure setting unit 25. P is a proportional valve control unit that controls the electric input to the electromagnetic coil of the proportional valve 4 according to P.

[0025] 28 is a tapping capacity calculating unit that calculates a tapping capacity G _{OU T} on the basis of the tapping temperature Th and the incoming water temperature Tc and the water flow rate Q, tapping ability G This calculated
_OUT and the set value G _IN of the heating capacity set by the heating capacity setting unit 23 are input to the determining unit 29, and when the predetermined condition is satisfied, the determining unit 29 sets the tapping capacity G _OUT and the heating capacity. The ratio with the value G _IN is compared with the reference value K and determined. The data of the gas pressure P set by the gas pressure setting unit 25 is also input to the determination unit 29. Reference numeral 30 denotes a forced stop unit that outputs a command such as closing the original electromagnetic valve 3 so as to forcibly stop the operation of the heating unit 1 based on the determination result of the determination unit 29.

The operation of the main part of this embodiment configured as described above will be described with reference to FIG. First, when it is determined that the water heater is operating and the heating unit 1 is performing steady combustion, that is, it is not during a specific operation such as an ignition operation (step 101), the determination unit 29 determines It is determined whether or not a predetermined determination start condition is satisfied (step 102).

The conditions for starting the determination include, for example, (1) that the set value G _IN set by the heating capacity setting unit 23 is a value equal to or greater than a predetermined number of signals, and (2) the set value G
_IN and tapping capacity G calculated by tapping capacity calculator 28
It is preferable that both _OUT and are stable. That is, condition (1) is that when the heating capacity and the tapping capacity are too small, the tapping capacity G _OUT
Is calculated, the influence of the measurement error of each of the tap water temperature sensor 10, the incoming water temperature sensor 9, and the flow rate sensor 8 greatly appears, so that this is avoided.
The condition (2) is for avoiding determination when the heating capacity or the tapping capacity is in the process of changing.

When it is determined that such a determination start condition is satisfied, it is determined whether the gas pressure P set by the gas pressure setting section 25 is equal to or higher than a predetermined value Ps (step 1).
03) When the value is equal to or more than the predetermined value Ps, the ratio G between the tapping capacity G _OUT calculated by the tapping capacity calculating section 28 and the set value G _IN of the heating capacity set by the heating capacity setting section 23.
_OUT / G _IN is compared with the reference value K (step 10).
4), the ratio G _OUT / G _IN is the reference value K (for example, K =
If it is less than 0.63), it is assumed that there is deterioration of the apparatus such as blockage of the fins of the heat exchanger 5.

In the present embodiment, the judgment unit 29 indicates the judgment result by a numerical value n, and as described above, the ratio G
_{When OUT} / G _IN is less than the reference value K, the determination unit 29
Is added to the numerical value n of (step 105), and as a result,
It is determined whether or not the numerical value n has become 12 or more (step 106). If it is less than 12, the combustion of the heating unit 1 is forcibly stopped by a command from the forced stop unit 30,
If a predetermined reset operation is performed by an operation switch or the like of the remote controller 19, the state is controlled again to a state in which operation can be resumed (first safety operation) (step 107). In this case, control is performed so that the combustion of the heating unit 1 is stopped by a command from the forced stop unit 30 and the operation is not returned to the operable state even after a predetermined reset operation (second safety operation). (Step 108).

In the determination at step 104, the tapping capacity G
Ratio G _OUT / G between _OUT and set value G _{IN of} heating capacity
_When it is determined that _IN is equal to or more than the reference value K, the determination unit 2
When 1 is subtracted from the numerical value n of 9 (step 109), when the numerical value n becomes a negative value, the numerical value n is set to 0 (steps 110 and 111). That is, step 1
If it is determined in step 04 that the process proceeds to step 105 three times in a row, the process proceeds to step 108 to not only stop the combustion of the heating unit 1 but also prevent the user from receiving a return operation (second operation). Safe operation).

As described above, in the present embodiment, the determination unit 29
Determines whether the gas pressure P is equal to or higher than a predetermined value Ps (step 103). If the gas pressure P is lower than the predetermined value Ps, a determination is made based on the tapping capacity G _OUT and the set value G _{IN of the} heating capacity (step 104). Is not performed, even if the actual gas pressure is lower than the set gas pressure P, it is possible to avoid a determination in a region where an erroneous determination is likely to occur due to the error.

FIG. 4 shows another embodiment.
Corresponding to FIG. 3, the same steps as those in FIG. 3 are denoted by the same reference numerals. The difference from FIG. 3 is that in FIG. 3, when the gas pressure P is equal to or higher than the predetermined value Ps in step 103, step 1
In contrast to FIG. 4, in FIG. 4, in step 112, the value of the reference value K used in step 104 is set according to the gas pressure P.

That is, in the above embodiment, when the gas pressure P set according to the set value G _IN of the heating capacity is less than the predetermined value Ps, that is, between the point A and the point B shown in FIG.
The determination is not performed when the distance is set between the point and the point D and between the point E and the point F. However, in the present embodiment, the determination is performed even when the distance is set in the above range. However, as shown in FIG. 6, the reference value K for determination is varied so that the lower the gas pressure P that is set, the lower the set value of the reference value K.

When the actual gas pressure is lower than the set gas pressure P, the influence of the error is greater as the gas pressure is lower, and the calculated tapping capacity G _OUT and the set heating capacity G _IN Ratio G _OUT / G _IN becomes smaller, but in this embodiment, the lower the set gas pressure P, the lower the reference value K
Is set to a low value, the influence of the error can be offset, and erroneous determination can be prevented.

A specific example of the effect of the gas pressure error will be described. For example, when the prescribed maximum gas pressure and minimum gas pressure are 90 mm water column and 20 mm water column, respectively, the electric input to the proportional valve and the gas pressure It is assumed that errors of minus 5 millimeters of water have occurred in the adjustment work, and the adjustment has actually been made to 85 millimeters and 15 millimeters of water. Since heating capacity is proportional to gas supply and gas supply is almost proportional to the square root of gas pressure,
Heating capacity is approximately proportional to the square root of gas pressure. According to this relationship, when the set gas pressure is 90 mm water column, the actual gas pressure is 85 mm water column. Therefore, the actual gas pressure is 85/90 of the set gas pressure, that is, about 94%. Is calculated to be about 97% of the set heating capacity. On the other hand, since the actual gas pressure when the set gas pressure is 20 mm water column is 15 mm water column, the actual gas pressure is 15/20 of the set gas pressure, that is, 75%, and the actual heating capacity is It is about 87% of the set heating capacity.

As described above, as the set gas pressure is lower, the decrease in the heating capacity due to the error is greater, and accordingly the tapping capacity is naturally lower. Thus, when there is such an error, the ratio between the calculated tapping capacity and the set heating capacity is more affected by the error as the set gas pressure is lower.

[0037]

According to the hot water supply apparatus of the present invention, the state of a decrease in output is determined, and the operation of the heating unit is stopped based on the determination result. The gas pressure set according to the heating capacity is lower than a predetermined value. Occasionally, by not performing the determination of the output decrease, if there is an error between the set gas pressure and the actual gas pressure controlled by the proportional valve, an erroneous determination is made under the influence of the error. It is possible to avoid the determination in the gas pressure range where there is a risk, and it is possible to prevent the operation of the heating unit from being stopped due to a gas pressure error that does not cause a practical problem.

Further, in the hot water supply apparatus of the present invention, the ratio of the calculated tapping capacity to the set heating capacity is compared with a reference value to determine the output reduction state, and the reference is determined according to the set gas pressure. By making the value variable, when there is an error between the set gas pressure and the actual gas pressure controlled by the proportional valve, the reference value is set in the gas pressure range where the influence of the error is large. Erroneous determination can be prevented by lowering the temperature, and the operation of the heating unit can be prevented from being stopped due to a gas pressure error that does not cause a practical problem.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a hot water supply apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a main part of the control device in the embodiment.

FIG. 3 is a flowchart showing a control operation of the control device.

FIG. 4 is a flowchart showing a second embodiment of the present invention.

FIG. 5 is a relationship diagram between a heating capacity and a gas pressure according to the first embodiment of the present invention.

FIG. 6 is a relationship diagram between a gas pressure and a reference value according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating part 4 Proportional valve 5 Heat exchanger 6 Inlet pipe 7 Outlet pipe 8 Flow rate sensor 9 Inlet temperature sensor 10 Outlet temperature sensor 20 Control device 23 Heating capacity setting part 25 Gas pressure setting part 28 Hot water ability calculating part 29 Judgment part 30 Forced Stop

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eiichi Tsuji No. 93, Edocho, Chuo-ku, Kobe-shi, Hyogo

Claims (2)

[Claims] 1. A heat exchanger connected to an inlet pipe and a tap water pipe, a heating unit for heating the heat exchanger, a proportional valve for controlling a gas pressure of fuel gas supplied to the heating unit, Capacity setting means for setting the heating capacity, gas pressure setting means for setting the gas pressure according to the set heating capacity, and tapping capacity calculation for calculating tapping capacity based on tapping temperature, inlet temperature and flow rate. Means, determining means for determining the output reduction state based on the calculated tapping capacity and the set heating capacity, and forced stopping means for stopping the operation of the heating unit based on the determination result of the determining means, The water heater is characterized in that the determination means does not perform the determination when the set gas pressure is less than a predetermined value. 2. A heat exchanger connected to the inlet and outlet pipes, a heating unit for heating the heat exchanger, a proportional valve for controlling a gas pressure of fuel gas supplied to the heating unit, Capacity setting means for setting the heating capacity, gas pressure setting means for setting the gas pressure according to the set heating capacity, and tapping capacity calculation for calculating tapping capacity based on tapping temperature, inlet temperature and flow rate. Means, a determining means for comparing the ratio of the calculated tapping capacity to the set heating capacity with a reference value to determine a power reduction state, and forcibly stopping the operation of the heating unit based on the determination result of the determining means. A hot water supply apparatus comprising: a stop unit; and the determination unit changes the reference value according to a set gas pressure.