JP5647489B2 - Water heater - Google Patents

Description

  The present invention relates to a water heater having a function of detecting incomplete combustion of a burner.

  There are outdoor installations and indoor installations as installation modes of the water heater. In the case of indoor installation, an exhaust pipe is connected to the water heater, and the combustion exhaust gas of the burner is discharged to the outdoors through the exhaust pipe. However, if the hot water heater is installed indoors without connecting the exhaust pipe accidentally, or if the exhaust gas from the burner is exhausted indoors due to a defective exhaust pipe, the oxygen concentration in the room where the hot water heater is installed decreases. As a result, incomplete combustion of the burner due to lack of oxygen occurs.

  Therefore, in a conventional water heater, a flame sensor such as a frame rod is provided to monitor the combustion state of the burner, and when incomplete combustion of the burner is detected due to a decrease in the detection level of the flame sensor, combustion of the burner is performed. The operation is forcibly stopped (for example, see Patent Document 1).

JP 2009-162442 A

  When the water heater is installed outdoors, incomplete combustion of the burner is hardly caused because ventilation around the water heater is performed well. However, if an enclosure is provided around the water heater to protect the water heater from snowfall or children's tampering, the enclosure will prevent ventilation around the water heater, resulting in incomplete burner due to lack of oxygen. Inappropriate use conditions where combustion is likely to occur may occur.

  Therefore, when incomplete combustion of the burner is detected by the flame sensor, the hot water heater is used in such an inappropriate usage state by prohibiting combustion of the burner or notifying the occurrence of incomplete combustion. Can be avoided.

  By the way, when the hot water heater is in an appropriate usage state installed outdoors without providing an enclosure, the burner may suddenly misfire due to the blowing of strong wind. In this case as well, the flame sensor detection level decreases in the same manner as in the case of incomplete combustion of the burner. Therefore, the flame sensor distinguishes between burner incomplete combustion due to lack of oxygen and burner misfire due to strong wind. It is difficult to detect.

  And when the burner misfires due to strong winds, as in the case where incomplete combustion is detected, if the subsequent burner combustion is prohibited, the hot water heater is used in an appropriate state. There is an inconvenience that the use of the water heater becomes impossible until the prohibition of combustion of the burner is canceled by contacting maintenance service or the like. Moreover, if the occurrence of incomplete combustion is reported when the burner misfires due to strong winds, the user feels uncomfortable or uneasy.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a water heater that can detect incomplete combustion of a burner separately from misfire of the burner due to strong wind.

The present invention has been made to achieve the above object, and a burner, a heat exchanger that is heated by the burner and heats hot water flowing inside, and a fan that supplies combustion air to the burner. A fuel gas supply unit for supplying fuel gas to the burner, a rotational speed of the fan and a fuel gas supply amount by the fuel gas supply unit so as to obtain a target combustion amount corresponding to a predetermined hot water supply set temperature, A combustion control unit for controlling the combustion of the burner for controlling the combustion, a flame sensor for detecting a combustion flame of the burner, and the fan is more than a wind pressure threshold value that assumes an air blowing pressure from the outside. while operating at a rotational speed is towards the supply pressure of the combustion air becomes higher, before Symbol burner have burned, soluble detection level of the flame sensor is below the combustion threshold by blowing air from the outside When low sexual, when the detected level of the flame sensor is below the combustion threshold, incomplete combustion of the incomplete combustion due hypoxia is determined that the burner has misfire detecting the incomplete combustion of the burner A detection unit , a detection counter that counts and holds the number of times that the incomplete combustion of the burner is detected by the incomplete combustion detection unit, and a count value held in the detection counter exceeds a predetermined value And a combustion prohibiting unit that is in an interlocked state in which the combustion operation of the burner by the combustion control unit is prohibited until a release operation is performed (first invention).

  According to the first invention, the incomplete combustion detector is configured such that the burner burns in a state where the fan is operated at a rotational speed at which the supply pressure of combustion air to the burner is higher than the wind pressure threshold. Incomplete combustion of the burner is detected only when it is in operation. In this case, in the situation where the supply pressure of the combustion air to the burner is low and the burner may be misfired by blowing strong wind from outside, the incomplete combustion detection of the burner is not performed by the incomplete combustion detection unit. I will not. Therefore, it is possible to detect incomplete combustion of the burner as distinguished from misfire caused by blowing strong wind from the outside.

Further , according to the first invention, when the hot water heater is installed outdoors with an enclosure and incomplete combustion of the burner is likely to occur due to insufficient ventilation, the hot water heater is used in an inappropriate state. , that combustion operation of the burner is continued, the combustion operation of the burner according to prior Symbol combustion control unit may prohibit by the interlock inhibited state.

Further, according to the first aspect of the present invention, when fuel gas is supplied from the fuel gas supply unit to the burner, air suddenly enters the fuel gas supply passage and the burner misfires. When the burner is extinguished due to a factor, it is possible to prevent the burner from being prohibited from being burned by being erroneously detected that incomplete combustion of the burner has occurred.

Further, in the first invention, the combustion prohibiting section operates such that the combustion operation of the burner operates at a rotational speed at which the supply pressure of combustion air to the burner is higher than the wind pressure threshold value of the fan, and When the incomplete combustion of the burner is not detected by the incomplete combustion detection unit, the count value of the detection counter is decreased when the burner continues for a predetermined time or longer ( second invention).

According to the second invention, the burner is operated at a rotational speed at which the supply pressure of the combustion air to the burner is higher than the wind pressure threshold value, and the incomplete combustion detection is performed. When incomplete combustion of the burner by the part is not detected and the burner continues for a predetermined time or more, it can be determined that the burner is stably burning normally and that the hot water heater is used properly. Therefore, in this case, by reducing the count value held in the detection counter, it is possible to prevent the combustion operation of the burner from being prohibited due to erroneous detection of incomplete combustion.

The block diagram of the water heater of this invention. The control block diagram of the water heater shown in FIG. The operation | movement flowchart of the water heater shown in FIG.

  Embodiments of the present invention will be described with reference to FIGS.

  Referring to FIG. 1, a water heater 1 according to this embodiment is installed outdoors, and includes a combustion housing 3 in a housing 2. An exhaust port 31 is provided at the upper end of the combustion housing 3.

  A burner 5 is accommodated in the lower part of the combustion housing 3. The burner 5 includes a first burner unit 51 including a plurality of unit burners 5 a and a second burner unit 52 including more unit burners 5 a than the first burner units 51. The burner 5 is provided with a spark plug 5b for igniting the burner 5, and a frame rod 5c (corresponding to the flame sensor of the present invention) for detecting the combustion flame of the burner 5.

  A gas supply path 6 for supplying fuel gas is connected to the burner 5. The downstream side of the gas supply path 6 is divided into a first branch path 61 connected to the first burner unit 51 and a second branch path 62 connected to the second burner unit 52. The first branch path 61 is provided with a first capacity switching valve 61 a for switching supply / cutoff of the fuel gas to the first burner unit 51, and the second branch path 62 has a fuel gas to the second burner unit 52. A second capacity switching valve 62a for switching between supply and shutoff of the engine is provided. Further, a gas proportional valve 63 and a gas source valve 64 are provided on the upstream side of the branch point of the gas supply path 6 to the first branch path 61 and the second branch path 62.

  An air supply chamber 81 partitioned by a distribution plate 81 a having a large number of air holes is formed below the burner 5 in the combustion housing 3. The air supply chamber 81 is partitioned by a partition plate 81 b into a first air supply chamber 82 corresponding to the first burner unit 51 and a second air supply chamber 83 corresponding to the second burner unit 52.

  A fan 84 that supplies combustion air for the burner 5 to an air supply chamber 81 via an air supply passage 85 is provided below the combustion housing 3. The downstream side of the air supply path 85 is branched into a first distribution path 86 a connected to the first air supply chamber 82 and a second distribution path 86 b connected to the second air supply chamber 83.

  A heat exchanger 71 for hot water supply heated by the burner 5 is accommodated in the upper part of the combustion housing 3. A water supply path 72 and a hot water supply path 73 are connected to the heat exchanger 71, and water supplied from the water supply path 72 to the heat exchanger 71 is heated by the heat exchanger 71 and supplied to the hot water supply path 73.

  The water supply path 72 is provided with a water amount sensor 72 a that detects the flow rate of water flowing through the water supply path 72 and a water amount adjustment valve 72 b that adjusts the flow rate of water supplied from the water supply path 72. The hot water outlet 73 is provided with a hot water temperature sensor 73 a that detects the temperature of hot water supplied from the hot water outlet 73.

  A controller 9 that controls the overall operation of the water heater 1 is provided in the housing 2. The controller 9 is an electronic unit configured by a CPU, a memory, and the like (not shown), and is connected to a remote controller 10 for remotely operating the water heater 1.

  Next, referring to FIG. 2, the controller 9 receives a temperature detection signal from the hot water temperature sensor 73a, a flow rate detection signal from the water amount sensor 72a, and a flame detection signal from the frame rod 5c. The operation of the water amount adjustment valve 72b, the gas source valve 64, the gas proportional valve 63, the first capacity switching valve 61a, the second capacity switching valve 62a, the fan 84, and the spark plug 5b is controlled by the control signal output from the controller 9. Is controlled.

  The controller 9 executes a control program for the hot water heater 1 held in the memory by the CPU, whereby a hot water supply control unit 91, a combustion control unit 92, a combustion prohibition unit 93, a detection counter 94, and an incomplete combustion detection unit. It functions as 95.

  The hot water supply control unit 91 determines the target combustion amount of the burner 5 so that the hot water supply temperature from the hot water supply path 73 detected by the hot water temperature sensor 73a becomes the hot water supply set temperature set by the remote controller 10, and is necessary. Accordingly, the flow rate of water supplied to the water supply path 72 is adjusted by the water amount adjustment valve 72b.

  The combustion control unit 92 opens both the first capacity switching valve 61a and the second capacity switching valve 62a to burn the first burner unit 51 and the second burner unit 52, and a state where the effective combustion range is large. The 1st capacity switching valve 61a is closed and the 2nd capacity switching valve 62a is opened, and “the state in the effective combustion range” in which only the second burner unit 52 is combusted, and the first capacity switching valve 61a is opened. Then, the second capacity switching valve 62a is closed to switch to the “effective combustion range small state” in which only the first burner unit 51 is combusted, and the opening of the gas proportional valve 63 is adjusted so that the target combustion amount is As obtained, the supply flow rate of the fuel gas to the burner 5 in each effective combustion range is controlled. Furthermore, the combustion control unit 92 controls the rotational speed of the fan 84 so that the target combustion amount is obtained.

  The incomplete combustion detector 95 detects incomplete combustion of the burner 5 based on the level of the flame detection signal of the frame rod 5c. The detection counter 94 counts the number of times that the incomplete combustion of the burner 5 is detected by the incomplete combustion detection unit 95. The combustion prohibition unit 93 prohibits the combustion control unit 92 from performing the combustion operation of the burner 5 when the count value of the detection counter 94 becomes a predetermined value or more. By prohibiting the combustion operation of the burner 5, the “interlock state” is entered in which the use of the water heater 1 is prohibited.

  Next, the operation of the controller 9 will be described according to the flowchart shown in FIG.

  When the water heater 1 is turned on, the controller 9 starts to operate, and when the operation switch (not shown) of the remote controller 10 is operated, the water heater 1 is put into an operation state (a state in which a hot water supply operation is executed). The process according to the flowchart of FIG. 3 is executed.

  When the controller 9 detects in STEP 1 that the supply of water to the water supply path 72 is started based on the detected flow rate of the water amount sensor 72a, the controller 9 proceeds to STEP 2 and starts the ignition process of the burner 5 and an ignition timer (for example, 4 seconds is set as the timer time).

  In the subsequent loop consisting of STEP3 and STEP20, the controller 9 confirms whether or not the ignition timer has timed out in STEP20, and in STEP3, the level of the flame detection signal FL of the frame rod 5c becomes the ignition threshold Ath (for example, 0. 0). It is determined whether or not it is larger than 1 μA).

  When the level of the flame detection signal FL of the frame rod 5c becomes larger than the combustion threshold value Ath in STEP3, the process proceeds to STEP4, and the controller 9 ends the ignition process and starts the hot water supply operation. The hot water supply operation is executed by the hot water supply control unit 91 as described above, and the combustion control unit 92 controls the combustion amount of the burner 5 according to the target combustion amount determined by the hot water supply control unit 91.

  Further, when the ignition timer expires in STEP 20, the process proceeds to STEP 21, and the controller 9 executes an ignition error process. As an ignition error process, the controller 9 closes the gas source valve 64, the first capacity switching valve 61a and the second capacity switching valve 62a, stops the operation of the fan 84, and displays the display unit (not shown) of the remote controller 10. Is displayed indicating a misfire error.

  During the hot water supply operation, the hot water supply control unit 91 determines whether or not the level of the flame detection signal FL of the frame rod 5c is larger than the combustion threshold Ath in STEP5, and in STEP6, the water supply path is determined based on the detected flow rate of the water amount sensor 72a. It is determined whether or not the water supply to 72 is stopped.

  When the level of the flame detection signal FL of the frame rod 5c becomes equal to or lower than the combustion threshold Ath in STEP5, the process branches to STEP30. STEP 30 is a process performed by the incomplete combustion detection unit 95. The incomplete combustion detection unit 95 detects the rotational speed of the fan 84 (when the level of the flame detection signal FL of the frame rod 5c becomes equal to or lower than the combustion threshold Ath in STEP 5). It is determined whether or not (the rotational speed of 84) is equal to or higher than the speed threshold value Nth.

Here, the speed threshold value Nth is higher in the supply pressure of the combustion air supplied to the burner 5 by the fan 84 than in the wind pressure threshold value determined by assuming the wind blown from the outside of the water heater 1 toward the burner 5. The lower limit of the rotational speed of the fan 84 is increased. For example, when a wind with a wind speed of 15 m / sec is assumed, the wind pressure threshold is determined to be 145 kPa (14.8 mH ₂ O) obtained by h in the following equation (1).

Where, V: average ejection speed of combustion air (corresponding to wind speed), g: acceleration of gravity (9.8 m / sec ² ), h: ejection pressure of combustion air, d: specific gravity of combustion air (1.0 ).

  The speed threshold Nth is set to a rotational speed (for example, 3000 rpm) at which the supply pressure of the combustion air supplied to the burner 5 by the rotation of the fan 84 becomes the wind pressure threshold 145 kPa. The speed threshold value Nth may be calculated from the assumed value as described above or determined by experiment.

  When the fan 84 is operating at the speed threshold value Nth or higher, there is a low possibility that the burner 5 will misfire due to the blowing of wind. Therefore, when the flame detection signal FL level of the frame rod 5c is equal to or lower than the combustion threshold Ath in STEP5 and the rotational speed of the fan 84 is equal to or higher than the speed threshold Nth in STEP30, the burner 5 is incompletely burned due to lack of oxygen. Can be determined to have misfired.

  Therefore, in this case, the process branches to STEP 40, and the count value CNT of the detection counter 94 is counted up (CNT + 1 → CNT). Subsequent STEP 41 to STEP 42 are processes performed by the combustion prohibition unit 93. In STEP 41, the combustion prohibition unit 93 determines whether or not the count value CNT of the detection counter 94 is 3 or more. If the count value CNT is 3 or more, the combustion prohibiting unit 93 proceeds to STEP 42 and performs an interlock process.

  As an interlock process, the combustion prohibition section 93 closes the gas source valve 64, the first capacity switching valve 61a, and the second capacity switching valve 62a and stops the operation of the fan 84, and then performs the combustion operation by the combustion control section 92. Is prohibited. Thereby, execution of the hot water supply operation by the hot water supply control unit 91 is prohibited, and the interlocked state in which the use of the hot water heater 9 is disabled becomes possible. In addition, when the water heater 9 is in the interlock state, an interlock display is made on the display unit of the remote controller 91. The interlock state is released by maintenance personnel or the like of the water heater 1 that has been contacted by the user.

  If the count value CNT of the detection counter 94 is less than 3 in STEP 41, the process proceeds to STEP 31, and the controller 9 performs misfire error processing. As the misfire error process, the controller 9 closes the gas source valve 64, the first capacity switching valve 61a and the second capacity switching valve 62a and stops the operation of the fan 84, and then displays a misfire error display on the display unit of the remote controller 10. I do.

  Next, when it is determined in STEP 6 that the supply of water to the water supply channel 72 is stopped by the detected flow rate of the water amount sensor 72a, the process proceeds to STEP7. STEP 7 to STEP 8 are processes performed by the combustion prohibition unit 93.

  In STEP 7, the combustion prohibition unit 93 determines whether or not there has been a state in which the rotation speed of the fan 84 is higher than the speed threshold value Nth for 3 minutes or more during the hot water supply operation. Here, when an inappropriate use state in which an enclosure is provided around the water heater 1, the burner 5 is burned with a large heating power in which the combustion amount of the burner 5 is large and the rotational speed of the fan 84 becomes the speed threshold value Nth. In such a case, incomplete combustion of the burner 5 due to lack of oxygen occurs in a short time.

  Therefore, when it is determined in STEP 7 that there has been a state in which the rotation speed of the fan 84 is higher than the speed threshold value Nth for 3 minutes or more during the hot water supply operation, the use state of the water heater 1 is appropriate and the enclosure is There is a high possibility that there is no such thing.

  Therefore, in this case, the process proceeds to STEP8, and the combustion prohibition unit 93 decreases the count value CNT of the detection counter 94 by 1 (CNT-1 → CNT), and proceeds to STEP9. As a result, when the burner 5 is accidentally misfired due to air clogging in the gas supply path 6 (a state where air is sandwiched in the fuel gas in the gas supply path 6) or the like, the burner 5 is prevented from being mistakenly detected as incomplete combustion.

  On the other hand, if it is not determined in STEP 7 that there has been a state in which the rotation speed of the fan 84 is higher than the speed threshold value Nth for 3 minutes or more during the hot water supply operation, the count value CNT of the detection counter 94 is not decreased. Proceed to STEP 9.

  In STEP 9, the hot water supply control unit 91 closes the gas source valve 64, the first capacity switching valve 61a, and the second capacity switching valve 62a, stops the operation of the fan 84, and ends the hot water supply operation.

In this embodiment, in STEP 7 to STEP 8 in FIG. 3, the burner 5 has performed the combustion operation for a predetermined time (3 minutes is illustrated in FIG. 3) or more with the rotational speed of the fan 84 being faster than the speed threshold Nth. In some cases, the process of decreasing the count value of the detection counter 94 by 1 is performed. Even when this process is not performed, the effect of the present invention can be obtained.

  In this embodiment, the flame rod is used as the flame sensor of the present invention, but other types of flame sensors such as a thermocouple may be used.

  DESCRIPTION OF SYMBOLS 1 ... Hot water heater, 3 ... Combustion housing, 5 ... Burner, 5c ... Frame rod, 9 ... Controller, 71 ... Heat exchanger, 84 ... Fan, 91 ... Hot water supply control part, 92 ... Combustion control part, 93 ... Combustion prohibition part 94. Detection counter, 95 ... Incomplete combustion detection unit.

Claims (2)

With a burner,
A heat exchanger that is heated by the burner and heats hot and cold water flowing through the interior;
A fan for supplying combustion air to the burner;
A fuel gas supply unit for supplying fuel gas to the burner;
A combustion control unit that performs a combustion operation of the burner for controlling a rotational speed of the fan and a supply amount of fuel gas by the fuel gas supply unit so that a target combustion amount corresponding to a predetermined hot water supply set temperature is obtained;
A flame sensor for detecting the combustion flame of the burner;
The fan is than wind pressure threshold that assumes the blowing pressure of air from the outside, while operating at a rotational speed towards the supply pressure of the combustion air to the burner is high, before Symbol burner have burned When the detection level of the flame sensor is less than the combustion threshold due to the blowing of wind from the outside, when the detection level of the flame sensor is lower than the combustion threshold, incomplete combustion due to lack of oxygen An incomplete combustion detector that determines that the burner has misfired and detects incomplete combustion of the burner ;
A detection counter that counts and holds the number of times that the incomplete combustion of the burner is detected by the incomplete combustion detection unit;
A combustion prohibiting unit that sets an interlock state in which the combustion control unit prohibits the combustion operation of the burner until a release operation is performed when the count value held in the detection counter becomes equal to or greater than a predetermined value; A water heater provided with />. The water heater according to claim 1 , wherein
The combustion prohibition unit operates when the burner is operated at a rotational speed at which the supply pressure of the combustion air to the burner is higher than the wind pressure threshold, and the incomplete combustion detection is performed. The hot water heater is characterized in that the count value of the detection counter is decreased when the burner has continued for a predetermined time or longer in a state where incomplete combustion of the burner is not detected.

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