JP7523739B2 - Hot water supply equipment - Google Patents

Description

The present invention relates to a combustion-type hot water heater, and in particular to a hot water heater that is configured to detect signs of a failure in the combustion section before it occurs.

Conventionally, there have been known techniques for detecting signs of failure due to deterioration of the combustion part, such as blockage of the flame hole of the combustion part, based on the ignition time required to ignite the combustion part, such as the water heater in Patent Document 1. The usable period (lifespan) of the water heater can be predicted based on the progress of deterioration, which is useful for considering countermeasures such as replacing parts or purchasing a new water heater.

JP 2002-149865 A

However, the ignition time of the combustion section tends to be longer, for example, at low temperatures because the capacity of the ignition device tends to decrease. Also, at the time of ignition, the amount of air blown by the combustion fan is reduced to make it easier to ignite the mixture of fuel gas and air. Therefore, in strong winds, the ignition time is likely to be longer due to the influence of outside air blown into the exhaust port and flowing back. In this way, since the ignition time is easily affected by external disturbance factors, there is a risk of false detection of a malfunction.

The objective of the present invention is to provide a water heater that can prevent false detection of malfunctions in the combustion section and can detect malfunctions before they occur, prompting inspection.

The hot water supply device of the invention of claim 1 includes a combustion section, a combustion fan for supplying combustion air to the combustion section, a heat exchange section, a water supply section, a hot water outlet section, and a control section for controlling a heating operation in which the heat exchange section uses the combustion heat generated in the combustion section to heat hot water supplied from the water supply section and the hot water is discharged from the hot water outlet section. The combustion section is divided into a plurality of combustion areas including an ignition area that is ignited at the start of the heating operation and a flame-transfer area adjacent to the ignition area, and is configured so that the combustion area to be burned is changed according to the required combustion amount. A plurality of flame detection means for detecting a flame are provided corresponding to the plurality of combustion areas including the ignition area and the flame-transfer area, and the control section detects a sign of failure in the combustion section based on the flame-transfer time when the flame is transferred to the flame-transfer area after detecting the flame in the ignition area that was ignited at the start of the heating operation using the corresponding flame detection means.

According to the above configuration, after the ignition area of the combustion unit is ignited and burned during heating operation, the combustion unit failure signs are detected based on the flame spread time when the combustion area expands to the flame spread area adjacent to the ignition area. This makes it possible to prevent erroneous detection of failure signs due to disturbances by avoiding the influence of the ignition device and strong winds.

The water heating device of the invention of claim 2 is characterized in that, in the invention of claim 1, the control unit stores initial data on the fire-spread time when the device was first installed, and detects signs of failure by comparing the current fire-spread time with the initial data.
According to the above configuration, since the failure signs of the combustion unit are detected by comparing with the initial data when the water heater was first installed, it is possible to detect failure signs due to deterioration of the combustion unit over time. Therefore, it is possible to prompt an inspection before the water heater becomes unable to operate due to a failure of the combustion unit.

The water heating apparatus of the invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the control unit stores the flame-catching time at which it is determined that a blockage failure has occurred in the combustion unit as a failure standard value, and if the current flame-catching time exceeds the failure standard value, it determines that a blockage failure has occurred in the combustion unit and alerts the user of the blockage failure in the combustion unit.
According to the above configuration, a blockage failure of the combustion section is judged based on a comparison between the current flame-catching time and a failure reference value for judging the occurrence of a blockage failure in the combustion section. Therefore, it is possible to prevent erroneous judgment of a failure in the combustion section due to disturbance, and to notify the occurrence of a blockage failure in the combustion section when it is judged that a blockage failure has occurred in the combustion section.

The water heater of the present invention can prevent false detection of signs of blockage in the combustion section due to disturbances, and can detect signs of failure before a breakdown occurs and issue an alert to prompt inspection.

1 is an explanatory diagram of a combustion type hot water supply device according to the present invention. 2 is an explanatory diagram of a configuration and communication paths of a control unit of the water heating apparatus; FIG. FIG. 4 is a process explanatory diagram of the heating operation of the water heater. 4 is a flowchart of a combustion unit failure sign detection control according to the embodiment.

The following describes the form for implementing the present invention based on examples.

The combustion-type hot water heater 1 is usually installed outdoors. As shown in FIG. 1, the hot water heater 1 has a combustion section 2, a heat exchange section 3, a water supply section 4, and a hot water outlet section 5, and is configured to perform a heating operation in which the heat of combustion generated in the combustion section 2 is used to heat clean water supplied from the water supply section 4 in the heat exchange section 3, and the clean water is then discharged to the hot water outlet section 5. A fuel supply section 6 for supplying fuel gas (natural gas or propane gas) is connected to the combustion section 2.

A combustion fan 8 is installed near the combustion section 2 to supply combustion air to the combustion section 2 and to send the combustion gas, which is the medium for the combustion heat generated by combustion, to the heat exchange section 3 and exhaust it to the outside from the exhaust port 7. The combustion section 2 is divided into multiple combustion areas, for example, first to fourth combustion areas 2a to 2d, where the fuel gas supplied from the fuel supply section 6 is mixed with the combustion air and burned, and the area in which combustion is performed is changed depending on the amount of combustion required to generate the required amount of heat.

The fuel supply unit 6 has first to fourth gas solenoid valves 6a to 6d corresponding to the first to fourth combustion regions 2a to 2d, and a fuel flow rate adjustment valve 6e that adjusts the fuel flow rate supplied to the combustion unit 2. The fuel supply unit 6 adjusts the fuel flow rate and is configured to be able to individually switch between supplying and stopping fuel gas to the first to fourth combustion regions 2a to 2d.

The heat exchange section 3 has a first fin-and-tube heat exchanger 3a and a second heat exchanger 3b consisting of multiple hot and cold water passages. The first heat exchanger 3a recovers the sensible heat of the high-temperature combustion gas immediately after combustion to heat the hot and cold water. The second heat exchanger 3b recovers the latent heat of the combustion gas (combustion exhaust) whose temperature has been reduced by recovering the sensible heat to heat the drinking water.

In this second heat exchanger 3b, the moisture contained in the combustion gas condenses to produce condensed water. This condensed water contains components of the combustion gas and is highly acidic. Therefore, it is inappropriate to drain it as is, so it is introduced into a neutralization tank 9a that contains, for example, calcium carbonate granules as a neutralizing agent, and is neutralized before being drained. The combustion gas, whose temperature has been reduced by recovering latent heat in the second heat exchanger 3b, is exhausted to the outside through the exhaust port 7.

The neutralization tank 9a is connected to an inlet passage 9b that guides the condensed water that has fallen into the drain pan 3c disposed below the second heat exchanger 3b into the neutralization tank 9a, and a drain passage 9c that drains the neutralized condensed water to the outside of the hot water supply device 1, forming a neutralization section 9. The upper end of the neutralization tank 9a is equipped with a pair of electrodes 9d as a water level detection means for detecting the water level of the condensed water (predetermined water level). A voltage is applied between the pair of electrodes 9d, and when the water level reaches the predetermined level, a current flows between the pair of electrodes 9d through the condensed water, detecting the predetermined water level.

The water supply section 4 has a water supply passage 4a that supplies clean water supplied from a clean water source to the second heat exchanger 3b, and a water supply branch passage 4b that branches off from the water supply passage 4a and is equipped with a flow rate adjustment valve 10. The hot water heated in the second heat exchanger 3b is introduced into the first heat exchanger 3a and is further heated to a high temperature. The hot water heated in the first heat exchanger 3a is supplied to the hot water outlet passage 5a. In the hot water outlet section 5 formed by connecting the water supply branch passage 4b to the hot water outlet passage 5a, the heated hot water and clean water are mixed and the temperature is adjusted, and the hot water is supplied to the hot water supply destination, for example, the hot water tap 11.

The first combustion area 2a of the combustion section 2 is the ignition area that is ignited and burned first when the heating operation starts. At a position corresponding to this first combustion area 2a, an ignition device 14 that generates sparks by discharge and a first flame rod 15a as a flame detection means that detects the flame in the first combustion area 2a to confirm ignition are arranged.

The second combustion area 2b adjacent to the first combustion area 2a is a flame-transfer area that first expands the combustion area from the first combustion area 2a in order to increase the amount of combustion and increase the generation of combustion heat. A second flame rod 15b is disposed in a position corresponding to this second combustion area 2b as a flame detection means for detecting the flame in the second combustion area 2b. By expanding the combustion area to the third and fourth combustion areas 2c and 2d, the amount of combustion can be increased. Note that flame rods corresponding to the third and fourth combustion areas 2c and 2d may be disposed as flame detection means for detecting the flame in the third and fourth combustion areas 2c and 2d.

In the water supply passage 4a, there is disposed a water supply flow rate sensor 4c for detecting the water supply flow rate of clean water supplied to the heat exchange section 3, and a water supply temperature sensor 4d for detecting the water supply temperature. In the hot water outlet passage 5a, there is disposed an outlet water temperature sensor 5b for detecting the outlet temperature of the hot water heated in the heat exchange section 3. Downstream of the connection of the hot water outlet passage 5a with the water supply branch passage 4b, there is disposed a hot water supply temperature sensor 5c for detecting the hot water supply temperature of the hot water that has been mixed with the clean water and has had its temperature adjusted.

The hot water supply device 1 is equipped with a control unit 16 that controls the heating operation to supply hot water at the set hot water supply temperature based on the water supply flow rate, water supply temperature, and hot water outlet temperature. The set hot water supply temperature is set by operating an operation terminal 17 connected to the control unit 16. In the heating operation, the control unit 16 calculates the required combustion amount (required heat amount) based on, for example, the set hot water supply temperature, water supply flow rate, and water supply temperature. Then, in order to generate the required heat amount, the control unit 16 sets the combustion area to be burned in the combustion unit 2, the target rotation speed of the combustion fan 8, and the fuel flow rate of the fuel supply unit 6. The control unit 16 also adjusts the opening of the flow rate adjustment valve 10 so that the hot water supply temperature approaches the set hot water supply temperature, and adjusts the mixing ratio of the clean water and the heated hot water.

As shown in FIG. 2, the control unit 16 has a calculation unit 16a that executes various control programs, a memory unit 16b that stores various control programs, control parameters, etc., and a communication unit 16c. The calculation unit 16a controls the flow rate control valve 10, the valves of the fuel supply unit 6, and the combustion fan 8 via the communication unit 16c, which communicates with the built-in devices of the water heater 1 and the operation terminal 17, and receives detection signals from sensors such as the water supply temperature sensor 4d, and the operation details of the operation terminal 17.

The operation terminal 17 is connected to an external communication network 19 (Internet) via a communication gateway 18 equipped with a home network construction function, for example. A management server 20 installed by a service shop or manufacturer that installs and maintains the water heating apparatus 1 is connected to this communication network 19 in order to manage information about currently installed water heating apparatuses, including the water heating apparatus 1, and other equipment. This enables the control unit 16 to communicate with the management server 20. Note that the communication unit 16c or the operation terminal 17 may be directly connected to the communication network 19.

When the water supply flow rate detected by the water supply flow rate sensor 4c reaches or exceeds a predetermined minimum flow rate due to the start of hot water supply use, heating operation is started. As shown in FIG. 3, heating operation is divided into a pre-purge process, an ignition process, a combustion process, and a post-purge process. In the pre-purge process, the target rotation speed of the combustion fan 8 is set to the scavenging rotation speed (e.g., 3000 rpm), and the combustion fan 8 is driven at the scavenging rotation speed for a predetermined pre-purge time (e.g., 5 seconds). As a result, air remaining in the combustion section 2 and the heat exchange section 3 is exhausted from the exhaust port 7, and the rotation speed of the combustion fan 8, which was stopped, increases to about the scavenging rotation speed.

Then, the process moves to the ignition process, in which the first gas solenoid valve 12a corresponding to the first combustion area 2a (ignition area) is opened, the target rotation speed is set to the ignition rotation speed (e.g., 2500 rpm), and the combustion fan 8 is driven at the ignition rotation speed. Then, the ignition device 14 is driven to ignite the first combustion area 2a. When the flame in the first combustion area 2a is detected (ignition is confirmed) by the first flame rod 15a, the process moves to the combustion process.

Next, in the combustion process, the combustion area in the combustion section 2 to be burned, the target rotation speed of the combustion fan 8, and the fuel flow rate of the fuel supply section 6 are set so that the calculated required heat amount can be supplied. The combustion fan 8 is then driven at the target rotation speed, and the fuel gas solenoid valve corresponding to the combustion area to be burned is opened to supply fuel at the set fuel flow rate, generating the required heat amount and supplying hot water at the hot water supply setting temperature.

When the water supply flow rate falls below a predetermined minimum flow rate due to the end of hot water supply use, the system transitions to the post-purge process. In the post-purge process, all open gas solenoid valves are closed to stop combustion in the combustion section 2, the target rotation speed is set to the scavenging rotation speed, and the combustion fan 8 is driven at the scavenging rotation speed for the post-purge time (e.g., 10 seconds). This exhausts the combustion gas so that it does not remain in the combustion section 2 and the heat exchange section 3. Finally, the combustion fan 8 is stopped, and the heating operation ends.

When the hot water supply device 1 is installed, a trial run is performed to confirm that the hot water supply device 1 operates normally. The control unit 16 stores the heating operation data from this trial run in the memory unit 16b or in the memory area of the management server 20 as initial data at the time of installation.

In heating operation, for example, the number of ignition retries (ignition time) in the ignition process and the flame-transfer time in the combustion process tend to gradually increase due to deterioration over time. Then, for example, when the flame-transfer time reaches a failure reference value stored in the control unit 16 that is determined to be a blockage failure of the combustion unit 2, the control unit 16 prohibits heating operation for safety reasons. The control unit 16 then notifies the user of the failure of the combustion unit 2, for example, via the operation terminal 17, and notifies, for example, a service shop of the failure of the combustion unit 2 via the management server 20. The user or service shop who learns of the failure will arrange for inspection and repair.

Simply notifying the occurrence of a failure in the combustion unit 2 is inconvenient because the water heater 1 cannot be used from the time the failure occurs until inspection and repair are completed. For this reason, the control unit 16 detects signs of failure in the combustion unit 2 before a failure occurs, and notifies the service shop via the management server 20 that a sign of failure has been detected, prompting an inspection. This detection of signs of failure in the combustion unit 2 will be explained based on the flowchart of the combustion unit failure sign detection control by the control unit 16 in Figure 4. In the figure, Si (i = 1, 2, ...) represents a step.

When the heating operation starts, the air that had been trapped in the combustion section 2 and heat exchange section 3 during the pre-purge process is exhausted and fresh air is introduced, and the process moves to the ignition process, in which combustion section failure sign detection control is started. In S1, the ignition operation by the ignition device 14 is started, and the process proceeds to S2.

Next, in S2, it is determined whether or not a flame has been detected in the first combustion area 2a (ignition area). This flame detection is performed by detecting the current flowing through the first flame rod 15a via the flame at predetermined time intervals (e.g., 0.5 seconds). If ignition is successful and a flame can be detected, and the determination in S2 is Yes, the process proceeds to S3. Then, in S3, the ignition operation is terminated, the number of non-ignition detections is reset to zero, and the process proceeds to the combustion process and to S4. The number of non-ignition detections is the number of times a flame was not detected in S2 during this heating operation.

In S4, the rotation speed of the combustion fan 8 is increased so that the amount of combustion can supply the calculated required amount of heat, and the second gas solenoid valve 6b in the second combustion area 2b (flame transfer area) is opened to transfer the flame from the first combustion area 2a to the second combustion area 2b, and the process proceeds to S5. Then, in S5, it is determined whether a flame has been detected in the second combustion area 2b. This flame detection is performed by detecting the current flowing through the second flame rod 15b via the flame at predetermined time intervals (e.g., 0.5 seconds). If the flame transfer is successful and a flame is detected, and the determination in S5 is Yes, the process proceeds to S6. If the determination in S5 is No, the process proceeds to S10.

In S6, the number of times that flame transfer was not detected is reset to zero and the process proceeds to S7. The number of times that flame transfer was not detected is the number of times that a flame was not detected in the second combustion area 2b in S5 during this heating operation.

In S7, the time it takes for the flame to spread from the first combustion area 2a to the second combustion area 2b is obtained, and the process proceeds to S8. The flame spread time is, for example, the time required from opening the second gas solenoid valve 12b after a flame is detected in the first combustion area 2a until a flame is detected in the second combustion area 2b. The flame spread time may be obtained by measuring the time, or may be obtained based on a predetermined time for flame detection and the number of times flame spread is not detected.

In S8, the flame-transfer time acquired in S7 is compared with the flame-transfer time of the initial data stored in the control unit 16 or management server 20 to determine whether the current flame-transfer time exceeds X times (e.g., 7 times) the initial data. If the flame-transfer time increases and the determination in S8 is Yes, proceed to S9. Then, in S9, it is notified that a failure sign in the combustion unit 2 has been detected, and the combustion unit failure sign notification control is terminated while continuing the heating operation. If the determination in S8 is No, it is determined that a failure sign in the combustion unit 2 has not been detected, and the combustion unit failure sign notification control is terminated while continuing the heating operation.

If the determination in S5 is No, in S10, the number of non-detected flame transfers is incremented by 1 and the process proceeds to S11, where it is determined whether the number of non-detected flame transfers has exceeded the reference number of non-detected flame transfers. If the failure reference value for determining that a blockage failure has occurred in the combustion section 2 is set to, for example, 5 seconds, the reference number of non-detected flame transfers is set to 10 times, and if the fire transfer time exceeds the failure reference value based on the specified flame detection time and the number of non-detected flame transfers, it is determined that a blockage failure has occurred in the combustion section 2. The determination can also be made based on the measured fire transfer time and the failure reference value.

If the determination in S11 is No, the process returns to S5. If the determination in S11 is Yes, the process proceeds to S12, where a notification is issued that a failure has occurred in the combustion unit 2, and the process transitions to the post-purge process to end the heating operation, and the combustion unit failure prediction control is terminated.

On the other hand, if no flame is confirmed in the first combustion region 2a during the ignition process and the determination in S2 is No, the process proceeds to S13, where the number of ignition non-detection occurrences is incremented by 1 and the process proceeds to S14. Then, in S14, it is determined whether the number of ignition non-detection occurrences has exceeded the reference number of ignition non-detection occurrences. The reference number of ignition non-detection occurrences is preset to, for example, 10 times.

If the determination in S14 is No, the process returns to S2. If the determination in S14 is Yes, the process proceeds to S15, where a failure of the ignition device 14 and the occurrence of a blockage failure in the combustion section 2 are notified, and the process transitions to the post-purge process to end the heating operation, and the combustion section failure sign detection control is terminated. Since it is unclear whether the cause of the ignition malfunction is in the ignition device 14 or the combustion section 2, the cause will be identified during inspection and repaired.

The operation and effects of the hot water supply device 1 will now be described.
Control unit 16 of water heater 1 detects a malfunction of combustion unit 2 based on a flame-transfer time when the combustion area expands to second combustion area 2b (flame-transfer area) adjacent to first combustion area 2a after igniting and burning first combustion area 2a (ignition area) of combustion unit 2 during heating operation. This prevents the influence of ignition device 14 and strong winds, and prevents erroneous detection of a malfunction caused by disturbances.

In addition, because signs of failure in the combustion unit 2 are detected by comparing with the initial data when the hot water heater 1 was first installed, signs of failure due to deterioration of the combustion unit 2 over time can be detected. Therefore, inspection can be encouraged before a failure in the combustion unit 2 makes it impossible to operate the hot water heater 1.

The determination of a blockage failure in the combustion section 2 is made based on a comparison between the current flame-catching time and the failure reference value at which a blockage failure in the combustion section 2 is determined to have occurred. This prevents erroneous determination of a blockage failure in the combustion section 2 caused by disturbances, and can notify the occurrence of a blockage failure in the combustion section 2 for safety reasons if it is determined that a blockage failure has occurred in the combustion section 2.

For example, if the increase in the flame transfer time is caused by the gradual accumulation of soot in the flame hole of the combustion section 2, causing it to become clogged, the more soot accumulates and the smaller the opening diameter of the flame hole becomes, the faster this opening diameter becomes smaller, and the greater the rate of increase in the flame transfer time. Therefore, for example, by comparing the previous and current flame transfer times, it is possible to detect signs of a malfunction based on the rate of increase in the flame transfer time.

In addition, those skilled in the art can implement the above-described embodiments in various modified forms without departing from the spirit of the present invention, and the present invention includes such modified forms.

1: Water heater 2: Combustion section 2a: First combustion region (ignition region)
2b: Secondary combustion zone (fire-transfer zone)
2c : third combustion region 2d : fourth combustion region 3 : heat exchange section 3a : first heat exchanger 3b : second heat exchanger 4 : water supply section 4a : water supply passage 4b : water supply branch passage 4c : water supply flow rate sensor 4d : water supply temperature sensor 5 : hot water outlet section 5a : hot water outlet passage 5b : hot water outlet temperature sensor 5c : hot water temperature sensor 6 : fuel supply passage 7 : exhaust port 8 : combustion fan 9 : neutralizer 10 : flow rate adjustment valve 11 : hot water taps 12a to 12d : first to fourth gas solenoid valves 14 : ignition device 15a : first frame rod 15b : second frame rod 16 : control section 16a : calculation section 16b : memory section 16c : communication section 17 : operation terminal 18 : communication gateway 19 : communication network 20 : management server

Claims (3)

A hot water supply device including a combustion section, a combustion fan for supplying combustion air to the combustion section, a heat exchange section, a water supply section, a hot water outlet section, and a control section for controlling a heating operation in which hot water supplied from the water supply section is heated by the heat exchange section that utilizes combustion heat generated in the combustion section, and the hot water is then discharged from the hot water outlet section,
The combustion section is divided into a plurality of combustion regions including an ignition region that is ignited at the start of the heating operation and a flame-transfer region adjacent to the ignition region, and is configured so that the combustion region to be burned is changed according to the required combustion amount,
A plurality of flame detection means for detecting a flame are provided corresponding to a plurality of combustion regions including the ignition region and the flame spread region,
The hot water supply device is characterized in that the control unit detects the flame in the ignition area that was ignited at the start of the heating operation using the corresponding flame detection means, and then detects signs of failure in the combustion unit based on the flame spread time when the flame spreads to the flame spread area. The hot water supply device according to claim 1, characterized in that the control unit stores initial data on the time it takes for the heat to spread when the device was first installed, and detects the signs of failure by comparing the current time it takes for the heat to spread with the initial data. The hot water supply device according to claim 1, characterized in that the control unit stores the flame-transfer time at which the combustion unit is judged to have a blockage failure as a failure reference value, and when the current flame-transfer time exceeds the failure reference value, it determines that a blockage failure has occurred in the combustion unit and notifies the user of the blockage failure of the combustion unit.