JP6924405B2 - Combustion device and hot water supply device equipped with it - Google Patents

Description

The present invention relates to a type of combustion device provided with a CO sensor, and a hot water supply device provided with the same.

The applicant has previously proposed the one described in Patent Document 1 as an example of a hot water supply device provided with a combustion device.
The hot water supply device described in the same document is capable of heating hot water by using a heat exchanger to recover heat from the combustion gas generated by the combustion device to generate hot water for hot water supply. A CO sensor is provided in the exhaust path of the combustion gas so that combustion defects such as incomplete combustion can be detected. When contaminants adhere to the surface of this CO sensor, an error occurs in the sensor output. Therefore, during the period when the combustion device is not driven, heat cleaning is performed intermittently (the CO sensor is heated up and the CO sensor becomes dirty. Is removed), and immediately after that, a process for correcting the zero point of the sensor output (zero point correction process) is performed.

On the other hand, in order to accurately perform the zero point correction process of the CO sensor, it is necessary to perform it in an atmosphere where CO does not exist. Therefore, in Patent Document 1, the exhaust gas is purged by blowing air from the fan toward the exhaust path of the combustion gas prior to the heat cleaning and the zero point correction process. Further, the exhaust gas purge amount at that time is changed according to the predicted time from when the drive of the combustion device is turned off until the next zero point correction process is started.
According to such a configuration, there is an advantage that the exhaust gas purge amount is insufficient or the exhaust gas purge is not excessively executed depending on the time when the drive of the combustion device is turned off.

However, in the above-mentioned prior art, there is still room for improvement as described below.

That is, when the fan is driven to execute the exhaust gas purge, the exhaust gas purge amount is not always constant even if the fan is driven at a constant speed and time. For example, when the exhaust port at the end of the exhaust path is located outdoors, wind may blow into the exhaust path from this exhaust port, but in such a case, the exhaust gas purge amount is reduced. In addition, the exhaust gas may be blocked at the location where the heat exchanger is arranged, but even in such a case, the exhaust gas purge amount is reduced. Under such circumstances, if a certain exhaust gas purge is completed and the zero point correction process is performed, there is a strong possibility that the zero point correction process will be performed in a situation where CO still remains in the exhaust path. May not be performed accurately and appropriately.
In Patent Document 1, the exhaust gas purge amount is changed according to the predicted time from when the drive of the combustion device is turned off until the next zero point correction process is started. However, in such control, the exhaust gas purge amount is changed. It is difficult to properly resolve the problems that have occurred.

Japanese Unexamined Patent Publication No. 2015-25600

The present invention has been conceived under the above-mentioned circumstances, and even when the exhaust resistance becomes large due to the blowing of wind into the exhaust path or the like, appropriate measures should be taken. It is an object of the present invention to provide a combustion device capable of appropriately performing zero point correction processing of a CO sensor and a hot water supply device equipped with the combustion device.

In order to solve the above problems, the following technical measures are taken in the present invention.

The combustion apparatus provided by the first aspect of the present invention is a burner, a CO sensor arranged in an exhaust path of the exhaust gas generated by the burner, and a zero point correction process of the CO sensor of the burner. It is possible to perform the exhaust gas purging of the exhaust gas path by blowing air toward the exhaust path prior to the zero point correction process and the control unit that is intermittently executed during the drive stop period, and for the fan. A combustion device including a fan driven by a motor, wherein the control unit can monitor motor output-corresponding data whose value changes in response to the output of the fan motor, and the control unit can monitor the motor output-corresponding data. When the output of the fan motor at the time of executing the exhaust gas purge does not meet the predetermined first criterion, and the motor output corresponding data is within the predetermined first range, the output of the fan motor is the said. The fan is configured to drive the fan under a condition that the amount of exhaust gas purge is larger than that when the exhaust gas purge amount is equal to or higher than the first reference . When the motor output corresponding data is within the predetermined second range due to the fact that the predetermined second criterion lower than the first criterion is not satisfied, the zero point correction process following the exhaust gas purge is not executed. It is characterized in that it is configured in this way.

According to such a configuration, the following effects can be obtained.
That is, when the exhaust gas blows into the exhaust path of the combustion gas, or when the exhaust resistance becomes large, such as when the exhaust path tends to be blocked, the amount of air blown from the fan to the exhaust path decreases. Originally, the exhaust gas purging of the exhaust path tends to be inadequate. When such a situation occurs, the work load per unit time of the fan is decreasing, and the output of the fan motor becomes low and falls below the first standard. As a result, the motor output corresponding data is predetermined. It is within the first range. When such a situation occurs, the fan is driven under the condition that the exhaust gas purge amount is larger than the original exhaust gas purge amount. Therefore, the exhaust gas purging is promoted, and it is appropriately avoided that the exhaust gas purging becomes insufficient. As a result, even if the exhaust resistance increases a little due to the blowing of wind into the exhaust path, the zero point is reached when there is no or almost no CO-containing exhaust gas in the exhaust path. The correction process can be performed appropriately.
On the other hand, the reason why the fan is driven under the condition that the exhaust gas purge amount is larger than the original exhaust gas purge amount is that the motor output corresponding data is within the predetermined first range due to the blowing of wind into the exhaust path or the like. Since it is limited to the case where the exhaust gas is purged excessively, waste such as excessive exhaust gas purging is appropriately avoided.
Further, according to such a configuration, for example, when a relatively strong wind continues to blow into the exhaust path, the exhaust gas purge of the exhaust path is hardly performed. When such a situation occurs, the amount of work per unit time of the fan is considerably reduced, and the output of the fan motor is greatly reduced. As a result, the motor output corresponding data is within a predetermined second range. In such a case, there is a possibility that sufficient improvement cannot be achieved simply by adopting a means such as extending the exhaust gas purging time to some extent. On the other hand, in the above situation, the control unit does not execute the subsequent zero point correction process, so that the zero point correction process is wastefully or improperly executed in a situation where the exhaust gas purge is not enabled. Is properly avoided.

In the present invention, preferably, the conditions for increasing the exhaust gas purge amount are that the exhaust gas purging time is longer than when the output of the fan motor is equal to or higher than the first reference. At least one of increasing the rotation speed of the fan.

According to such a configuration, it is possible to easily and accurately increase the amount of exhaust gas purge.

In the present invention, preferably, when the motor output corresponding data is within the second range, the control unit performs the exhaust gas purge again and the subsequent zero after a predetermined standby time elapses. It is configured to perform control that attempts point correction processing.

According to such a configuration, the following effects can be obtained.
That is, even if an abnormal situation occurs in which the exhaust gas purging of the exhaust path is not sufficiently performed, the abnormal situation may be resolved when an appropriate time elapses thereafter. For example, this is the case when the blowing of strong wind into the exhaust path is stopped. According to the above configuration, in such a case, the zero point correction process is appropriately executed, which is preferable for surely executing the zero point correction process at an appropriate frequency.

In the present invention, preferably, the value of the drive current or the drive voltage of the fan motor is used as the data corresponding to the motor output.

According to such a configuration, the output of the fan motor can be accurately and easily grasped, and the accuracy of control intended by the present invention can be improved and facilitated.

The hot water supply device provided by the second aspect of the present invention is a heat exchange for heating hot water that recovers heat from the combustion device provided by the first aspect of the present invention and the combustion gas generated by the combustion device. It is characterized by having a vessel.

With such a configuration, the same effect as described for the combustion apparatus provided by the first aspect of the present invention can be obtained.

Other features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings.

It is a schematic explanatory drawing which shows an example of the hot water supply apparatus which concerns on this invention. It is explanatory drawing of the numerical value used in the operation processing executed by the hot water supply apparatus of FIG. It is a flowchart which shows an example of the operation processing procedure executed by the hot water supply apparatus of FIG.

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

The hot water supply device WH shown in FIG. 1 is a combination of a combustion device C and a heat exchanger 1, and further includes a CO sensor Sa and a control unit 2 for controlling the operation of each unit.
The elements constituting the combustion device C include a burner 3 for burning fuel gas, a fan 4 for supplying combustion air to the burner 3, and a fan motor M for driving the burner 3. .. The heat exchanger 1 is provided with, for example, a tube with fins through which hot water flows, and heats the hot water by recovering heat from the combustion gas generated by the burner 3 to generate hot water for hot water supply. It is possible.

The CO sensor Sa is for detecting the CO concentration of the combustion gas (exhaust gas) that has completed heat recovery by the heat exchanger 1, and is provided in the exhaust path of the combustion gas. As the CO sensor Sa, a conventionally known one can be used. For example, a platinum wire coil coated with a catalyst such as aluminum oxide and dried / fired is used. When CO is present in the exhaust gas, the resistance value of the platinum wire coil increases due to the heat of reaction with this CO. Based on this principle, the CO concentration can be detected by the control unit 2.

When contaminants adhere to the surface of the CO sensor Sa, the sensor output value deviates (drifts) from the original appropriate output value. In order to solve this problem, the control unit 2 includes a zero point correction processing control unit 2a for performing heat cleaning of the CO sensor Sa and zero point correction processing. The heat cleaning is a process of removing the pollutant by passing a larger current than usual to the CO sensor Sa to generate heat. The zero point correction process is a process for eliminating the deviation of the sensor output value from the CO sensor Sa.

The control unit 2 is configured by combining a microcomputer and various electric / electronic circuits, and is a drive current detection unit 2b that detects the drive current of the fan motor M, and a motor control that controls the drive of the fan motor M. A part 2c is further provided. The zero point correction process of the CO sensor Sa is executed in a fixed cycle in principle under the condition that the burner 3 is not driven and burned, but before the zero point correction process is executed, the fan 4 is driven. Then, by blowing air into the exhaust path, exhaust gas purging is executed to discharge the combustion exhaust gas remaining in the exhaust path to the outside. When performing such exhaust gas purging, the control unit 2 is configured to perform control as described later based on the drive current of the fan motor M.

Next, the operation of the hot water supply device WH and an example of the operation processing procedure will be described with reference to the explanatory diagram shown in FIG. 2 and the flowchart of FIG.

First, in the present embodiment, the control unit 2 determines whether or not the exhaust gas purging of the exhaust path, which is executed prior to the zero point correction process of the CO sensor Sa, is normally performed. Determines the range in which the output of the fan motor M is compared with the predetermined first and second criteria. However, in the present embodiment, the drive current of the fan motor M is used as the motor output corresponding data for easily grasping the output of the fan motor M. As shown in FIG. 2, the first and second threshold values TH1 and TH2 are used as the values corresponding to the first and second criteria, and the following determination is made.

That is, in FIG. 2, when the drive current of the fan motor M at the time of executing the exhaust gas purge is in the range of the first threshold value TH1 or more, it is determined that the exhaust gas purge is normal. On the other hand, in the first range between the first threshold value TH1 and the second threshold value TH2, it is said that the exhaust gas purge is a slight abnormality. In the second range below the second threshold TH2, the exhaust gas purge is considered to be a severe anomaly.

Next, a specific operation processing procedure for performing the zero point correction processing of the CO sensor Sa will be described.
First, when the burner 3 is stopped for driving combustion and Ta elapses for a predetermined time from the previous zero point correction process, the control unit 2 sets the fan 4 when the scheduled execution time of the zero point correction process arrives. It is driven by Tb for a certain period of time to execute exhaust gas purging of the exhaust path (S1: YE).
S, S2: YES, S3). When the drive current I of the fan motor M is in the relationship of TH1 ≦ I at the time of executing this exhaust gas purge and is within the normal range of FIG. 2 (S4; YES), after that, basically, Normal operation processing is executed toward the zero point correction processing. That is, after the exhaust gas purging is completed, the heat cleaning of the CO sensor Sa is started, and when the heat cleaning is completed without interruption of the drive combustion of the burner 3, the zero point correction process is started (S5, S6: YES, S7: YES, S8). If there is no interrupt in the drive combustion of the burner 3 during the execution of this zero point correction process, the zero point correction process ends as it is (S9: YES, S10: YES), but when there is an interrupt, the zero point correction process is performed. It is canceled (S9: NO, S11).

Unlike the above, when the drive current I of the fan motor M has a relationship of TH2 ≦ I <TH1 and is in the first range of FIG. 2, the control unit 2 extends the exhaust gas purging time by a predetermined time Tc. (S12: YES, S13). For example, when a phenomenon such as wind blowing into the exhaust path occurs, the amount of air blown from the fan 4 to the exhaust path decreases, and the drive current I slightly falls below the first threshold value TH1 and falls within the first range described above. (Mild abnormality) may occur. In this case, there is a possibility that the exhaust gas purge amount in the exhaust path may be insufficient. However, according to the present embodiment, since the exhaust gas purge time is extended, it is possible to prevent the exhaust gas purge amount from being insufficient. Is. The time Tc does not have to be constant, and may be changed according to the drive current I, for example, the smaller the drive current I is, the longer the time Tc is.

In the present invention, instead of or in addition to the extension of the exhaust gas purging time described above, the rotation speed of the fan 4 may be controlled to be faster than the original rotation speed. If the rotation speed of the fan 4 is increased, it is possible to prevent the exhaust gas purge amount from becoming insufficient.

Unlike the above case, when the drive current I of the fan motor M has a relationship of I <TH2 and is in the second range of FIG. 2, the control unit 2 prepares for the subsequent zero point correction process. (S12: NO, S14). For example, if strong wind continues to blow into the exhaust path, or if the exhaust path is slightly blocked, the amount of air blown from the fan 4 to the exhaust path is considerably reduced, and the drive current is reduced. I may fall below the second threshold TH2 and fall within the above-mentioned second range (severe abnormality). In this case, even if the exhaust gas purging time is extended, it is unlikely that an appropriate exhaust gas purging will be performed. In such an operation process, the zero point correction process is stopped in such a case, so that the zero point correction process may be unnecessarily or improperly executed in a situation where the exhaust gas purge is not properly performed. Properly avoided.

After the above-mentioned zero point correction process is canceled, the start of the zero point correction process is waited for a predetermined waiting time Td from the time when the decision to cancel is made, and when the waiting time Td elapses, the zero point is reached. The process proceeds to the initial step for starting the correction process (S15, S1). Even if it is determined that the abnormality is severe at the time of executing the exhaust gas purge, such an abnormal state may be resolved during the predetermined standby time Td. For example, the case where the blowing of strong wind into the exhaust path stops. According to the operation process described above, in such a case, the zero point correction process and the predetermined process prior to the zero point correction process can be appropriately restarted.

In FIG. 3, steps S16 to S19 show a procedure when an interrupt of the drive combustion of the burner 3 occurs during heat cleaning of the CO sensor Sa. These series of procedures are the same as those in steps S3, S4, S12, and S13 described above, and when there is a risk that the exhaust gas purge is insufficient, the exhaust gas purge time can be extended so that the exhaust gas purge is not insufficient. The same effect as described above can be obtained.

The present invention is not limited to the contents of the above-described embodiments. The specific configuration of each part of the combustion device and the hot water supply device according to the present invention can be variously redesigned within the scope intended by the present invention.

In the above-described embodiment, the drive current of the fan motor is used as the "motor output corresponding data" in the present invention, but the present invention is not limited to this, and other parameters can also be used. As a specific example, it is also possible to use the drive voltage of the fan motor. That is, the drive voltage of the fan motor decreases as the fan load increases. On the contrary, as the load on the fan decreases, the voltage increases. Therefore, it is possible to set such a voltage as a parameter corresponding to the motor output and determine whether or not the exhaust gas purging is properly performed based on this voltage. The "motor output compatible data" referred to in the present invention may be any data whose value changes according to the output of the fan motor, and may be the value of the motor output (electric power) itself.

The types of fans and fan motors are not limited. The CO sensor may be any as long as it can output a sensor corresponding to the CO concentration, and its specific configuration does not matter. As the burner, for example, an oil burner can be used instead of the gas burner. The combustion device according to the present invention does not necessarily have to be for a hot water supply device, and may be configured as a combustion device for, for example, a heating device or an incinerator.

C Combustion device WH Hot water supply device Sa CO sensor M Fan motor 1 Heat exchanger 2 Control unit 3 Burner 4 Fan

Claims (5)

With a burner
The CO sensor located in the exhaust path of the combustion gas generated by this burner,
A control unit that intermittently executes the zero point correction process of the CO sensor during the drive stop period of the burner, and a control unit.
Prior to the zero point correction process, air is blown toward the exhaust path to purge the exhaust gas in the exhaust path, and the fan is driven by a fan motor.
It is a combustion device equipped with
The control unit can monitor the motor output-corresponding data whose value changes according to the output of the fan motor, and can also monitor the motor output-corresponding data.
When the output of the fan motor at the time of executing the exhaust gas purge does not meet the predetermined first criterion, and the motor output corresponding data is within the predetermined first range, the output of the fan motor is increased. It is configured to drive the fan under the condition that the exhaust gas purge amount is larger than that when the value is equal to or higher than the first standard .
In the control unit, the output of the fan motor at the time of executing the exhaust gas purge does not meet a predetermined second reference lower than the first reference, so that the motor output corresponding data is a predetermined second reference. The combustion apparatus is configured so as not to execute the zero point correction process following the exhaust gas purge when it is within the range of. The combustion apparatus according to claim 1.
The conditions for increasing the exhaust gas purge amount are that the exhaust gas purging time is longer and the rotation speed of the fan is increased as compared with the case where the output of the fan motor is equal to or higher than the first reference. At least one of the combustion devices. The combustion apparatus according to claim 1 or 2.
When the motor output corresponding data is within the second range, the control unit controls to try the exhaust gas purge again and the subsequent zero point correction process after a predetermined standby time has elapsed. A combustion device that is configured to run. The combustion apparatus according to any one of claims 1 to 3.
A combustion device in which a value of a drive current or a drive voltage of the fan motor is used as the data corresponding to the motor output. The combustion apparatus according to any one of claims 1 to 4,
A heat exchanger for heating hot water that recovers heat from the combustion gas generated by this combustion device,
A hot water supply device characterized by being equipped with.

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