JP2860926B2 - Exhaust system abnormality detection method and apparatus for combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting an abnormality which may occur in an exhaust system of a combustion apparatus such as an automatic water heater which performs combustion while forcibly supplying air to a combustion section by a fan motor. About.

[0002]

2. Description of the Related Art Conventionally, in a combustion apparatus for forcibly supplying air to a combustion section, the number of revolutions of a fan motor is controlled by controlling the number of revolutions of a fan motor in accordance with a combustion amount required at each time in the combustion section. In general, a microcomputer is used to stabilize a desired amount (hereinafter simply referred to as a microcomputer; the same applies to the notation in the attached drawings).
The fan motor is feedback-controlled by a main control circuit including the above. However, even if the supply amount is controlled appropriately, if an abnormality occurs in the exhaust system,
In some cases, serious dangers such as incomplete combustion may occur.To deal with this, install an oxygen monoxide sensor in the exhaust pipe, or provide a ventilation sensor, etc. We are trying to detect abnormalities.

[0003]

However, such sensors are not completely free from the possibility of failure. If it breaks down, unless other fail-safe mechanisms are substantial,
Serious accidents can occur. The present invention has basically been made in view of this point. Instead of, or in addition to, a safety measure using such a sensor, in order to further ensure safety, an abnormality in the exhaust system is performed according to a new principle. To provide a method and apparatus capable of detecting the

[0004]

According to the present invention, in order to achieve the above object, first, a feedback control circuit for a fan motor is required to satisfy a fan motor set rotation speed in a state where the exhaust system can be regarded as normal. (Including extraction from the circuit), and store this in the storage means as a set feedback amount.
In actual operation, a method is proposed in which the current feedback amount used by the feedback control circuit at each time is compared with the set feedback amount stored in the storage means, and if the difference exceeds an allowable range, it is determined that the exhaust system is abnormal. I do.

On the other hand, in a second aspect of the present invention, in the above configuration, the feedback amount required by the feedback control circuit when the fan motor is rotated at the set rotation speed is stored as the set feedback amount. However, instead of this, a pair of feedback amounts required by the feedback control circuit when obtaining the upper and lower limit rotational speeds in the allowable range for the set rotational speed are obtained, and these are stored in the storage means as a pair of set feedback amounts. In addition, a method of determining that the exhaust system is abnormal when the current feedback amount used by the feedback control circuit from time to time in actual operation does not fall between the pair of set feedback amounts is also proposed.

Further, the present invention can be embodied as an apparatus. That is, a fan motor that supplies air to the combustion unit, an exhaust system that exhausts air from the combustion unit, and a fan motor rotation speed that is required according to the amount of combustion at each time are calculated and set as the rotation speed. As an improvement in the combustion equipment having a feedback control circuit for performing feedback control of the fan motor to satisfy the rotation speed, the above-described feedback control circuit is required to satisfy the fan motor setting rotation speed when the exhaust system can be regarded as normal. Storage means for storing the feedback amount as the set feedback amount, a comparison circuit for comparing the current feedback amount used by the fan motor feedback control circuit with the set feedback amount at each time under actual operation, and a comparison circuit for comparing the current feedback amount with the set feedback amount. As a result, the difference between the current feedback amount and the set feedback amount If the value exceeds capacity range, newly added and a determination circuit that the exhaust system is determined to be abnormal.

In the case of the present invention as such a device patent, the same alternative configuration as in the above-mentioned method patent is also possible, and the storage means obtains the upper and lower limit rotation speeds in the allowable range for the fan motor set rotation speed. When a pair of feedback amounts required by the feedback control circuit are stored as a pair of set feedback amounts, the current feedback amount used by the feedback control circuit at each time under actual operation is between the pair of set feedback amounts. It is also possible to propose a configuration in which a comparison circuit compares whether or not the exhaust gas is included, and if not, the determination circuit determines that the exhaust system is abnormal.

In addition to satisfying the above basic configuration, the present invention further provides a subordinate configuration in which, when an abnormality is determined or when the determination circuit determines an abnormality, a light emitting diode or other visual display means, a speaker or the like is used. Also proposed is a configuration for driving an alarm device by an audible notification means or the like, and a configuration for forcibly reducing the fuel supply amount control valve to reduce the combustion amount.

In addition, if the combustion equipment to be improved according to the present invention is a water heater in which the amount of combustion increases as the flow rate of hot water increases, and the amount of combustion decreases as the flow rate of hot water decreases, an abnormality in the exhaust system A configuration is also proposed in which the hot water supply flow rate is forcibly limited in accordance with the determination, and as a result, the combustion amount is reduced.

[0010]

FIG. 1 schematically shows the structure of a main part of an embodiment of an exhaust system abnormality detecting device for a combustion apparatus constructed according to the present invention. As shown schematically in FIG. 3 to be described later, the combustion equipment assumed in this embodiment heats water supplied from water supply or the like by a heat exchanger 22 included in a combustion unit. It is a water heater for supplying hot water to a bathtub or a hot water supply port, and its basic function may be the same as that of an existing automatic water heater of this kind. For example, in this type of hot water heater, it is no longer a very common function, but as the hot water flow increases, the combustion amount in the combustion section also increases, and when the hot water flow decreases, the combustion amount also decreases. The supplied hot water should be kept at a set temperature as much as possible, or at least prevented from becoming undesirably low or high. As discussed below, this can be used to advantage in certain aspects of the invention.

However, in the various types of combustion equipment such as the hot water heater shown in the drawings, the combustion in the combustion section is intended to be as complete as possible, or in order to improve the efficiency, the combustion section is forcibly forced on the combustion section from time to time. The amount of air corresponding to the combustion amount is supplied by a fan motor, and the fan motor is closed-loop controlled (feedback control) by a feedback control circuit in order to stabilize the supply amount. This is the same in the present invention.

That is, in the embodiment of the present invention shown in FIG. 1, the feedback control circuit 26 for the fan motor 14 is also provided.
Is provided. This feedback control circuit 26
As such, it is only necessary to perform the same function as in a known existing type of combustion equipment.For example, the air supply amount is calculated and determined according to the amount of combustion required for the combustion unit at each time, and the determined air supply amount is determined. First, the fan motor rotation speed for obtaining the air supply amount is determined and set as the set rotation speed so that the amount of electricity corresponding to the set rotation speed (in the case of an analog case, Is supplied to the drive circuit 13 to rotate the fan motor 14 with the set rotation speed as a target value.

On the other hand, the fan motor 14 also has a sensor 15 for detecting the actual rotational speed at that time, and the actual rotational speed information obtained by a rotational speed detecting circuit 16 for processing a signal from the sensor 15 is: The signal is fed back to the feedback control circuit 26. The feedback control circuit 26 receiving this calculates a feedback amount β _{A such} that β _A = Σα (set rotation speed−actual rotation speed), for example, as a constant that can determine α in design, and calculates an electric amount taking this into account. The rotation of the fan motor 14 is controlled so as to eliminate the difference between the set rotation speed and the actual rotation speed by providing the rotation to the drive circuit 13.

However, in this manner, the fan motor 14
Even if feedback control is performed to stably maintain the set number of revolutions, if an abnormality occurs in the exhaust system from the combustion unit, for example, a crack may occur in the exhaust port or the exhaust pipe leading to the exhaust port,
Conversely, clogging cannot guarantee normal combustion. In particular, in the case of clogging of the exhaust system, it is likely to directly lead to incomplete combustion, which is dangerous. Therefore, in the present embodiment, abnormality of the exhaust system is determined by the following method and circuit configuration according to the present invention.

As shown in FIGS. 3A and 3B, there are basically two types of water heaters of this type, one for indoor installation and one for outdoor installation. FIG. 2A shows a model for indoor installation. In this case, an exhaust system mechanically connected to the water heater main body 21, that is, an exhaust pipe 23 and an exhaust port 22 are appropriately provided for each house 30. As a result, the length, cross-sectional area, shape, and the like are various. In other words, on the water heater manufacturer's side, until the water heater is actually installed, various information regarding the exhaust system cannot be known in advance, and even under normal conditions without cracks or clogging in the exhaust system. , Fan motor 14
It is unknown how much load will be applied to. On the other hand, as shown in FIG. 3 (B), in the case of a model in which the water heater main body 21 is installed outdoors, the exhaust system is provided with a fixed exhaust port 25.
As shown in the figure, since the water heater main body 21 can be provided in advance, naturally, the dimensions or capacity thereof is known to the water heater maker's side even before the installation of the water heater main body 21, and the fan It is possible to know in advance how much the load of the motor 14 is. Rather, in the case of the model shown in FIG. 3B, the exhaust system or the fan motor load is not changed depending on the house 30 installed.

Therefore, in the case of FIG. 3 (A), after the water heater main body 21 is installed in each house 30, before the water heater is used for the user, the exhaust system including the exhaust pipe 23 and the exhaust port 24 is provided. When it is recognized that cracks and clogging have not occurred (when the exhaust system can be regarded as normal), it is necessary to perform a test operation and make the following initial settings. In the case of FIG. The following initial setting operations can be performed at a stage before product shipment or, in some cases, at a product development stage.

First, in the case of a model whose exhaust system cannot be uniquely predicted, as in the model of FIG.
By operating the setting operation unit 12 incorporated in the
Set the mode to write the set feedback amount for 11. On the other hand, as shown in FIG. 3B, in the case of a model in which the exhaust system does not change, it is not necessary to incorporate it into the water heater main body 21 or its control circuit.
The setting operation unit 12 may be operated as long as it is a means that can instruct the storage unit 11 to write data. In the illustrated case, the storage unit 11 is at least an electrically writable nonvolatile memory 11.

In any case, when the test operation of the water heater is started in the set feedback amount writing mode, the exhaust system can be regarded as normal here as described above. The above feedback amount β _A required by the feedback control circuit 26 to maintain the number is typically shown by a curve in FIG. 2 when exemplarily showing the elapsed time from the start of combustion. In other words, the fan motor 14 starts to rotate according to the combustion start command and rises rapidly until it approaches the set number of revolutions,
After the start of combustion, the combustion is stabilized, and when the fan motor rotation speed substantially matches the set rotation speed, thereafter, the value becomes substantially constant at a certain value β unless an abnormality occurs in the exhaust system. Thus, at the stage where the combustion is stabilized in this way, the current feedback amount β _A = β used by the feedback control circuit 26 to maintain the fan motor set rotation speed at this time is extracted, and the setting operation shown in FIG. The extracted current feedback amount β _A = β is set to the set feedback amount β (FIGS. 1 and 2).
To the nonvolatile memory.

This operation is repeated at a desired resolution over the entire dynamic range of the rotation speed of the fan motor, and all the data groups obtained thereby are stored in the nonvolatile memory 11.
It is desirable to store in. For example, to extract the rotation if the fan motor 14 to be used to the maximum 4000rpm from a minimum 2000 rpm, a suitable resolution, for example, the current feedback amount beta _A sample point of all 21 points with 100rpm resolution, setting all of them Non-volatile memory as feedback amount β
Write it to 11.

Since the initial writing operation is completed in this manner, when the above-mentioned operation is performed after the device is installed, the setting feedback amount writing mode by the setting operation unit 12 is released, and a state in which the device is ready for actual operation is provided. Before product shipment,
Or if you have made the above initial settings during the development phase,
The nonvolatile memory in which the necessary data is written in such a manner may be incorporated in the control circuit. Therefore, at least the electrically rewritable nonvolatile memory 11 can be electrically rewritable in the former case.
It is preferable to use a ROM, whereas in the latter case, it is not always necessary to use a
OM is sufficient. Although not shown,
When the current feedback amount β _A is extracted as an analog amount, an A / D converter or the like is required in the middle of the data input path to the nonvolatile memory 11, and the comparison in the comparison circuit 27 described later is also an analog comparison. Requires a D / A converter or the like in a data read line from the nonvolatile memory 11, and such a data write operation itself and a data read operation described later are performed by a known existing type. The technique may be followed, and detailed description and illustration are omitted.

After the initial setting operation is completed as described above, the following operation is performed according to the present invention in the water heater that has been put into practical use. First, after the start of combustion, when the combustion is stabilized, thereafter, the feedback control circuit is continuously or with an appropriate time resolution (for example, every few seconds).
26, then the feedback control circuit
The comparison circuit 27 compares the current feedback amount β _A required by the controller 26 with the set feedback amount β written by the above-described initial setting operation corresponding to the set fan motor rotation speed at that time.

However, referring to FIG. 2 again, two curves other than the normal case are also shown.
If, for example, a crack is formed in the exhaust system after the installation of the equipment, the load on the fan motor 14 is effectively increased (because the amount of air to be blown is increased). The feedback amount β _A required by the feedback control circuit 26 is smaller than that in a normal case.
growing. Conversely, if the exhaust system becomes clogged, the load on the fan motor 14 is effectively reduced, and at this time, the feedback amount β _A required by the feedback control circuit 26 also becomes smaller than in the normal case.

If the normal range (permissible range) of + X in the positive direction and -Y in the negative direction is set for the set feedback amount β set by the initial setting at each set rotation speed, the comparison circuit 27 when the difference information between the current feedback amount beta _a at the output and configured feedback amount beta exceeds the range can be determined circuit 28 determines that the exhaust system abnormality. Here, the magnitudes X and Y of the allowable range in the absolute value may be generally equal, but in principle they can be set independently, and if necessary, they can be changed for each set rotation speed. You can also.

In the embodiment shown in FIG.
When the 28 makes an abnormality determination as described above and issues an abnormality detection output, the output signal provides a visual display means which can be constituted by, for example, a light emitting diode or the like, or alternatively or additionally, a speaker. By driving an alarm device 18 having an appropriate configuration, such as an audible notifying device, which can be configured by the above-mentioned method, an alarm is issued to the user for an abnormality in the exhaust system.

Further, in this embodiment, the abnormality detection output from the judgment circuit 28 is also supplied to a fuel supply amount control valve 19 for controlling the flow rate of fuel supplied to the combustion section of the water heater, and this is forcibly controlled. By squeezing, the amount of combustion is reduced substantially. Of course, it is possible to completely shut off the fuel supply by completely closing the fuel supply control valve 19 or the original solenoid valve (not shown). However, until the exhaust system is repaired or replaced, the hot water supply can be stopped. Would be inconvenient in practical use because it would not be usable at all. However, considering that there may be a user who ignores the alarm even though it has been issued and continues to use the alarm as it is, for example, when the abnormality detection signal from the determination circuit 28 continues for a certain amount of integration time or more. In this case, the fuel supply control valve may be completely shut off instead of being throttled.

In the case of an automatic water heater or the like assumed here, the combustion amount can be effectively reduced even if the flow rate of hot water from the water heater is reduced. As described above, in addition to or instead of the control of the fuel supply amount control valve 19, the hot water supply flow control valve 20 can be forcibly throttled by an abnormality detection signal generated by the determination circuit 28.

In the above-described embodiment, the data of the set feedback amount β to be written to the nonvolatile memory 11 in the initial setting is the feedback amount β _A itself required by the feedback control circuit 26 at each set rotation speed. A predetermined allowable range + X, -Y is provided for this, and it is left to the determination circuit 28 to detect and determine whether or not the range is out of the range. It can also be written in the 11 direction.
In other words, it is possible to store a pair of feedback amounts necessary for obtaining the upper and lower limit rotational speeds of the predetermined allowable range for the fan motor set rotational speed for each set rotational speed. For example, referring to FIG. 2, a predetermined value of + X and -Y is added to and subtracted from β _A extracted from the feedback control circuit 26 by the above-described initialization operation, and the result is stored in a nonvolatile memory. 11 or the fan motor 14 is actually rotated at the upper and lower limit rotation speeds of the permissible range at the time of the initial setting. At this time, the feedback amount required by the feedback control circuit 26 is converted into a pair of set feedback amount (β + X ) And (β-Y) in the non-volatile memory 11, and the comparison circuit 27 is configured as a window comparator. As a result of the comparison by the comparison circuit 27, the fan motor setting at each time under the actual operation of the combustion equipment is obtained. The current feedback amount β _A actually used by the feedback control circuit 26 according to the rotation speed is stored in the nonvolatile memory 11.
, A pair of set feedback amounts (β + X) stored in
The determination circuit 28 may be configured to emit an abnormality detection signal when the difference does not fall between (β−Y).

Although the preferred embodiment of the present invention has been described above, if the combustion equipment to be improved according to the present invention is such that the commercial power supply is always supplied thereto, the storage means 11 is used in principle. May be a volatile RAM. However, in consideration of a backup against a temporary power failure, a possibility of a long power failure, and the like, a nonvolatile memory is also desirable.

Also, as mentioned at the beginning, many of the recent various types of combustion equipment use a microcomputer as a main control circuit. The main control circuit 10 is also used in the embodiment of the present invention.
May be a microcomputer, and some or all of the feedback control circuit 26, the comparison circuit 27, the judgment circuit 28, etc., which have been described above as discrete hardware circuits, may be implemented by software processing. Can be configured substantially. Comparison circuit 27
Is not continuous as mentioned earlier,
The intermittent execution at a predetermined time resolution is, in a sense, inevitable when using a microcomputer in this way.

[0030]

According to the present invention, an abnormality in the exhaust system of a combustion device is detected based on the addition of a mechanical mechanism or the sensing output of various sensors for which a failure cannot be absolutely trusted. Instead, it is performed by detecting an abnormal change in the feedback amount at which the set rotation speed of the fan motor should be maintained, so that the reliability with respect to aging is relatively high. In addition, not only based on the abnormality of the exhaust system, but also when an abnormality occurs in the feedback system itself, for example, if the degree is severe, the feedback amount may greatly deviate from the normal case. Therefore, even in such a case, the abnormality can be detected, which is safer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a combustion equipment exhaust system abnormality detection device configured according to the present invention.

FIG. 2 is an explanatory diagram of a feedback amount used in a feedback control circuit that controls the number of revolutions of a fan motor.

FIG. 3 is an explanatory diagram of an installation state of an automatic water heater as an example of a combustion device.

[Explanation of symbols]

 10 Main control circuit (microcomputer); 11 Non-volatile memory (storage means); 12 Setting operation section; 13 Fan motor drive circuit; 14 Fan motor; 15 Fan motor rotation speed detection sensor; 16 Fan motor rotation speed detection circuit; Alarm device; 19 Fuel supply control valve; 20 Hot water supply flow control valve; 21 Water heater main body; 22 Heat exchanger; 23 Exhaust pipe; 24 Exhaust port; 25 Standard exhaust port; 26 Feedback control circuit; 27 Comparison circuit; 30 houses.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshifumi Yoshifumi 2-1-26-1 Tsutodori, Nada-ku, Kobe-shi, Hyogo Inside Hanshin Electric Co., Ltd. (56) References JP-A-61-101714 (JP, A) JP-A-5-118532 (JP, A)

Claims (12)

(57) [Claims] 1. A fan motor for supplying air to a combustion section, an exhaust system for exhausting air from the combustion section, and a rotation speed of the fan motor required in accordance with a current combustion amount in the combustion section. A feedback control circuit for performing feedback control of the fan motor in order to satisfy the set rotational speed by calculating the set rotational speed. In a state where the system can be regarded as normal, a feedback amount required by the feedback control circuit to satisfy the fan motor set rotation number is stored in a storage means as a set feedback amount; The current feedback amount used by the feedback control circuit at each time is stored in the storage means. Comparing with the set feedback amount and, when the difference exceeds a predetermined allowable range, determining that an abnormality has occurred in the exhaust system; 2. The method according to claim 1, wherein a feedback amount required by the feedback control circuit to satisfy the fan motor set speed is set as the set feedback amount. Instead, the storage means may be used to obtain upper and lower limit rotation speeds within a predetermined allowable range including the set rotation speed of the fan motor in a state where the exhaust system can be regarded as normal. Is stored as a pair of set feedback amounts; a current feedback amount used by the feedback control circuit from time to time under the actual operation of the combustion device falls between the pair of set feedback amounts. If not, determining that an abnormality has occurred in the exhaust system; 3. An exhaust system abnormality detection method for a combustion apparatus according to claim 1 or 2, wherein when the abnormality of the exhaust system is determined, an alarm device for notifying a user of the abnormality is operated. A method characterized by: 4. A method for detecting an abnormality in an exhaust system of a combustion apparatus according to claim 1, 2 or 3, wherein when the abnormality in the exhaust system is determined, the amount of fuel supplied to the combustion section is reduced. Forcing the control valve to be controlled to reduce the fuel supply. 5. The exhaust system abnormality detection method for a combustion device according to claim 1, 2, 3, or 4, wherein the combustion device heats feed water by a heat exchanger included in the combustion unit. When hot water is supplied and the flow rate of hot water increases, the amount of combustion increases,
This is a water heater that reduces the amount of combustion when the flow rate of hot water is reduced;
Forcibly restricting a control valve for controlling the hot water supply flow rate. 6. A fan motor for supplying air to a combustion section, an exhaust system for exhausting air from the combustion section, and a fan motor rotation number required according to the amount of combustion at each time are calculated to set a rotation number. A combustion device having a feedback control circuit for performing feedback control of the fan motor to satisfy the set number of revolutions, a device for detecting an abnormality in the exhaust system; a state in which the exhaust system can be regarded as normal Storage means for storing, as a set feedback amount, a feedback amount required by the feedback control circuit in order to satisfy the fan motor set rotation speed; and using the feedback control circuit from time to time under actual operation of the combustion equipment A comparison circuit for comparing the current feedback amount with the set feedback amount stored in the storage means; As a result of the comparison by the comparison circuit,
A determination circuit for determining that the exhaust system is abnormal when the difference between the current feedback amount and the set feedback amount exceeds a predetermined allowable range; 7. The exhaust system abnormality detection device for a combustion apparatus according to claim 6, wherein a feedback amount required by the feedback control circuit to satisfy the fan motor set rotation number is set in the storage unit. Instead of storing as the feedback amount, the storage means may obtain upper and lower limit rotation speeds in a permissible range including the set rotation speed of the fan motor in a state where the exhaust system can be regarded as normal. The comparison circuit compares the pair of set feedback amounts and the current feedback amount at the time of the actual operation of the combustion equipment with the pair of set feedback amounts being stored as a pair of set feedback amounts; The determination circuit determines that the current feedback amount is the pair of set feedback amounts as a result of the comparison by the comparison circuit. If not, it is determined that there is an abnormality in the exhaust system. 8. The exhaust system abnormality detection device for a combustion apparatus according to claim 6, wherein the determination circuit is configured to notify a user of the abnormality when the abnormality is determined in the exhaust system. Activating an alarm device. 9. The exhaust system abnormality detection device for a combustion apparatus according to claim 6, 7 or 8, wherein the determination circuit supplies the abnormality to the combustion section when the abnormality is determined in the exhaust system. A control valve for controlling a fuel supply amount is forcibly throttled to reduce the fuel supply amount. 10. The exhaust system abnormality detection apparatus for a combustion apparatus according to claim 6, 7, 8, or 9, wherein the combustion apparatus heats feed water by a heat exchanger included in the combustion section. When hot water is supplied and the flow rate of hot water increases, the amount of combustion increases,
A water heater that reduces the amount of combustion when the flow rate of hot water is reduced; when the determination circuit determines the abnormality in the exhaust system, the control valve for controlling the flow rate of hot water is forcibly throttled. Equipment to do. 11. The exhaust system abnormality detection device for a combustion apparatus according to claim 6, 7, 8, 9, or 10, wherein the feedback circuit, the comparison circuit, and the determination circuit include:
At least some or all of them are constituted by microcomputers. 12. The method of claim 6, 7, 8, 9, 10, or 1.
2. The exhaust system abnormality detection device for a combustion device according to 1 above,
The storage means is at least an electrically writable nonvolatile memory;