JPH1151381A - Burning appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a normal combustion even when indoor negative pressure is high. SOLUTION: An intermediate point (point J) to which a prescribed gas quantity between a minimum gas quantity and a maximum gas quantity and prescribed rotating speed during its combustion are set is stored. The rise of the rotating speed of a fan is controlled so as to be proportional to the increase of a supplied gas quantity respectively between a minimum point (point H) and the intermediate point (point J) and between the intermediate point (point J) and a maximum point (point I) straight lines i, j). The rate of climb in the rotating speed of the fan upon rotation at low speed can be suppressed and an air/fuel ratio λ can be controlled to a value suitable to the supplied gas quantity as shown in a deviation g under a control on the broken lines (i, j) as described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus, and more particularly, to a control for supplying combustion air in a forced combustion apparatus.

[0002]

2. Description of the Related Art Conventionally, a gas water heater controls a gas amount in accordance with a deviation between a tapping temperature and a set temperature, and changes a fan rotation speed in accordance with the gas amount to adjust a combustion air amount corresponding to the gas amount. Is controlled to be supplied. Among these gas water heaters, those of the forced exhaust type are those that take in combustion air from indoors by driving a fan and forcibly exhaust the exhaust gas generated by gas combustion to the outside through an exhaust pipe. It is widely used without the need for

[0003]

However, when such a forced exhaust gas water heater is installed in a highly airtight house, the negative pressure in the room becomes large and the amount of combustion air becomes insufficient, so that normal combustion cannot be maintained. There are cases. In particular, in the state where the operation is performed with the minimum gas amount, the influence is large because the fan rotation speed is low. On the other hand, if the fan rotation speed at the minimum gas amount is set high, the air becomes excessive when the indoor negative pressure is small, and problems such as lift and blow-off occur. If the minimum gas amount is set high, lift, blow-off and the like can be prevented, but the usability deteriorates because the capacity adjustment range is narrowed by increasing the minimum combustion amount.
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems and to perform normal combustion even in a state where indoor negative pressure is large.

[0004]

According to a first aspect of the present invention, there is provided a combustion apparatus, comprising: a burner for burning fuel gas; a gas amount adjusting means for adjusting an amount of gas supplied to the burner; A fan for supplying combustion air to the burner, a minimum point at which a minimum gas amount and a corresponding minimum rotation speed of the fan are set, and a maximum gas amount and a corresponding maximum rotation speed of the fan are set. A combustion device comprising: air-fuel ratio control means for controlling the number of revolutions of the fan with respect to the amount of gas supplied to the burner based on the maximum point; and an exhaust passage for discharging exhaust gas generated by combustion of the burner to the outside. The opening in the exhaust passage or the combustion air supply path downstream of the fan at an opening corresponding to the exhaust pressure or the supply pressure, and the larger the opening, the smaller the force in the closing direction. A variable variable damper, which stores an arbitrary gas amount between the minimum gas amount and the maximum gas amount and an intermediate point at which a corresponding fan rotation speed is set, and the air-fuel ratio control means stores the minimum point From the intermediate point to the intermediate point, and from the intermediate point to the maximum point, controlling the rotation speed of the fan in proportion to the amount of gas supplied to the burner, and controlling the rotation speed of the fan from the minimum point to the intermediate point. The gist is that the rate of increase in the number of revolutions is lower than the rate of increase in the number of revolutions of the fan from the intermediate point to the maximum point.

According to a second aspect of the present invention, there is provided a combustion apparatus according to the first aspect of the present invention, wherein a storage medium for storing the intermediate point is detachably provided.

In the combustion apparatus according to the first aspect of the present invention, the minimum point at which the minimum gas amount and the corresponding minimum rotational speed of the fan are set, the maximum gas amount and the maximum rotational speed of the fan corresponding thereto are set. The number of rotations of the fan relative to the amount of gas supplied to the burner is controlled based on the maximum point at which the number is set. When the supply gas amount is small, the rotation speed is controlled to be low, so that the supply pressure and exhaust pressure of the combustion air are reduced. Therefore, the opening of the variable resistance damper is reduced, the force in the closing direction is increased, and the flow path resistance is increased. Can be reduced. In addition, when the supply gas amount is large, the rotation speed is controlled to be high, so that the supply pressure and exhaust pressure of the combustion air increase. Therefore, the opening of the variable resistance damper increases,
Since the force in the closing direction is reduced and the flow path resistance is reduced, the rotation speed for supplying the required amount of air can be suppressed to about the conventional rotation speed without increasing the rotation speed so much. As a result, normal combustion can be performed even at the time of negative pressure without changing the maximum number of revolutions and the minimum gas amount much as compared with the conventional one.

As described above, in the state where the damper opening has not reached the maximum opening, the damper opening is increased and the flow path resistance is reduced by increasing the fan rotation speed. Increases at a rate higher than the rate of increase in the fan speed. On the other hand, when the damper opening reaches the maximum opening, the flow rate resistance does not change even if the fan rotation speed is increased, so that the supply amount of the combustion air increases according to the rising rate of the fan rotation speed. . for that reason,
If you try to control the fan speed in proportion to the amount of gas supplied to the burner between the minimum point and the maximum point as in the past, the supply amount of combustion air at low rotation becomes unnecessarily large. This causes a problem such as that. Therefore, an intermediate point at which a fan rotation speed corresponding to an arbitrary gas amount between the minimum gas amount and the maximum gas amount is stored, and from the minimum point to the intermediate point and from the intermediate point to the maximum point, By controlling the fan speed in proportion to the amount of gas supplied to the burner, the rate of increase of the fan speed from the minimum point to the intermediate point was made lower than that of the fan speed from the intermediate point to the maximum point. . By performing such control, the supply amount of the combustion air can be controlled to an amount suitable for the supply gas amount.

[0008] The combustion apparatus according to the second aspect of the present invention having the above-described configuration is provided with a removable storage medium for storing an intermediate point, so that it is suitable for an apparatus having different conditions such as gas type and structure. By using a storage medium that stores the data, the setting can be easily performed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the combustion apparatus of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a forced exhaust gas water heater as one embodiment of the present invention. This forced exhaust gas water heater has a case 1 forming an outer shell.
A burner 3 that burns gas supplied from the gas supply passage 2, a heat exchanger 6 that heats water passed through the water supply pipe 4 by the combustion heat of the burner 3 and sends out the water to the tapping pipe 5, and a water supply pipe 4.
A flow sensor 7 for detecting a flow rate of incoming water, a thermistor 8 for detecting a temperature of hot water in a tapping pipe 5, a combustion chamber 9 containing a burner 3 and a heat exchanger 6, and sending out exhaust gas generated by combustion to the outside. It comprises an exhaust pipe 10 serving as a passage, a variable resistance damper 11 provided in the exhaust pipe 10, a fan 12 for supplying combustion air into the combustion chamber 9, and a controller 13 for controlling combustion.

In the gas supply path 2, a main solenoid valve 14, a proportional solenoid valve 15, and a main solenoid valve 16 are provided in series. The source solenoid valve 14 and the main solenoid valve 16 are valves that only open and close the gas flow path, and the proportional solenoid valve 15 is a control valve that is set to an opening degree according to a control signal and adjusts to a desired supply gas amount. is there.

The controller 13 includes a CPU, a RAM, and a ROM that constitute a well-known arithmetic and logic operation circuit (not shown).
It consists of an input interface that inputs signals from various sensors and an output interface that outputs drive signals to various actuators, and performs not only combustion control but also hot water temperature control and ignition control. Descriptions and illustrations of ignition devices and the like not directly related to the present invention are omitted. The controller 13 stores an EE (not shown) that stores a fan rotation speed corresponding to a gas type or the like.
A chip containing a PROM (hereinafter, referred to as a gas type connector) is detachably inserted.

As shown in FIG. 2, the variable resistance damper 11 is a lightweight circular plate 11b (60 mm in diameter in this embodiment, which is swingably supported by a rotating shaft 11a in an exhaust pipe 10).
A weight 11c is fixed to the end of a 0.3mm thick aluminum product). Further, stoppers 10a and 10b for limiting the swing width of the resistance variable damper 11 are provided in the exhaust pipe 10. The opening of the weight 11c is maximized before the resistance variable damper 11 starts to open just by the fan rotation speed corresponding to the combustion with the minimum gas amount and rises to the fan rotation speed corresponding to the combustion with the maximum gas amount. The weight (10 g in this embodiment) and the fixed position are set as described above. By fixing the weight 11c in this manner, a force is applied in the closing direction. This force becomes maximum when the resistance variable damper 11 is horizontal (W1), decreases as the damper opening increases (W2), and becomes minimum when the damper opening reaches a maximum (W3). It should be noted that a conventional forced exhaust gas water heater using a damper in an exhaust pipe is also known, but this is for preventing cold air from flowing back into a room in a cold region, and is extremely lightweight. The exhaust pressure at the time of combustion with the gas amount is fully open, and the influence at the time of combustion can be ignored, and therefore, it is completely different from the resistance variable damper 11 of the present invention.

Next, the operation of the forced exhaust gas water heater of this embodiment will be described. When a hot water tap (not shown) is opened and water flows, water flow is detected by the flow sensor 7 and the fan 12
Is rotated to perform prepurge. After the prepurge, the original solenoid valve 14 and the main solenoid valve 16 are opened, and the proportional solenoid valve 1 is opened.
The gas is supplied to the burner 3 by adjusting the opening degree of the burner 3 to a gentle ignition operation, and the gas is ignited by an ignition device (not shown). Then, when it is confirmed that the flame is burning by detecting the flame by a flame detecting device (not shown), the mild ignition operation ends. When the mild ignition operation is completed, proportional control is started, and the controller 1 is controlled according to the difference between the hot water temperature detected by the thermistor 8 and the set temperature.
3 sends a signal to the proportional solenoid valve 15 to continuously change the gas amount to keep the tapping temperature constant. Then, the number of revolutions of the fan 12 is controlled according to the change in the gas amount by the proportional solenoid valve 15.

Next, the variable resistance damper 11 of the present embodiment
In order to compare a forced exhaust gas water heater provided with a pressure-variable damper 11 and a conventional gas water heater provided with a variable resistance type damper 11, pressure loss curves a and b when a room negative pressure is not applied and when a room negative pressure is applied are obtained. b, the pressure loss curves c and d of the present embodiment when no negative pressure is applied and when a negative pressure is applied are shown in the PQ characteristics diagram of FIG. 3, respectively.

In the prior art, the fan speed is set to 2000 rpm in order to obtain the required air flow of 0.3 m ³ / min with the minimum gas flow as shown at point A of the pressure loss curve a. Since the pressure is slightly lower than 10 mmH ₂ O, for example, in a situation where the indoor negative pressure is −10 mmH ₂ O, the combustion air is not sent in as indicated by the point B of the pressure loss curve b and the fire is extinguished. If the minimum fan speed is set to, for example, 3000 rpm to solve this problem, the air volume becomes 0.27 m ³ / min as shown at point C, and the indoor negative pressure becomes −10.
Although the fire does not extinguish even in the condition of mmH ₂ O, when the negative pressure is not applied, the air volume is 0.4
At 6 m ³ / min, the air becomes excessive and problems such as lift and blow-off occur.

On the other hand, in the case where the resistance variable damper 11 is provided as in the present embodiment, the exhaust resistance increases when the fan rotation speed is low, and the minimum gas amount as shown at the point E of the pressure loss curve c. The fan speed can be set to 3300 rpm to obtain the required air volume of 0.3 m ³ / min for combustion. Therefore, even when the indoor negative pressure is −10 mmH ₂ O, the air volume is 0.23 m ³ as shown at the point F of the pressure loss curve d.
/ Min, and the combustion can be continued without extinguishing the burner 3.

Here, considering the case where a constant exhaust resistance is simply added, the transition becomes as shown in a pressure loss curve e, and the required air volume at the time of combustion of the maximum gas amount is 1.0 m ³ / min.
It can be seen that the fan speed must be greatly increased in order to obtain a good value. In contrast, in the present embodiment,
Variable resistance damper 11 as fan speed increases
With the configuration that the exhaust opening resistance increases and the exhaust resistance decreases,
As shown in a pressure loss curve c, the pressure loss approaches a pressure loss curve a of the conventional damper. Therefore, the fan rotation speed for obtaining the required air flow of 1.0 m ³ / min at the maximum gas amount can be set to the same rotation speed (6200 rpm) as the conventional one, as shown at point G.

Next, a method of controlling the number of revolutions of the fan in the variable exhaust resistance type as in this embodiment will be described in comparison with the conventional exhaust resistance fixed type. In the conventional exhaust resistance fixed type, the air volume increases in accordance with the rising rate of the fan rotation speed. Therefore, the minimum point (point H) at which the minimum gas amount and the number of revolutions for supplying the optimal air volume at the time of combustion are set.
And the maximum point (point I) at which the maximum gas amount and the number of revolutions for supplying the optimal air volume during combustion are set,
By controlling the increase in the number of rotations of the fan with respect to the increase in the supply gas amount from the minimum point (point H) to the maximum point (point I) in a proportional relationship (straight line f), an arbitrary supply gas amount is obtained. It is possible to send an optimal air volume to the air. By such control, the value of the air-fuel ratio λ (the ratio of the actual air amount to the theoretical air amount) with respect to the supply gas amount can be controlled as shown by a transition g in the graph of FIG.

On the other hand, in the case where the resistance variable damper 11 is provided as in the present embodiment, if the damper opening does not reach the maximum opening, the damper opening increases with the increase in the fan speed. Since the exhaust resistance increases and the exhaust resistance decreases, the amount of air increases at a higher rate than the rate of increase of the fan speed. On the other hand, in a state where the damper opening reaches the maximum opening, the exhaust resistance does not change even if the fan rotation speed is increased, so that the air flow increases in accordance with the rising rate of the fan rotation speed. Therefore, when trying to control the fan rotation speed with respect to the supply gas amount on the straight line f as described above,
The rate of increase of the air volume during low rotation increases, and the air-fuel ratio λ in that range becomes unnecessarily high, as indicated by the transition h.

In order to prevent such a problem, a predetermined gas amount between the minimum gas amount and the maximum gas amount and an intermediate point (point J) at which a predetermined rotation speed at the time of combustion is set are stored, and a minimum point (point J) is stored. From point H) to the intermediate point (point J)
From the intermediate point (point J) to the maximum point (point I), control is performed such that the increase in the number of rotations of the fan with respect to the increase in the supply gas amount is proportional to each other (straight lines i,
j). By controlling on the polygonal line (straight lines i, j) in this way, the rate of increase in the fan rotation speed during low rotation is suppressed, and the air-fuel ratio λ is controlled to a value suitable for the supply gas amount as indicated by the transition g. can do.

Next, an example of a method of setting an intermediate point (point J) will be described. First, the air-fuel ratio λ with respect to the gas supply amount is measured when the increase in the fan rotation speed with respect to the increase in the supply gas amount is controlled so as to be in a proportional relationship from the minimum point (point H) to the maximum point (point I). , The air-fuel ratio λ at the time of low rotation becomes higher than necessary. Therefore, how much the air-fuel ratio λ should be reduced in order to bring the measured transition h closer to the ideal transition g is examined in a plurality of gas supply amounts, and the fan rotation speed is obtained from these values to obtain the respective gas supply amounts. Plot each time. Then, an intermediate point (point J) is set at a position where a broken line approximating the plotted point is obtained. By setting the intermediate point (point J) and controlling on the polygonal line in this way, the control is not complicated and the data to be stored can be reduced as compared with the case of controlling with a curve. Further, since the control pattern is changed only by the position of the intermediate point (point J), the change and the fine adjustment are easy.

Further, since the data of the fan rotation speed with respect to the supplied gas amount is stored in the EEPROM of the gas type connector inserted into the controller 13, the data of the gas type, the structure and the like are different for the equipment. However, it can be easily set by using a gas type connector that stores rotation speed data (ie, minimum point, maximum point, intermediate point) corresponding to each. For the intermediate point, for example, a predetermined gas amount is stored as a ratio to the maximum gas amount based on the minimum gas amount, and the fan rotation connecting the minimum point (point H) and the maximum point (point I) at the predetermined gas amount is performed. The predetermined number of revolutions is stored as a value indicating how much the number is reduced from the number.

As described above, in the forced exhaust gas water heater of the present embodiment, the exhaust air resistance is changed by the variable resistance damper 11, so that the amount of air flow increases at a higher rate than the rate of increase of the fan speed. By reducing the rate of increase of the fan rotation speed with respect to the supply gas amount at a low rotation speed, it is possible to supply an air flow suitable for the supply gas amount. Furthermore, in addition to the previously stored minimum point and maximum point, an intermediate point is newly stored for controlling the number of rotations of the fan with respect to the supply gas amount, and a polygonal line (straight line i, Since the control is performed only on j), the control can be prevented from becoming complicated as compared with the case where the control is performed on a curve. Further, even for instruments having different conditions such as gas type and structure, by inserting a gas type connector that stores data corresponding to the conditions, it is possible to perform control suitable for such a device.

Further, by providing a variable resistance damper and increasing the exhaust resistance, it is possible to set the fan speed at the minimum capacity to be high, so that it is possible to supply combustion air required even at the time of indoor negative pressure. it can. Furthermore, the fan speed for obtaining the required air volume at the maximum capacity is the same as the conventional one, and there is no need to set the fan speed higher. Therefore, fan noise at the time of maximum capacity is not a problem.

In this embodiment, the variable resistance damper is provided in the exhaust pipe, but may be provided in a passage for supplying combustion air from a fan.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

[0027]

As described in detail above, claim 1 of the present invention
According to the combustion apparatus described above, the flow rate resistance is changed by the variable resistance damper, so that the supply amount of combustion air increases at a rate higher than the rate of increase of the fan rotation speed. By reducing the rate of increase in the number of revolutions at low revolutions, the supply amount of combustion air can be controlled to an amount suitable for the supply gas amount. Moreover, in order to control the number of rotations of the fan with respect to the supply gas amount, an intermediate point is newly stored in addition to the previously stored minimum point and maximum point, and control is performed so that a proportional relationship exists between them. Therefore, there is no need for complicated control. Also, by providing a variable resistance damper and providing exhaust resistance, the fan speed at the minimum capacity can be set high, so that normal combustion can be achieved even at the time of indoor negative pressure. Further, the fan speed at the maximum capacity does not need to be set so high by changing the resistance, and the same capacity width as the conventional one can be secured, so that the usability is very good.

Further, according to the combustion apparatus of the second aspect of the present invention, it is possible to easily set an apparatus having different conditions by using a storage medium for storing data suitable for the apparatus. Control suitable for the conditions can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a forced exhaust gas water heater as one embodiment.

FIG. 2 is a diagram illustrating the operation of a variable resistance damper.

FIG. 3 is a PQ characteristic diagram of the forced exhaust gas water heater of the present embodiment.

FIG. 4 is a graph showing a relationship between a gas supply amount and a fan rotation speed.

[Explanation of symbols]

1 ... case, 2 ... gas supply path, 3 ... burner, 4 ...
Water supply pipe, 5 ... tapping pipe, 6 ... heat exchanger, 10 ... exhaust pipe, 11 ... variable resistance damper, 12 ... fan, 1
3. Controller.

Claims (2)

[Claims] 1. A burner for burning fuel gas, gas amount adjusting means for adjusting an amount of gas supplied to the burner, a fan for supplying combustion air to the burner, a minimum gas amount and the corresponding fan Based on the minimum point at which the minimum number of revolutions of the fan is set, and the maximum point at which the maximum amount of gas and the corresponding maximum number of revolutions of the fan are set, in proportion to the amount of gas supplied to the burner. In a combustion device having an air-fuel ratio control means for controlling a rotation speed, and an exhaust passage for discharging exhaust gas generated by combustion of the burner to the outside, the exhaust passage or a combustion air supply passage downstream of the fan may be provided. , Open with the opening degree according to exhaust pressure or supply pressure,
Equipped with a variable resistance damper that reduces the force in the closing direction as the degree of opening increases, and stores an arbitrary gas amount between the minimum gas amount and the maximum gas amount and an intermediate point where the corresponding fan rotation speed is set. The air-fuel ratio control means controls the number of revolutions of the fan in proportion to the amount of gas supplied to the burner from the minimum point to the intermediate point and from the intermediate point to the maximum point. A combustion apparatus wherein the rate of increase in the number of revolutions of the fan from the minimum point to the intermediate point is lower than the rate of increase in the number of revolutions of the fan from the intermediate point to the maximum point. 2. The combustion apparatus according to claim 1, wherein a storage medium for storing the intermediate point is provided detachably.