JP2001165436A - Combustion controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control combustion for a safe shutoff so that an abnormal combustion is not generated in the case of intake and exhaust paths are blocked up. SOLUTION: When a pressure loss has become great due to a blockage of intake/outlet paths and the like, a current-passage rate to a fan motor is reduced, and a predetermined number of revolution is maintained, in the above condition, when a load point calculated on the basis of a relation between the current-passage rate and a power source voltage is determined to be not in a combustion range for a satisfactory combustion, but to be a load point in a region in which an abnormal operation is possibly conducted due to insufficient air amount, then it is observed to determine whether such a state continues for a certain time or not, and if it continues, the pump drive is stopped to shut off the combustion to attain a safe and ensured operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fan motor which is driven by an AC power supply and supplies combustion air to a burner, and a target number of revolutions of the fan motor corresponding to a fuel supply amount to the burner is set in advance. The present invention relates to a combustion control device including a target rotation speed setting unit and a fan motor drive control unit that controls the duty ratio of the fan motor so that the rotation speed of the fan motor becomes the target rotation speed.

[0002]

2. Description of the Related Art In a conventional combustion apparatus, a method for controlling the air-fuel ratio to be constant is provided with a rotation speed detector for detecting a rotation speed of a fan motor, and a signal of the rotation speed detector is fed back to a motor drive control circuit. By doing so, the rotational speed is kept at the target rotational speed set based on the combustion amount. Therefore, even if there are variations in the characteristics of the motor or fluctuations in the power supply voltage, a stable rotation speed can always be obtained.

[0003]

However, in such a system, the supply / exhaust passage is blocked and the pressure loss increases,
When the pressure loss of the combustion device is increased due to assembly variation, the supply amount of combustion air may be controlled in a direction that causes poor combustion by the following mechanism.

That is, when the pressure loss increases, the amount of combustion air decreases, but the load decreases, and consequently the rotation speed of the fan motor increases.

FIGS. 2 and 3 both show the relationship between the duty ratio of the fan motor and the rotation speed. In order to maintain a constant rotation speed N ₀ while the power supply voltage changes, the duty ratio must be changed. In addition to this, it shows that even when there is a difference in pressure loss, it is necessary to change the duty ratio in order to maintain the constant rotation speed N ₀ . Figure 3 of these
This is an example of a case where the pressure loss is large, and indicates that control must be performed to reduce the duty ratio in order to maintain the constant rotation speed N ₀ .

That is, the control circuit reduces the duty ratio to the fan motor based on the rotation speed information detected by the rotation speed detector, and reduces the increased rotation speed so that the target rotation speed is maintained. It is.

[0007] However, in this case, the supply amount of the combustion air is rather reduced, and the combustion failure occurs.

The technique of controlling the rotation speed of the fan motor by reducing the duty ratio is also applied to a case where the power supply voltage changes. When the voltage is high, the duty ratio is reduced to reduce the rotation ratio of the fan motor. By reducing the rotation speed, it was possible to control the air amount to a normal value, contrary to the case where the above-mentioned pressure loss became high.

FIG. 4 shows the relationship between the duty ratio and the power supply voltage when maintaining a constant number of revolutions N ₀ in the case of different pressure losses, where La denotes the characteristic when the pressure loss is standard. Lb indicates a case where the pressure loss is large, and Lc indicates a case where the pressure loss is small. These characteristic curves are
In other words, it is a load curve when the fan motor is operated at the rotation speed N ₀ , so that if the duty ratio of the fan motor and the power supply voltage are known, the load point of the fan motor can be known. become.

The present invention is directed to solving the above-mentioned conventional problems by paying attention to this point.

[0011]

For this purpose, a pump for supplying fuel to a burner, a fan motor for supplying combustion air to the burner, and a power supply voltage detecting section for detecting a voltage of a power supply for driving the fan motor are provided. And the air-fuel ratio is kept constant by controlling the duty ratio so that the rotation speed of the fan motor becomes a target rotation speed set in advance based on the amount of fuel supplied to the pump. In the combustion control device, a load point calculation unit that calculates a load point of the fan motor from a relationship between a duty ratio to a fan motor and a voltage detected by the power supply voltage detection unit is provided, and the load point calculation unit calculates the load point. A state in which the load point is not a load point within the good combustion area which is set in advance according to the target rotation speed of the fan motor as a good burn area of the burner continuously for a certain period of time. When followed by the so as to extinguish the combustion of the burner to drive the pump is stopped.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has the above-described configuration, and when the power supply voltage is reduced or when the pressure loss of the air path is reduced and the number of revolutions of the fan motor is reduced, the control device controls the fan. A predetermined rotation speed is maintained by increasing the energization rate to the motor. In that case, it is determined that the load point calculated based on the duty ratio and the power supply voltage is within the combustion region where good combustion is performed, and safe driving can be performed, and the operation is continued. On the other hand, if the pressure loss of the combustion device increases due to blockage of the supply / exhaust passage, the control device reduces the duty ratio to the fan motor to maintain the rotation speed at a predetermined speed. The load point calculated from the relationship with the voltage is not within the combustion range where good combustion is performed,
If it is a load point where abnormal operation due to insufficient air volume can be performed, determine whether the state continues for a certain period of time,
When a certain period of time has passed, the operation of the pump was stopped to extinguish the combustion of the burner, thereby ensuring safety.

[0013]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a control block diagram. 1 is a microcomputer, 2 is a fan motor to be controlled, 3 is a rotation speed detecting unit for detecting the rotation speed of the fan motor 2, Is a target rotation speed setting unit in which data of a target rotation speed set in advance according to the combustion amount is stored, and 5 is a rotation speed detection unit 3 and the fan motor 2 based on signals from the target rotation speed setting unit 4. A duty ratio calculation unit that calculates the duty ratio required to rotate at the target rotation speed.

Reference numeral 6 denotes a fan motor drive control unit. Reference numeral 7 denotes a duty ratio setting unit that sets the duty ratio calculated by the duty ratio calculation unit 5 in the fan motor drive control unit 6.

Reference numeral 8 denotes a power supply voltage detection unit for detecting the voltage of the power supply supplied to the fan motor 2. Reference numeral 9 denotes a power supply voltage detection unit for the fan motor 2 based on the signal of the power supply voltage detection unit 8 and the signal of the duty ratio setting unit 7. This is a load point calculation unit that calculates a current load point.

Reference numeral 10 denotes a good combustion area reference load point setting unit in which load point data serving as a reference for performing good combustion is stored in advance. This is a load point abnormality detection unit that determines whether the load point calculated by the load point calculation unit 9 is normal or abnormal by comparing the data calculated by the load point calculation unit 9 described above. Reference numeral 12 denotes a pump drive control unit which executes control for stopping the fuel supply operation of the pump when the load point abnormality detection unit 11 has continued to determine abnormality for a certain period of time or more. This is another pump whose drive is controlled by the drive control unit 12.

In the embodiment having such a configuration, when the combustion operation is started, the control device executes the steps shown in the flowchart of FIG. 5 to determine that the load point of the fan motor is abnormal. If it continues for a certain period of time, control is performed so that the driving of the pump is stopped and the combustion operation is stopped to ensure safety, that is, the fire is extinguished.

If the power supply voltage of the fan motor 2 fluctuates or the pressure loss in the air supply / exhaust path changes due to the influence of strong wind, the rotation speed of the fan motor 2 changes. As a result, the rotation speed is detected, and information on the rotation speed and the target rotation speed stored in the target rotation speed setting unit 4 is input to the duty ratio calculation unit 5. Calculate and output the duty ratio for operating at the rotation speed.

The duty ratio setting unit 7, which has received the duty ratio information from the duty ratio calculation unit 5, sets the duty ratio to the fan motor drive control unit 6, and sets the duty ratio to the fan motor drive control unit. 6 drives the fan motor 2 accordingly.

The duty ratio information of the duty ratio setting unit 7 is also output to the load point calculation unit 9, where, based on the voltage information detected by the power supply voltage detection unit 8, the load The point is calculated, and the calculation result is transmitted to the load point abnormality detection unit 1
1 is output.

FIG. 6 shows an experimentally determined load curve in a good combustion range when the fan motor 2 is operating at the rotational speed N ₀ during strong combustion. The load curve LL on the side where air is insufficient is created as a limit value at which good combustion is performed, and FIG. 7 shows a matrix of the duty ratio and the power supply voltage. Since the matrix of FIG. 7 is stored in the load point calculation unit 9 as a data table, when the above-described information of the duty ratio setting unit 7 and the power supply voltage detection unit 8 is input, the load point calculation unit 9 The corresponding load point will be output.

More specifically, when the output of the duty ratio setting unit 7 is in the range of R _{3 to} R _{4 and} the output of the power supply voltage detecting unit 8 is in the range of V _{3 to} V ₄ , FIG. , The load point is a ₂₄ . From the load point calculation unit 9, therefore, the load point a ₂₄ is output.

The load point abnormality detection unit 11 which received the load point a ₂₄ is a comparing the reference load point stored in good combustion zone reference load point setting unit 10 and the load point a _24.

FIG. 8 is a data table of the reference load points stored in the good combustion zone reference load point setting section 10.
The normal and abnormal load points as viewed from the limit load curve LL on the side where combustion air becomes insufficient are indicated by Δ and X, respectively. The load point abnormality detection unit 11 determines whether the load point a ₂₄ from the load point calculation unit 9 is a load point at the given duty ratios R _{3 to} R ₄ and power supply voltages V _{3 to} V ₄ . It is determined whether the value is × by comparing with FIG. As a practical matter, it is ８ in FIG.
Since the operation is performed at the load point A in the good combustion range in the above, it is determined that the load point is normal, and the load point abnormality detection unit 11 does not perform the pump drive control without making the abnormality determination. The driving of the pump 13 by the unit 12 is continued.

In response to the determination that the vehicle is operating at the normal load point, for example, when there is no change in the power supply voltage, the output from the duty ratio setting unit 7 is R _{1 to} R _2.
In this case, the load point calculation unit 9 _converts the load point information a22 in the data table of FIG.
Output to Then, the load point abnormality detection unit 11, similarly to the case described above, in FIG. 6 as good combustion zone based on the data table of reference load point setting unit 10 determines the normality / abnormality of the load point a _22, practice Since the operation is performed at the load point B outside the good combustion range, the result of the determination that the operation is abnormal is made, and the determination is made for a predetermined time T.
_It is determined whether or not the operation is continuous, and when the operation is continued, the drive of the pump 13 by the pump drive control unit 12 is stopped. Thus, abnormal combustion is prevented from being performed with insufficient combustion air.

[0027]

As described above, according to the present invention, when the pressure loss of the combustion device becomes large due to the blockage of the supply / exhaust passage or the like, the duty ratio to the fan motor is reduced to maintain the predetermined rotation speed. Among them, it was determined that the load point calculated from the relationship between the duty factor and the power supply voltage was not in the combustion region where good combustion was performed, but was a load point where abnormal operation due to insufficient air amount could be performed. In such a case, it is determined whether or not the state continues for a certain period of time. If the state continues for a certain period of time, the drive of the pump is stopped to extinguish the combustion of the burner, so that safe and reliable operation can be performed. .

[Brief description of the drawings]

FIG. 1 is a control block diagram of one embodiment of the present invention.

FIG. 2 is a characteristic diagram of a fan motor used in one embodiment of the present invention.

FIG. 3 is a characteristic diagram of a fan motor used in one embodiment of the present invention.

FIG. 4 is a characteristic diagram with respect to a load point of a fan motor used in one embodiment of the present invention.

FIG. 5 is a characteristic diagram of a load point of a fan motor used in one embodiment of the present invention.

FIG. 6 is a characteristic diagram with respect to a load point of a fan motor used in one embodiment of the present invention.

FIG. 7 is a characteristic diagram with respect to a load point of a fan motor used in one embodiment of the present invention.

FIG. 8 is a characteristic diagram of a load point of a fan motor used in one embodiment of the present invention.

[Explanation of symbols]

1: microcomputer, 2: fan motor, 3: rotation speed detection unit, 4 target rotation speed setting unit, 5: duty ratio calculation unit, 6 fan motor drive control unit, 7: duty ratio setting unit, 8: power supply voltage detection unit , 9: load point calculation unit, 10: good combustion area reference load point setting unit, 11: load point abnormality detection unit, 12: pump drive control unit, 13: pump.

Claims (1)

[Claims] 1. A pump (1) for supplying fuel to a burner.
3), a fan motor (2) for supplying combustion air to the burner, and a power supply voltage detector (8) for detecting a voltage of a power supply for driving the fan motor, and a rotation speed of the fan motor. In the combustion control device in which the air-fuel ratio is kept constant by controlling the duty ratio so as to reach a preset target rotation speed based on the fuel supply amount to the pump, the fan motor A load point calculation unit (9) for calculating a load point of the fan motor from a relationship between a duty ratio and a voltage detected by the power supply voltage detection unit is provided, and the load point calculated by the load point calculation unit is set for a predetermined time. Continuously, when the state is not a load point in the good combustion region that is set in advance according to the target rotation speed of the fan motor as a good combustion region of the burner,
A combustion control device wherein the drive of the pump is stopped to extinguish the combustion of the burner.