JPH1151375A - Air/fuel ratio controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air/fuel ratio controller wherein even when actual revolutions of a fan does not reach target revolutions not easily, there is avoided a trouble that correction is applied to supply gas pressure indefinitely to prevent hot water effluent characteristics from being deteriorated. SOLUTION: A title air/fuel ratio controller includes a heat exchanger, a gas burner, a combustion fan, a fan control part, and a hot water supply control part. In the apparatus, a correction control timer is provided, and the hot water control part is adapted such that when revolutions of the combustion fan satisfy target revolutions actual revolutions < Xrpm (X :a constant), the correction control timer is reset without correcting gas pressure, and when the revolutions of the combustion fan satisfy |target revolutions-actual revolutions| >=Xrpm (X: the constant), correction is applied to the gas pressure, and when predetermined timer time by the correction control timer is elapsed, the correction of the gas pressure is finished even when the revolutions successively satisfy |target revolutions-actual revolutions| >=Xrpm (X: the constant).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a forced water supply / exhaust type water heater such as a water heater or a hot water heater, and operates to maintain a good air-fuel ratio balance in a transitional period when these devices are operated. To an air-fuel ratio control device.

[0002]

2. Description of the Related Art Conventionally, it is used in a forced water supply / exhaust water heater such as a water heater or a hot water heater, and when these devices are operated,
As control for maintaining the balance of the air-fuel ratio in the transition period, control has been performed such that the output of the gas pressure is corrected by the difference between the target rotation speed and the actual rotation speed of the fan. This conventional control means will be described with reference to the flowchart of FIG. When it is determined that (difference between the target rotation speed and the actual rotation speed of the fan) ≧ X rpm (Yes in step S1), the gas pressure is corrected (step S2), and conversely, in the case of no in step S1. Are configured such that the gas pressure is not corrected (step S3).

[0003]

However, in the above-mentioned conventional control means, if "the difference between the target rotation speed of the fan and the actual rotation speed ≧ X rpm", the gas pressure is always corrected. However, even when the actual rotation speed of the fan does not approach the target rotation speed forever, the output of the gas pressure will be continuously corrected, and as a result, the phenomenon that the hot water supply does not reach the set temperature will occur. For example, there was a possibility that the tapping characteristics would be deteriorated.

In view of the above-mentioned disadvantages of the conventional control means, the present invention provides a state in which the supplied gas pressure is forever corrected even when the actual rotational speed of the fan does not approach the target rotational speed forever. It is an object of the present invention to provide an air-fuel ratio control device capable of avoiding a situation in which the hot water supply continues, thereby preventing deterioration of the hot water supply characteristics in air-fuel ratio control.

[0005]

To achieve the above object, an air-fuel ratio control apparatus according to the present invention comprises a heat exchanger for heating water flowing through a hot water supply pipe, a gas burner, and a combustion fan for supplying combustion air. And a fan control unit that controls the number of revolutions of the fan according to the combustion amount of the combustion unit, a gas supply pipe that supplies gas to the gas burner, a gas proportional valve provided in the gas supply pipe, and a gas proportional valve. An air-fuel ratio control device comprising a hot water supply control unit for controlling a degree of opening to adjust a combustion amount of the gas burner and outputting a signal indicating a combustion amount of the gas burner to a fan control unit. A correction control timer is provided to limit the time for correction, and the hot water supply control unit controls the rotation speed of the combustion fan to |
When the target rotation speed−the actual rotation speed | <X rpm (X is a constant), the gas pressure is not corrected and the correction control timer is reset, and the rotation speed of the combustion fan is | target rotation speed−actual rotation speed. When the number of rotations | ≧ X rpm (X is a constant), the gas pressure is corrected, and when a predetermined timer time of the correction control timer elapses, the number of rotations of the combustion fan continues to be | target number of rotations−actual number of rotations. Number of rotations | ≧ Xrpm
The first feature is that the correction of the gas pressure is ended even when (X is a constant). In the above description, an appropriate time can be determined in advance by experiment for the certain timer time. Further, the air-fuel ratio control device of the present invention controls a heat exchanger and a gas burner for heating water flowing through a hot water supply pipe, a combustion fan for supplying combustion air, and a fan rotation speed according to a combustion amount of a combustion unit. A fan control unit, a gas supply pipe for supplying gas to the gas burner, a gas proportional valve provided in the gas supply pipe, and a combustion amount of the gas burner by controlling an opening degree of the gas proportional valve. An air-fuel ratio control device used in a hot water supply device having a hot water supply control unit for outputting a signal indicating a combustion amount of a gas burner to a fan control unit, and a time limit for correcting gas pressure. A correction control timer is provided. When the rotation speed of the combustion fan is | target rotation speed-actual rotation speed | <Xrpm (X is a constant), the hot water supply control unit outputs the gas pressure obtained by equation (1). Along with The positive control timer is reset, and the rotation speed of the combustion fan is | target rotation speed-actual rotation speed | ≧ Xrpm (X is a constant)
In the case of, the corrected gas pressure obtained by the equation (2) is output, and when a fixed timer time of the correction control timer elapses, for example, the rotation speed of the combustion fan becomes |
The second feature is that even if target rotation speed−actual rotation speed | ≧ X rpm (X is a constant), the output is returned to the gas pressure output by equation (1). P ₁ = a × G ² + b Expression (1) P ₂ = P ₁ + (actual rotation speed−target rotation speed) × α ÷ β Expression (2) P ₁ : gas pressure output data without correction G: required scale number a, b: gas calculation constants P _2: corrected gas pressure output data alpha, beta: correction factor

[0006]

Embodiments of the present invention will be described below. FIG. 1 is a schematic diagram showing a water heater provided with an air-fuel ratio control device according to an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the air-fuel ratio control device.

First, referring to FIG. 1, a water heater 1
A heat exchanger 4 for heating water flowing through the hot water supply pipe 3 and a gas burner 5 are accommodated in the can body 2. The gas burner 5 is disposed below the heat exchanger 4. An exhaust port 6 is opened on the upper surface of the can 2, and combustion air is forcibly supplied into the can 2 by a combustion fan 8 to an intake port 7 on the lower surface, and gas is burned at an optimal air-fuel ratio. It is configured to be able to. Further, the flow rate sensor 9 provided in the hot water supply pipe 3 is connected to a hot water supply control unit 10, and when the hot water supply is started, the hot water supply flow rate Q is equal to or more than a minimum operation amount (MOQ) (hereinafter, MOQ). When the determination is made, the hot water supply control unit 10 outputs a signal to the fan control unit 11 indicating that the MOQ is equal to or higher than the MOQ. On the other hand, a gas proportional valve 13 is provided in a gas supply pipe 12 for supplying gas to the gas burner 5, and the opening degree of the gas proportional valve 13 is determined by the hot water supply control unit 1.
It is configured so that the combustion amount of the gas burner 5 can be adjusted by controlling by 0, and a signal indicating the combustion amount of the gas burner 5 is output from the hot water supply control unit 10 to the fan control unit 11. I have. The fan rotation speed of the combustion fan 8 is controlled by the fan control unit 11 by changing the fan drive current supplied to the DC motor 14, and the fan rotation speed and the fan drive current are respectively detected by the fan rotation speed detection unit. 15 and the fan drive current detector 16, and each detection signal is input to the fan controller 11. The fan control unit 11 is configured to be able to feedback-control the fan rotation speed of the combustion fan 8 so as to obtain a desired fan rotation speed according to the combustion amount while detecting the fan rotation speed. In the control device for the water heater configured as described above, a correction control timer 17 is added between the fan control unit 11 and the hot water supply control unit 10, whereby “(” obtained by the fan control unit 11 is obtained. Based on the determination result of “difference between target rotation speed and actual rotation speed) ≧ X rpm (X is a constant)”, the hot water supply control unit 10 corrects the increase or decrease of the gas pressure by adjusting the opening of the gas proportional valve 13. Time control can be performed. To explain this specifically,
If (difference between the target rotation speed and the actual rotation speed) <X rpm, the gas pressure is not corrected, the gas pressure output obtained by the expression (1) is output, and the correction control timer 17 is reset. Is controlled. If (difference between target rotation speed and actual rotation speed) ≧ X rpm, the gas pressure obtained by equation (2) is output until the correction control timer 17 is up, and
After the correction control timer 17 is up, it is controlled to output without correction. Formula for correcting gas pressure, P ₁ = a × G ² + b Formula (1) P ₂ = P ₁ + (actual rotation speed−target rotation speed) × α ÷ β... Formula ( 2) P ₁ : gas pressure output data without correction G: required number a, b: gas calculation constant P ₂ : gas pressure output data after correction α, β: correction coefficient According to these formulas, the actual rotation speed is the target rotation speed. If so, the gas pressure is corrected to be higher than no correction, and if the actual rotation speed is equal to or lower than the target rotation speed, the gas pressure is corrected to be lower than no correction.

The operation of the correction control timer will be described with reference to the flowchart of FIG. In the transition period of combustion, if the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | <Xrpm (No in step S11), the correction control timer 17
Is reset (step S15), and the gas pressure output determined by P ₁ = a × G ² + b (Equation (1)) is performed without correcting the gas pressure (step S16). On the other hand, when the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | ≧ X rpm
If this is the case (yes in step S11), P ₂ = P ₁ + (actual rotation speed−target rotation speed) × α ÷ β (expression ( ₁ ) until the correction control timer 17 increases (elapses) the fixed timer time. Output the gas pressure obtained in 2)) (Step S1)
No in step S2). Thereafter, after the correction control timer 17 has counted up (step S12).
No), an output without correction of the gas pressure is performed (step S13). If the correction control timer 17 does not count up (No in step S12), the gas pressure is corrected (step S14), and it is determined again in step S12 whether the correction control timer 17 has counted up. If the answer is "yes" and the correction control timer 17 is up, an output without correction of the gas pressure is performed in the same manner as described above (step S13). Therefore, unless the timer for correction control 17 is up, the gas pressure is corrected until the determination in step S12 is affirmative (step S14), and whether the timer for correction control 17 is up again in step S12. The determination as to whether or not is repeated in the same manner.

As described above, during the combustion transition period, the deviation between the target rotation speed and the actual rotation speed of the fan is corrected by the gas pressure. This is because the gas pressure is more responsive in balancing the air-fuel ratio. Is fast. On the other hand, after a predetermined period of time (time-up of the correction control timer) after the end of the transition period, the correction of the gas pressure is stopped, and the combustion is performed by the feedback of the combustion fan. With this configuration, not only can the gas pressure be properly corrected during the transitional period of combustion, but also if the combustion fan malfunctions for any reason, the gas pressure will not be corrected forever. It is possible to prevent abnormal hot water supply in a forced water supply / exhaust water heater such as a water heater or a hot water heater.

[0010]

According to the first aspect of the present invention, a heat exchanger for heating water flowing through a hot water supply pipe, a gas burner, and combustion air are provided. And a fan control unit that controls the number of revolutions of the fan according to the amount of combustion in the combustion unit, a gas supply pipe that supplies gas to the gas burner, and a gas proportional valve provided in the gas supply pipe, An air-fuel ratio control device comprising a hot water supply control unit for controlling a degree of combustion of the gas burner by controlling an opening degree of the gas proportional valve and outputting a signal indicating a combustion amount of the gas burner to a fan control unit. hand,
A correction control timer is provided to limit the time of gas pressure correction, and the hot water supply control unit determines that the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | <Xrpm (X is a constant)
In this case, the gas pressure is not corrected and the correction control timer is reset. When the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | ≧ Xrpm (X is a constant), the gas pressure is reduced. When the correction is performed and a predetermined timer time by the correction control timer has elapsed, even if the rotation speed of the combustion fan continues to be | target rotation speed−actual rotation speed | ≧ X rpm (X is a constant), Since the correction of the gas pressure is configured to end, it is possible to avoid a situation where the supply gas pressure is continuously corrected when the actual rotation speed of the fan does not approach the target rotation speed forever. Thus, it is possible to prevent deterioration of the tapping characteristics in the air-fuel ratio control. Further, according to the air-fuel ratio control device of the second aspect, a heat exchanger for heating water flowing through the hot water supply pipe, a gas burner, a combustion fan for supplying combustion air, and a combustion amount of the combustion unit are provided. A fan control unit that controls a fan rotation speed, a gas supply pipe that supplies gas to a gas burner, a gas proportional valve provided in the gas supply pipe, and a gas proportional valve that is controlled by controlling an opening degree of the gas proportional valve. An air-fuel ratio control device for use in a hot water supply device having a hot water supply control unit for adjusting a combustion amount and outputting a signal indicating a combustion amount of a gas burner to a fan control unit. A correction control timer for imposing a restriction is provided, and the hot water supply control unit determines that the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | <X rpm
When (X is a constant), the gas pressure determined by the equation (1) is output, the correction control timer is reset, and the rotation speed of the combustion fan is | target rotation speed-actual rotation speed | ≧ X rpm When (X is a constant), the corrected gas pressure obtained by the equation (2) is output, and when a fixed timer time by the correction control timer elapses, for example, the rotation speed of the combustion fan becomes | target. Number of rotations-actual number of rotations | ≧
Even if it is Xrpm (X is a constant), it is configured to return to the gas pressure output according to the equation (1). Therefore, in a water heater such as a water heater or a hot water heater, it is more appropriate according to the equation (2) during a combustion transition period. In the combustion stabilization period, it is possible to perform stable combustion at a preferable air-fuel ratio according to the equation (1). In addition, when the fan abnormally operates, the gas pressure is incorrectly corrected. It is possible to prevent the abnormal hot water from flowing out forever. As described above, according to the first and second aspects of the present invention, a good air-fuel ratio can be maintained and a good combustion state can be maintained, and a forced water supply / exhaust water supply such as a water heater or a hot water heater can be provided. Trouble of the device can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a hot water supply device provided with an air-fuel ratio control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the air-fuel ratio control device of the present invention.

FIG. 3 is a flowchart showing the operation of a conventional air-fuel ratio control device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 hot water supply pipe 4 heat exchanger 5 gas burner 8 combustion fan 10 hot water supply control unit 11 fan control unit 12 gas supply pipe 13 gas proportional valve 15 fan rotation speed detection unit 16 fan drive current detection unit 17 correction control timer

Claims (2)

[Claims] 1. A heat exchanger for heating water flowing through a hot water supply pipe, a gas burner, a combustion fan for supplying combustion air, and a fan control unit for controlling a fan speed according to a combustion amount of a combustion unit. A gas supply pipe for supplying gas to the gas burner, and a gas proportional valve provided on the gas supply pipe,
An air-fuel ratio control device comprising a hot water supply control unit for controlling a degree of combustion of the gas burner by controlling an opening degree of the gas proportional valve and outputting a signal indicating a combustion amount of the gas burner to a fan control unit. In addition, a correction control timer is provided to limit the correction of the gas pressure with time, and the hot water supply control unit determines that the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | <Xrpm (X is a constant )
In this case, the gas pressure is not corrected and the correction control timer is reset. When the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | ≧ Xrpm (X is a constant), the gas pressure is reduced. When the correction is performed and a predetermined timer time by the correction control timer has elapsed, even if the rotation speed of the combustion fan continues to be | target rotation speed−actual rotation speed | ≧ X rpm (X is a constant), An air-fuel ratio control device configured to end the correction of the gas pressure. 2. A heat exchanger for heating water flowing through a hot water supply pipe, a gas burner, a combustion fan for supplying combustion air, and a fan control unit for controlling a fan speed according to a combustion amount of a combustion unit. A gas supply pipe for supplying gas to the gas burner, and a gas proportional valve provided on the gas supply pipe,
It is used in a hot water supply apparatus having a hot water supply control unit for controlling a degree of combustion of the gas burner by controlling an opening degree of the gas proportional valve and outputting a signal indicating a combustion amount of the gas burner to a fan control unit. An air-fuel ratio control device, wherein a correction control timer is provided to limit the correction of gas pressure in time, and the hot water supply control unit determines that the rotation speed of the combustion fan is | target rotation speed−actual rotation speed | < When Xrpm (X is a constant), the gas pressure calculated by the equation (1) is output, the correction control timer is reset, and the rotation speed of the combustion fan is | target rotation speed-actual rotation speed | ≧ Xrpm
When (X is a constant), the corrected gas pressure obtained by the equation (2) is output, and when a fixed timer time by the correction control timer elapses, for example, the rotation speed of the combustion fan becomes | target. An air-fuel ratio control device characterized in that even if the number of revolutions-the actual number of revolutions | ≧ X rpm (X is a constant), the output is returned to the gas pressure output according to the equation (1). P ₁ = a × G ² + b Expression (1) P ₂ = P ₁ + (actual rotation speed−target rotation speed) × α ÷ β Expression (2) P ₁ : gas pressure output data without correction G: required scale number a, b: gas calculation constants P _2: corrected gas pressure output data alpha, beta: correction factor