JPH0533925A - Method for controlling spray nozzle in burner - Google Patents

Abstract

PURPOSE:To obtain the title method wherein a spray nozzle is quickly shifted to a correct position even if there are transmission losses in a transmission line. CONSTITUTION:For a position of a spray nozzle 11 operated in correspondence with the required rate of combustion, the ideal number of steps by a step motor 12, which is a distance between the above-mentioned position and a reference position, is operated. As the amount of hysteresis, a median value of transmission losses in a transmission line 14 between the step motor and the spray nozzle is added to the ideal number of the steps, and thus the number of the steps can be obtained. The number of the steps is used as the number of the steps for feedforward control, and the spray nozzle 11 is shifted. The difference between the actual rate of the combustion and the required amount thereof, which difference is produced again as the result of the above process, is modified by feedback control.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for controlling a spray nozzle of a combustor.

[0002]

2. Description of the Related Art Conventionally, in a petroleum water heater or the like in which a combustion amount of a combustor is adjusted by controlling a position of a fuel spray nozzle to obtain a predetermined hot water temperature, a stepping motor is used to move the nozzle of the combustor section. Methods of using are known.

[0003]

However, in the above combustor, when the spray nozzle is driven by the stepping motor, the transfer system between the stepping motor and the spray nozzle suffers a transmission loss due to backlash or the like, so that the motor is running. It is not always easy to move the spray nozzle to the calculated accurate position because the spray nozzle is not moving. Moreover, since the transmission loss is not the same in each combustor, it is difficult to correct it.

Therefore, the present invention solves the above-mentioned drawbacks of the prior art, and provides a method for controlling a spray nozzle of a combustor which can quickly move the spray nozzle to an accurate position even if there is a transmission loss in the transmission system. With the goal.

[0005]

In order to achieve the above object, the method of the present invention comprises a fuel spray nozzle, a spray cut plate,
A stepping motor for moving the fuel spray nozzle forward and backward,
And a control unit with a built-in microcomputer for controlling each part of the combustor, wherein the amount of spray used for combustion is adjusted by changing the advancing / retreating position of the spray nozzle to obtain the required amount of combustion heat. In the method for controlling the spray nozzle in step 1, the ideal step number by the stepping motor from the reference position is calculated for the nozzle position calculated corresponding to the required combustion heat quantity, and the stepping motor and the spray are set to the ideal step number. The spray nozzle is moved with the number of steps, which is the median of the transmission loss in the transfer system between nozzles added as a hysteresis, as the number of steps in the feedforward control, and the difference between the actual combustion heat quantity and the required combustion heat quantity that is generated is corrected by feedback control. The first feature is that this is done. Further, the method of the present invention comprises at least a fuel spray nozzle, a spray cut plate, a stepping motor for moving the fuel spray nozzle forward and backward, and a control unit with a built-in microcomputer for controlling each part of the combustor, and the forward and backward position of the spray nozzle is set. A method of controlling the spray nozzle in a combustor in which the amount of spray used for combustion is adjusted to obtain the required amount of heat of combustion, by changing the nozzle position calculated corresponding to the required amount of heat of combustion. Then, the ideal number of steps from the reference position by the stepping motor is calculated, and the number of steps obtained by adding the transmission loss in the transmission system between the stepping motor and the spray nozzle as a hysteresis component to the ideal number of steps is used as the feedforward control step number. To move the difference between the actual combustion heat quantity and the required combustion heat quantity. As modified by Dobakku control, and and a value obtained by adding the number of steps that have been modified by the feedback control as the second, characterized in that the next hysteresis amount. Further, in the method of the present invention, in the second feature, when the value obtained by adding the number of steps corrected by the feedback control is not used as the next hysteresis amount, but the number of steps corrected by the feedback control is equal to or more than a certain value. The third feature is that the value obtained by adding the number of correction steps is used as the next hysteresis amount.

[0006]

According to the first feature described above, when the spray nozzle is feed-forward controlled, the stepping motor is rotated in a form that a hysteresis component consisting of the median of the transmission loss is added, so that the spray nozzle actually moves. Even if the position is a position that is deviated from the calculated position, the position does not deviate so much. Therefore, the amount of adjustment is reduced by the subsequent feedback control, and as a result, the spray nozzle can be quickly moved to a position where the required combustion heat amount is actually obtained. As the median value, a value near the center with respect to the minimum value and the maximum value of the variation of the transmission loss occurring in each transmission system of the combustor is experimentally obtained in advance and used. Further, according to the second feature, the number of steps corrected by the feedback control is added to the original hysteresis amount and is added to the next feedforward control amount as a new hysteresis amount, so that the learning effect is exhibited. The accuracy of the feedforward control is improved, the fitting time by the feedback control is shortened, and the tapping property is improved. Further, according to the third feature, in addition to the action of the second feature, it is added to the original hysteresis amount only when the number of steps corrected by the feedback control is equal to or more than a certain value. After the accuracy of the feedforward control is increased, the hysteresis is not corrected so much, so that the processing execution time is shortened.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings. 1 is a schematic overall configuration diagram of a water heater that implements the method of the present invention, FIG. 2 is a schematic configuration diagram of a combustor portion, FIG. 3 is a diagram illustrating the relationship between the number of steps of a stepping motor and the spray nozzle position, and FIG. Is a flowchart showing a method for carrying out the method of the present invention, FIG. 5 is a flowchart showing another method for carrying out the method of the present invention, and FIG. 6 is a flowchart showing a further method for carrying out the method of the present invention. Reference numeral 10 denotes a combustor having a fuel spray nozzle, which will be described later, and also serves as a blower fan 14. twenty one
Is a heat exchanger having a finned pipe 22 for heat exchange. A water inlet pipe 23 is connected to one end of the pipe 22, and a hot water outlet pipe 24 is connected to the other end of the pipe 22. A flow rate detector 25 and a water temperature detector 26 made up of a thermistor are installed in the water inlet pipe 23, and a hot water temperature detector 27 made up of a thermistor and a flow rate adjusting valve 28 are placed in the hot water outlet pipe 24. . The members 21 to 28 form the hot water supply unit 20. Reference numeral 30 denotes a control unit having a built-in microcomputer, and the output ends of the control unit 30 are connected to the output ends of the flow rate detector 25, the water temperature detector 26, and the hot water temperature detector 27 at the input end of the control unit 30. Are connected to the burner unit 10 and the respective input ends of the flow rate adjusting valve 28. A remote controller 40 is connected to the control unit 30.

A fuel spray nozzle provided in the combustor 10.
As shown in FIG. 2, the nozzle 11 can be moved forward and backward by a stepping motor 12 for moving a nozzle through a transmission means 14 which is a transmission system, and the spray cut plate 13 can be moved forward and backward depending on the forward and backward positions.
The amount of spray cut by is changed. That is, the amount of fuel spray supply actually used for combustion is adjusted by the advancing / retreating position of the fuel spray nozzle 11, whereby the heat of combustion is adjusted and the output number corresponding to the hot water supply condition set by the remote controller 40 is set. . In addition, the hot water discharge capacity of a water heater is expressed by the number of outputs, and 1 liter equals 1
The output number 1 is the ability to increase 25 ° C per minute.

Since the transmission means 14 has a backlash 15, etc., a transmission loss 1 occurs. This transmission loss l does not become the same in each combustor, but varies. Referring to FIG. 3, when moving the spray nozzle position from the reference position y ₀ to the target position y ₁ , if there is no transmission loss l, the stepping motor is moved from the reference position x ₀ to the step from x _1. It suffices to drive only a few x, but actually the transmission loss l
Therefore, it is necessary to rotate the step number (x + 1) obtained by adding the transmission loss 1 to the step number x. However, the transmission loss l varies in each combustor,
Not constant. This transmission loss l varies in various ways from the minimum value l _min to the maximum value l _max for many combustors. Therefore, if the median value l _cen with a large number of distributions is adopted, it is on average close to the target position y ₁ . The spray nozzle can be moved to the position. The first implementation method of the present invention described below is a method that takes such points into consideration.

The first method of automatically controlling the spray nozzle by the control unit 30 will be described with reference to FIG.
Now, when the hot water temperature is set by the remote controller 40, the required heat of combustion is calculated based on it, and the spray nozzle position is further calculated, the ideal number of steps x from the current position (reference position) is first calculated based on that. Then, the median value l _cen of the transmission loss 1 in the transmission means 14 obtained in advance by the experiment is used as the hysteresis component h to calculate the feedforward (FF) step number (x + h) (step 52). And the stepping motor is set to F
F number of steps (x + h) feed forward (F
F) Control (step 53). Then, after that, the difference between the set hot water temperature (required combustion heat quantity) and the actual hot water temperature (actual combustion heat quantity) is detected, and the hot water temperature (actual combustion heat quantity) is adjusted by the control amount proportional to the difference. Feedback (FB) control is performed until the heat quantity is reached (steps 54 and 55).
. By performing the control as described above, the moving position of the spray nozzle by the FF control does not deviate so much even if it deviates from the calculated target position.
Therefore, the amount to be adjusted (corrected) is reduced by the subsequent FB control, and as a result, the spray nozzle can be quickly moved to a position where the required combustion heat amount can be obtained.

Next, a second implementation method of the automatic control method of the spray nozzle according to the method of the present invention will be described with reference to FIG. When the hot water temperature is set by the remote controller 40,
At 30, the required heat of combustion is calculated, the spray nozzle position is further calculated, and the ideal step number x from the current position (reference position) is first calculated (step 61). Next, the hysteresis amount h such as the transmission loss 1 in the transmission means 14 is added to calculate the FF step number (x + h) (step 62). As the hysteresis amount h, the minimum value l _min of the transmission loss l is adopted at the very beginning of the operation. The minimum value l _min is set to the minimum value by selecting a value near the minimum value from the transmission loss distribution obtained experimentally in advance. Then, the calculated FF step number (x
After storing + h) (step 63), the stepping motor is feed-forward controlled by the FF number (x + h) (step 64). Then, after that, the difference between the set hot water temperature (required combustion heat quantity) and the actual hot water temperature (actual combustion heat quantity) is detected, and the hot water temperature (actual combustion heat quantity) is adjusted by the control amount proportional to the difference. Perform feedback control until the heat quantity is reached (steps 65 and 66).

When the hot water outlet temperature reaches the set temperature in step 65, the correction step number in the FB control is calculated from the FF step number and the final step number, and the obtained correction step number is set to the current hysteresis amount h. In addition, a new hysteresis amount h is stored (step 67). Therefore, in the next operation, the FF step number is calculated using the new hysteresis amount h. By performing the control as described above, the value of the hysteresis amount added to the ideal number of steps is corrected to a more appropriate value for the combustor, so that the accuracy of the FF control is gradually improved and the hot water discharge characteristic is improved. Will get better. Of course, the FB control amount becomes small, and the adjustment time becomes short.

Next, a third implementation method of the spray nozzle automatic control method according to the method of the present invention will be described with reference to FIG. This implementation method is almost the same as the second implementation method, except that F
The handling of the number of correction steps by B control is slightly different. That is, in FIG. 6, the FF control and the FB control from steps 71 to 76 are the control of the second embodiment method (from step 61 to
(Up to 66). The difference is that it is determined whether the number of correction steps calculated at the time when the hot water temperature reaches the set temperature by the FB control is a constant value a or more (step 77). Only when the correction step number is a constant value a or more, the correction step is performed. The point is that the number is added to the current hysteresis amount and this is newly stored as the hysteresis amount (step 79). If the value is less than a certain value a, the current one will be continuously used. By doing so, it is possible to shorten the processing execution time because the hysteresis is not always corrected in terms of software. The constant value a is
Predetermine an appropriate value.

[0014]

According to the present invention, which has the above-described structure,
According to the spray nozzle control method for the combustor described in (1), the number of steps obtained by adding the median value of the transmission loss in the transmission system between the stepping motor and the spray nozzle to the ideal number of steps as the hysteresis amount is taken as the feedforward control step number. , FB control reduces the amount of adjustment, and as a result, the spray nozzle can be quickly moved to a position where the required combustion heat amount is actually obtained. Further, according to the spray nozzle control method of the combustor according to the second aspect, the number of steps corrected by the FB control is added to the original hysteresis amount and used as the new hysteresis amount for the next FF control amount calculation. Thus, the learning effect is exerted, the accuracy of FF control is improved, the fitting time by FB control is shortened, and the hot water discharge characteristics are improved. According to the spray nozzle control method of the combustor of claim 3, in addition to the effect of the configuration of claim 2, the original hysteresis is obtained only when the number of steps corrected by the FB control is a certain number or more. Since the FF control accuracy is improved, the hysteresis is not corrected so much, so that the processing execution time can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic overall configuration diagram of a water heater embodying the present invention.

FIG. 2 is a schematic configuration diagram of a combustor.

FIG. 3 is a diagram illustrating a relationship between the number of steps of a stepping motor and a spray nozzle position.

FIG. 4 is a flowchart showing a method of implementing the method of the present invention.

FIG. 5 is a flowchart showing another implementation method of the method of the present invention.

FIG. 6 is a flowchart showing another method for carrying out the method of the present invention.

[Explanation of symbols]

10 Combustor 11 Fuel spray nozzle 12 stepper motor 13 Spray cut plate 14 Blower fan 20 Hot water supply 30 Control unit

Claims (3)

[Claims] 1. A fuel spray nozzle, a spray cut plate, a stepping motor for moving the fuel spray nozzle forward and backward, and a control unit with a built-in microcomputer for controlling each part of the combustor, and changing the forward and backward position of the spray nozzle. By the method of controlling the spray nozzle in the combustor to adjust the amount of spray provided for combustion to obtain the required heat of combustion by the nozzle position calculated corresponding to the required amount of heat of combustion, Calculate the ideal number of steps from the reference position by the stepping motor, and add the median value of the transmission loss in the transmission system between the stepping motor and the spray nozzle as a hysteresis to the ideal number of steps as the feedforward control step number. Move the nozzle to check the difference between the actual combustion heat quantity and the required combustion heat quantity. A method for controlling a spray nozzle of a combustor, characterized in that correction is made by feedback control. 2. A fuel spray nozzle, a spray cut plate, a stepping motor for moving the fuel spray nozzle forward and backward, and a control unit with a built-in microcomputer for controlling each part of the combustor, and changing the forward and backward position of the spray nozzle. By the method of controlling the spray nozzle in the combustor to adjust the amount of spray provided for combustion to obtain the required heat of combustion by the nozzle position calculated corresponding to the required amount of heat of combustion, Calculates the ideal number of steps from the reference position by the stepping motor, and moves the spray nozzle by using the number of steps obtained by adding the transmission loss in the transfer system between the stepping motor and the spray nozzle as a hysteresis amount to the feedforward control step number. The difference between the actual combustion heat quantity and the required combustion heat quantity So that you can correct it by
A method of controlling a spray nozzle of a combustor, wherein a value obtained by adding the number of steps corrected by the feedback control is set as a hysteresis amount for the next time. 3. A value obtained by adding the correction step number only when the step number corrected by the feedback control is equal to or more than a certain value, instead of using all the values obtained by adding the step number corrected by the feedback control as the amount of hysteresis for the next time. 3. The method for controlling a spray nozzle of a combustor according to claim 2, wherein is defined as a hysteresis amount for the next time.