JPH0221235B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a combustion control device for a water heater, etc., and is a combustion control device for supplying an amount of air to a combustion section according to the amount of combustion required from time to time. The present invention relates to a fan motor control and abnormality detection method that is optimal for a combustion device having a fan motor rotation control system.

[Prior art] Modern combustion devices for water heaters detect the temperature and amount of water supplied, as well as the temperature of the hot water being tapped, and based on these data, set the hot water temperature to the user's set temperature. Increasingly, the number of devices equipped with a main control device that controls the temperature as close as possible to .

Therefore, in such a combustion engine, the amount of air supplied to the combustion section must be optimally controlled according to the required combustion amount determined from time to time as described above. Otherwise, not only will the combustion efficiency be reduced, but there will also be a risk of incomplete combustion. That is, this means that a feedback type control system is required that can also control the rotation of the fan motor with high precision.

Conventionally, fan motor feedback control systems have been adopted for this reason, but most of these feedback control systems only use the principle of feedback control itself;
The set rotation speed data (target rotation speed data) sent from the main control circuit is compared with the actual rotation speed data sent back from the fan motor via an appropriate rotation sensor, and the A closed loop is formed in which a correction is made to compensate for the amount of deviation, resulting in corrected or updated set rotation speed data, and this data is again sent to the fan motor drive circuit.

On the other hand, for safety reasons, it is also necessary to have a means to detect when the fan motor can no longer be controlled by the feedback control described above, that is, when an abnormal rotation occurs in the fan motor. However, in the past, this information was extracted separately from the rotation speed sensor that captures the actual rotation speed of the fan motor, and the actual rotation speed of the fan motor was determined by simply setting the minimum allowable rotation speed and maximum allowable rotation speed. The only thing left to do was to detect whether or not it was within that range.

[Problem to be Solved by the Invention] However, simply multiplying the correction by an amount corresponding to the deviation between the set rotational speed data and the actual rotational speed data at each time as in the past, the response time will not change due to the deviation. The amount changes proportionally, and the larger the deviation amount,
It takes a long time until the rotational speed of the fan motor is drawn into an allowable range that can be considered to be substantially the same as the set rotational speed.

This is highly undesirable. The greater the amount of deviation, the higher the probability of generation of harmful gases, and the greater the reduction in combustion efficiency.Conversely, it is difficult to maintain the rotation of the fan motor within the allowable range for the set rotation speed in such a short period of time. Because it has to be done.

In spite of this, conventionally, there is no control system configured with these points in mind.

Furthermore, detection of abnormal rotation of the fan motor has traditionally been treated as a completely separate and independent issue from fan motor rotation speed control, and in some cases, circuit systems that can be shared are also separately provided. At the very least, no one has tried to rationally use the means for control to detect anomalies.

Moreover, as mentioned above, the method merely sets the minimum allowable rotation speed and maximum allowable rotation speed and detects whether or not the actual fan motor rotation speed is always within this range. In some cases, even though the fan motor was actually rotating at an inappropriate rotation speed, this could not be detected.

This is because the permissible fan/motor rotational speed fluctuation range for each set rotational speed is actually quite narrow, and if the set rotational speed changes, this permissible fluctuation range also changes accordingly. Even if it is within the minimum and maximum tolerance range as above,
Depending on the set rotation speed, the fan may turn off at an inappropriate rotation speed.
This is because the motor may be spinning.

In response to this conventional situation, the present invention provides an additional correction system in addition to the correction by the normal closed-loop feedback control system, so that the amount of correction can be increased as the deviation becomes larger. In addition, considering the size of this additional correction amount, abnormalities in the fan motor that deviate from the permissible fluctuation range for the set rotation speed at each time and are rotating at an inappropriate rotation speed or are stopped. We also attempted to detect this.

[Means for Solving the Problems] In order to achieve the above object, the present invention determines the magnitude of the deviation by controlling the feedback control system to adjust the fan motor to the target set rotation speed after the deviation occurs. We focused on the fact that it is proportional to the length of time it takes to settle down.

Therefore, when a deviation larger than the planned size is detected, the deviation is gradually adjusted according to the elapsed time from the time of detection.
The amount of additional correction was increased and this was superimposed on the currently set rotational speed data by the feedback control system.

Furthermore, in the present invention, in view of the magnitude of the additional correction amount itself in terms of absolute value, if the additional correction amount continues to increase gradually due to changes over time as described above and reaches a predetermined size, Juan
It is now determined that an abnormal rotation has occurred in the motor.

In summary, in the present invention, in order to match the rotation of the fan motor with the set rotation speed at each time, the main control circuit uses feedback control to adjust the actual rotation speed and the set rotation speed of the fan motor at each time. In a combustion control device that sends data that has undergone main correction to compensate for the deviation from As a fan motor control and abnormality detection method that simultaneously detects rotational abnormalities of the fan motor, the fan motor set rotation speed at any given time is sent from the main control device and subjected to the main correction. Monitor the amount of deviation between the data and the actual rotation speed data of the fan motor at that time; If the amount of deviation exceeds the expected size, it will increase according to the elapsed time from the time when this was detected. Create additional correction amount data; Depending on whether the fan motor control at that time is acceleration control or deceleration control, apply the above additional correction amount data to the main correction set rotation speed data. While superimposing data in either the positive or negative direction; If the deviation amount falls within the scheduled size, stop superimposing the additional correction amount data; and When the size reaches the specified size,
Provided is a method characterized by: determining that an abnormality has occurred in a fan motor.

In addition, when increasing the deviation amount data from the time when the deviation amount exceeding the planned size is detected, the method of increase may be analog, continuous, digital,
It may be done in stages.

[Function] In the present invention, as evident from the above configuration,
If the rotation speed of the fan motor falls within the tolerance range of less than the planned deviation from the set rotation speed data, even if feedback control is performed by the existing feedback control system, it will deviate from the tolerance range and exceed the planned deviation. In this case, an additional correction amount data changing circuit or the like is used to convert the passage of time into an increase in additional correction amount data, and the additional correction amount data, which is temporarily increased in the absolute value thus generated, is controlled by the main feedback control system. It can be superimposed on the set rotation speed data.

Therefore, even in situations where the amount of deviation is large and the response time would be proportionally longer if only the normal main feedback control system were used, the correction amount will increase in absolute value as time passes, so the amount of deviation will be reduced. As in the case where is small, the actual fan motor rotation speed can be quickly brought to the set rotation speed.

In addition, even if there is a long-term fluctuation in the power supply voltage and the fan motor cannot be brought to the set rotation speed with only correction by the main feedback control system, the additional correction amount will be temporarily increased, so it will be forcibly allowed. It can be pulled within the rotation speed fluctuation range.

On the other hand, even though the additional correction amount gradually increases over time, the deviation amount does not fall within the expected range, so the additional correction amount itself reaches a predetermined size. If this occurs, the present invention determines that an abnormality has occurred in the fan motor.

In other words, the more the additional correction amount increases,
The fact that over time the fan motor speed still does not fall within the range that can be controlled by basic feedback control alone means that the fan motor will run at a speed that is undesirable for combustion. This means that the time for which the light is on or off becomes longer, which is by no means desirable for safety reasons, so it is better to determine that there is an abnormality after a certain amount of time has elapsed. It is becoming more and more satisfying.

[Embodiments] Various circuit systems for carrying out the method of the present invention can be assembled using existing electronic circuit technology. FIG. 1 shows an example of a desirable configuration selected from among these, but before explaining this additional correction circuit 10, we will first explain the main feedback control system and combustion control system related to the fan motor. Reference will be made to FIG. 4 in order to also explain other control modes and device outlines of existing water heaters of this type, such as combustion section control associated with quantity determination.

When the main control circuit 1 receives a water quantity signal S6 from a water quantity sensor 6 provided in the water supply channel, it sends a set temperature signal Ss that commands the hot water temperature desired by the user, and a water supply temperature sensor 7 provided in the water supply channel. The water supply temperature signal S7 from the hot water outlet and the outlet hot water temperature signal S8 from the outlet hot water temperature sensor 8 provided in the outlet path for detecting the actual outlet temperature are respectively taken in, and from these signals, the combustion part such as a gas burner etc. Calculate the amount of combustion that should be given to 3.

Then, according to the result, the gas proportional valve control signal S4 is sent to the gas proportional valve 4 to control the fuel gas supply amount, and the air supply amount corresponding to the combustion amount or the fan motor setting rotation speed data is controlled. , fan motor rotation control signal Sc to fan motor 5
Send out.

From the fan motor 5, fan motor rotation speed data Frpm indicating the actual rotation speed is fed back to the main control circuit by attaching an appropriate sensor to the fan motor 5, and this actual rotation speed data and the previously set rotation are fed back to the main control circuit. Feedback control is performed according to the deviation from the numerical data.

In addition, if the combustion amount calculated above exceeds the capacity of the gas burner, the main control circuit 1
A water flow valve control signal S9 is output from the water flow valve 9, and upon receiving this signal, the water flow valve 9 controls the hot water outlet path to regulate the hot water flow rate.

Next, to explain in more detail the main feedback control system that can be used with the existing configuration shown in Fig. 1, the main control circuit 1
From there, fan motor set rotational speed data corresponding to the air supply amount according to the combustion amount calculated and determined from time to time as described above is sent as a voltage signal Vso.

In the existing configuration, there is no arithmetic unit 19 shown in the figure, and this fan motor set rotation speed data Vso
is connected to the fan motor 5 via a suitable drive circuit 11.
It is converted into a set rotation speed frequency signal or a set rotation speed power signal Sc that is convenient for driving the fan.
The signal is sent to the motor 5 to control it.

On the other hand, actual rotational speed data is sent from the fan motor 5 via an appropriate rotational speed detection sensor attached thereto, but as already mentioned with reference to FIG. often takes the form of a rotational speed versus frequency conversion signal Frpm.

Therefore, since each signal is generally treated as a voltage-dimensional signal, the frequency-converted actual rotational speed data Frpm is further converted into corresponding voltage-dimensional rotational speed data by an appropriate F/V converter 12.
Converted to Vrpm.

In the fan motor main feedback control system by the main controller 1, this actual fan motor rotation speed data Vrpm and the above set rotation speed data at that time are used.
Vso is compared, and correction is made according to the amount of deviation to create corrected or updated set rotational speed data Vso, and this data is used to control the fan motor again.

If the fan motor control method of the present invention is incorporated in addition to the main feedback control system, which may have an existing configuration, the configuration shown by the additional correction circuit 10 in FIG. 1 can be adopted.

First, based on the fan motor set rotational speed voltage signal Vso sent from the main control circuit 1 at any given time, in order to define a minute deviation amount range that can be left only to the control of the main feedback control system, that is, an allowable range.
The upper critical value Vupr and lower critical value Vlwr of the range are created.

This includes, for example, the first potentiometer P1 for forming the upper critical voltage value Vupr and the lower critical voltage value Vupr.
This can be easily done by using the second potentiometer P2 for Vlwr formation. Therefore, of course, if the tolerance range that does not require additional correction according to the present invention is an equal tolerance range above and below the center value, then the center value Vctr=
(Vupr+Vlwr)/2 corresponds to the voltage value at the set rotation speed.

The upper limit critical voltage value (hereinafter simply referred to as upper limit value) Vupr thus created is applied to the positive phase input of the upper limit value comparator CMP1, and the lower limit value Jlwr is applied to the positive phase input of the lower limit value comparator CMP2.

On the other hand, the fan motor rotation speed voltage signal Vrpm from the F/V converter 12 is input to each negative phase input of both comparators CMP1 and CMP2. Adjustment is made so that the rotational speed data Vrpm value when the rotational speed is correctly rotated at the set rotational speed corresponds to the above-mentioned center value Vctr. This adjustment can be done using the first and second potentiometers P1 and P2 mentioned above.
Although not shown in the diagram, actual fan
This can also be done by attaching a potentiometer to the motor rotational speed voltage signal Vrpm.

Of course, by adjusting each of these potentiometers, it is also possible to specify different deviation widths for the upper and lower sides even within the tolerance range that does not require additional correction, or by intentionally narrowing this range to an extremely small deviation amount. It is also possible to set only the range to be left to the control of the main control system, and to operate the additional correction system to be described later most of the time when a significant value occurs.

The outputs of both comparators OMP1 and CMP2 are both connected to each input of an exclusive OR gate (EX.OR) 15, and the output of the exclusive OR gate 15 is connected to a resistor R via a switching element 16. and the additional correction amount data changing circuit 17, which is simply formed by the capacitor C, is selectively activated. Also, the switching element 16 is again constituted by an npn type transistor in this case, and therefore the exclusive OR gate 1
When the exclusive OR is obtained in 5, it is in the on state.

As can be seen from the above configuration, the actual fan motor rotation speed voltage signal Vrpm at that time
is between the upper limit value Vupr and the lower limit value Vlwr at that time, the output of the upper limit comparison circuit CMP1 is logic "H" and the output of the lower limit value comparison circuit CMP2 is logic "L". Exclusive OR gate 1
The output of No. 5 (point a in the figure) is logic "H".

Therefore, the transistor 16 remains on, and in this circuit example, the additional correction amount data change circuit 1
Since both ends of the capacitor C in 7 are short-circuited, the additional correction amount data signal Vm, which is the potential at both ends, is also transformed into a voltage dimension and is zero.

Therefore, in this circuit system, a computing unit 19 is provided in order to selectively superimpose additional correction amount data on the set rotational speed data Vso issued by the main control circuit 1. When the exclusive OR gate 15 performs an exclusive OR, that is, when the output of the upper limit comparator CMP1 is logic "H" and the output of the lower limit comparator CMP2 is logic "L", it is equivalent. Pass the set rotation speed data Vso.

Therefore, as described above, even if a deviation occurs, it is left to the feedback control by the main control circuit 1 only in the minute deviation amount range that is predetermined from time to time by the upper and lower critical values.

However, the set rotation speed data Vso sent from the main control circuit 1 changes, and the actual rotation of the fan motor 5 does not catch up with this change during the feedback control response transition period, or some other disturbance occurs. etc.,
Actual rotation speed of fan motor 5 at that time Vrpm
exceeds the upper limit of the allowable range Vupr at that time, or
When the range falls below the lower limit value Vlwr, the output of the exclusive OR gate 15 is inverted to logic "L". This point is indicated as time to in FIG.

Then, the transistor 16, which had been on until then, is turned off, and the additional correction amount data changing circuit 17 is activated. Specifically, in this case, charging of the capacitor C by the power supply potential Vcc starts via the resistor R, and the additional correction amount data Vm, which is the potential across the capacitor C, changes in potential with a time constant RC as shown in Figure 2. begins to increase.

When the output of the upper limit comparator CMP1 is "L" in a state in which the rotational deviation amount of the fan motor 5 deviates from the non-additional correction range or the allowable range, that is, the rotation deviation amount of the fan motor 5 is If the rotation speed Vrpm is higher than the set rotation speed data Vso and deceleration control is required, set rotation speed data
If the additional correction amount data Vm is subtracted from Vso and the output of the lower limit value comparator CMP2 is "H", that is, the rotation speed Vrpm of the fan motor 5 is lower than the set rotation speed data Vso, and acceleration control is performed. If necessary, add correction amount data to set rotation speed data Vso
Add Vm.

For example, the actual rotation speed Vrpm of the fan motor 5
If it is assumed that
Acceleration control for the fan motor 5 is accelerated to quickly bring the rotational speed of the fan motor 5 into an allowable range.

As a result, if the pull-in into the tolerance range is completed at time t1 in FIG. 2, the output a of the exclusive OR gate 15 is again inverted to logic "H".
Turn on transistor 16.

Then, both ends of the capacitor C in the additional correction amount data changing circuit 17, which had been charged up to that point, are quickly short-circuited and reset to the initial state, so that the additional amount data Vm also becomes zero in terms of potential. The arithmetic unit 19 also becomes an equivalent passing mode of the set rotational speed data Vso, and the corrected data Vc becomes the set rotational speed data Vso sent out from the main control circuit 1 itself.

The above operation is the same when controlling the deceleration of the fan motor 5, except that the direction in which the additional correction amount output Vm is superimposed on the set rotational speed data Vso in the calculator 19 is different from positive to negative.

Further, by using the additional correction amount data changing circuit 17 like this circuit example, abnormal rotation of the fan motor can also be detected.

For example, if the fan motor rotation speed Vrpm, which is out of the allowable range, does not fall within the allowable range even after applying the additional correction according to the method of the present invention described above, each As the signal is shown by a virtual line, the potential across the capacitor, that is, the additional correction amount data Vm, continues to increase in terms of potential, so if this potential increase is monitored by the inverter 18 with an appropriate threshold value Etho, the logic "H" is normally reached. However, when an abnormality is detected, an abnormality detection signal Sa that falls to logic "L" can be obtained.

When this abnormality detection signal Sa is issued,
In general, the main control circuit 1 can be used to stop combustion in the combustion section and/or cut off fuel supply.

Therefore, it can be seen that the additional correction amount data changing circuit 17 shown in FIG. 1 functions as a timer circuit for detecting abnormal rotation of the fan motor 5.
In other words, even if a certain amount of time is accepted as the margin time Tx, if it still does not fall within the allowable range, the abnormality is detected as the time up of the timer as shown at time t2. can do.

Such an abnormality detection circuit is extremely effective in itself. In the past, only two points were determined: the maximum permissible fan motor rotation speed and the minimum permissible fan motor rotation speed, and everything within that range was considered normal. In many cases, the permissible fan/motor rotational speed fluctuation range is relatively narrow, and if the set rotational speed changes, the relatively narrow permissible fluctuation range also changes accordingly. - It was not possible to detect that the motor was rotating at an inappropriate speed.

On the other hand, if the abnormality detection circuit as shown in Figure 1 is used, it is possible to determine the permissible range for each set rotation speed at any given time, and therefore it is possible to prevent defects that may cause a decrease in combustion efficiency or even incomplete combustion. Proper fan motor rotation will allow this to be detected quickly.

In the above embodiment, the additional correction amount data changing circuit 17
is configured as a simple RC timer circuit type, but
In addition, it can also be configured using a counter. That is, the time is discretely counted from the time when the deviation of the fan motor rotation speed data Vrpm from the allowable range of the set rotation speed data Vso is detected, and the correction amount data Vm that increases in absolute value according to the counted value is calculated. You can also create one yourself. Of course,
As mentioned earlier, the additional correction amount data Vm that increases in absolute value may also be a discrete amount instead of a continuous amount.

Furthermore, the additional correction circuit 10 for realizing the method of the present invention can be constructed by utilizing the built-in registers, timers, and counters of a microcomputer that is generally used as the main control circuit 1, and by programming an appropriate program. It is also possible to configure it in the same state as when it was assembled in terms of hardware.

Figure 3 shows a flow chart for such a case.

When the control in the microcomputer as the main control circuit 1 reaches the FAN control routine, the fan motor set rotation speed data (SETRPM) corresponding to the combustion amount at that time and the input from the fan motor are input. The difference from the rotational speed data (EANRPM) is calculated, and this data is stored in the register as rotational speed deviation amount data (DIFRPM).

Next, it is determined whether the absolute value 1 (DIFRPM) of this rotational speed deviation data (DIFRPM) is larger than a predetermined minute deviation amount range, that is, the above-mentioned tolerance range α, and if it is smaller, the timer means Clear the contents of the counter (COUNTR) used as
If so, this routine ends.

Although it is smaller than the allowable range α, there may be a deviation, and if the content of (DIFRPM) is not “O”, the previous corrected data will have a positive or negative value depending on whether the control mode is acceleration or deceleration. This routine is completed by adding a small correction in the direction of , creating the current corrected data, and outputting it to the fan motor drive circuit. The above is substantially the same as when the existing feedback control system is used as the main feedback control system and control is performed only by this system.

However, the absolute value of the rotation speed deviation | (DIFRPM) |
is larger than the allowable range α, the counter content (COUNTR) is incremented by "1", and it is determined whether the value in the counter is equal to "N". This "N" is a predetermined number of times of correction, and corresponds to the time Tx from the additional correction start time to in FIG. 2 to the time up at time t2 in the first illustrated circuit system. Therefore, if the counter content (COUNTR) is equal to "N", for example, combustion is stopped to ensure safety.

If the counter content (COUNTR) is not equal to “N”, the corresponding counter content (COUNTR)
Calculate the additional correction value according to the additional correction value table, or read the corresponding additional correction value from the additional correction value table, store it in the register (CNTCOM), and calculate the main correction value according to the contents of (DIFRPM). or derived and stored in the (DIFCOM) register.

In this way, the contents of (CNTCOM) and (DIFCOM) are added to obtain correction data (COMPEN), which manipulates the previous corrected data in a predetermined direction and outputs it to the fan motor drive circuit. End the routine.

Of course, the correction associated with the contents of the correction number counter described above may be performed based on the time value measured by the timer.

[Effects of the Invention] According to the present invention, the fan motor can be optimally controlled. In particular, the larger the actual rotation speed of the fan motor deviates from the set rotation speed data or target rotation speed, the larger the correction amount will be in absolute value as time passes, so even if the deviation amount is large, it is still within the allowable range. It doesn't take a long time to get drawn into it.

On the other hand, if the rotation speed of the fan motor does not fall within the expected range that does not require additional correction, no matter how much additional correction is made over time, there is an abnormality in the fan motor. Since it can be determined that a
Unlike dangerous methods that assume that everything is normal if it is within the maximum set rotation speed, even if the set rotation speed changes,
In other words, the same rotation speed tolerance range can be provided at any set rotation speed.

Therefore, the release of gases harmful to the human body can be prevented with a high degree of certainty, and combustion efficiency can also be maintained at a good level.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram of an example of a circuit for carrying out the method of the present invention, Fig. 2 is a waveform diagram of the main parts of the signals in Fig. 1, and Fig. 3 is a diagram of realizing the method of the present invention using a microcomputer. FIG. 4 is a flow chart for a case in which the present invention is applicable. In the figure, 1 is the main control circuit, 2 is a heat converter, 3 is a combustion part such as a gas burner, 4 is a gas proportional valve, 5 is a fan motor, 6 is a water flow sensor, 7 is a feed water temperature sensor, and 8 is a A hot water temperature sensor 10 is an additional correction circuit as a whole in a circuit implementing the method of the present invention; 1
1 is a fan motor drive circuit, 12 is an F/V converter, 15 is an exclusive OR gate, 17 is an additional correction amount data change circuit, 18 is an inverter, P
1, P2 is potentio meter, CMP1, CMP
2 is a comparator.

Claims (1)

[Claims] 1. In order to match the rotation speed of the fan motor with the set rotation speed at each time, the main control circuit uses feedback control to adjust the actual rotation speed of the fan motor at each time and the set rotation speed. The data with the main correction to compensate for the deviation is used as the new set rotation speed data for the fan.
A fan motor control and abnormality detection method that superimposes the main correction set rotation speed data on the combustion control device that sends data to the motor, provides additional correction, and also detects abnormal rotation of the fan motor. and; the amount of deviation between the fan motor set rotation speed data sent from the main controller and subjected to the main correction at each time and the actual fan motor rotation speed data at that time; Monitor; If the deviation amount exceeds the planned size, create additional correction amount data that increases according to the elapsed time from the time when this is detected; The fan motor control at that time is acceleration control. The above-mentioned additional correction amount data is superimposed on the above-mentioned main corrected setting rotation speed data in either the positive or negative direction depending on whether the above-mentioned deviation amount is within the above-mentioned planned size. If the above-mentioned additional correction amount data increases over time, the superimposition of the additional correction amount data is stopped; and when the size of the above-mentioned additional correction amount that increases over time reaches a predetermined value, it is determined that an abnormality has occurred in the fan motor. A fan motor control and abnormality detection method for a combustion control device, characterized by: