JPS58102026A - Combustion controller for boiler - Google Patents

Abstract

PURPOSE:To control overshoot and undershoot by improving delay in the response with increase or decrease of the gain of a control circuit in a combustion controller according to alteration of the amount of hot water to be fed. CONSTITUTION:A fluidity state detector 10 detects variation in the amount of water passing through a heat exchanger 9. In response to the detection signal of the detector 10, a gain switching circuit 19 changes the gain of a PID arithmetic circuit 18 according to increase or decrease in the amount of water in such a manner as to reduce it when the amount of water is at a low level while to enhance it when it is at a high level. The variation in the amount of water is detected immediately with the fluidity detector 10 before the detection of the temperature of hot water fed with a temperature sensor 12 to alter the gain of the PID arithmetic circuit 18. This regulates the flow control valve 5 at a given opening to control the combustion of a burner 2 according to the variation in the amount of water thereby minimizing changes in the temperature of hot water fed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in combustion control devices for combustion equipment such as water heaters.

In recent years, water heaters have been developed by detecting the temperature of hot water coming out of a heat exchanger, determining the deviation from an arbitrarily set target temperature, and controlling the flow rate control valve installed in the fuel supply path according to the deviation. Some devices have appeared that are equipped with a combustion control device that operates to maintain the hot water temperature at a target temperature regardless of changes in the used WA temperature or water temperature.

In this way, in this type of water heater, the detected water temperature is set at wAr.
! Because feedback control is performed to match I, unlike water heaters that have been widely used in the past, where the combustion control ability is constant or can only be changed in stages, water temperature and output
This has the great effect of consistently providing hot water at the desired temperature regardless of changes in i.

However, this type of water heater is used with frequent changes in the amount of hot water that comes out, and the temperature of the hot water that comes out changes accordingly. The flow control valve is actuated based on the deviation caused by the change in output maim. That is, in principle, there is a response delay in the control operation of this combustion control device. Changes in the aim degree during this response delay time can be practically ignored if the change in the amount of hot water dispensed is slow, but
If the change is sudden, there will be a sudden temperature rise (overshoot) or temperature drop (undershoot).In particular, the overshoot that occurs when changing from the high hot water output side to the low hot water output side is not practical. This has become a problem that cannot be ignored.

This invention was made focusing on the above problems,
The purpose of this is to significantly improve the response delay mentioned above, suppress overshoot and undershoot, and achieve relatively stable and uniform hot water output over the entire range of hot water output. The purpose of the present invention is to provide a control device.

In order to achieve the above object, the present invention is characterized in that the gain of the control circuit in the combustion control device is configured to increase or decrease in response to changes in the amount of hot water dispensed.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a diagram showing the basic configuration of a water heater equipped with a combustion control device according to the present invention.

In the figure, the fuel supply path leading to the burner 2 in the main body 1 of the water heater includes an electromagnetic switching valve 3 that turns on and off the supply of fuel. A governor 4 and a flow control valve 5 for adjusting the fuel basin are provided, and an igniter 6 for generating an ignition spark in conjunction with the burner 2 and a flame detector 7 for detecting whether or not the ignition is normally ignited by the ignition operation are provided. It is also equipped with an alarm device 8 that issues an alarm in the event of an abnormality such as when normal ignition has not been achieved.

At the water inlet leading to the heat exchanger 9, there is a flow state detection device 10 for detecting the flow state of the water flow passing through the heat exchanger 9.
However, a temperature sensor 12 such as a thermistor for detecting the degree of am output is provided on the outlet side.

The fluid state detection device 10 detects that when the faucet is opened, the amount of water passing through the heat exchanger 9 has reached the minimum operating amount required for the water heater to operate, and also detects that the amount of water passing through the heat exchanger 9 has reached the minimum operating amount required for the water heater to operate. This is a device that detects in stages when the amount of water in the water bottle has reached a predetermined amount that is greater than or equal to the minimum operating water pot.

Further, a combustion control device 13 that controls the temperature of the water heater to be constant is a combustion sequence control circuit 14 and a combustion sequence control circuit 14.
It consists of a hot water temperature control circuit 15, and the combustion sequence control circuit 14 includes a 3° electromagnetic switching valve, 6. Flame detector7. Each element such as the alarm device 8 is connected. Further, the mm control circuit 15 includes a flow plow control valve 5. I! Each element such as temperature sensor 12 and temperature setting device 16 is connected, and the minimum operating water pot detection signal of the flow state detection device 10 is sent to the combustion sequence control circuit 14 as a starting signal, and the change water pot signal is sent to the S temperature control circuit. 15 respectively.

The hot water m11 control circuit 15 includes a deviation detection circuit 17 that generates a deviation signal from the temperature signal detected by the temperature sensor 12 and the target temperature signal from the target temperature setting device 16, and a PrDili calculation circuit that outputs a predetermined control amount from this deviation signal. circuit 18 and the heat exchanger 9 detected by the flow state detection device 10
a gain switching circuit 19 that switches the gain of the PID calculation circuit 18 in response to a changed water volume signal passing through the circuit; and a valve drive circuit 20 that adjusts the valve opening of the flow rate control valve 5 to a predetermined opening according to the output of the PID calculation circuit 18. It is made up of.

What should be noted here is that the flow state detection device @10 detects a change in the amount of water passing through the heat exchanger 9, and this detection signal causes the gain switching circuit 19 to change the gain of the calculation circuit 18 (P11) to indicate that the water amount is low. When it is on the water volume side, it is small, and when it is on the water volume side, it is large, so it changes according to the increase or decrease in water volume. That is, before the temperature sensor 12 detects the output S temperature that has changed due to an increase or decrease in the amount of water,
An increase or decrease in the amount of water is immediately detected by the flow state detection device 10.
Since the gain of the ID calculation circuit 18 is changed and the flow rate control valve 5 is adjusted to a predetermined valve opening degree, the combustion of the burner 2 is controlled as the amount of water increases or decreases, and changes in the outlet temperature are suppressed to a minimum. Ru. Therefore, control response delay is significantly improved, and the above-mentioned overshoot and undershoot are also suppressed.

This will be explained next.

Now, when one faucet is opened and water flow is detected by the flow state detection device 10, the combustion sequence control circuit 14 is driven and the electromagnetic switching valve 3 is opened. At the same time P
The gain of the ID calculation circuit 18 is set to a predetermined value according to the amount of water by the gain switching circuit 19, and the water temperature detected by the temperature sensor 12 and the target I! The deviation from the target temperature determined by the trace film setting device 6 is determined by the deviation detection circuit 17, and the PI
It is output to the D calculation circuit 18. As a result, the PID calculation circuit 18 outputs a predetermined control amount to the flow rate control valve 5 via the valve drive circuit 20, and the valve opening degree of the flow rate control valve 5 is adjusted.
Since a predetermined flow rate of fuel is supplied to the burner 2, the combustion sequence control circuit 14 operates the igniter 6 to generate an ignition spark. As a result, when the burner 2 is ignited normally, this is detected by the flame detector 7, and when there is an ignition error, the alarm 8 is activated.

As the burner 2 is normally ignited and enters a normal combustion state, heat exchange in the heat exchanger 9 progresses and hot water is dispensed from the snake [], but this S temperature is detected by the temperature sensor 12.
The deviation between this temperature and the target temperature is again determined by the deviation detection circuit 17. Based on this newly determined deviation, the PID calculation circuit 18 outputs a predetermined control amount to the flow control valve 5 via the valve drive circuit 20 in order to reduce the deviation, and the valve opening of the flow control valve 5 is adjusted. .

Thereafter, the above-described operation is repeated, and feedback control is performed so that the detected mm matches the set temperature, and a desired lagoon with a stable s-temperature is obtained.

Now, if you open the remaining two faucets at the same time, heat exchanger 9
The amount of water passing through the faucet increases rapidly, and the temperature of the hot water that comes out of the faucet drops rapidly. At this time, the sudden increase in the amount of water is immediately detected by the flow state detection device 11o and inputted to the gain switching circuit 19, so that the gain of the PID calculation circuit 18 changes to the gain before the temperature sensor 12 detects the sudden drop in temperature. The flow rate is increased by the switching circuit 19, whereby the flow rate control valve 5 is adjusted to a predetermined laparotomy.

As a result, the amount of sudden drop in the m-temperature is suppressed to a negligible extent, and the temperature sensor 12 detects this suppressed temperature change. Thereafter, the steady-state control operation described above is performed, and the temperature of the hot water dispensed from the three faucets is quickly maintained at the desired concentration.

In addition, if you initially open and use three faucets, please use the PI
The gain of the D calculation circuit 18 is increased, and a sudden decrease in the amount of water passing through the heat exchanger 9 when two faucets are turned on at the same time is immediately detected by the flow state detection device 10, and the m temperature is detected as described above. Rapid increases are suppressed to a negligible level.

As described above, since changes in the amount of hot water dispensed are detected by the flow state detection device 10 and the gain of the PID calculation circuit 18 is changed accordingly, the above-mentioned overshoot and undershoot can be effectively suppressed. Moreover, a relatively stable and uniform WaS degree can be obtained over the entire range of the amount of hot water dispensed. If this flow state detection device 10 detects changes in the output wA profit continuously, ideal output hot water temperature characteristics can be obtained, but even if the detection is performed in one step, a good output wA profit can be obtained.
IA temperature characteristics are obtained.

Further, specific embodiments of the present invention are shown in FIGS. 2 to 4.

FIGS. 2 and 3 are diagrams showing a specific example of the above-mentioned flow state detection device, and this device main body 30 is installed in the water inflow pipe (see Fig. 1) or the hot water outflow pipe of the heat exchanger. As a result, dry water flows in the flow path 31 in the direction of the arrow.

A holder 34 having a bottle 33 is provided on the lower surface of the lid 32, and one end of an actuation plate 35 is rotatably supported by the bottle 33. The other end of the actuating plate 35 is provided to extend so as to close the flow path 31, and when hot water flows in the direction of the arrow, the actuating plate 35 is urged by the hot water and rotates.

One end of a magnet 36 is fixed to the other end of the actuating plate 35, and the other end of the magnet 36 extends toward the downstream side of the flow path 31. This magnet 36 is formed into a circular arc shape as a whole in the longitudinal direction, so that it does not come into contact with the wall surface of the flow path 31 when the actuating plate 34 rotates 4.

Further, the actuating plate 35 is provided with a balance weight 37, so that when there is no water flow in the flow path 31, the actuating plate 35 is held in a state hanging from the holder 34 without tilting at a flow rate of 36. ing.

Further, two reed switches 38 and 39 are provided on the outer periphery of the main body 30 along the flow path 31, and these reed switches 38 and 39 are sequentially activated by the magnet 36 as the actuation plate 35 rotates. There is. That is, when the actuating plate 35 rotates at the minimum amount of water required to operate the water heater, one end of the magnet 36 reaches the reed switch 38 and activates it, and the output signal of the reed switch 38 is The signal is input to the combustion sequence control circuit 14 as a starting signal. When the amount of water increases further and reaches a predetermined amount of water that is less than the maximum amount of water, one end of the magnet 36 reaches the reed switch 39 and activates it, and the reed switch 38 is operated by the intermediate portion of the magnet 36. The operating state is maintained (the broken line in Figure 2 shows this state). The output signal of this reed switch 39 is input to the gain switching circuit 19 as a water change signal.

In this way, the reed switch 38 operates at the minimum operating water flow rate and remains in the operating state until the water heater is stopped thereafter, so that its output signal becomes the above-mentioned activation signal, and
Accompanied by a stop signal. As a result, the combustion sequence control circuit 14 does not need to be provided with a storage means for indicating that the water heater is in operation, and simply uses the reed switch 3.
It is sufficient to follow the output signal of No.8.

In addition, a magnetic shielding plate 40 is installed between the reed switches 38 and 39.
are provided so that the reed switches 38 and 39 operate only when the magnet 36 reaches a predetermined position.

Next, FIG. 4 is a diagram showing a specific configuration of the ms control circuit, in which the deviation detection circuit 17 is connected to the target temperature setting device 16.
and the temperature sensor 12 on one side.
The output voltage v1 to v2 of this bridge circuit 45
is input to the PID control circuit 18 as the deviation signal. Further, the gain switching circuit 19 is composed of constant voltage diodes 46 and 47 that supply power to the bridge circuit 45, and the reed switch 39 is connected in parallel to the constant voltage diode 47. This reed switch 39 operates as described above, and is closed when the amount of water is low and opened when the amount of water is low.

With this configuration, when the amount of water passing through the heat exchanger 9 is low, the reed switch 39 is closed, and the power supply voltage supplied to the bridge circuit 45 is determined by the constant voltage diode 46, so that it is lower than vCC. , and the input voltage v1 to ■2 of the PIDlli sieve circuit 18 decreases, so the flow 11 control valve 5 is
The control most outputted is such that the valve opening degree of the control valve 5 is decreased. In other words, the gain of the PID calculation circuit 18 is reduced in accordance with the decrease in flow rate.

Furthermore, when the flow rate increases and the reed switch 39 is opened, the power supply voltage supplied to the bridge circuit 45 becomes approximately VCC due to the constant voltage diodes 46 and 47, so contrary to the above, the gain of the PID calculation circuit 18 increases. It will be done.

Therefore, it is an object of the present invention to simply change the gain of the PID arithmetic circuit 18 into two stages by setting the high water volume at which the reed switch 39 operates to an appropriate water volume between the minimum operating water volume and the maximum water volume of the water heater. It is possible to effectively suppress overshoot and undershoot, and to make the output mm characteristic so good that there is no ★ star in practical use.

As described in detail above, if the water heater is equipped with the combustion control device according to the present invention, overshoot or undershoot will not occur even if there is a sudden change in the amount of hot water dispensed, and the water heater will not cause overshoot or undershoot even if there is a sudden change in the amount of hot water dispensed. It is possible to make the temperature of the hot water stable and uniform.

Furthermore, the flow state detection device can be realized with a simple configuration, is easy to manufacture, and is easy to integrate into a water pipe. In addition, since this flow state detection device can detect the minimum operating water volume and the stoppage of the water heater, it is possible to omit the flow switch conventionally used to detect the minimum operating water volume, and also to control the combustion sequence. The circuit can be simplified. Since the gain of the m-temperature-1-circuit can be changed in stages, the gain switching means is simplified and the cost of the combustion control device does not increase.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of a water heater showing an embodiment of the present invention, FIGS. 2 and 3 are a side sectional view and a side external appearance schematic diagram showing a specific example of a flow state detection device according to the present invention, FIG. 4 is a schematic diagram showing a specific example of the lii temperature control circuit according to the present invention. 2...Burner 5...Flow control valve 9...Heat exchanger 10...Flow state detection device 12. ... Concentration sensor 13 ... Combustion control device 14 ... Combustion sequence control circuit 15 ...
...sa! Control circuit 19... Gain switching circuit 34... Actuation plate 36... Magnet 38, 39... Reed switch 40...
・Magnetic passing plate 46.47... Constant voltage diode patent applicant Tateishi Electric Co., Ltd. Figure 1

Claims (5)

[Claims] (1) A temperature sensor that detects the temperature of hot water discharged from the heat exchanger, a target temperature setter, and a control amount that is controlled according to the deviation between the detected temperature of the temperature sensor and the target temperature determined by the target temperature setter. mm control circuit for output, a flow rate control valve that is driven according to the output of the temperature control circuit and varies the fuel supply, and a flow rate control valve that is provided in the middle of the water inflow pipe or the hot water outflow pipe of the heat exchanger. , a flow state in which there is an actuating plate that is displaced by a minute flow in the pipe to activate the flow detector, and is further displaced to activate the flow rate detector when the flow rate of hot water in the pipe exceeds a predetermined value. a detection device, a combustion sequence i control circuit that starts a combustion sequence in response to an output signal from the flow detector, and a gain control circuit for controlling the hot water control circuit in response to an output signal from the upper flow detector. A combustion control device for a water heater, which includes a gain adjustment circuit that changes the flow rate to increase when the flow rate is large. (2) The flow detector and the flow detector consist of first and second reed switches respectively actuated by magnets attached to the actuating plate, and when the actuating plate is displaced by the minute flow, the first reed switch Only the reed switch works,
Claim 1, characterized in that when the reed switch is further displaced by the flow exceeding the predetermined value, the second reed switch is activated, and the first reed switch is maintained in the activated state by the magnet. Combustion of water heater &lJ I) device as described in Section 1. (3) The magnet attached to the actuating plate extends in the longitudinal direction, with its tip extending in the axial direction of the conduit, and the overall shape in the longitudinal direction is approximately the length of the actuating plate up to the magnet fixing position. The combustion control device for a water heater according to claim 2, wherein the combustion control device for a water heater is formed into an arc shape having a radius of a circular arc. (4) Combustion control for a water heater according to claim 2, wherein the actuating plate is provided with a balancer that prevents the actuating plate from being arbitrarily displaced due to the weight of the magnet. Device. (5) The combustion control device for a water heater according to claim 2, wherein the two reed switches are separated by a magnetic shielding plate.