JPH0467091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device that controls a combustion device used in a water heater, a heating device, or the like.

[Prior Art] A blower that supplies combustion air to a combustion chamber includes a rotating body with a large mass, so its rotational speed cannot change rapidly. On the other hand, a fuel regulator (for example, a proportional valve) that supplies fuel to the combustion chamber can easily change the amount of fuel supplied because the mass of the valve body is small. For this reason, when the blower and fuel regulator are controlled independently or the fuel regulator and blower are controlled simultaneously, when the combustion amount changes,
The amount of fuel supplied by the fuel regulator and the air volume of the blower do not match, resulting in an abnormal air-fuel ratio.

Therefore, the air volume of the blower is controlled according to the amount of combustion, and the opening degree of the fuel regulator is controlled according to the amount of air of the blower (for example, rotational speed) and the combustion state (air-fuel ratio). A combustion device has been devised to prevent the occurrence of air-fuel ratio abnormalities (Japanese Unexamined Patent Publication No.
62-252826).

[Problems to be Solved by the Invention] However, when the air-fuel ratio is controlled by a fuel regulator, the amount of fuel supplied changes due to the air-fuel ratio correction. Then, there was a problem in that the amount of heat determined by the combustion device could not be obtained in the combustion section.

An object of the present invention is to provide a control device for a combustion device that can obtain a target amount of heat in a combustion section even when the air-fuel ratio is corrected by changing the amount of fuel supplied.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following technical means.

The combustion device includes a combustion section that burns fuel, a blower that supplies air for combustion to the combustion section, a fuel regulator that supplies fuel to the combustion section, and a control unit that controls the amount of air blown by the blower. Therefore, the amount of fuel combusted in the combustion section is controlled by supplying fuel corresponding to the amount of combustion air supplied to the combustion section from the fuel regulator to the combustion section. A control device including a combustion amount control means and an air-fuel ratio correction means for feedback-correcting the amount of fuel supplied to the fuel regulator according to the air-fuel ratio in the combustion section.

The combustion amount control means of the control device controls the combustion amount supplied to the combustion section by the blower when the fuel regulator increases fuel to the combustion section by the air-fuel ratio correction means. reducing the amount of air by correction according to the increase amount,
To suppress fluctuations in the amount of fuel burned in the combustion section, and conversely, when the fuel regulator decreases the amount of fuel to the combustion section by the air-fuel ratio correction means, the combustion section by the blower The amount of combustion air supplied to the combustion section is increased by correction according to the amount of decrease, thereby suppressing fluctuations in the amount of fuel combusted in the combustion section.

[Operation and Effects of the Invention] If the combustion state in the combustion section is that combustion is not being performed within a predetermined air-fuel ratio, the control device changes the amount of fuel supplied by the fuel regulator so that combustion is performed at a predetermined air-fuel ratio. let However, the combustion amount is corrected in advance by the amount of combustion that is increased or decreased by the air-fuel ratio correction. As a result, even if air-fuel ratio correction is performed, the target amount of heat can be obtained in the combustion section.

[Effects of the Invention] According to the present invention, even if the amount of fuel supplied changes due to air-fuel ratio correction, the amount of change in fuel is corrected in advance and the combustion amount is determined. Therefore, compared to the conventional control device, by correcting the air-fuel ratio, the control device of the present invention can eliminate the disadvantage that the combustion amount changes and the required amount of heat cannot be obtained.

[Example] Next, an example in which the present invention is applied to a bypass mixing water heater will be described with reference to the drawings.

Figure 2 shows a schematic diagram of a bypass mixing type gas water heater.

This gas water heater is roughly divided into a combustion section 10 that burns fuel, a gas supply pipe 20, and a water pipe 30.
and a control device 40.

The combustion section 10 consists of a combustion case 12 in which a ceramic surface-combustion burner 11 is disposed, and a blower 13 that supplies air for combustion into the combustion case 12. After the combustion air introduced into the combustion chamber 12 is combusted, it is discharged as combustion gas from an exhaust port (not shown).

The gas supply pipe 20 supplies fuel gas to a nozzle 21 that opens on the inner periphery of the centrifugal fan 14 of the blower 13, and connects the former solenoid valve 22,
A main solenoid valve 23 and a proportional valve 24 are provided in this order. The downstream side of the proportional valve 24 is branched into two parts, one of which is provided with a switching solenoid valve 25 and the other with an orifice 26. The main solenoid valve 22, the main solenoid valve 23, and the switching solenoid valve 25 open and close the gas supply pipe 20 through energization control, and the proportional valve 2
4 has a nozzle 21 whose aperture ratio changes depending on the amount of energization.
This is to adjust the amount of gas supplied to the Note that the proportional valve 24 and the switching solenoid valve 25 are the fuel regulator of the present invention.

One end of the water pipe 30 is connected to a water supply source,
The other side is connected to the hot water supply port, and the heat exchanger 31 exchanges heat generated by combustion of gas in the burner 11 with water flowing inside and heats the water passing through the inside. A bypass water channel 32 that bypasses the exchanger 31 is provided.

The water pipe 30 upstream of the branch path between the heat exchanger 31 and the bypass waterway 32 is equipped with a governor valve that keeps the amount of water flowing into the heat exchanger 31 and the bypass waterway 32 constant even if the water pressure flowing into the heat exchanger 31 and the bypass waterway 32 changes. An electric water flow control device 33 is provided which combines the function of a water flow control valve and the function of a water flow control valve that adjusts the water flow. Further, the bypass waterway 32 is provided with a throttle valve 34 that can adjust the amount of water passing through the bypass waterway 32 and open and close the bypass waterway 32 .

Note that the throttle ratio of the electric water flow control device 33 is set to be the same as or smaller than the throttle valve 34 in order to regulate the total amount of water flowing into the heat exchanger 31 and the bypass waterway 32. Further, the electric water flow control device 33 and the throttle valve 34 use a geared motor to drive a valve body that can open and close the waterway as means for adjusting the water flow.

As shown in FIG. 3, the control device 40 is composed of a microcomputer 41, a relay circuit 42, and a drive circuit 43, and according to the outputs of a controller 44 and various sensors operated by the user, Sparker 4 ignites burner 11
5, original solenoid valve 22, main solenoid valve 23, proportional valve 24,
The switching solenoid valve 25, the electric water flow control device 33, and the throttle valve 34 are energized and controlled.

Various sensors of the control device 40 are linked to a flame rod 46 and a thermocouple 47 for detecting the flame of the burner 11 and the air-fuel ratio, an electric water flow control device 33, and a valve body of the throttle valve 34 to detect the opening degree. potentiometers 48 and 49, an air volume detection sensor 50 that detects the air volume of the blower 13 based on its rotational speed, an inlet water temperature sensor 51 that detects the temperature of water flowing into the heat exchanger 31 and the bypass waterway 32, and the heat exchanger 31. A hot water temperature sensor 52 detects the temperature of hot water that has passed through the heat exchanger 31 and the bypass waterway 32, an outlet hot water temperature sensor 53 that detects the temperature of the mixed hot water that has passed through the heat exchanger 31 and the bypass waterway 32, the heat exchanger 31, and the bypass waterway 3.
Water amount detection sensor 54 that detects the amount of water flowing into 2
Equipped with.

Note that the air volume detection sensor 50 includes a rotating body that is interlocked with the motor of the blower 13, and generates a pulse signal according to the rotation of the rotating body. Further, the water amount detection sensor 54 includes a rotating body that rotates with the flow of water, and generates a pulse signal according to the rotation of the rotating body. Then, the computer 41 detects the rotational speed of the blower 13 and the rotational speed of the rotating body from the interval between pulse signals generated by the airflow detection sensor 50 and the water amount detection sensor 54, and detects the airflow and water volume.

Next, combustion control and water amount control by the computer 41 will be briefly explained.

The user operates the clicker connected to the hot water inlet,
When water flow occurs in the water pipe 30, the water amount detection sensor 5
The rotating body inside 4 rotates and combustion starts. The amount of combustion after the start of combustion is determined based on the water amount, inlet water temperature, and heat exchanger 31 obtained by various sensors so that the set temperature set by the controller 44 is obtained.
The voltage of the blower 13 is controlled so that the blower 13 supplies the burner 11 with an air volume corresponding to the determined combustion amount. In other words, combustion amount equals blower 13
The air flow rate is assumed to be . Then, a proportional valve 24 and a switching solenoid valve 25 are provided so that the amount of gas corresponding to the rotational speed of the blower 13 and the temperature of the flame of the burner 11 can be obtained.
is energized and controlled. In addition, the combustion amount is the heat exchanger 3
The temperature of the hot water passing through the heat exchanger 31 is set to be maintained above a temperature (for example, 60° C.) at which water generated by combustion (drain water) does not adhere to the heat exchanger 31.

The throttle valve 34 is fixed at an appropriate opening calculated from the incoming water temperature, the set temperature, the temperature of the hot water that has passed through the heat exchanger 31, and the outlet temperature. Note that this fixation is set so that the flow rate flowing through the bypass waterway 32 is twice the amount of water flowing through the heat exchanger 31. That is, the ratio of flow resistance between the bypass waterway 32 and the heat exchanger 31 is set to about 2:1 by the throttle valve 34.
Further, the opening degree of the throttle valve 34 is fixed when the amount of water entering is small or when the temperature of hot water coming out is lowered, and the opening degree of the throttle valve 34 is fixed so that the opening degree is calculated according to the amount of water entering and the temperature of hot water coming out. Energization is controlled.

Further, the electric water flow rate control device 33 is controlled to be energized so as not to exceed the maximum flow rate required to obtain the hot water temperature.

Next, the control of the combustion amount by the combustion amount control means programmed in the computer 41 will be described in detail.

The combustion amount Q is the feed forward combustion amount FF,
Heat exchange capacity corrected combustion amount K and air-fuel ratio corrected combustion amount T
, the proportional correction combustion amount P, and the integral correction combustion amount I, which is expressed by the formula Q=FF+K+T+P+I.

The feed forward combustion amount FF is determined by the difference between the set temperature Ts set by the controller 44 and the inlet water temperature Ti detected by the inlet water temperature sensor 51,
Water amount W detected by the water amount detection sensor 54
and the heat exchange efficiency of the heat exchanger 31, 1/eff.

This is expressed by the formula FF=(Ts-Ti)W/eff.

The heat exchange capacity correction combustion amount K is set in advance according to the difference between the set temperature Ts set by the controller 44 and the hot water outlet temperature Tm detected by the hot water outlet temperature sensor 53, and the heat exchanger 31 used. heat capacity M
and a constant a according to the bypass ratio of the heat exchanger 31 and the bypass waterway 32.

This is expressed by the formula K=a(Ts-Tm)M.

Note that the heat exchange capacity corrected combustion amount K is calculated by calculating the virtual temperature Te of the heat exchanger 31 necessary to obtain the set temperature Ts set by the controller 44,
The same result can be obtained by calculating from the heat capacity M and the difference between the virtual temperature Te and the hot water temperature To detected by the hot water temperature sensor 52. Note that this is K=(Te−To)
It is expressed by the formula of M.

The air-fuel ratio corrected combustion amount T according to the present invention corrects the gas amount increased or decreased by the air-fuel ratio correction, and is obtained by inverting the sign of the corrected combustion amount N due to the air-fuel ratio correction. Note that the air-fuel ratio correction means according to the present invention is controlled by the computer 41 together with the combustion amount control means.
programmed within.

This is expressed by the equation T=-N.

The calculation of the proportionally corrected combustion amount P is performed by the controller 44.
It is calculated from the difference between the set temperature Ts set in and the hot water temperature To detected by the hot water temperature sensor 52, the water amount W detected by the water amount detection sensor 54, and the proportionality constant E.

This is expressed by the formula P=E(Ts-To)W.
Note that (Ts−To)W indicates a deviation value. Further, in this embodiment, E=approximately 0.8 is appropriate.

Calculation of the integral corrected combustion amount I is performed by the controller 44.
This value is obtained by integrating the difference between the set temperature Ts set in , and the hot water temperature To detected by the hot water temperature sensor 52.

This is expressed by the formula I _o = I _o-1 + bW _o (Ts - To). Note that b×W _o represents an integral constant, I _o is the currently calculated integral corrected combustion amount, and I _o-1 is the previously calculated integral corrected combustion amount. Integral corrected combustion amount I
By making the amount of change in W o proportional to the flow rate W _o , the time delay required for feedback can be corrected and the integral corrected combustion amount I can be evaluated uniformly. Alternatively, the integral corrected combustion amount I may be a product of the change ratio of the FF value, and the once converged integral value may be rationally evaluated and then adapted to the change.

According to this embodiment, the feed forward combustion amount
By adding the air-fuel ratio corrected combustion amount T to FF, the gas that is increased or decreased by the air-fuel ratio correction is corrected to the combustion amount in advance. Therefore, even if the gas supply amount changes due to air-fuel ratio correction, the target amount of heat can be obtained in the combustion section 10. As a result, the hot water temperature set by the user can be supplied to the user without the influence of the combustion amount changing due to air-fuel ratio control.

Moreover, by setting the combustion amount Q=FF+K+T+P+I, the hot water temperature set by the user can always be stably supplied.

(Modified example) In order to apply a voltage to the blower according to the amount of combustion,
The calculation of the combustion amount described above may be performed directly by calculating the voltage. That is, the voltage applied to the blower is determined by adding the feedforward voltage, the heat exchange capacity correction voltage, the air-fuel ratio correction voltage, the proportional correction voltage, and the integral correction voltage.

In addition, although a water heater with a bypass waterway was shown as an example, it goes without saying that water heaters without a bypass waterway can also be used.
The present invention may be applied to combustion type heating devices and the like.

Further, although an example using gas as fuel has been shown, the present invention may also be applied to a combustion device using liquid fuel such as kerosene or heavy oil.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
The figure is a schematic block diagram of a bypass mixing type gas water heater, and FIG. 3 is a schematic block diagram of a control device. In the figure, 1... combustion section, 2... blower, 3... fuel regulator, 4... combustion amount control means, 5... air-fuel ratio correction means,
6...Control device.

Claims (1)

[Scope of Claims] 1. A combustion section that burns fuel; a blower that supplies air for combustion to the combustion section; a fuel regulator that supplies fuel to the combustion section; and a control unit that controls the amount of air blown by the blower. By doing,
Combustion amount control that controls the amount of fuel combusted in the combustion section by supplying fuel corresponding to the amount of combustion air supplied to the combustion section from the fuel regulator to the combustion section. and a control device comprising air-fuel ratio correction means for feedback-correcting the amount of fuel supplied in the fuel regulator according to the air-fuel ratio in the combustion section, the combustion apparatus comprising: The control means adjusts the amount of combustion air supplied to the combustion section by the blower to the increased amount when the fuel regulator increases the amount of fuel to the combustion section by the air-fuel ratio correction means. Accordingly, the amount of fuel combusted in the combustor is reduced by correction to suppress fluctuations in the amount of fuel combusted in the combustor, and conversely, the fuel regulator reduces the amount of fuel to the combustor by the air-fuel ratio correction means. In this case, the amount of combustion air supplied to the combustion section by the blower is increased by correction according to the amount of decrease to suppress fluctuations in the amount of fuel burned in the combustion section. Characteristic control device for combustion equipment.