JPH0413006A - Device for controlling combustion - Google Patents

Abstract

PURPOSE:To enable changing the amount of combustion, while the air-fuel ration is kept constant or almost constant, by a method wherein, when the amount of combustion is changed, the supply pressure of the air for combustion is changed, in the same manner as the quantity of the fuel supplied, in straight-line proportion, or substantially in straight-line proportion, to the amount of the combustion. CONSTITUTION:On the basis of the temperature (ti) determined by a stored-hot-water temperature sensor 10 a means for setting the amount of combustion, designated by 13, computes the necessary amount of combustion G, on the basis of which a fuel-controlling means 14 controls the opening of an electromagnetic proportional valve 12 by means of current passed. On the basis of the proportional valve-operating current (i) determined by a current-setting means 14A a revolution number-controlling means 15 controls the revolution number N of a fan in such a manner as to keep the air-fuel ration virtually constant, that is, to maintain a predetermined interrelationship between the amount of combustion G and the revolution number N in which the supply pressure of the air for combustion sent by the fan varies virtually in straight-line proportion to the amount of combustion G. A revolution number- setting means 15A works out a revolution number N and outputs a drive signal A corresponding thereto. On the basis of this drive signal A a fan-controlling means 15C automatically adjusts the revolution of the fan to the number N.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to, for example, a hot water boiler in which water in a hot water storage tank is heated by a burner, and the combustion of the burner to maintain the hot water storage temperature at a set temperature. The present invention relates to a combustion control device used for adjusting the amount.

Specifically, the combustion amount specifying means specifies the combustion amount to be changed, and the fuel control means automatically adjusts the amount of fuel supplied to the burner to be linearly proportional to the combustion amount specified by the combustion amount specifying means. , rotation speed designation means for specifying a rotation speed of a fan that supplies combustion air to the burner that corresponds to the combustion amount designated by the combustion amount designation means;
The present invention also relates to a fan control device that automatically adjusts the rotation speed of the fan to a rotation speed specified by the rotation speed designation device.

[Conventional technology]

In the conventional combustion control device, the rotation speed specifying means specifies the rotation speed so that the rotation speed of the fan is changed linearly in proportion to the amount of combustion.

[Problem to be solved by the invention]

However, the amount of combustion changes linearly in proportion to the supply pressure (wind pressure) of combustion air, and the wind pressure changes in proportion to the square of the rotation speed. As a result, when using the above conventional technology, the combustion supply amount changes linearly in proportion to the combustion amount, whereas the wind pressure does not change linearly in proportion to the combustion amount, so the air-fuel ratio is kept constant. I couldn't keep it.

An object of the present invention is to maintain a constant air-fuel ratio regardless of changes in combustion amount.

[Means to solve the problem]

A characteristic configuration of the combustion control device according to the present invention is such that the rotation speed specifying means specifies the rotation speed so that the supply pressure of combustion air by the fan changes linearly or almost linearly in proportion to the combustion amount. There are certain points.

[Function] According to the above characteristic structure, the supply pressure of combustion air can be changed linearly or almost linearly in proportion to the combustion amount, similarly to the fuel supply amount, as the combustion amount is changed.

〔Effect of the invention〕

Therefore, according to the present invention, it has become possible to provide a combustion control device that can change the combustion amount while keeping the air-fuel ratio constant or almost constant.

〔Example〕

Examples of the present invention are shown below.

As shown in FIG. 4, a hot water storage tank (1) is provided, and a heating furnace (2) and a smoke pipe (3) are provided in the hot water storage tank (1).
A combustion device (4) having a combustion chamber in the furnace (2) and a combustion control device (5) are provided, and storage is stored by combustion) (1)
It consists of a hot water boiler that heats the water inside.

The hot water tank (1) has a water supply port (
1a), a hot water outlet (1b) connected to the hot water supply path (8) to the usage terminal (7), and a return path (9) with a pump (P) connected to the end of the hot water supply path (<8). Return port to connect (1
c). Moreover, this hot water storage tank (1) is provided with a hot water storage temperature detection sensor (10).

The combustion device (4) is of a forced draft type original mixing type, and includes a burner (4A) and a fan (4B) using a sirocco fan that supplies combustion air to the burner (4A). There is. The burner (4A) has a burner main body (4A).
a) and a combustion plate (4b) forming a flame hole. The fuel supply path (11) is connected to supply fuel into the fan (4B), and the fuel supply path (11)
is equipped with an electromagnetic proportional valve (12) for adjusting the fuel supply amount.
is interposed. and the fan (4B) is a DC
This is a C brushless morph drive motor (4C). .

The combustion control device (5) controls the fuel supply amount and the drive motor (4c), that is, the fan (4B
), and as shown in FIG.
) and rotation speed designating means (15A).

The combustion amount specifying means (13) determines the combustion amount (G) necessary to obtain the set temperature (ts) by the temperature setting device (I6) based on the temperature (ti) detected by the hot water storage temperature detection sensor (10). is calculated sequentially.

The fuel control means (14) is configured to control the combustion amount specifying means (1).
Based on the combustion amount (G) calculated in 3), the combustion amount (G
) The valve opening of the electromagnetic proportional valve (12) is adjusted to the current so that the preset correlation between the combustion amount (G) and the fuel supply amount is maintained. The current determining means (14A)
and valve control means (14B).

The current determining means (14A) determines, based on the calculated combustion amount (G), a proportional valve operating current (1) that causes the valve opening to maintain the above-mentioned correlation.

The valve control means (14B) is configured to control the current determining means (14B).
The valve opening degree of the electromagnetic proportional valve (14B) is automatically adjusted using the proportional valve changing current (1) determined in step 14A).

The rotation speed control means (15) is configured to control the current determining means (1
Based on the proportional valve operating current (i) determined in 4A),
A preset correlation between the combustion amount (G) and the rotation speed (N) that makes the supply pressure of combustion air by the fan (4B) almost linearly proportional to the combustion amount (G) so as to keep the air-fuel ratio almost constant. The rotation speed (N) is controlled so that the relationship (shown by the correlation line (A) in FIG. 3 (A)) is maintained, and the rotation speed designating means (15A) and the correction means (15B)
and fan control means (15C). As shown in Figure 3 (b), the correlation line (a) shows the relationship between the combustion amount (G) and the rotation speed (N), which makes the supply pressure linearly proportional to the combustion amount (G).
) A plurality of inflection points (a) provided on the correlation line (b) are connected by a straight line, that is, it is a polygonal line that approximates the correlation line (b).

The position and number of the inflection points (a) are appropriately selected depending on various combustion conditions such as the structure of the combustion device (4) and the method of combustion operation.

The rotation speed specifying means (15A) calculates a rotation speed (N) that maintains the above correlation based on the determined proportional valve operation current (i), and outputs a drive signal (A) commensurate with the rotation speed (N).
) is output.

The correction means (15B) is for keeping the air-fuel ratio almost constant regardless of clogging of the burner (4A) or flue (3), changes in exhaust conditions, changes over time such as room temperature, etc. Specifically, when the detected temperature is higher than the set temperature based on the temperature detected by the temperature sensor (17) that detects the flame temperature or the temperature of the combustion plate (4b), the set rotation speed (10 ~5Qrpm) Outputs a drive signal (A) commensurate with the high rotational speed, and when the detected temperature is lower than the set temperature, the rotational speed is set lower than the calculated rotational speed by about 10~5Qrpm. The rotation speed specifying means (15A) is operated to correct so as to output an appropriate drive signal (A).

The fan control means (15C) is a fan (4B)
Means for automatically adjusting the rotation speed of the drive motor (N) to the rotation speed (N) calculated by the rotation speed specifying means (15A) by a pulse width modulation method, as shown in FIG.
4C), a rectification/smoothing circuit (18) for rectifying and smoothing the alternating current and supplying the same to the inverter (17), and a rectification/smoothing circuit (18) for rectifying and smoothing the alternating current and supplying the same to the inverter (17). drive signal input (
A), a PWM generation circuit (20) that variably controls the oscillation frequency of the inverter (17) based on the PWM generation circuit (20), and a PWM generation circuit (20) that controls the inverter (17) in synchronization with the drive motor (4c). It consists of a rotation logic (21) to perform the rotation.

In addition, in the rotation speed control means (15), the fan (4
B) Rotation speed sensor (22) that detects the rotation speed (N+)
is provided to perform feedback control.

According to the above configuration, both the fuel supply amount and the supply pressure, which are involved in the air-fuel ratio, change almost linearly in proportion to the combustion amount (G), so the air-fuel ratio changes within the range of changing the combustion amount (G). remains almost constant.

[Another example]

Another embodiment of the invention is shown below.

[1 piece In the above embodiment, the drive motor of the fan (4B) (
4C) The DCC brushless motor has better rotational speed response characteristics than an AC motor, can use a less expensive rotational speed control means (15), and has a longer lifespan than a brushed DC motor. Although the morph is shown, the drive motor (4c)
Alternatively, a DC motor or an AC motor may be used.

[2] In the above embodiment, the rotation speed (N) is controlled so as to maintain the correlation between the combustion amount (G) and the rotation speed (N) shown by the correlation line (A), and the rotation speed (N) is ), but of course, the rotation speed control means (
15) is the combustion amount (G) shown by the correlation line (b).
The number of rotations (N) may be controlled so as to maintain the correlation between the number of rotations and the number of rotations (normal).

[3] In the above embodiment, the target is a forced draft type original mixing type combustion device (4), but the present invention can be applied to any combustion device (4) equipped with a forced draft fan (4B). It can also be applied to things like

[4] Note that although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the combustion control device according to the present invention.
FIG. 2 is a control block diagram, FIG. 2 is a circuit block diagram, FIGS. 3(A) and 3(B) are graphs showing the relationship between combustion amount and rotation speed, and FIG. 4 is a schematic longitudinal sectional view. (13)... Combustion amount specifying means, (4A)...
... Burner, (14) ... Fuel control means, (
4B)...Fan, (15A)...Rotation speed designation means, (15C)...Fan control means.

Claims (1)

[Claims] Combustion amount specifying means (13) for specifying the combustion amount to be changed, and automatically adjusting the amount of fuel supplied to the burner (4A) to an amount linearly proportional to the combustion amount specified by the combustion amount specifying means (13). a fuel control means (14) for adjusting; and a fuel control means (14) for adjusting the burner (
4) a rotation speed designating means (15A) for specifying a rotation speed corresponding to the combustion amount designated by the combustion amount designation means (13) among the rotation speeds of the fan (4B) that supplies combustion air to the combustion amount designation means (13);
and fan control means (15C) for automatically adjusting the rotation speed of the fan (4B) to the rotation speed designated by the rotation speed designation means (15A), the combustion control device comprising: The combustion control device is provided with a designation means (15A) that designates the rotation speed so that the pressure of combustion air supplied by the fan (4B) changes linearly or almost linearly in proportion to the combustion amount.