JPH05248628A - Combustion apparatus - Google Patents

Abstract

PURPOSE:To enable achieving stability in the condition of combustion at a transition by a method wherein, when a command signal from a commanding means shifts the objective degree of combustion toward a decrease, the command to alter the number of revolutions is inputted to a blower-controlling means with a lag in time from the command to alter the valve opening inputted to a valve opening-controlling means. CONSTITUTION:A hot-water supply apparatus is equipped with an objective value-setting means 41 and a commanding means 44: the objective value-setting means 41 is for setting, according to a set objective degree of combustion, an objective degree of valve opening of a solenoid proportional valve 29 for controlling the rate of the supply of fuel to a burner B appertaining to a heat exchanger 21 and also for setting an objective number of revolutions of a blower 30 for supplying air to the combustion at the burner B; the commanding means 44 is for giving, according to an alteration in the objective degree of combustion, a command for altering the degree of valve opening to a valve opening-controlling means 42 and also for giving a command for altering the number of revolutions to a blower-controlling means 43. The present invention relates to this mechanism with modification in the function of the commanding means 44 wherein, when the objective degree of combustion is shifted toward a decrease, the command to alter the number of revolutions is inputted to a blower-controlling means 43 with a lag in time from the command to alter the valve opening inputted to the valve opening-controlling means 42 so that, by increasing the air ratio over the fixed ratio before decreasing the supply of air, stability in the combustion can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with an electromagnetic proportional valve for adjusting a fuel supply amount to a burner and a blower for supplying combustion air to the burner, and sets a target combustion amount of the burner. And, a target value setting means for setting the target opening of the solenoid proportional valve and the target rotation speed of the blower so as to maintain the air ratio at a predetermined value according to the set target combustion amount, and the target combustion amount In response to the change, an opening change command is issued to a valve control means for changing and adjusting the opening of the solenoid proportional valve to the target opening, and the rotation speed of the blower is adjusted to the target rotation speed. And a command means for commanding a rotation speed change command to the blower control means.

[0002]

2. Description of the Related Art Conventionally, in such a combustion apparatus, when the target combustion amount is changed to a decreasing side, the opening degree of the valve control means for adjusting the opening degree of the solenoid proportional valve to a new target opening degree is changed. The command means is configured to simultaneously issue a command and a rotation speed change command to the blower control means for reducing and adjusting the rotation speed of the blower to a new target rotation speed.

[0003]

By the way, in the reduction adjustment of the fuel supply amount by the adjustment adjustment of the opening of the solenoid proportional valve, the reduction rate is stable, but the target rotation speed of the blower is In the reduction adjustment of the blown air volume by the reduction adjustment, the reduction rate becomes unstable due to the mechanical resistance of the blower. However, when the target combustion amount is changed to the decreasing side as in the above-described conventional technique, in the configuration in which the opening change command of the solenoid proportional valve and the rotation speed change command of the blower are simultaneously instructed, the opening change command and the rotation speed are changed. In the transition period from the command of the number change command to the opening of the solenoid proportional valve reaching the target opening and the rotation speed of the blower reaching the target rotation speed, Due to the instability, the air ratio becomes larger or smaller than a predetermined value and cannot be adjusted to a constant state, resulting in a continuous state, in particular,
There is a problem that soot is generated when the reduction rate of the blown air is larger than the reduction rate of the fuel supply and the air ratio is smaller than a predetermined value. The present invention has been made in view of the above circumstances, and an object thereof is to solve the above-mentioned conventional problems and provide a combustion device capable of stable combustion even in a transition period.

[0004]

According to a characteristic structure of a combustion apparatus according to the present invention, when the command means changes the target combustion amount to a decreasing side, an opening change command to the valve control means is issued. Thus, the rotation speed change command to the blower control means is delayed.

[0005]

According to the above characteristic structure, the amount of air blown to the previous amount from the time when the opening change command is issued to the valve control means until the rotation speed change command is issued to the blower control means. In the maintained state, only the fuel supply amount is adjusted to be decreased, so that the air ratio becomes larger than the predetermined value. continue,
Although the reduction rate of the blown air is unstable as described above after the rotation speed change command is issued to the blower control means,
Since the fuel supply amount is adjusted to be reduced in advance, the air ratio can be maintained at a value higher than the predetermined value. Then, the air ratio becomes a predetermined value when the rotation speed of the blower reaches the target rotation speed after the opening of the solenoid proportional valve reaches the target opening. That is, in the transition period, the air ratio can be maintained at a state that is always higher than the predetermined value.

[0006]

As a result, it is possible to surely solve the problem that the air ratio becomes a transitional state in the transitional period, in particular, the soot is generated when the air ratio becomes smaller than a predetermined value, as in the above-mentioned prior art. It has become possible to provide a combustion device capable of stable combustion even in a transitional period.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a water heater will be described below with reference to the drawings.

FIG. 1 shows the entire structure of the hot water supply apparatus. In the figure, 21 is a heat exchanger for heating water, and B is a burner for heating the heat exchanger 21. Reference numeral 22 denotes a hot water supply passage from the heat exchanger 21, and a hot water supply temperature sensor S1 for detecting the hot water supply temperature is interposed in the hot water supply passage 22 and a hot water supply tap 23 is connected thereto. Reference numeral 24 denotes a water supply passage to the heat exchanger 21, and in the water supply passage 24, a water amount sensor 25 for detecting the amount of water passing through the heat exchanger 21 and an incoming water temperature sensor S2 for detecting the water supply temperature to the heat exchanger 21. And through.

Reference numeral 26 denotes a fuel gas supply passage to the burner B. The fuel gas supply passage 26 has two solenoid valves 27 and 28 for connecting and disconnecting the fuel gas supply to the burner B and a burner B.
And an electromagnetic proportional valve 29 for adjusting the amount of fuel gas supplied to the fuel cell.

A blower 30 supplies combustion air to the burner B. 31 is a spark plug for igniting the burner B, 3
Reference numeral 2 is a frame rod for detecting ignition of the burner B.

Reference numeral S denotes an operation unit for instructing start / stop of the hot water supply operation, setting of a hot water supply target temperature, etc., and C denotes a controller for executing operation control described later.

Next, the burner B will be described with reference to FIGS.
Will be added.

A central vertical wall 2 is erected at the center of the burner casing 1 in the left-right direction, two left and right burner spaces are formed in the space inside the casing 1, and burner portions of the same shape and the same structure are formed in the left and right burner spaces. is there.

Next, the left and right burner portions will be described. In the burner space inside the burner casing 1, a large number of upward flame openings 6 having a rectangular opening shape are arranged in the long side direction to form a flame opening row, and the flame opening rows are provided in two rows in a parallel arrangement with a predetermined spacing. There is. For each of the flame port arrays, a pair of left and right combustion surface forming walls 3 and 4 extending over the entire length of each of the flame port arrays are viewed from the outer edge portions of the flame port 6 of each of the left and right flame port arrays when viewed in the flame port array direction. It is extended in an inclined posture that the upper part is separated.

Regarding the formation of the flame ports 6 in both rows, the cross-sectional shape when viewed in the flame port array direction is substantially V-shaped, and both side portions of the V-shape are elongated recesses 5a in the flame port array direction. And the short convex portion 5b are alternately formed. The flame port forming material 5 is burned in parallel with the lower end inclined surfaces of the left and right combustion surface forming walls 3 and 4 and inward of the lower end inclined surfaces. The convex portions 5b are arranged in contact with the lower end inclined surfaces of the surface forming wall bodies 3 and 4, respectively.
As a result, the upper ends of the recesses 5a of the flame outlet forming member 5 and the left and right lower end inclined surfaces respectively form a pair of left and right rectangular flame outlets 6, 6 in plan view.

Reference numeral 7 in the drawing denotes a primary mixed gas supply passage for guiding the primary mixed gas of the primary fuel gas and the primary air for combustion to the flame ports 6 and 6. Inside the primary mixed gas supply passage 7, a tip is provided. A primary mixed gas jet header pipe 9 having a jet port 9a and an opening 9b formed at the other end is attached along the flame nozzle row direction.

The burner casing 1 is located on the rear surface side of the combustion surface forming wall body 3 so as to face the combustion surface forming wall body 3 and the primary mixed gas supply passage 7, and the combustion surface forming wall body 3 is formed. The primary mixed gas supply passage 7 is connected to each of the upper end portions.
Is provided so as to extend downward. Also, the central vertical wall 2 is
On the back side of the combustion surface forming wall body 4, the combustion surface forming wall body 4 is formed.
And the primary mixed gas supply passage 7 and are connected to the upper end of the combustion surface forming wall body 4, and extend downward from the primary mixed gas supply passage 7. or,
The bottom surface of the burner casing 1 is formed into a rectangular opening K, and a fan 30 is connected to the opening K.

The two secondary fuel gas supply pipes 8, 8 are arranged in parallel with the primary mixed gas supply passage 7. A large number of gas ejection holes 8a are formed in a row in the longitudinal direction on the peripheral wall portions of each of the secondary fuel gas supply pipes 8 and 8.

Then, between the burner casing 1 and the combustion surface forming wall body 3 and the primary mixed gas supply path 7, and between the central vertical wall 2, the combustion surface forming wall body 4 and the primary mixed gas supply path 7.
And the secondary combustion gas from the blower 30 or the secondary mixed gas supply paths 10 and 10 of the secondary air for combustion and the secondary fuel gas from the secondary fuel gas supply pipe 8, respectively. ..

Reference numeral 11 is a flow passage narrowing body, and 12 is a plate-like body for forming the narrow flow passage portion 12a, both of which promote mixing of secondary air for combustion and secondary fuel gas. It is provided. Reference numeral 13 is a straightening punching plate having a large number of communication holes.

The left and right combustion surface forming walls 3 and 4 are provided with combustion secondary air or secondary mixed gas flowing upward in the secondary mixed gas supply passages 10 and 10, respectively, to form left and right combustion surface forming walls. Slit-shaped ejection port 1 ejecting to the surface side of each of the bodies 3 and 4
4 are arranged so as to be staggered in a state where they are staggered from each other with the flame mouth 6.

The fuel gas supply passage 26 is branched into two gas passages 26a and 26b.

The nozzle 3 is provided at the tip of one gas flow path 26a.
No. 3 is connected, and its nozzle 33 faces the opening 9b of the header pipe 9 for jetting the primary mixed gas in the same axial center state.
Therefore, the primary fuel gas ejected from the nozzle 33 enters the nozzle 33 during the process of entering the primary mixed gas ejection header pipe 9.
The primary air for combustion is sucked by the ejector effect created by the opening 9b of the header pipe 9 and becomes the primary mixed gas for Bunsen combustion, and the primary mixed gas is ejected from the ejection port 9a into the primary mixed gas supply passage 7. .. The excess air ratio of this primary mixed gas is 1 or less.

The other gas passage 26b is connected to the secondary fuel gas supply pipe 8, and the supply of the secondary fuel gas to the secondary fuel gas supply pipe 8 is intermittently connected to the gas passage 26b. A solenoid valve 34 is interposed.

Therefore, by closing the solenoid valve 34, the secondary air for combustion is ejected from the discharge port 14, and by opening the solenoid valve 34, the air is discharged from the discharge port 14. A dilute mixed gas having an excess ratio of 1.3 or more can be ejected as a secondary mixed gas.

That is, with the above-described structure, the burner B causes only the secondary air for combustion to be ejected from the discharge port 14 with the solenoid valve 34 closed in the range where the target combustion amount is smaller than the set value. And the secondary air for combustion causes flame tip 6
Slowly combust the primary mixed gas from the above, and in the range where the target combustion amount is larger than the set value, the solenoid valve 34 is opened and the diluted mixed gas as the secondary mixed gas is ejected from the discharge port 14. By the flame holding action of the flame of the primary mixed gas ejected from the flame port 6, the lean combustion for burning the lean mixed gas is executed.

Next, the operation control of the hot water supply apparatus by the controller C will be described.

The controller C is constructed by using a microcomputer, and various setting information from the operation unit S,
Also, the solenoid valves 27, 28, 34, the solenoid proportional valve 29, the blower 30, and the ignition plug 31 operate based on the detection information of the hot water supply temperature sensor S1, the incoming water temperature sensor S2, the water amount sensor 25, and the frame rod 32, respectively. Is configured to control.

The controller C executes the start / stop control of the hot water supply operation, but since the control is well known, its explanation is omitted.

The controller C has a block structure as shown in FIG. That is, reference numeral 41 sets the target combustion amount of the burner B based on the set hot water supply target temperature from the operation unit S, the incoming water temperature detected by the incoming water temperature sensor S2, and the amount of water detected by the water amount sensor 25, and the setting target thereof. It is a target value setting means for setting the target opening degree of the solenoid proportional valve 29 and the target rotation speed of the blower 30 so as to maintain the air ratio at a predetermined value according to the combustion amount. Reference numeral 42 is a valve control means for changing and adjusting the opening of the solenoid proportional valve 29 to a new target opening.
Is a blower control means for changing and adjusting the rotation speed of the blower 30 to a new target rotation speed, and 44 issues an opening degree change command to the valve control means 42 according to the change in the target combustion amount, Further, it is a command means for issuing a rotation speed change command to the blower control means 43.

Reference numeral 45 denotes the solenoid valve 3 according to the target combustion amount.
4 is a lean burn control means for opening and closing 4 as described above.

Next, the opening change command and the rotation speed change command by the command means 44 will be described with reference to FIG.

That is, as shown in FIG. 5A, when the target combustion amount changes to the increasing side at time T ₁ due to an increase in the water amount or the like, the command means 44 immediately instructs the blower control means 43 to change the rotation speed. The blower control means 4
In response to the rotational speed increase change command to 3, the opening degree increase change command to the valve control means 42 is delayed by the set time t ₁ and then issued. That is, the air flow rate (that is, the secondary mixed gas supply passage 10
Fig. 5 shows the secondary air flow rate for combustion flowing through
(B), and the fuel gas supply amount (that is, the combined amount of the primary fuel gas ejected from the primary mixed gas ejection header pipe 9 and the secondary fuel gas supplied from the secondary fuel gas supply pipe 8, The same applies hereinafter) increases and changes as shown in FIG.

Then, until the opening of the solenoid proportional valve 29 reaches the target opening and the rotation speed of the blower 30 reaches the target rotation speed (at the time point T _{2 in} FIG. 5), that is, the fuel gas supply amount and the feeding amount are increased. As shown in FIG. 5D, the air ratio in the transitional period (the period from T _{1 to} T _{2 in} FIG. 5) during the change in the increase in the air volume is changed from the opening degree change commanded by the rotation speed increase change command. Until the command is issued, only the blown air amount is increased and adjusted while the fuel gas supply amount is maintained at the previous amount, so that the air ratio becomes larger than the predetermined value λ, and subsequently, Since the amount of blown air has been increased and adjusted in advance after the opening increase change command is issued, the air ratio is maintained at a value larger than the predetermined value λ, and then the opening of the solenoid proportional valve 29 is set to the target. When the opening degree is reached and the rotation speed of the blower 30 reaches the target rotation speed T
_{At 2} , the air ratio becomes a predetermined value λ.

Further, as shown in FIG. 5A, when the target combustion amount changes to the decreasing side at the time of T ₃ due to the decrease of the water amount or the like,
The command means 44 immediately issues an opening degree decrease change command to the valve control means 42 and, in response to the opening degree decrease change command to the valve control means 42, issues a rotation speed decrease change command to the blower control means 43. The command is delayed by the set time t ₂ . That is, the amount of blown air is shown in FIG. 5B, and the amount of fuel gas supplied is shown in FIG.
It decreases and changes as shown in (c).

Then, until the opening of the solenoid proportional valve 29 reaches the target opening and the rotation speed of the blower 30 reaches the target rotation speed (at the time point T _{4 in} FIG. 5), that is, the fuel gas supply amount and the feeding speed are increased. As shown in FIG. 5D, the air ratio in the transitional period (the period of T _{3 to} T _{4 in} FIG. 5) during the change in the decrease of the air flow is changed from the rotation speed decrease command after the opening decrease change command is issued. Until the command is given, only the fuel supply amount is adjusted to decrease while the air flow rate is maintained at the previous amount, so the air ratio becomes larger than the predetermined value λ, and the rotation speed continues. Since the fuel supply amount has been reduced and adjusted in advance after the number reduction change command is issued, the air ratio is maintained at a value larger than the predetermined value λ, and subsequently, the opening of the solenoid proportional valve 29 is set to the target. At the time point T ₄ when the opening degree is reached and the rotation speed of the blower 30 reaches the target rotation speed, the air ratio is a predetermined value. becomes λ.

That is, by configuring the command means 44 so as to command the opening degree change command and the rotation speed change command as described above, when the target combustion amount changes to the increase side, and
In any case of changing to the decreasing side, after the opening degree change command and the rotation speed change command are commanded, the solenoid proportional valve 2
In the transitional period in which the opening degree of 9 reaches the target opening degree and the rotation speed of the blower 30 reaches the target rotation speed, the air ratio can be always kept larger than the predetermined value λ.

[Other Embodiments] Next, other embodiments will be listed.

In the above embodiment, it is possible to switch between the state in which the secondary combustion air is jetted from the discharge port 14 and the state in which the secondary mixed gas of the secondary air for combustion and the secondary fuel gas is jetted. Although the case of configuring the burner B has been described as an example, the burner B may be configured to eject only the secondary air for combustion from the discharge port 14 instead of this.

The burner B may be an all primary air type burner, and in this case, the primary air for combustion is supplied by the blower 30.

The present invention can be applied not only to the water heater but also to various combustion devices.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a hot water supply device to which the present invention is applied

FIG. 2 is a vertical sectional front view of a burner in the hot water supply device.

FIG. 3 is a side view of the burner in the hot water supply device with a part thereof cut away.

FIG. 4 is a diagram illustrating an air ratio in a transition period.

[Explanation of symbols]

 29 Electromagnetic proportional valve 30 Blower 41 Target value setting means 42 Valve control means 43 Blower control means 44 Command means B Burner

Claims (1)

[Claims] 1. A solenoid proportional valve (29) for adjusting the amount of fuel supplied to the burner (B), and a blower (30) for supplying combustion air to the burner (B) are provided. ), The target opening of the solenoid proportional valve (29) and the target rotation speed of the blower (30) are set so that the air ratio is maintained at a predetermined value in accordance with the set target combustion. To the target value setting means (41) for setting and the valve control means (42) for changing and adjusting the opening of the solenoid proportional valve (29) to the target opening according to the change of the target combustion amount. To issue an opening change command, and the blower (30)
And a command means (44) for issuing a rotation speed change command to a blower control means (43) for changing and adjusting the rotation speed of the fan to the target rotation speed, the command means (44) However, when the target combustion amount changes to the decreasing side, the rotation speed change command to the blower control means (43) is delayed with respect to the opening change command to the valve control means (42). Combustion device configured in.