JPH0759966B2 - Burning plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion plate which is provided with a large number of flame holes in a heat-resistant plate such as ceramic and is used as a crater of a combustion device.

[0002]

2. Description of the Related Art In a combustion plate of this type, when the cross-sectional area of each flame hole is made constant, the flame resonates and resonates at the time of combustion to increase noise, and when the amount of heat generation is increased or decreased over a wide range, An unstable region of combustion occurs. In order to solve this, if the flame hole is composed of a large flame hole and a medium flame hole surrounding the large flame hole, the combustion noise can be reduced and the combustion can be stabilized in a relatively wide range. Are known.

In Japanese Patent Publication No. 57-41648,
An invention is described in which a combustion plate in which flame holes having different opening areas are irregularly provided to reduce combustion noise is applied to a gas burner. Further, Japanese Patent Publication No. 50-7125 discloses a burner plate in which two or more types of different-diameter flame holes are alternately and evenly arranged to change the amount of heat generation in a wide range and to improve combustion stability. Is proposed.

[0004]

However, when the present inventor uses two types of flame holes, large and medium, if the arrangement of the flame holes of this kind is set to the optimum arrangement for high-load combustion, the present invention has a wider range. It was found that, when the calorific value is increased or decreased, the stability of combustion becomes insufficient at the time of light load combustion.

That is, in order to stabilize the flame of this type of combustion plate, there is a relationship between the flame hole diameter and the pitch depending on the combustion load. That is, stabilization cannot be achieved without increasing the pitch when the load is high and decreasing the pitch when the load is low. If the medium flame holes and large flame holes required for flame stabilization are arranged at a certain pitch in the range from medium load combustion to high load combustion, the large flame pitch at low load combustion will improve the flame holding property of the large flame holes. bad.

Further, Japanese Patent Publication No. 57-41648 discloses that
There is no description as to how irregularly provided flame holes having different opening areas can prevent abnormal combustion noise, and no specific means for preventing abnormal combustion noise has been proposed.

Furthermore, Japanese Patent Publication No. 50-7125 does not clarify which type of flame hole diameter and its arrangement are optimal.

The object of the present invention is, in a combustion plate,
The purpose of the present invention is to provide a flame hole pattern that can prevent abnormal combustion noise and stabilize combustion in all forced combustion regions even if the combustion in the burner is changed over a wide range.

[0009]

[Means for Solving the Problems] In order to achieve the above purpose,
In the combustion plate of the present invention, a heat-resistant plate having a predetermined shape is provided with a large number of large and medium-sized cross-sectional areas having a large number of flame holes penetrating to the front and back, and the various flame holes are dispersed in a grid pattern. The large flame hole is located at the center of four adjacent small flame holes, is located at the center of four adjacent medium flame holes, and each of the small flame holes is adjacent to the two adjacent small flame holes. In the combustion plate for forced combustion set in the middle of the medium flame hole, the combustion plate is provided with a recess formed concentrically with the large flame hole, and this recess defines at least a part of the small flame hole. The configuration adopted is included.

[0010]

Since the flame of the large flame hole having large vibration energy is surrounded on all sides by the medium flame hole of medium frequency and vibration energy, the vibration energy is effectively attenuated by interference. Further, the vibration energy of the flame in the medium flame hole is smoothly attenuated by the vibration energy of the flame in the small flame hole. As a result, it is possible to reduce the combustion noise over the entire range of the change of the heat generation amount in a wide range.

Further, in order to improve the flame holding property of the large flame hole at the time of low load combustion, if the small flame holes are provided at a small pitch as the flame holding flame holes, the flame group at the time of low load combustion can be stabilized. . At this time, the large flame hole and the medium flame hole are dominant in the flame group during high load combustion, and the stabilization of the flame group during high load combustion is not impaired. Therefore, if the three types of flame holding diameters are formed in the above pattern, stable combustion in an extremely wide combustion load range can be ensured, and destabilization of the flame hole group that causes abnormal combustion noise can be prevented.

That is, the large flame hole is surrounded on all sides by small flame holes having good flame stability at low load combustion, and is surrounded on all sides by medium flame hole having good flame stability at medium load combustion. Since the flame stability is essentially good at times, the flame stability is good in a wide range of change in the calorific value.

Further, the combustion plate is provided with a recess formed concentrically with the large flame hole, and since the recess contains at least a part of the small flame hole, The flame from the small pits is sucked into the flame in a merged state at the root, and the overall flame becomes a large-diameter flame and the flame formation state is stabilized. With such stabilization of the flame, the generation of noise due to oscillatory combustion is favorably suppressed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on a first embodiment shown in FIGS. 1, 2 and 8. The combustion plate 1 according to the present invention is made of ceramics, and in this embodiment, a heat-resistant plate having a rectangular outer shape is provided with a large number of flame holes penetrating both sides. The planar shape of the combustion plate can be selected as desired, depending on the application, such as a circle or a triangle, and the overall shape may be spherical, convex or concave other than flat.

The flame holes are of three types: 252 large flame holes of 1.9 mm in diameter, 3932 medium flame holes of 1.3 mm in diameter, and 1050 small flame holes of 1.0 mm in diameter. Consists of. Each of these three types of flame holes has a circular shape, and various types are dispersed and regularly arranged in a lattice pattern. One of the large flame holes 3a is surrounded on all sides by four small flame holes 5a, 5b, 5c, 5d which are located at equal intervals on a concentric circle with a center distance of 2.4 mm from the center. , Four medium flame holes 4a, 4b, 4 which are concentrically arranged at equal intervals with a center distance of 3.4 mm.
It is surrounded on all four sides by c and 4d (Fig. 1).
Shown in). That is, the four small flame holes 5a, 5b, 5c,
5d are the four medium flame holes 4a, 4b, 4c, 4 respectively.
It is set to be located in the middle of d. Further, blind holes for reducing a thermal shock are provided in a row around the combustion plate 1 and a mounting position of the ignition device.

Further, a conical recess D is formed on the combustion plate 1 concentrically with the large flame hole 3a, and this recess D is formed in the region of the outer peripheral edge with the regions of the four small flame holes 5a, respectively. The size is set to have a common part.
The apex angle Θ of the depression D is set to, for example, 120 degrees, the diameter of the depression D is set to 4.5 mm, and the vertical dimension t formed by the common portion between the outer peripheral edge portion and the small flame hole 5a. Is set to 1.0 mm to 1.5 mm.

FIG. 8 shows a gas water heater 6 using a forced air blower type gas burner 50 using the combustion plate 1. Two combustion plates 1 are mounted in parallel in the longitudinal direction, and are forced by a blower 7. The blown air and the fuel gas are mixed in the mixing chamber 8 upstream of the plate 1,
Is ignited and burned in the combustion chamber 9 on the downstream side of. The heat generated by the combustion is absorbed by the heat exchanger mainly composed of the water pipe 10 and the fins 11 and transferred to the running water in the water pipe 10. In this gas burner 50, the calorific value is set so that it can be changed from 6000 kcal / hr to 30,000 kcal / hr, and the amounts of gas and air supplied are adjusted according to the calorific value.

In this case, the low heat value region (600
At 0 kcal / hr to 10000 kcal / hr), the flame of the large flame is stabilized by the small flame, and similarly, the middle flame is also stabilized, and the stabilization of the entire flame group is realized. Further, in the high calorific value region (20,000 kcal / hr or more), the flames of the medium flame holes and the large flame holes become a dominant flame group and are stabilized.

Further, due to the depression D, the flame from the small flame hole 5a is sucked into the flame from the large flame hole 3a in a merged state at the root, and a large-diameter flame is generally formed at the root to form the flame. Is stable. With such stabilization of the flame, the generation of noise due to oscillatory combustion is favorably suppressed.
By the way, FIG. 2 is a graph showing the frequency (Hz) on the horizontal axis and the noise level (dB) on the vertical axis, and the component in the range of 400 Hz to 600 Hz, which is the main frequency of combustion noise, is indicated by a broken line. Compared with the one shown in (1), it can be greatly reduced and can contribute to ultra-low noise reduction. It should be noted that the size of the depression D may be formed to be a size of a region including the small flame holes 5d over the entire surface.

As described above, the cross-sectional areas of the flame holes are large, medium, and small, and the cross-sectional area is different in three steps. In this case, the cross-sectional area ratio of the large, medium, and small flame holes is about 4: 2: 1. Is most preferable, and when set in this way, the ratio of the number of large, medium, and small flame holes is most preferably about 4: 2: 1. When set in this way, large, medium, and small The best effect is obtained when the ratio of the number of flame holes is approximately 1: 3: 4. Also, these ratios ±
If it is within 30%, the object of the present invention can be achieved.

Next, FIGS. 3 to 5 show second to fourth embodiments of the present invention. In the second embodiment of FIG. 3,
The inner peripheral surface of the depression D is formed into a rectangular cross section, and
In the embodiment, the inner peripheral surface of the depression D is formed into an elliptical shape,
In the fifth embodiment of FIG. 5, the inner peripheral surface of the depression D is formed in a spherical shape. In this case, the shape of the depressions D is not limited to the above-mentioned shape, and grooves extending in the radial direction may be formed on the surface of the depressions D at equal intervals.

Next, FIGS. 6 and 7 show fifth and sixth embodiments of the present invention. First, in the fifth embodiment of FIG. 6, in the combustion plate 1, the large flame holes 3 and the small flame holes 5 are alternately arranged in the vertical direction as a first flame hole group, and on both sides of this first flame hole group. The small crater holes 5 and the medium flame holes 4 are vertically arranged alternately, and are referred to as a second crater group. Then, a groove M extending in the vertical direction is formed within a lateral dimension range extending from the first crater group to a part of the second crater group as indicated by a mesh line in the plan view of FIG. 6 as appropriate. The grooves M act as the depressions of the present invention, and have a rectangular cross section and are alternately arranged on the combustion plate 1 every other row with the first crater group.

In the sixth embodiment of FIG. 7, the grooves M are arranged in an inclined state instead of the vertical type, and the first flame hole group in the fifth embodiment has the medium flame holes 4 and the large flame holes 3 alternately. It is assumed that the small flame holes 5 are arranged side by side in the second flame hole group. These 5th
Even if it is configured as in the sixth embodiment, an effect similar to that of the first embodiment can be obtained. In the case of these embodiments, the shape of the groove M is not limited to the rectangular shape, and may be an elliptical shape or a spherical shape. In addition, in concrete implementation, various modifications can be made without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view showing a main part of a combustion plate according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between noise level (dB) and frequency (Hz).

FIG. 3 is a sectional view of a main part of a combustion plate according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a combustion plate according to a third embodiment of the present invention.

FIG. 5 is a sectional view of an essential part of a combustion plate according to a fourth embodiment of the present invention.

6A and 6B are a plan view and a sectional view of a main part of a combustion plate according to a fifth embodiment of the present invention.

FIG. 7 is a plan view showing a main part of a combustion plate according to a sixth embodiment of the present invention.

FIG. 8 is a cross-sectional view of a water heater using the combustion plate of the present invention.

[Explanation of symbols]

 1 ... Combustion plate 2 ... Heat-resistant plate 3, 3a ... Large flame hole 4, 4a, 4b, 4c, 4d ... Medium flame hole 5, 5a, 5b, 5c, 5d ... Small flame hole D ... Dimple

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Ishikawa 2-26 Fukuzumi-cho, Nakagawa-ku, Nagoya, Aichi Prefecture Linnai Co., Ltd. No. within Linnai Co., Ltd.

Claims (2)

[Claims] 1. A heat-resistant plate having a predetermined shape is provided with a large number of flame holes having three kinds of large, medium and small cross-sectional areas and penetrating to the front and back so that each of the flame holes is dispersed in a lattice pattern. The large flame hole is located at the center of four adjacent small flame holes and at the center of four adjacent medium flame holes, and each of the small flame holes is defined by the two adjacent medium flames. In the combustion plate for forced combustion set in the middle of the holes, the combustion plate is provided with a recess formed concentrically with the large flame hole, and the recess includes at least a part of the small flame hole. Combustion plate characterized by being. 2. The combustion plate according to claim 1, wherein the shape of the depression has a conical inner peripheral surface whose width gradually increases upward.