JP2726381B2 - Combustion chamber structure of hot air generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an outlet of a combustion chamber of a hot air generator generally called a liquid fuel combustion type hot air generator which is used for heating or drying in a factory or the like. It is.

[0002]

2. Description of the Related Art FIG. 5 shows a general schematic structure of a liquid fuel combustion type hot air generator. In the liquid fuel combustion type hot air generator 1, a substantially cylindrical housing 3 for generating hot air is installed on a fuel tank 2, and a cylindrical combustion chamber 4 is provided therein.
Is provided. A burner 8 for combustion is arranged at the rear end of the combustion chamber 4 and an umbrella-shaped flame stopper 17 is mounted at the front end. The fuel in the fuel tank 2 is supplied to the burner 8 via the suction pipe 12, the fuel filter 15, and the fuel pump 11, and is burned in the combustion chamber 4. Combustion air is supplied from a blower 10 and ignition is performed by an igniter 1
This is done by an ignition rod 9 connected to 6. The combustion gas generated by this combustion is released from the gap 14 between the flame stopper 17 and the combustion chamber 4 to the housing 3 and mixed with the outside air supplied from the blower fan 13 installed behind the combustion chamber 4. The mixed hot air is blown out through a louver 6 installed at the outlet of the outer cylinder 3.

This liquid fuel combustion type hot air generator is safe because it can efficiently supply a large amount of hot air and there is no red heat on the surface of the hot air generator. Therefore, it is used for various purposes such as heating inside a factory and drying food.

[0004]

Since this type of hot air generator can efficiently burn in a combustion chamber, it can be downsized compared to a device for heating the same heat capacity, for example, an infrared heating device. Therefore, in order to further utilize this merit, further downsizing of this type of hot air generator has been studied in recent years.

In order to reduce the size of the housing occupying most of the volume of the hot air generator, it is effective to reduce the size of the combustion chamber installed inside. If the combustion chamber is simply miniaturized in the shape of the conventional flame stop, the clearance 14 between the flame stop and the combustion chamber is reduced.
Since the combustion may transfer into the housing in the state of a flame, the combustion gas diffuses and flows out into the housing while maintaining the temperature in the combustion chamber, and functions as a flame stopper to efficiently perform secondary oxidation. Cannot be fulfilled.

Further, when the size of the combustion chamber is reduced, noise due to combustion increases. For this reason, in the conventional flame stop shape, noise is emitted to the outside through the gap 14, so that
There is also a problem that noise generated from the hot air generator also increases. It is possible to reduce noise by installing a baffle or the like for soundproofing in the outer cylinder, but a space for inserting them is required, and the hot air generator becomes large. For this reason, the merit of reducing the size of the combustion chamber is lost.

[0007]

Therefore, in the present invention, the efficiency of the secondary oxidation is improved by shielding the central portion of the outlet end of the combustion chamber and providing a plurality of fine openings in the peripheral portion. Is suppressed. That is, a cylindrical housing having a front end serving as a hot air outlet according to the present invention, and disposed substantially coaxially inside the housing, and a position retracted from the hot air outlet serves as an outlet end of the combustion gas. In a hot air generator of a type having a cylindrical combustion chamber that has a combustion gas mixed with outside air introduced between the housing and the combustion chamber and blown out from a hot air outlet, the outlet end is A shielded central portion and a peripheral portion having a plurality of minute openings are provided.

In the combustion chamber provided with the outlet end having such a configuration, the generated combustion gas diffuses from the shielded central portion to the peripheral portion. Open to the periphery are minute openings, through which the flame does not blow into the housing, so combustion concentrates on the periphery and the temperature near the periphery in the combustion chamber is kept high. . Therefore, the combustion in the peripheral portion is promoted, and the combustion efficiency in the peripheral portion increases.

Since the high-temperature fuel gas burned in the peripheral portion is released into the housing through the minute opening, the combustion gas and metal, ceramic or the like constituting the outlet end are efficiently contacted. For this reason, the temperature of the member constituting the outlet end rises rapidly, and when the temperature becomes high, it is maintained as it is. Therefore, the temperature of the combustion gas discharged into the housing through the high-temperature opening can be increased, and the unburned portion in the combustion gas discharged into the housing is oxidized, which is the so-called secondary oxidation efficiency. Can be higher.

[0010] The noise density generated in the combustion chamber tends to increase at the center of the combustion chamber. However, in the present invention, since the center of the outlet end of the combustion chamber is shielded, noise is externally transmitted from the high-density central area. Can be prevented from propagating directly to Therefore, the noise intensity outside the housing can be reduced. Further, also in the peripheral portion, since the noise is only transmitted to the outside through the minute opening, the noise attenuation rate is higher than that in the conventional case where the noise is transmitted through a wide gap.

As described above, by employing the combustion chamber having the outlet end according to the present invention, the combustion efficiency in the combustion chamber can be improved, and the efficiency of secondary oxidation can be improved. For this reason, even if the combustion chamber is miniaturized, the flame does not jump out into the housing, and the housing does not become hot, uncombustible components are present in the hot air to generate an unpleasant odor, or the heating efficiency does not decrease. . In particular, these problems are likely to occur early in the combustion start, but in the hot air generator according to the present invention, since the temperature at the outlet end can be rapidly increased, the combustion efficiency in the combustion chamber can be increased from the initial combustion start. Can be prevented. Further, even if the noise density in the combustion chamber is increased by downsizing the combustion chamber, the intensity of noise transmitted from the outlet end to the outside can be reduced, so that the intensity of noise emitted from the hot air generator can be reduced.

Further, when the opening provided in the peripheral portion is opened in a direction inclined with respect to the central axis of the combustion chamber, the end of the opening inclined with respect to the central axis comes into contact with the discharged combustion gas. The temperature at the outlet end can be raised efficiently,
It is raised to the temperature of the combustion gas to be blown out. Also, the noise in the combustion chamber does not directly propagate to the outside because the opening is inclined, and most of the noise is reflected to the end of the opening or inside the housing and then propagates to the outside. Get higher. Therefore, the intensity of noise transmitted outside the hot air generator can be further reduced.

Further, by providing a frame cone such as a cone open toward the outlet end around the burner nozzle on the burner side of the combustion chamber located on the side opposite to the outlet end, the combustion efficiency in the combustion chamber is further improved. it can. Because the flame extending from the burner nozzle spreads along the frame cone, the center of the flame approaches the burner nozzle side, and the length of the flame can be shortened. Therefore, it is possible to improve the burning rate in the primary oxidation in the combustion chamber.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a liquid fuel combustion type hot air generator according to the present invention. The liquid fuel combustion type hot air generator 1 of this example is a hot air generator having substantially the same configuration as the liquid fuel combustion type hot air generator described above with reference to FIG. The description is omitted by attaching reference numerals.
The liquid-fuel-fired hot-air generator 1 of the present embodiment also has a cylindrical combustion chamber 4 installed inside a cylindrical housing 3 so as to be substantially coaxial. The rear (burner side) 4 of the combustion chamber 4
A burner 8 is installed in a, and fuel such as oil sprayed here is burned inside the combustion chamber 4. Combustion chamber 4
On the burner side 4a, a frame cone 40 having a substantially conical shape opened toward the front 4b from around the burner nozzle at the tip of the burner 8 is mounted. The fuel sprayed from the burner 8 spreads along the frame cone 40, and a flame is formed. The combustion gas generated by the fuel is discharged from the outlet end 20 at the front 4b of the combustion chamber 4 into the housing 3. In the liquid fuel combustion type hot air generator 1 of this example, a plurality of holes 25 are formed in a peripheral portion 22 excluding a central portion 21 of an outlet end 20.

The right half of FIG. 2 shows the combustion chamber 4 as viewed from outside the outlet end 20, and the left half shows the combustion chamber 4 as viewed from inside the outlet end 20. FIG. 3 shows a cross section near the outlet end 20. In the hot air generator 1 of the present example, a stainless steel plate is used as the outlet end 20 of the combustion chamber, and a plurality of holes 25 having a diameter of several mm are formed concentrically in the peripheral portion 22 outside the central portion 21. Have been. Peripheral part 2
2 are formed such that the average opening ratio of the outlet end 20 excluding the region of the outer periphery 23 is about 15 to 25%, preferably about 15 to 20%. The aperture ratio of only the peripheral portion 22 excluding the central portion 21 where no 25 is formed is about 20 to 30%, preferably 2 to 30%.
It is adjusted to be 0 to 25%. 250m diameter
For example, the diameter of the central portion 21 is approximately 60 mm, and the diameter of the central portion 21 is approximately 60 mm to approximately 210 m.
The area of m is the peripheral part 22. A total of 575 holes 25 having a diameter of 4.2 mm are formed concentrically in the peripheral portion 22, and the aperture ratio of the peripheral portion 22 is set to approximately 20%. The average opening ratio of the outlet end 20 is set to approximately 17%.

Referring to the configuration of the combustion chamber 4 shown in the left half of FIG. 2, the center 21 of the outlet end 20 covers the front of the burner 8. A frame cone 40 extends around the burner 8, and an inner cylinder (combustion cylinder) 5 made of stainless steel is located outside the frame cone 40.

When the fuel supplied from the burner 8 burns in such a combustion chamber 4, the flame extends along the frame cone 40, and a portion relatively close to the burner 8 becomes the center of the flame. Therefore, even if the length of the combustion chamber 4 is shortened, the distance from the center of the flame to the outlet end 20 can be sufficiently ensured, and shortage of the combustion distance can be prevented. For this reason, even if the combustion chamber 4 is small, the fuel efficiency is high. Further, the tip of the flame and the fuel gas reaching the outlet end 20 diffuse toward the peripheral portion 22 having a large number of holes since the central portion 21 of the outlet end 20 is shielded. Since the opening area of the hole 25 formed in the peripheral portion 22 is as small as about 4 mm in diameter, there is almost no blow-through of the flame. For this reason, most of the fuel is burned off in the vicinity of the peripheral portion 22, and the temperature in this region rapidly rises,
It will be hot. Therefore, the temperature of the combustion gas in the vicinity of the peripheral portion 22 is high, and the temperature of the members constituting the peripheral portion 22 is also high.

The combustion gas is discharged into the inside of the housing 3 through a minute hole 25 formed in the peripheral portion 22. By using the configuration of the outlet end 20 of the present embodiment, compared with the case where the gas is discharged through the gap formed in the conventional flame stop, the members constituting the outlet end 20 with the combustion gas, in this example, stainless steel The contact area with the plate made of steel becomes large.
Therefore, the temperature of the peripheral portion 22 at the outlet end rises rapidly and is maintained at a high temperature. When the temperature of the peripheral portion 22 rises once, the combustion gas released into the housing 3 passes through the minute opening 25 of the peripheral portion 22, so that the temperature of the combustion gas after release becomes high. For this reason, the efficiency of the secondary oxidation inside the housing 3 can be improved.

As described above, in the heater unit of this embodiment, the combustion efficiency can be improved by the structure of the frame cone 40 and the outlet end 20, so that even if the combustion chamber 4 is downsized, unburned components are discharged into the housing 3. Few things. For this reason, even if the warm air generator 1 is miniaturized, high combustion efficiency can be maintained, and the danger such as generation of flame outside the combustion chamber and the increase of unburned components causing unpleasant odor can be prevented. .

Further, the central portion 21 of the outlet end 20 of the combustion chamber of the present embodiment is shielded, and the burner front part of the combustion chamber having high noise density is shielded from the outside of the hot air generator 1. Therefore, noise from a high-density noise source is not directly emitted to the outside of the hot air generator 1, and external noise can be reduced. Furthermore, the minute opening 2
The noise at the outlet end 20 is high because the noise is emitted to the outside via 5. Therefore, even if the combustion chamber 4 is miniaturized and the noise density in the combustion chamber increases, the intensity of noise transmitted to the outside can be greatly reduced, so that the small-sized but quiet hot air generator 1 can be provided.

FIG. 4 shows a modified example of the outlet end 20. At the outlet end 20, a minute opening 25 is formed in the peripheral portion 22.
Is opened in such a shape as to cut and raise a stainless steel plate constituting the outlet end 20. For this reason, the opening 25 faces a direction substantially perpendicular to the central axis 4 c of the combustion chamber 4. In FIG. 4, the direction of the opening 25 is the center axis 4.
Although it is on the outside with respect to c, the opening 25 may be formed toward the central axis 4c, or the opening 25 may be opened in a direction along the circumference.

When the opening 25 is opened in a direction substantially perpendicular to the center axis 4c, a part 26 of the side end of the opening 25
Is substantially perpendicular to. In the outlet end 20 shown in FIG. 4, the cut and raised portion corresponds to a side end 26 that is substantially perpendicular to the central axis 4c.

When the opening 25 is opened like this, the combustion chamber 4
The combustion gas generated in the step (3) is emitted to the inside of the housing 3 while changing its direction at substantially a right angle while contacting the side end 26, so that the contact efficiency between the outlet end 20 and the combustion gas can be further improved. Therefore, the temperature of the outlet end 20 can be raised more rapidly in the early stage of the combustion start. When the temperature of the outlet end 20 increases, the temperature of the passing combustion gas can be further increased,
Further, since the contact efficiency is improved, the uniformity of the emitted temperature is further improved. For this reason, the efficiency of the secondary oxidation can be further increased.

The noise in the combustion chamber transmitted to the outside of the housing 3 and the hot air generator 1 through the opening 25 is also:
It does not propagate directly from the combustion chamber to the outside,
And is attenuated by being reflected by the housing 3. Therefore, the noise intensity outside the hot air generator 1 can be further reduced. Note that the direction of the opening does not necessarily have to be substantially perpendicular to the central axis, and by inclining at a certain angle, it is possible to improve the contact efficiency and the ability to attenuate noise. Further, the inclination angle may be different for each opening.

As described above, in the hot air generator using the combustion chamber having the outlet structure as in the present embodiment, the primary and secondary combustion efficiencies can be maintained high even if the combustion chamber is small, and the external Therefore, the performance of the liquid fuel combustion type hot air generator can be maintained or enhanced, and the size can be further reduced.

In this embodiment, the outlet end is formed by a plate made of stainless steel, but by using a ceramic plate such as alumina or a member obtained by spraying ceramic such as zirconia on a stainless plate or the like. It is also possible to extend the life and improve the sound absorbing effect. Also, in this example, many holes are formed concentrically on the shielding member, but may be arranged in a grid or the like, and the shape, size, distribution, etc. of the holes may vary depending on the load on the combustion chamber. An appropriate one can be selected. Further, the area of the peripheral portion where a large number of openings are formed is not limited to the side surface facing the front of the combustion chamber, but may be provided on the outer peripheral surface in front of the combustion chamber. Further, in the present embodiment, a curved outlet end is used to suppress thermal deformation, but various shapes such as a flat plate shape and a cone shape can be adopted.

[0027]

As described above, by employing the combustion chamber outlet structure according to the present invention, one of the combustion chamber outlets is provided.
Since the secondary and secondary oxidation efficiencies can be greatly improved and the noise can be attenuated at the same time, a good combustion state can be maintained efficiently even if the combustion chamber is downsized, and the external noise intensity can also be kept low. Therefore, by adopting the outlet structure according to the present invention in a combustion chamber of a hot air generator such as a liquid fuel combustion type hot air generator, a small size, low cost, and easy use in a narrow place are possible. A hot air generator having advantages can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main configuration of a liquid fuel combustion type hot air generator according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a structure of a combustion chamber and a shielding member of the liquid fuel combustion type hot air generator shown in FIG. 1 with a part of the combustion chamber being omitted.

FIG. 3 is a sectional view showing a structure of an outlet of the combustion chamber shown in FIG. 2;

FIG. 4 is a sectional view showing a modification of the outlet structure of the combustion chamber according to the present invention.

FIG. 5 is a cross-sectional view showing a main configuration of a conventional liquid fuel combustion type hot air generator.

[Explanation of symbols]

1. Hot air generator with liquid fuel combustion 2. Fuel tank 3. Housing 4. Combustion chamber 4c. Central axis of combustion chamber 5. Combustion cylinder 6. Louver 8. Burner 9. Ignition Rod 10 Blower 11 Fuel pump 12 Suction pipe 13 Blower fan 14 Flame stop gap 15 Fuel filter 16 Igniter 17 Flame stop 20 Outlet end of combustion chamber 21 ..The central part of the outlet end 22..the peripheral part of the outlet end 25..the opening 26..the side end of the opening 40..the frame cone

Claims (3)

(57) [Claims] 1. A cylindrical housing having a front end serving as a hot air outlet, and disposed substantially coaxially inside the housing, and a position retreated from the hot air outlet serving as a combustion gas outlet end. A hot air generator having a cylindrical combustion chamber, wherein the combustion gas is mixed with outside air introduced between the housing and the combustion chamber, and is blown out from the hot air blowing port. Is a combustion chamber structure of a hot air generator having a shielded central portion and a peripheral portion having a plurality of minute openings. 2. The combustion chamber structure of a hot air generator according to claim 1, wherein the opening is opened in a direction inclined with respect to a center axis of the combustion chamber. 3. The hot air generator according to claim 1, further comprising a frame cone open toward the outlet end around a burner nozzle on a burner side of the combustion chamber facing the outlet end. Combustion chamber structure.