JPS60213708A - Pulse combustion apparatus - Google Patents

Abstract

PURPOSE:To obtain a low-noise pulse combustion apparatus, by providing a porous plate with a space between the plate and the inner wall of an air choke valve device and filling up the space with acoustic material. CONSTITUTION:A porous plate 7 is provided with a space between the plate and the inner wall of an air choke valve device 6, and the space is filled up with acoustic material 11. Combustion noise introduced into the space is absorbed by the acoustic material 11 between the porous plate 7 and the inner wall surface of the air choke valve chamber 12 generating the noise impact and dispersion continuously. Some noise introduced into the space is discharged again to the air choke valve chamber 12 and continuously generates the impact and dispersion between the noise and the reverberating noise in the chamber 12. Thus, the combustion noise is silenced by mutual interference as the result of the continuous impact and dispersion inside the chamber 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pulse combustor that serves as a heat source for household or industrial water heaters, space heaters, and the like.

Conventional Structure and Problems When a pulse combustor is started, fuel and combustion air are supplied to the combustion chamber by a blower fan, and combustion is forced by operating a spark plug.

Once the system stabilizes and forms a combustion cycle, even if the spark plugs and blower fan are stopped, combustion air is automatically sucked in and self-ignition continues pulsed combustion at a constant frequency of tens to hundreds of hertz.

This type of pulse combustor burns under high load, has good heat transfer characteristics, and performs ignition, air supply and exhaust automatically except during startup.
, has advantages such as simple structure.

However, the pulse combustor has the problem of high noise during combustion. For this reason, various functional parts are sound insulated and mufflers are installed. However, when a muffler is installed, the acoustic impedance changes, which can change the fundamental frequency of the combustion cycle. The muffler that you have taken the pains to install on your car is often not as effective as expected.

Therefore, by surrounding the air pulping device with an air cushion chamber, the sound leakage from the air pulping device is made large enough to be sound-insulated, and even when a muffler is installed, the same wave number can be maintained.
Effective muffler muffling. However, in the case of pulse combustion, the combustion noise is very loud, so if the air pulp equipment is surrounded by an air cushion chamber, the vibration of the wall of the air cushion chamber and the leakage of sound from the wall, especially in the low frequency range, will increase. The thickness of the air cushion chamber must be increased. Therefore, even if a muffler is installed to reduce the noise emitted from the supply and exhaust ports, the noise leaking from the air cushion chamber becomes louder, and a problem arises in that countermeasures must be taken.

OBJECTS OF THE INVENTION The present invention has been made in view of this problem, and aims to provide a pulse combustor with a simple structure and low noise by improving an air pulp device.

Structure of the Invention In order to achieve the above-mentioned object, the present invention provides a perforated plate in an air pulp apparatus with a gap between the inner wall surface of the air pulp apparatus and a sound absorbing material filled in the gap.

Description of examples An embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1, the pulse combustor of the present invention has a combustion chamber 1
．． Tishif 4121 spark plug 3 at one end, air chamber 4
．． Air supply path6. Air valve device 6° perforated plate a, air cushion chamber 8. Fuel supply path9. Fuel pulp device 1
01. It is composed of a sound absorbing material 11.

The combustion sound of a pulse combustor comes from combustion chamber 1 and tail pipe 1.
It has a fundamental frequency determined by the shape of , and harmonic components consisting of integral multiples of the fundamental frequency.

Since this fundamental frequency is a low frequency sound ranging from several tens of hertz to several hundred hertz, this sound is radiated from the air valve device 6 to the air cushion chamber 8, vibrates the wall surface of the air cushion chamber 8, and causes the sound to be emitted from the wall surface. Sound leakage, especially low-frequency components, is thickened and reduced.

Therefore, in the embodiment of the present invention, in order to reduce the combustion sound when it passes through the air pulp device 6, a perforated plate is provided in the air pulp device 6 by creating a gap with the inner wall surface of the air pulp device 6. The gap between the inner wall surface of the air pulp device 6 and the perforated plate 7 is filled with a sound absorbing material 11. The perforated plate 7 may be a metal plate or the like with many small holes, or a material with many small holes such as sintered metal or foamed ceramic.

As shown in FIG. 2, the air valve device 6 includes an air valve chamber 13. Air pulp port 14. It is composed of air pulp 15. A perforated plate 7 is provided inside the air pulp chamber 12 with a gap between it and the wall surface.

When combustion occurs in the combustion chamber 1, a rapid pressure rise occurs within the combustion chamber 1, and due to the pressure propagation, the air pulp 14 is pressed against the air pulp boat 13 and blocks the air port 16 on the air port. On the other hand, the combustion sound is simultaneously radiated into the two empty pulp chambers 12 via the air supply path 6. The combustion sound 16 that has entered the air pulp chamber 12 is absorbed by a large number of small holes 17 formed on the surface of the perforated plate 7, and the sound absorbing material 11 between the inner wall surface of the air pulp chamber 12 and the perforated plate 7 absorbs the sound. Fill the void.

The combustion sound 16 that has entered this gap repeatedly collides and disperses between the inner wall surface of the air pulp chamber 12 and the surface of the perforated plate 70 while being absorbed by the sound absorbing material 11. A part of the sound that has entered the air gap is radiated to the air pulp chamber 12 again, and collisions and dispersion are repeated between this sound and the sound reverberating in the air pulp chamber 12. In this way, the combustion sound 16 repeatedly collides and disperses within the air pulp chamber 12, and the combustion sound is muffled by mutual interference.゛Sound reduction due to this mutual interference is effective over a wide range from low frequency ranges to high frequency ranges. Furthermore, muffling the combustion noise in the air pulp chamber 12 also prevents vibrations of the air pulp device 6 itself, which also has the effect of preventing new secondary noises from being generated in the air pulp device 6.

As described above, the combustion noise generated in the combustion chamber 1 is muffled when passing through the air valve device 6 and is radiated to the air cushion chamber 8. Hence the air cushion chamber 8
Low-frequency sound components that cause the wall to vibrate are attenuated, the wall of the air cushion chamber 8 hardly vibrates, and sound leakage from the wall is significantly reduced. Therefore, noise can be reduced compared to conventional pulse combustors.

Effects of the Invention According to the present invention, since the combustion sound passing through the air valve chamber and radiated to the air cushion chamber is reduced, the vibration of the wall surface of the air cushion chamber and the leakage of sound from the wall surface are significantly reduced. Effective in reducing noise from pulse combustors.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a pulse combustor according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of an air valve device of the same pulse combustor. 1... Combustion chamber, 2... Tail pipe,
6... Air supply path, 6... Air valve device, 7... Perforated plate, 8... Air cushion chamber, 11...・Air valve chamber, 12
...Air valve port. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] A tail pipe connected to one end of the combustion chamber, a fuel supply passage and an air supply passage connected to the other end of the combustion chamber, a fuel pulp device communicating with the fuel supply passage, and air communicating with the air supply passage. The air cushion chamber includes a pulp apparatus, and an air cushion chamber that accommodates the air pulp apparatus therein and communicates with the air supply path, and is provided in the air pulp apparatus with a gap between the air cushion chamber and the inner wall surface of the air pulp apparatus. A pulse combustor in which a perforated plate is provided and a gap between the inner wall surface of the air pulp device and the perforated plate is filled with a sound absorbing material.