JPH041246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a pulse combustion device for use in industrial, commercial and domestic heating devices.

Conventional configurations and their problems Despite their excellent combustion characteristics and high heat exchange rate, pulse combustors have not been widely used because they generate excessive noise and lack appropriate means to muffle the noise. Conventional sound reduction measures mainly include noise reduction using sound insulating materials and mufflers, but
As a pulse combustor, low-frequency noise below 100 Hz is large, and it is difficult to sufficiently reduce it with the above measures.Also, noise reduction methods using phase canceling downstream of the tail pipe have been used, but On the side, the combustion exhaust gas is discharged through the heat exchange path, so the sound energy is also reduced, and the sound reduction effect is not small.However, appropriate sound reduction measures in the air path on the upstream side of the combustion chamber There is nothing to do but surround it with a material of sufficient thickness and use a muffler to muffle the noise.

OBJECTS OF THE INVENTION The present invention was devised in view of the conventional problems and provides a low-noise pulse combustor that reduces noise on the intake side with a simple configuration.

Composition of the Invention The present invention has an operating condition that two pulse combustors are fired alternately, and the air valves provided in the air path communicating with the combustion chamber are arranged to face each other, so that the phase of the noise generated in the combustion chamber is The configuration is such that the phase is opposite at the exit of the air, and it is surrounded by a housing having an air passage.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 13 and 14, an air cushion chamber 15 consisting of a housing surrounding air chambers 9 and 10, and an air inlet 16.

For starting, combustion is performed alternately by separately provided control means.
The air inlet 1 is activated by the blower installed separately.
Combustion air is sent from 6 to the combustion chamber 1 via the air valve chamber 9, and fuel is supplied into the combustion chamber from the combustion supply pipe 5 for forced combustion.The combustion chamber 1 and tail pipe 3 form a Helmholtz type combustion chamber. Since it constitutes a resonator, it forms a self-exciting cycle when ignited. Once combustion occurs, positive and negative pressure fluctuations occur inside the combustion chamber 1, and the air valve 11 is activated to suck in combustion air and combustion continues by spontaneous ignition, so the ignition plug 7
In the present invention, there is no need to operate a blower to send combustion air.In the present invention, two combustors are provided and the combustion is performed alternately.

Next, noise reduction according to the present invention will be explained. As shown in Figure 2, the combustion sound of a pulse combustor has a fundamental frequency f ₀ determined by the shapes of the combustion chamber 1 and tail pipe 3, and harmonic components consisting of sounds that are integral multiples of f ₀ . The sound pressure is highest at f ₀ , so it can be seen that sound reduction measures are most effective if they are applied to the sound with the fundamental frequency f ₀ . Therefore, by making a pair of combustors the same shape, the fundamental frequencies are made equal, and the combustion is performed alternately. Naturally, the sound waves at the air inlets 13 and 14 have the same frequency, and the waveform has a back and an antinode. , which will interfere with each other and cancel each other out.At this time, the air valve 11,
Since the sound emitted from No. 12 spreads radially, the air inlet No.
3 and 14 should be closer than the valve diameter, and the air cushion chamber 15 should be closer to the air valves 11 and 1.
It is desirable to have a volume that can sufficiently absorb the pressure fluctuations caused by 2. With such a configuration, not only the fundamental frequency f ₀ but also high frequency sounds can be lowered.

Effects of the Invention As described above, the present invention muffles noise by causing two combustion chambers to burn alternately and by phase canceling on the air supply side. The valve sends air to the upstream side and the other combustion chamber becomes negative and sucks air, so they complement each other and have the effect of expanding the combustion range, making it an extremely useful invention. Since the pulse combustor does not need to be large, a compact pulse combustor can be realized.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a pulse combustor according to an embodiment of the present invention, and FIG. 2 is a frequency distribution diagram of sound in a conventional pulse combustor. 1, 2... Combustion chamber, 3, 4... Tail pipe,
5, 6... Fuel supply pipe, 7, 8... Spark plug, 9,
10... Air valve chamber, 11, 12... Air valve, 1
3, 14...Air valve inlet, 15...Air cushion chamber, 16...Air inlet.

Claims (1)

[Claims] 1 Two pulse combustors each having a valve in a path for supplying fuel and air to a combustion chamber are arranged side by side, and openings of the valves in the combustion air supply path of the pulse combustor are opposed to each other, and the valves are opposed to each other. A pulse combustion device characterized in that the interval between the openings is equal to or smaller than the outer diameter of the valve, and the periphery is surrounded by a casing having an air passage.