JPH0617723B2 - Pulse combustion device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a pulse combustion device used as a heating device for industrial, commercial or domestic water heaters, hot air blowers and the like.

Conventional example configuration and its problems Conventionally, the pulse combustor can be used as a combustor with high heat exchange efficiency because the flow velocity of the combustion gas is large and pulsating, and further, no power source is required except during operation. Therefore, it was a promising combustor with low running cost. Such a pulse combustor has a large combustion noise and a narrow variable range of heat output. In order to reduce the combustion noise, there is a method of dividing into a combustor with a small heat output. Therefore, we attempted to burn two pulse combustors with a small heat output in parallel to reduce the combustion noise and increase the variable range of the heat output.

At this time, if the exhaust cushion chamber is shared by one unit and the tail pipes of both pulse combustors are connected to the exhaust cushion chamber, the ignition performance is poor. In particular, it is difficult to ignite one pulse combustor while it is operating. In addition, frequent combustion failures occur even when both are burning,
A combustion stop has occurred.

On the other hand, when the exhaust cushion chamber is provided in each pulse combustor, each pulse combustor has a combustion amount, an intake air amount,
Since the frequency of pulse combustion differs due to the difference in structural dimensions, the combustion noise accompanied a beat phenomenon. As a result, the combustion noise did not decrease as expected, and a harsh sound remained.

OBJECT OF THE INVENTION It is an object of the present invention to remedy the drawbacks of the prior art and to provide a quiet pulse combustion device which prevents beat noise of combustion noise.

The present invention is characterized in that a plurality of pulse combustors having exhaust pipes are provided in parallel at the outlet of the combustion chamber and its tail pipe, and an exhaust cushion chamber is provided at the outlet of the tail pipe, and a communication part is provided between the exhaust cushion chambers. It is a pulse combustion device.

Description of Embodiments The drawings show the essentials of a pulse combustion apparatus according to an embodiment of the present invention. In the figure, 1 and 2 are pulse combustors. Three
4 is a combustion chamber, 5 and 6 are tail pipes, 7 and 8 are exhaust cushion chambers, 9 and 10 are gas distributors,
11, 12 are air passages, 13 and 14 are spark plugs, 1
5, 16 are air valves, 17 and 18 are gas valves, 19
Is an air cushion chamber, 20 is a partition plate, 21 is a communication part, 22 and 23 are exhaust pipes, 24 is combustion air, 2
5 and 26 are fuel gases, 27 and 28 are combustion gases, and 29 is water.

Next, the operation will be described. Combustion gases 25 and 26 pass through gas valves 17 and 18, and are supplied to combustion chambers 3 and 4 from distributors 9 and 10 having a large number of nozzle holes.

The combustion air 24 is supplied from a blower (not shown), and is supplied to the combustion chambers 3 and 4 through the air cushion chamber 19, the air valves 15 and 16 and the air passages 11 and 12. The fuel gas and the combustion air supplied to the combustion chambers 3 and 4 are mixed to form an air-fuel mixture, which explodes and burns due to discharge from the spark plugs 13 and 14. Due to the explosion, the pressure in the combustion chambers 3, 4 rises, the air valves 15, 16 and the gas valves 17, 18 are closed, and the supply of the fuel gas 25, 26 and the combustion air 24 is stopped. The high-temperature combustion gases 27, 28 exchange heat with the water 29 while passing through the thin tail pipes 5, 6 and flow into the exhaust cushion chambers 7, 8 while lowering the temperature. A partition plate 20 is provided so as to divide the exhaust cushion chamber into equal parts, and a communication portion 21 for the exhaust cushion chambers 7 and 8 is provided on the partition plate. This communication portion is composed of a hole formed in the partition plate and communicates with the exhaust cushion chambers 7 and 8. Exhaust pipes 22 and 23 are installed on the exhaust gas flow outlet sides of the exhaust cushion chambers 7 and 8, respectively. Therefore, the combustion gas flowing into the exhaust cushion chambers 7 and 8 is discharged through the exhaust pipes 22 and 23 and further through the exhaust muffler (not shown).

When the combustion gases 27 and 28 pass through the tail pipes 5 and 6, the pressure in the combustion chambers 3 and 4 becomes a negative pressure, and the air valve 15 and
16, the gas valves 17 and 18 are opened, the combustion air 24,
Fuel gas 25, 26 is sucked into the combustion chambers 3, 4. At that time, the high temperature combustion gas in the combustion chamber explodes a mixture of the combustion air and the combustion gas. Then, similar explosions are repeated one after another to become a pulse combustion state. In the pulse combustion state, the fuel gases 25 and 26 and the combustion air 24 are automatically sucked even if the blower is stopped.

When two pulse combustors are burned, it is difficult to match the frequencies of the pulse combustors as described above, and a slight difference occurs in the frequencies. This difference caused the beating phenomenon of combustion noise. When the exhaust cushion chambers are communicated with each other through the communication portion 21 as in the present invention, the pressure vibration of the combustion gas 28 in the exhaust cushion chamber 8 acts as a forced vibration against the pressure vibration of the combustion gas 27 flowing into the exhaust cushion chamber 7. . This changes the frequency of pulse combustion, which is the oscillation source of the pressure oscillation of the combustion gas 27. On the other hand, the pressure oscillation of the combustion gas 27 acts on the pressure oscillation of the combustion gas 28 as a forced oscillation as in the above. In this way, the pressure oscillations of the combustion gas of each pulse combustor act as forced oscillations, and pulse combustion is performed at the same frequency. As a result, the combustion noise of each pulse combustor becomes the same. Therefore, no humming noise is generated.

When there is no communication section, for example, the pulse combustors 1 and 2 burn at 70 Hz and 72 Hz, respectively, and generate a beat noise, but when the communication section is provided, no beat noise is generated. At this time, the opening area of the communicating portion is 1/10 of the cross-sectional area of the tail pipe 5 or 6.
The above results in instability of combustion and further deteriorates ignition performance.
In this case, the same drawback as in the conventional example in which the exhaust cushion chamber is shared occurs. The instability of combustion is due to the following reasons. When the action of the pressure oscillations of the combustion gases 27, 28 becomes stronger through the communication portion and the combustion and state of one pulse combustor fluctuates, the combustion state of the other pulse combustor is affected and combustion is stopped. Induce. The reason why the ignition performance is poor is as follows. When the pulse combustor is ignited, one of them is ignited first, and the combustion gas thereof flows from the exhaust cushion chamber into the combustion chamber of the other pulse combustor, which obstructs the inflow of combustion air and makes ignition difficult. Therefore, both pulse combustors cannot be burned at the same time.

Next, when the opening area of the communicating portion is 1/20 or less of the cross-sectional area of the tail pipe 5 or 6, the action of pressure vibration between the exhaust cushion chambers becomes small, and a whining noise is generated.
As described above, the stability of the synchronization of the combustion cycle is dominated by the size of the cross-sectional area of the communicating portion, and it has been empirically proved that the area is appropriately 1/20 to 1/10 of the cross-sectional area of the tail pipe. In this case, the same drawbacks as in the conventional example having no communication portion occur. Further, the diameter of the communicating portion is preferably 3 mm or more in order to prevent shielding by the condensed water of the combustion gas.

When the frequencies of the pulse combustors 1 and 2 are as close as possible, the effect of the communication section is ensured. Therefore, it is desirable that the pulse combustors 1 and 2 have the same shape and the same size.

In the figure, two pulse combustors are configured in parallel,
Even if three or more units are connected to each exhaust cushion chamber, the same effect can be expected. Further, the pulse combustors are not arranged side by side in a row, but are arranged on the circumference, and between the exhaust cushion chambers and the chamber provided at the center of the circumference so that the pressures of the exhaust cushion chambers may affect each other. You may connect with a pipe.

EFFECTS OF THE INVENTION As is clear from the above description of the embodiments, the pulse combustion device of the present invention allows the exhaust cushion chambers of a plurality of combustors to communicate with each other through the communication portion, thereby allowing a slight difference in the combustion frequency of each combustor. Even if occurs, due to the action of the communicating portion, ignition is performed at the same timing, and the combustion cycles are matched. As a result, the occurrence of "beat noise", which is an interference phenomenon between the combustors of the plurality of pulse combustors, is suppressed, the noise level becomes constant, and a low noise ratio can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a pulse combustion device according to an embodiment of the present invention. 1, 2 ... Pulse combustor, 3, 4 ... Combustion chamber, 5, 6 ...
… Tail pipes, 7,8 …… Exhaust cushion chamber,
20 ... partition plate, 21 ... communication part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Inoue 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-48-59430 (JP, A) JP-A-58-2522 (JP, A)

Claims (1)

[Claims] 1. An exhaust cushion chamber and a plurality of pulse combustors each having an exhaust pipe communicating with the exhaust cushion chamber are provided in parallel downstream of the tail pipe, and a communicating portion is provided between the exhaust cushion chambers. The opening area of the part is 1/10 or less of the cross-sectional area of the tail pipe.
/ 20 or more pulse combustion device.