JPH0432288B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application and Summary of the Invention] The present invention relates to a forced combustion device, particularly a forced combustion device in which combustion air is sent into a combustion chamber by a blowing fan.
This relates to a so-called premix combustion device, and relates to a forced combustion device in which gas is caused to flow into a fan and a mixture of gas and combustion air is sent into a combustion chamber.

[Prior art and its problems] For example, there is a forced combustion device as shown in Fig. 6, which uses a blowing fan to send combustion air into the combustion chamber. As shown in the figure, the combustion surface 1 has a structure including a large number of small holes 10, 10, and the lower part of the box 4 is divided into upper and lower parts by this combustion surface 1. The upper part is a combustion chamber 40 equipped with a heat exchanger, and the lower part is a mixing chamber 41, and the discharge port 30 of the fan 3 for blowing air is communicated with this chamber 41.

A gas inlet pipe 32 is connected to the suction port 31 of the fan 3.
The downstream end of the gas inlet pipe 32 faces the downstream end, and the gas discharged from the gas introduction pipe 32 is sucked together with the air from the suction port 31.
The discharge port 30 reaches the empty chamber 41 . This vacant room 41
Inside, the air and gas are in a mixed state, and once a flame is formed on the upper surface of the combustion surface 1 by suitable ignition means, combustion on this surface is sustained.

In some cases, the gas introduction pipe 32 may be directly connected to the casing of the fan 3.

However, this forced combustion device has the problem of poor gas combustibility.

This is because, especially when the combustion device is downsized, the path from the suction port 31 to the combustion surface 1 becomes shorter, resulting in insufficient mixing of the gas and combustion air in the combustion chamber 40. Because there is.

[Technical Problem] The present invention provides such a "forced combustion device equipped with a fan 3 for feeding combustion air and a gas introduction pipe 32 for introducing gas into the fan 3".
The technical objective is to improve the degree of mixing of gas and combustion air in the combustion chamber in order to improve the combustibility of gas.

[Technical Means] The technical means of the present invention taken to solve the above technical problems are as follows:
A return passage 9 is provided which communicates with the intake side of the air conditioner.

[Effect] The above technical means works as follows.

Since gas is flowing into the fan 3 through the gas introduction pipe 32, this gas and the combustion air sucked from the suction port of the fan 3 are in a mixed state, and this mixture flows from the empty chamber to the combustion chamber. sent. Here, since a return passage 9 is provided between the intake side and the discharge side of the fan 3, a part of the air-fuel mixture is transferred to the intake side of the fan 3 due to the differential pressure between the intake side and the discharge side of the fan 3. He will return to Japan. That is, return passage 9
A part of the air-fuel mixture will be circulated through the air-fuel mixture, and the air-fuel mixture will be remixed.

[Effects] Since the present invention has the above configuration, it has the following unique effects.

In this forced combustion device, part of the air-fuel mixture is circulated and remixed via the return passage 9, so even if the air-gas mixing path is short, the gas and combustion The degree of mixing with commercial air is further improved, and the combustibility of the gas is improved.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5.

A first embodiment of the present invention is shown in FIG.

The combustion device of this embodiment has almost the same configuration as the conventional example described above, but as shown in FIG. The tip portion faces the suction port 31 of the fan 3. That is, the communication pipe 37 becomes the return passage 9 described in the technical means section above,
A part of the air-fuel mixture is sent to the fan 3 through this communication pipe 37.
The water is returned to the suction port 31 of.

Therefore, due to the above-mentioned action, a part of the air-fuel mixture is circulated and remixed, and the degree of mixing of the gas and combustion air is lower than that of the conventional one.
It will be improved.

In this case, the tip of the communication pipe 37 is only exposed to the suction port 31 of the fan 3, but the returned air-fuel mixture is reliably sucked by the suction force of the fan 3, which improves safety. is guaranteed.

Next, a second embodiment of the present invention will be described based on FIG. 2.

In the combustion device of this embodiment, as shown in FIG. 2, the suction port 31 of the fan 3 is
The vicinity of the downstream end of the L-shaped intake duct 2 connected to the fan 3 and the vicinity of the discharge port 30 of the fan 3 are connected in a communicating state by a communication pipe 38, and the air-fuel mixture is guided to the suction port 31 of the fan 3. It is. That is, this communication pipe 3
8 and the intake duct 2 serve as the return passage 9 described in the technical means section above, and return the air-fuel mixture to the suction port 31 of the fan 3.

As shown in the figure, the communication pipe 38 is bent into an L-shape, and its tip is slightly bent toward the suction port 31 of the fan 3, so that the returned air-fuel mixture flows into the suction port 31. It is designed to be easily guided.

Next, a third embodiment of the present invention will be described based on FIGS. 3 to 5.

In the combustion device of this embodiment, the intake duct 2 is
As shown in FIG. 5, the wall surface of the casing provided with the suction port 31 of the fan 3 is used as the constituent wall surface of the intake duct 2, and as shown in FIG. The wall 29 is bent in a spiral shape. The fan 3 corresponding to the vicinity of the intake port 20 of the intake duct 2
As shown in FIGS. 3 and 4, a communication hole 39 is formed in the side wall of the engine, and the air-fuel mixture is returned through the communication hole 39. That is, in this case, the communication hole 39 and the intake passage of the intake duct 2 are connected to the return passage 9 described in the technical means section above.
It has become.

Further, as shown in FIG. 4, the above-mentioned partition wall 29 has a water droplet-shaped cross section 28 with a thick and round end section on the center side (downstream side of the intake passage). A guide plate 27 for guiding intake air into the fan 3 is provided at a position substantially opposite to this end portion. Therefore, on the downstream side of the intake passage, the droplet-shaped cross section 28 alleviates sudden changes in the flow direction at the end of the partition wall 29, and the guide plate 27 prevents suction from the downstream end of the intake duct 2. The direction of the flow toward the mouth 31 also changes smoothly.

In this case, the return passage is not exposed to the outside as in the first and second embodiments, so the appearance is compact.

Furthermore, since the position where the air-fuel mixture is returned is near the upstream portion of the intake duct 2, the remixing section is long and the degree of mixing is further improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a return passage in a combustion apparatus according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram of a return passage in a combustion apparatus according to a second embodiment of the present invention, and FIG.
FIG. 5 is an explanatory diagram of a return passage in a combustion apparatus according to a third embodiment of the present invention, and FIG. 6 is an explanatory diagram of a conventional combustion apparatus. In the figure, 3...fan, 9...return passage, 32...Gas introduction pipe.

Claims (1)

[Claims] 1. In a forced combustion device equipped with a fan 3 for feeding combustion air and a gas introduction pipe 32 for introducing gas into the fan 3, the discharge side of the fan 3,
A forced combustion device provided with a return passage 9 that communicates with the intake side of the fan 3.