JPH0327820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a blowing pressure detection device for a forced air gas combustion apparatus that detects blowing pressure and automatically supplies or stops fuel gas.

[Prior Art] Conventionally, in forced-air gas combustion devices, a wind pressure switch that detects the blowing pressure of a fan (hereinafter referred to as wind pressure) is used as a safety device, and the operation of the wind pressure switch controls the supply or the supply of fuel gas. Combustion is controlled by automatically stopping the fuel.

[Problems to be solved by the invention] However, in the conventional forced air gas combustion device,
Since the wind pressure detection tube connected to the wind pressure switch was made to protrude into the air passage, there was a problem in that the air blowing capacity was reduced. For this reason, in forced-air gas combustion apparatuses having a small combustion capacity, there are cases where wind pressure cannot be reliably detected in the case of light winds.

SUMMARY OF THE INVENTION An object of the present invention is to provide a forced-air gas combustion apparatus that can reliably detect wind pressure even when the air-blowing capacity is reduced.

[Means for Solving the Problems] The air blowing pressure detection device of the present invention includes a fan provided in a fan case, and a protrusion provided on the inner circumferential surface of the fan case between the fan and the fan case. a detection hole provided on the inner circumferential surface of the fan case near the protrusion; and a detection hole connected to the detection hole;
A method of providing a wind pressure switch for detecting the air blowing pressure of the fan was adopted.

(Configuration of Example) In this example, a fan is provided in a fan case, and a fan is provided between the fan and the fan case on the inner circumferential surface of the fan case to generate negative pressure immediately below the downstream side. a detection hole provided directly below the downstream side of the projection, and a detection hole connected to the detection hole;
and a wind pressure switch for detecting the negative pressure.

[Function] The air blowing pressure detection device of the present invention provides a detection hole in the inner circumferential surface of the fan case between the fan and the fan case, so that the air passing through the inner circumferential surface of the fan case is prevented from losing air volume. becomes smaller.

In addition, by providing a protrusion on the inner peripheral surface of the fan case between the fan and the fan case, when air passes through the protrusion, a vortex is generated immediately below the protrusion, regardless of the size of the air blowing capacity. Negative pressure is generated immediately downstream of the

[Effects of the Invention] Due to the configuration and operation described above, the air blowing pressure detection device of the present invention can reliably detect wind pressure even when the air blowing ability is reduced in fans having similar air blowing ability.

(Operations and effects of the embodiment) In this embodiment, by providing a protrusion on the inner circumferential surface of the fan case between the fan and the fan case, when air passes through the protrusion, immediately below the protrusion, A vortex is generated regardless of the level of the air blowing capacity (for example, the rotational speed of the fan), and negative pressure is generated directly below the downstream side of the protrusion. By providing a detection hole connected to a wind pressure switch immediately below the protrusion where this negative pressure is generated, negative pressure can be easily detected, thereby improving the wind pressure detection performance.

[Example] An example of the blowing pressure detection device of the present invention will be described based on the drawings.

1 to 3 show a blowing pressure detecting device for a forced air gas water heater to which a first embodiment of the blowing pressure detecting device of the present invention is applied.

The forced air gas water heater A includes a blowing pressure detection device 1, a combustion section 2, a heat exchange section 3, and a gas supply path 5.
It consists of The blowing pressure detection device 1 includes a centrifugal blower 4, a wind pressure switch 6, and an electronic control circuit 7.

The combustion section 2 includes a ceramic surface combustion burner 21 to which combustion air is supplied by a centrifugal blower 4.
The exhaust port 23 is provided below the combustion chamber 22 and exhausts the combustion gas combusted by the burner 21.

The heat exchange section 3 includes a fan 31 that increases the heat exchange rate.
It consists of a water supply pipe 32 and a hot water supply pipe 33, and the burner 2
1 and the exhaust port 23 and sent from the upstream of the water supply pipe 32, the water exchanges heat with the exhaust gas in the combustion chamber 22 and flows out from the water supply pipe 33 as hot water.

In this embodiment, the centrifugal blower 4 of the blowing pressure detection device 1 of the present invention includes a Sirotsko fan 40 having a cylindrical shape with a width of, for example, 2 cm, and the fan 4.
The scroll casing 42 is a fan case having a width of, for example, 3 cm and has a suction port 41 and a motor (not shown) for driving the fan 40. The motor is an electronic control circuit 7
The rotational speed of the fan 40, that is, the amount of air blown is controlled.

On the upstream side of the inner circumferential surface 43 of the scroll casing 42 between the fan 40 and the scroll casing 42, as shown in FIGS. A protrusion 45 is formed at 44 to generate negative pressure.

The protrusion 45 has an upstream surface 46 formed perpendicularly to the tangential direction of the inner circumference of the scroll casing 42 , and a downstream surface 47 formed perpendicularly to the tangential direction of the scroll casing 42 .
It is formed to be inclined at a predetermined angle with respect to the tangential direction of the inner circumference. Further, as shown in FIG. 3, the height H of the projection 45 (in the radial direction of the scroll casing 42) is 5 mm, and the tip 48 of the projection 45 is 5 mm.
The distance L between this and the outer circumference 49 of the fan 40 is set to 9 mm. As a result, a negative pressure of approximately -8H ₂ O can be generated directly below the protrusion 45 .
The protrusion 45 is integrally molded with the scroll casing 42 by aluminum die casting.

The gas supply passage 5 is integrally molded with the scroll casing 42, and includes a gas jet nozzle 51 that discharges fuel gas to a portion where negative pressure is generated downstream of the protrusion 45, and a gas jet nozzle 51 that supplies fuel gas to the gas jet nozzle 51. It consists of a gas supply pipe 52 and a gas control unit 53.

The gas control unit 53 includes a gas ejection nozzle 51
An on-off valve (not shown) is provided between the on-off valve and the gas supply pipe 52 and opens and closes when energized or de-energized, and a governor valve (not shown) is provided on the downstream side of the on-off valve to adjust the gas flow rate. ), and a proportional control valve (not shown) which is provided downstream of the governor valve and has an opening ratio that is variable depending on the amount of energization.

Three ejection passages 54 are provided at the tip of the gas ejection nozzle 51 (on the left in FIG. 3), and as shown in FIG.
Three gas ejection ports 55 are formed so as to have a width substantially the same as that of 0. Furthermore, an orifice 56 for adjusting the supply pressure and flow rate of fuel gas is attached to the other end (left side in FIG. 3) of the gas jet nozzle 51.
is formed to have a smaller cross-sectional diameter than the cross-sectional diameter of the jetting passage 54. In other words, the orifice 56 also serves to prevent backflow of fuel gas.

The air pressure switch 6 of the air blowing pressure detection device 1 of the present invention includes a protrusion 45 of the scroll casing 42.
A positive pressure detection hole 60 and a connecting pipe 61 formed upstream of
The pressure chamber 62 is connected to a negative pressure detection hole 63 formed in one of the three gas ejection passages 54 of the gas ejection nozzle 51 as shown in FIG. 3 via a connecting pipe 64. and a rod 68 interlocked with a diaphragm 67 provided between the pressure chambers 62 and 65 and having a spring 66 on its back.
and a contact 69 that is opened and closed by.

The electronic control circuit 7 of the blowing pressure detection device 1 of the present invention includes a wind pressure switch 6, a start switch (not shown) that is turned ON when the gas water heater A is used, and a hot water supply pipe 33 that is operated by the user. A temperature adjustment volume (not shown) that sets the outflow water temperature, a thermocouple 71 that detects the oxygen supply state of the flame of the burner 21, and a thermocouple 71 that is attached to the outflow part of the hot water supply pipe 33 of the heat exchange section 3 to detect the water temperature. burner 2 at the time of ignition according to the input from the water temperature sensor 72, etc.
It controls the energization and de-energization of the spark electrode 73 that makes sparks fly on the combustion surface of the fuel cell 1, the motor of the centrifugal blower 4, the gas control unit 53, and the like.

The operation of this embodiment will be explained based on FIGS. 1 to 3.

In the gas water heater A, when the start switch is turned on, the fan 40 of the centrifugal blower 4 rotates, and combustion air is supplied to the burner 21 from the suction port 41 of the scroll casing 42.

At this time, the air supplied upstream of the protrusion 45 due to the rotation of the fan 40 flows in the left rotation direction in FIG. 1 due to the rotation direction of the fan 40 and the vortex shape of the scroll casing 42. This air flow avoids the protrusion 45, and the air directly below the protrusion 44 is pulled by the air that has avoided the protrusion 45. As a result, a negative pressure is generated near the gas outlet 55 directly below the protrusion 45 .

This negative pressure is introduced from the negative pressure detection hole 63 into the pressure chamber 65 of the wind pressure switch 6 via the connecting pipe 64. At this time, the air or positive pressure supplied upstream of the protrusion 45 is introduced from the positive pressure detection hole 60 into the pressure chamber 62 of the wind pressure switch 6 via the connecting pipe 61. Therefore, the wind pressure switch 6 displaces the diaphragm 67 due to the pressure difference between the positive pressure and the negative pressure in the low-pressure pressure chamber 65, overcoming the biasing force of the spring 66, and displacing the rod interlocking with the diaphragm 67. 68 closes contact 69.

In addition, a protrusion 45 is provided within the scroll casing 42.
For example, even if the rotational speed of the fan 40 is low, negative pressure is generated directly under the protrusion 45 in the combustion air flowing from upstream to downstream. Regardless of the situation, stable negative pressure detection can be performed.

By closing the contact 69 of the wind pressure switch 6,
The electronic control circuit 7 outputs an output to the on-off valve and the proportional control valve of the gas control unit 53 to open the on-off valve and the proportional control valve. Therefore, fuel gas flows out from the three gas jet ports 55 downstream of the protrusion 45. Since this fuel gas is ejected into the negative pressure generating area downstream of the protrusion 45, the fuel gas is sucked into the scroll casing 42 by the negative pressure.

The fuel gas sucked into the scroll casing 42 is agitated by the vortex generated downstream of the protrusion 45 and is supplied to the burner 21 by riding on the combustion air flowing between the fan 40 and the scroll casing 42. The fuel gas is diffused throughout the air, and the fuel gas uniformly diffused throughout the burner 21 can be stably supplied. Therefore, a uniform air-fuel ratio can be obtained throughout the burner 21, and incomplete combustion due to uneven supply of fuel gas can be prevented.

Further, since the fuel gas flowing out from the gas jet port 55 is sucked by the negative pressure generated directly below the protrusion 45, the fuel gas can be stably supplied to the burner 21 even in the case of slight combustion where the supply amount of fuel gas is small. supply.

Here, the centrifugal blower 4 stops rotating due to some kind of failure (motor failure, disconnection of electric wiring of the motor, etc.), and the suction port 41 of the scroll casing 42 stops rotating.
When the suction of combustion air stops, the pressure chamber 62 in which the diaphragm 67 is at low pressure due to the differential pressure between the positive pressure and the negative pressure is displaced by the biasing force of the spring 66, and the diaphragm 67 is displaced by the biasing force of the spring 66. 6
A contact 69 is opened by a rod 68 in conjunction with 7.

By opening the contact point 69 of the wind pressure switch 6,
The electronic control circuit 7 outputs an output to the on-off valve and the proportional control valve of the gas control unit 53 to close the on-off valve and the proportional control valve. Therefore, the outflow of fuel gas from the three gas jet ports 55 downstream of the protrusion 45 is stopped.

Therefore, when suction of combustion air is stopped, it is possible to reliably avoid the risk of emitting carbon monoxide or raw gas in the burner 21 due to incomplete combustion or flame extinction.

4 to 6 show a second embodiment of the blowing pressure detection device of the present invention.

In this embodiment, two ejection passages 57 are provided at the tip (left side in FIG. 5) of the gas ejection nozzle 51.
As shown in FIG. 4, two gas ejection ports 58 are formed in this ejection passage 57 immediately below 44 downstream of the protrusion 45. Further, a negative pressure detection hole 81 connected to the wind pressure switch 6 via a connecting pipe 82 is arranged in parallel with the gas outlet 58 directly below the protrusion 45 downstream 44 .

In this embodiment, both the positive pressure and the negative pressure are detected by the wind pressure switch, but a wind pressure switch that detects only the negative pressure or the positive pressure to detect the wind pressure of the fan may also be used.

In this embodiment, since the negative pressure detection hole 81 is not provided in the ejection path 57 of the gas ejection nozzle 51, there is no resistance to introducing negative pressure due to the outflow of fuel gas, so the wind pressure switch can be detected more reliably than in the first embodiment. 6 can introduce negative pressure.

In this example, the shape of the protrusion was such that the upstream side was upright and the downstream side was inclined. Any other shape may be used as long as this occurs.

In this embodiment, the protrusions were formed over the entire width of the scroll casing, but the protrusions may also be formed on a part of the scroll casing. In this case, the gas outlet and negative pressure detection hole are also formed on the protrusions. It suffices to provide it in a part of the downstream.

In this example, the scroll casing and the gas jet nozzle are integrally molded, but they may be provided separately. In this case, the protrusion and the negative pressure detection hole are integrally formed at the gas jet port of the gas jet nozzle. By molding, the present invention can be applied without significantly modifying the scroll casing.

In this embodiment, the protrusions are integrally molded onto the scroll casing, but the protrusions may be formed separately from the scroll casing or the gas ejection nozzle.

In this embodiment, the blowing pressure detection device of the present invention is applied to a forced air gas water heater, but it may also be applied to other gas combustion devices such as a bathtub or a combustion heating device.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a blowing pressure detecting device for a forced air gas water heater to which the first embodiment of the blowing pressure detecting device of the present invention is applied, and Fig. 2 is a diagram of a scroll casing according to the first embodiment of the present invention. FIG. 3 is an enlarged sectional view of the gas jet nozzle according to the first embodiment of the present invention, and FIG. 4 is a perspective view of the protrusion formed on the inner circumferential surface of the scroll casing according to the second embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view of a gas ejection nozzle according to a second embodiment of the present invention, and FIG. 6 is an enlarged cross-sectional view of a negative pressure detection hole according to a second embodiment of the present invention. be. In the diagram, A...forced air gas water heater, 1...blow pressure detection device, 2...combustion section, 3...heat exchange section,
4...Centrifugal blower, 5...Gas supply path, 6...
Wind pressure switch, 7...Electronic control circuit, 42...Scroll casing, 45...Protrusion, 51...Gas jet nozzle, 55, 58...Gas jet port, 60
...Positive pressure detection hole, 63, 81...Negative pressure detection hole.

Claims (1)

[Scope of Claims] 1. A fan provided in a fan case, a protrusion provided on the inner circumferential surface of the fan case between the fan and the fan case, and an inner surface of the fan case near the protrusion. A blowing pressure detection device comprising: a detection hole provided on a peripheral surface; and a wind pressure switch connected to the detection hole to detect the blowing pressure of the fan. 2. The blowing pressure detection device according to claim 1, wherein the detection hole is provided immediately below the upstream side of the protrusion, and the wind pressure switch detects positive pressure through the detection hole. 3. The detection hole is provided directly below the downstream side of the protrusion, and the wind pressure switch detects negative pressure generated directly below the downstream side of the protrusion using the detection hole. The air blowing pressure detection device described in Section 1. 4. Claims characterized in that the portion where the negative pressure is generated is provided with a gas ejection passage for discharging fuel gas and having a gas ejection port formed on the inner circumferential surface of the fan case. The air blowing pressure detection device according to item 3. 5. The blowing pressure detection device according to claim 4, wherein the detection hole is formed in the gas ejection path. 6. The blowing pressure detection device according to claim 4, wherein the detection hole is arranged in parallel with the gas ejection port.