JPH0742934A - Combustion apparatus - Google Patents

Abstract

PURPOSE:To accurately measure a flow rate of combustion air to be supplied from a combustion fan to a burner side. CONSTITUTION:An air introducing hole 5 is provided at an air flow outlet side of a combustion fan 2, a bypass passage 6 is branched, and an air exhaust port 9 of an outlet side of the passage 6 is opened from an exhaust hole 7 of a hot water supplying unit toward an outside. A straight part 10 is provided at the passage 6, and a wind velocity sensor 8 is installed at the outlet side of the part 10. Part of the air supplied from the fan 2 is introduced into the passage 6, and straightened through the part 10, flowing direction of the air is uniformly straightened, an unevenness of a flowing velocity distribution is removed, and supplied to the sensor 8 side. The sensor 8 obtains accurate wind velocity detection data via the straightened air. The data is converted to an air flow rate to obtain accurately measured data of the air flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device equipped with a combustion air supply amount measuring means.

[0002]

2. Description of the Related Art FIG. 15 shows a schematic configuration of a water heater generally known as a combustion device. In the figure, 1 is an instrument case, 2 is a combustion fan, 3 is a burner, 4
Indicate hot water supply heat exchangers. In this type of water heater, the water supplied from the water supply pipe (not shown) to the hot water heat exchanger 4 is heated by the combustion heat of the burner 3 to produce hot water, and this hot water of the hot water heat exchanger 4 is used. From the outlet side, it is guided to a desired hot water supply location through a hot water supply pipe (not shown).

The combustion operation of the water heater is controlled by a controller, which receives information on the incoming water temperature, the incoming water amount, and the outgoing hot water temperature, and controls the burning amount so that the incoming water temperature becomes a set temperature. In addition, the supply amount of combustion air is controlled so as to match the combustion amount.

In order to control the supply amount of this combustion air,
In this type of water heater, the amount of air supplied from the combustion fan 2 to the burner 3 is measured using, for example, a wind speed sensor. Based on this measurement value, the air amount control corresponding to the combustion amount is performed by controlling the rotation speed of the combustion fan 2.

[0005]

As a candidate installation location for the sensor for measuring the air amount, generally, A to A in FIG.
Any position of E is considered.

A is the area of the suction port of the combustion fan 2, and B is
Is an outlet area of the combustion fan 2, C is an air chamber, D is a mixing area for mixing the primary air of the burner 3 (air introduced into the burner 3) with fuel gas, and E is an exhaust top area. There is. When the sensor is provided in the portion D, the influence of the fuel gas ejected from the gas nozzle (not shown) into the burner 3 is feared, and when the sensor is provided in the portion E, the air amount is directly changed. It is necessary to detect the flow velocity of the combustion exhaust gas and indirectly measure the supply air amount without measuring the flow rate of the combustion exhaust gas. However, there is a problem that the detected value fluctuates due to the difference in the installation position of the sensor as well as the temporal fluctuation.

At the position A, the direction of the air flow is complicated, at the position B, the flow velocity of the air varies greatly depending on the place and time, and at the position C, the direction of the air flow is the same. If the sensors are not arranged and the sensors are provided at any of these locations, there arises a problem that it becomes difficult to measure the accurate air supply amount.

The inventor of the present invention has confirmed by experiments the occurrence state of variations in the detection output of the wind speed sensor caused by such spatial variations in the air flow direction and flow velocity distribution.
FIGS. 5 to 8 show the results of this experiment. In FIG. 5, a wind speed sensor of the heat wire heater type is arranged at the air outlet (blow-out port) of the combustion fan 2, and this air velocity sensor is used to blow air as shown in FIG. 6mm, 12mm, 18m from the origin of the Y-axis, with the bottom side on the plane that is the square of the exit as the X side and the left and right left sides as the Y side.
The positions of m, 30 mm, 36 mm, and 42 mm are set as fixed points in the Y direction, and at each fixed point in the Y direction, the wind speed sensor detects the wind speed at each moving position when moving in the X axis direction. The values are plotted and shown in a graph.

In contrast to the case of FIG. 5, the graph of FIG. 6 is 6 mm, 12 mm, 18 mm, 30 mm, 42 mm, 48 mm from the origin of the X axis.
Is set as a fixed point position, the wind speed sensor is moved in the Y axis direction on each fixed point position in the X axis direction, and the wind speed detection data of the wind speed sensor at the moved position in each Y axis direction is plotted and displayed in a graph. Fig. 7 shows 6 mm on the X-axis,
The 12 mm, 18 mm, 30 mm, 36 mm, and 42 mm positions are set as fixed point positions in the X direction, and the wind speed sensor is moved in the Y-axis direction on each of these fixed point positions to obtain the wind speed detection data. The turbulence intensity of the flow, that is, the wind velocity effective value with respect to the average flow velocity U of the air flow is plotted as the turbulence intensity and is represented in a graph.

In the graph shown in FIG. 8, the position in the X-axis direction is 24.
mm, the position of 24 mm in the Y-axis direction, that is, the position of the center point of the air outlet and the position of 30 mm in the X-axis direction, and the position of 24 mm in the Y-axis direction, the wind speed sensor Detect and
The relationship between the wind speed and the air flow rate obtained from the differential pressure across the orifice arranged at the blowing port is shown. As is clear from the graphs of FIGS. 5 to 7, in the combustion fan outlet area B, the wind speed detection data varies depending on the installation position of the wind speed sensor. Further, as is clear from the graph of FIG. 8, although the wind speed detection value with respect to the air flow rate varies depending on the installation position of the wind speed sensor,
It was confirmed that there is a linear relationship between the air volume and the wind speed.

The present inventor believes that such data variation is caused by the air flow direction and flow velocity variation, and in order to confirm this, as shown in FIG. 10, the combustion fan 2 is used. A 160 mm long rectifying cylinder was extended and formed at the air outlet of the, and the wind speed sensor was moved on the outlet side of this rectifying cylinder in the same manner to conduct an experiment to see how the local variations in wind speed were improved. I tried. The experimental results are shown in FIGS. 11 is shown in FIG. 5, FIG. 12 is shown in FIG. 6, and FIG.
Corresponds to FIG. 7 and FIG. 14 corresponds to FIG. As is clear from this experimental result, by providing the rectifying cylinder, the air delivered from the air outlet of the combustion fan is rectified by the rectifying cylinder to suppress the variation in the air flow direction and the variation in the flow velocity distribution. As a result, compared to the data when the rectifying cylinder is not provided, the data having less variation is obtained by providing the rectifying cylinder. In addition, it can be seen from Fig. 13 that the extension cylinder of 160 mm reduces velocity fluctuation disturbance.

As described above, by providing the flow straightening cylinder on the blower outlet side of the combustion fan, it is possible to obtain detection data with little variation. However, the provision of the straightening cylinder causes a new problem that the dimension of the water heater in the height direction increases correspondingly and the water heater becomes large.

The present invention has been made in order to solve the above problems, and an object thereof is to avoid an increase in the size of the device due to the provision of the flow straightening cylinder, and moreover, to improve the direction of air flow and the flow velocity. An object of the present invention is to provide a combustion device that can accurately measure the supply air amount without being affected by variations and the like.

[0014]

In order to achieve the above object, the present invention is constructed as follows. That is, the present invention is, in a combustion device in which a combustion fan for supply and exhaust is provided on the upstream side of a burner, an air introduction port is provided in an air flow path from a blowout port of the combustion fan to an exhaust top portion, An air outlet is provided on the downstream side of the inlet to form an air bypass passage, and a sensor for measuring the amount of air blown by the fan is provided in the bypass passage.

[0015]

In the present invention having the above-mentioned structure, the air sent from the combustion fan flows along the air flow path from the air outlet of the combustion fan to the exhaust top portion, but a part of the air flow is branched to the bypass passage. Then flow. The air flowing through this bypass passage is rectified and the direction of the flow is adjusted,
The flow velocity is made uniform and passes through the sensor installation area. At this time, the sensor detects the air amount measurement information such as the flow velocity of the air, thereby achieving the accurate air amount measurement without the influence of the variation of the flow velocity and the variation of the flow direction.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an embodiment of a combustion apparatus according to the present invention. Similarly to the conventional example, the combustion apparatus of the present embodiment is also shown by taking the water heater as an example. The same parts as those of the conventional example are designated by the same reference numerals, and the duplicate description will be omitted.

This embodiment is different from the conventional example in that an air introduction hole 5 is provided in the side wall on the outlet side of the combustion fan 2 to form a bypass passage 6 in a branched manner.
The outlet (air exhaust port) 9 is led out from the exhaust hole 7 on the exhaust top side, and a wind speed sensor 8 for measuring the amount of air is provided in the middle of the bypass passage 6. Further, in this embodiment, a straight portion 10 having a straight passage is formed over the long section L on the upstream side of the wind speed sensor 8, and the flow of air entering the bypass passage 6 from the side of the combustion fan 2 is directed to the straight portion 10. Is rectified to align the direction of the air flow to make the flow velocity distribution in the bypass passage 6 uniform, and the rectified air flow is supplied to the wind speed sensor 8 side.

As described above, in this embodiment, the combustion fan 2
Since a part of the air supplied from the side to the burner 3 side is taken into the bypass passage 6 and rectified and the wind speed thereof is detected by the wind speed sensor 8, it is affected by the fluctuation of the air flow direction and the fluctuation of the flow velocity distribution. Not accurate wind speed can be detected. The wind speed detection signal detected by the wind speed sensor 8 is supplied to the control device (not shown), converted into an air amount by a microcomputer of the control device, and used as air supply amount information for combustion control. Will be done. The amount of air flowing through the bypass passage 6 is a part of the total amount of air sent from the combustion fan 2. The partial amount of air is obtained by the sensor. Since there is a constant proportional correlation between the amount of basic air supplied from the combustion fan 2 to the burner 3 side, and by the arithmetic processing on the control device side,
Based on the wind speed information of the wind speed sensor 8, the amount of air supplied from the combustion fan 2 to the burner 3 can be accurately obtained.

2 and 3 show experimental data for measuring the amount of air using the apparatus of this embodiment. Figure 2
The relationship between the air flow rate and the sensor output for each air flow rate is shown, and the sensor output has a linear relationship with the air flow rate.

FIG. 3 is a graph in which the horizontal axis represents the air flow rate and the vertical axis represents the wind speed. The value of the wind speed is obtained by converting the sensor output voltage into the value of the wind speed. As can be seen from the graph of FIG. 3, the wind speed has a linear relationship with each air flow rate, and it has been proved that highly accurate detection data is obtained. This Figure 3
As can be seen from the above, since the wind speed and the air flow rate (air flow rate) have a proportional relationship, by converting the wind speed value into the air flow rate, highly accurate air supply amount data can be obtained from the detection output of the wind speed sensor 8. You can understand that you can get it.

According to this embodiment, a part of the air is diverted to the side of the bypass passage 6 and the diverted air is rectified by the straight portion 10, so that the velocity and direction of the air flow vary locally and temporally. It has become possible to measure the air volume with extremely high accuracy. If the length of the straight portion 10 is too short, the rectifying action will be insufficient, and if it is too long, the pressure loss of the air flow will not be large, so the length of the straight portion 10 is not too short or too long. Need to be length. The present inventor examined the rectification effect on the length of the straight portion 10 by an experiment, and found that when the length of the straight portion 10 is L and the diameter of the bypass passage 6 is D, the pressure loss of the air flow is a problem. It has been obtained that it is desirable to set the relationship of L ≧ 3d within the range that does not occur, and in this embodiment, the length of the straight portion 10 is set based on this result.

Further, in this embodiment, since the bypass air passage 6 is branched from the main air passage extending from the combustion fan 2 to the burner 3, even if the blown air contains dust, this dust will be generated. Since the inertia tends to flow along the main air passage, it is possible to prevent dust from entering the bypass passage 6 side, and this dust adheres to and accumulates on the wind velocity detecting element (hot resistance wire) of the wind velocity sensor to cause the sensor. It is possible to prevent the problem that the performance is deteriorated.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above embodiment, the air inlet of the bypass passage 6 is connected to the combustion fan 2
The air discharge port 9 of the bypass passage is formed on the exhaust hole 7 side of the exhaust top side.
The air introduction port 5 is provided at an appropriate position in the air flow path from the blower outlet of the combustion fan 2 to the exhaust top, and the air discharge port 9 of the bypass passage is provided downstream of the air introduction port 5. Of course, various bypass passage configurations other than the present embodiment can be adopted.

FIG. 4 shows various other configurations of the bypass passage 6, in which the bypass passage 6a has an air introduction port 5
And the air outlet 9 are both provided in the air outlet area of the combustion fan 2, the bypass passage 6b is provided with the air inlet 5 at the air outlet of the combustion fan 2, and the air outlet 9 is provided in the air chamber. The bypass passage 6c is provided with the air inlet port 5 on the blower outlet side of the combustion fan 2 and the air outlet port 9 in the combustion chamber.
Similarly, the air inlet 5 is similarly provided at the air outlet of the combustion fan 2, and the air outlet 9 is provided at the exhaust top side.

The bypass passage 6e is provided with the air inlet 5 at the air outlet of the combustion fan 2, and the air outlet 9 is open to the atmosphere in the instrument case 1. The bypass passage 6f blows the air through the air inlet 5. It is provided at the outlet, the air outlet 9 is open to the atmosphere outside the instrument case 1, and the bypass passage 6g is provided with the air inlet 5 inside the air chamber and the air outlet 9 inside the combustion chamber. Yes, bypass passage 6
The symbol h indicates that the air inlet is provided in the air chamber and the air outlet 9 is provided on the exhaust top side.
Reference numeral i designates the air inlet 5 provided in the air chamber and the air outlet 9 opened to the atmosphere in the instrument case 1, and the bypass passage 6j provides the air inlet 5 in the air chamber and the air outlet 9 Is opened to the atmosphere outside the instrument case 1, and thus the bypass passage can be formed in various configurations.

Among these passages, the bypass passage 6
By providing the air discharge port 9 in the air flow path from the combustion fan 2 to the burner 3 as in a and 6b, the air that has entered the bypass passage returns to the main air flow of the main flow, so that the loss of the combustion air amount. Can be prevented. Also,
In the case of the bypass passages 6c to 6j, a sufficient distance can be secured from the air introduction port 5 to the air discharge port 9, so that the rectifying effect of the slate portion 10 of the air flow can be sufficiently enhanced. In particular, when the bypass passages 6c and 6g are configured, the rectifying effect of the air flowing through the bypass passage can be expected sufficiently and the air that has passed through the bypass passage is discharged into the combustion chamber. Even if the exhaust gas passage 4 is somewhat blocked due to soot, the effect that the wind speed (air volume) can be accurately detected is obtained.

That is, when the air exhaust port 9 of the bypass passage is provided open to the exhaust top side or the outside atmosphere,
When soot adheres to and accumulates on the hot water supply heat exchanger 4, the air resistance of the soot reduces the basic air flow rate flowing to the burner 3 side. On the other hand, since the soot air resistance does not act on the bypass passage, it is rather normal. An air flow of more than an hour flows, the proportional relationship between the air flow through the bypass passage and the basic air flow is broken, and an error occurs in the air flow detection result by the wind speed sensor. On the other hand, when the air exhaust port 9 of the bypass passage is provided in the combustion chamber, the soot adhering to the hot water supply heat exchanger 4 becomes a resistance component of the air flowing through the bypass passage, so the air flow rate of the bypass passage also decreases. Therefore, the proportional relationship between the basic air flow rate and the air flow rate in the bypass passage is maintained, and this has the effect that the air flow rate can be accurately detected even if soot adheres. is there.

Further, the wind speed sensor 8 in the above embodiment is of a hot wire type (when the wind hits the heater wire, it detects the wind speed based on the resistance change due to cooling corresponding to the magnitude of the wind speed). However, it is possible to use various types of wind speed sensors such as those that use the Karman vortex to detect the wind speed and those that use the differential pressure between the upstream side and the downstream side to detect the wind speed. it can.

Further, in the above embodiment, the air velocity sensor indirectly detecting the air flow rate is used as the sensor for measuring the air flow rate, but of course, a sensor directly detecting the air flow rate may be used.

Further, in the above embodiment, as the combustion device,
Although the water heater has been described as an example, the present invention is also applicable to other types of combustion devices such as a bath kettle and a heater that uses gas or oil as a fuel.

[0031]

According to the present invention, an air inlet is provided in the air flow path from the air outlet of the combustion fan to the exhaust top portion to form a bypass passage, and the amount of air blown by the fan is measured in this bypass passage. Since the sensor is provided, the air can be rectified while passing through the bypass passage, and the air flow direction and the flow velocity distribution can be made spatially and temporally uniform to obtain information on the air flow rate. The amount of combustion supply air can be detected accurately and accurately without being affected by variations in the air flow direction and flow velocity distribution.

Further, since the bypass passage can be formed through a narrow space of the combustion device, the size of the device is not increased by providing the bypass passage, and the space in the combustion device is used to rectify the air. The length of the bypass passage necessary for the above can be sufficiently secured, and the air amount can be measured with high accuracy even in a small combustion device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a combustion apparatus according to the present invention.

FIG. 2 is a graph of experimental data of air flow rate and sensor output obtained by using the apparatus of the same example.

FIG. 3 is a graph of experimental data on the relationship between air flow rate and wind speed in the example.

FIG. 4 is an explanatory view showing various other examples of the bypass passage.

FIG. 5 is a graph showing variations in wind speed detection data when the wind speed sensor is moved in the X-axis direction to detect the wind speed at the air outlet of the combustion fan using the conventional combustion apparatus.

FIG. 6 is a graph showing a variation state of the wind speed detection data when the wind speed sensor is moved in the Y-axis direction at the air outlet of the combustion fan to detect the wind speed using the device of the conventional example.

FIG. 7 is a graph of experimental data in which the horizontal axis represents the amount of movement of the wind speed sensor in the Y-axis direction and the vertical axis represents the turbulence intensity of the air flow using a conventional apparatus.

FIG. 8 is a graph showing relational data of wind speed and air flow rate of a conventional device in a measurement comparison state at two point positions.

FIG. 9 is a diagram for explaining a moving position of a wind speed sensor during a wind speed measurement experiment.

FIG. 10 is an explanatory diagram showing a state in which a rectifying cylinder is connected to the air outlet of the combustion fan.

FIG. 11 is a graph corresponding to FIG. 5 showing a relationship between a moving position in the X-axis direction of a wind speed sensor and wind speed detection data by providing a rectifying cylinder at a combustion fan air outlet of a conventional combustion device.

FIG. 12 is a graph corresponding to FIG. 6 showing the relationship between the moving position of the wind speed sensor in the Y-axis direction and the wind speed detection data when a rectifying cylinder is provided on the blower outlet side of the combustion fan of the conventional device.

FIG. 13 corresponds to FIG. 7 showing the relationship between the moving position of the wind speed sensor in the Y-axis direction and the turbulence intensity of the air flow at each moving position when a rectifying cylinder is provided on the combustion fan air outlet side of the conventional device. It is a graph.

FIG. 14 is a graph corresponding to FIG. 8, in which a relationship between the air flow rate and the wind speed is measured at two points on the outlet side of the rectifying cylinder by providing the rectifying cylinder on the exhaust side of the combustion fan exhaust of the conventional combustion device.

FIG. 15 is an explanatory diagram showing a schematic configuration of a water heater generally known as a combustion device.

[Explanation of symbols]

 2 Combustion fan 4 Hot water supply heat exchanger 5 Air introduction hole 6, 6a-6h Bypass passage 8 Wind speed sensor 9 Air discharge port 10 Straight section

Claims (1)

[Claims] 1. A combustion device in which a combustion fan for supply and exhaust is provided on the upstream side of a burner, and an air introduction port is provided in an air flow path from a blower outlet of the combustion fan to an exhaust top portion. A combustion apparatus in which an air outlet is provided on the downstream side of the mouth to form an air bypass passage, and a sensor for measuring the amount of air blown by a fan is provided in the bypass passage.