JP2642272B2 - Forced air combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the flammability of a combustion apparatus using a forced blast type burner having a variable amount of combustion.

[0002]

2. Description of the Related Art In recent years, there has been a demand for combustion equipment to have a compact physique in order to improve wearability, and to increase the range of increase and decrease in the amount of combustion (heat generation) in order to improve functions. For this reason, the amount of combustion (combustion load) per unit volume is increasing, and a forced air blower that performs forced air supply or forced exhaust by a blower fan is employed. At the same time, the ratio between the maximum load combustion amount and the minimum load combustion amount tends to be set as large as 10 times or more.

[0003] This forced-air burner has a narrower air-fuel ratio range in which stable combustion can be performed than a conventional burner. In particular, during low load combustion, the rotation speed of the blower fan is low,
Since the air volume and the air pressure are at low levels, fluctuations in the power supply voltage and gusts are likely to cause unstable combustion. In order to prevent such combustion instability, while maintaining a high rotation speed of the blower fan, a bypass passage is provided in the blower passage to allow excess air to bypass, thereby improving the stability of combustion including low load combustion. Various combustion devices have been proposed.

[0004]

In the conventional bypass-type combustion equipment, in the combustion equipment which greatly changes from high load combustion to low load combustion, no consideration has been given to adopting an optimum bypass ratio. When the ratio of bypass air is high, the noise level of the blower fan increases greatly during high load combustion, and when the ratio of bypass air is low, it is difficult to sufficiently improve the combustion stability during low load combustion. I understood. An object of the present invention is to provide a burner having a bypass fan with a bypass, and a burner whose combustion amount varies over a wide range, can achieve a reduction in noise level during high load combustion and an improvement in combustion stability during low load combustion, It is an object of the present invention to provide a forced blast combustion device capable of obtaining good combustion over the entire combustion range.

[0005]

According to the present invention, there is provided a burner in which the ratio of the maximum load combustion amount to the minimum load combustion amount is 10 times or more, a proportional solenoid valve for adjusting fuel supply to the burner, In a forced blast-type combustion apparatus including a blower fan that supplies air to the burner in an amount corresponding to the amount of combustion, and a bypass passage that partially bypasses a blown air by the blower fan, a ratio of bypass air to combustion air 0.5
As mentioned above, it is characterized by being set to 1.0 or less.

[0006]

When the ratio of bypass air to combustion air is set to 1.0 or less by experiments, the inventor of the present invention can suppress the increase in noise of the blower fan during high load combustion to a relatively low level. I found that I can do it.
Further, by setting the ratio to 0.5 or more, the rotation speed of the blower fan can be maintained in a high stability range even during low load combustion, and combustion against air-fuel ratio disturbance factors such as power supply voltage fluctuations and gusts can be achieved. It was found that stability could be improved. Therefore, by setting the ratio of the bypass air to the combustion air at 0.5 or more and 1.0 or less, reduction of the noise level at the time of high load combustion and improvement of the combustion stability at the time of low load combustion are achieved. Good combustion can be obtained over the entire combustion range.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas water heater 100 which is an embodiment of a forced blast combustion device of the present invention will be described with reference to the drawings. The gas water heater 100 has a vertically long, flat, box-shaped water heater case 10.
1, a combustion cylinder 20 having a combustion chamber 200 inside.
1 and the exhaust collecting cylinder 30 connected to the upper end of the combustion cylinder 201.
0, and a forced air blow type full premix (all primary air combustion) burner 1 mounted below the combustion cylinder 201. The burner 1 changes its combustion amount (heat generation amount) in accordance with the set hot water temperature, the supply water temperature, and the incoming water temperature.
No. 2.4 hot-water discharge capacity at minimum load combustion.

The gas water heater 100 comprises a fuel gas supply means 2
And a blower fan 3 for supplying combustion air to the burner 1
And a bypass device 4 for bypassing a part of the air blown by the blower fan 3, and a control device 5. Further, the gas water heater 100 has a water supply pipe 61 connected to a water supply, a combustion chamber 2
00 heat exchanger 63 and tapping pipe 64
Is provided.

The premixing burner 1 has a housing 10 having a premixing chamber for fuel gas and combustion air, a combustion plate 11 facing the combustion cylinder 201 and closing the upper surface of the housing 10, It has an ignition device 12 mounted on the upper surface of the plate 11, a frame rod 13 for detecting misfire, and a thermocouple 14 for controlling the air-fuel ratio. The fuel gas supply means 2 includes a fuel gas injection nozzle 21 disposed in the housing 10 and a gas connecting the fuel gas source to the nozzle 21 via a main valve 22, a safety valve 23, and a proportional solenoid valve 24. And a flow path 25. The combustion plate 11 has a large number of small flame openings formed in a ceramic plate, and the nozzle 21 has a large number of fuel gas injection holes arranged in a metal pipe.

The blower fan 3 includes a scroll casing 3
1, a centrifugal fan 32 is provided, and a fan rotation speed sensor 33 is additionally provided. The communication passage 34 between the outlet of the casing 31 and the housing 10 has a blower fan 3
The bypass passage 4 for bypassing a part of the air blown by the air passage is provided. The outlet of the bypass 4 is connected to the blower fan 3 and the electrical component box 202 to cool the motor of the blower fan 3 and the control device 5.

The flow rate of the fuel gas, which is controlled by the proportional solenoid valve 24 and is blown out from the nozzle 21, is increased in the housing 10 by combustion air (for the air blown by the blower fan 3, which is not bypassed) and excess air. Rate λ = 1.1
Premixed with the degree as a target value, supplied from the combustion plate 11 into the combustion cylinder 201, ignited by the ignition device 12, and all-primary combustion in the combustion chamber 200 to heat the water flowing through the heat exchanger 63 and exhaust the water. Air is exhausted from the collecting cylinder 300.

The control device 5 is installed in an electrical component box 202 installed in the case 101, and processes input signals from a tap water temperature setting means, a water amount sensor 62, and an incoming water temperature sensor (not shown). The amount of combustion is determined based on control data previously measured or calculated to control the blower fan 3, and the rotation speed sensor 33 controls the blower fan 3.
Is detected, and a predetermined current is supplied to the proportional solenoid valve 24 based on the detected rotation speed.

Further, during combustion, the air-fuel ratio is detected by the thermocouple 14 to correct the rotation speed of the blower fan 3, and misfire is detected by the frame rod 13. When this occurs, the safety valve 23 is closed to stop combustion. Stop.

In this embodiment, the bypass ratio between the amount of combustion air supplied to the burner 1 and the amount of air bypassed from the bypass passage 4 is set to 1: 0.6 in advance by a test or the like. It is necessary that the ratio R of the bypass air to the combustion air amount be set to 0.5 or more and 1.0 or less. By setting the ratio R to 1.0 or less, it is possible to prevent the noise of the blower fan 3 from being too high during the combustion under the highest load (No. 24) (see FIG. 3). Further, by setting the ratio R to 0.5 or more, the rotation speed of the blower fan 3 during the lowest load combustion (No. 2.4) can be maintained relatively high (see FIG. 4). As a result, the blower fan 3
The air pressure is high, the air volume can be maintained relatively large, and the air-fuel ratio of the burner 1 increases due to the excess air ratio λ due to clogging of the filter, lowering of the power supply voltage, gusts, and other disturbances of the air-fuel ratio.
= 1.1 can be prevented from being largely deviated. At least λ = 1.1 to 1.1, which is the stable combustion range of the premix burner.
6, the probability of being kept in the range of 6 is large, and the combustion stability is improved.

In the above-described embodiment, the forced-air-supply type combustion device in which the blower fan 3 is provided on the upstream side of the entire premix burner 1 is shown. It may be adopted in the provided forced exhaust combustion equipment. In the above embodiment, a premix burner is used as a burner, but a Bunsen-type burner may be used.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a water heater according to one embodiment of the present invention.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is a graph showing the relationship between the ratio R of bypass air to the amount of combustion air and noise.

FIG. 4 is a graph showing a relationship between a combustion load of a burner and a rotation speed of a fan.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Premix burner (burner) 2 Fuel gas supply means 3 Blower fan 4 Bypass path 5 Control device 24 Proportional solenoid valve 100 Gas water heater

Claims (1)

(57) [Claims] 1. The ratio between the maximum load combustion amount and the minimum load combustion amount.
, A proportional solenoid valve for adjusting fuel supplied to the burner, a blower fan for supplying air to the burner in an amount corresponding to the amount of combustion, and a blower for the blower fan. And a bypass passage for bypassing the section, wherein the ratio of bypass air to combustion air is 0.5 or more,
A forced blast combustion device characterized by being set to 1.0 or less.