JPH0245633Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a forced air heater equipped with a combustion blower.

[Problems to be solved by conventional techniques and ideas]

Conventionally, among these types of heaters, especially those that discharge exhaust gas naturally outdoors through exhaust pipes,
The installation structure of the exhaust pipe has a subtle effect on combustion conditions.
That is, the exhaust gas is discharged using the draft effect of the exhaust pipe, and as the overall length or lateral length of the exhaust pipe increases, the draft becomes worse and the exhaust gas is not drawn properly. If the exhaust pipe is short, there is no need for a draft, but this makes it vulnerable to headwinds, or a crosswind hitting the tip of the exhaust pipe will draw in more exhaust gas than necessary, worsening combustion conditions. For this reason, there is a problem in that the user may mistakenly believe that the heater is malfunctioning or defective, even though there is no abnormality in the heater itself.

In view of these problems, it is an object of the present invention to provide a forced air heater that can always provide a stable combustion state without being affected by the exhaust pipe installation structure or outdoor natural conditions.

[Means for solving problems]

The present invention provides a forced air heater equipped with a combustion blower, which includes a circuit that provides pressure sensors in each of the combustion air passage and the exhaust gas passage, and detects the difference in pressure detected by these pressure sensors. The present invention is characterized by comprising a circuit for controlling the rotation speed of the combustion blower and a circuit for controlling the combustion amount in accordance with the output signal of the pressure difference detection circuit.

[Effect]

In this invention, we focus on the fact that the pressure difference ΔP between the pressure in the combustion air passage and the pressure in the exhaust gas passage changes in proportion to the change in combustion quantity. I try to keep it inside. For example, if a head wind is applied to the tip of the exhaust pipe at a certain set combustion amount and the pressure difference ΔP decreases, the combustion amount is reduced and the combustion blower is controlled to increase the rotational speed, thereby reducing the pressure difference. ΔP
When the combustion rate returns to its original value, the combustion amount is returned to the original set value. On the other hand, when the exhaust gas is pulled by a crosswind, etc., the combustion amount is increased and the rotation speed of the combustion fan is controlled to decrease, and the combustion amount is returned to its original setting as the pressure difference ΔP returns to its original value. It acts to restore the value.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. This heater is provided with a burner 2 at the lower part of the main body. An upper combustion tube 4 is provided above the burner 2 via an intermediate combustion tube 3 formed of a transparent material such as glass. The upper combustion tube 4 has a cylindrical portion 5 provided above the intermediate combustion tube 3. The upper end of the cylindrical portion 5 has an annular lower exhaust plate 6 extending outward from the upper end. Exhaust lower plate 6
It has a side plate 7 extending upward from the periphery. The upper end of the opening of the side plate 7 is connected to the exhaust upper plate 8.
It is closed. There is an intermediate plate 9 in the upper combustion tube 4.
an inner lid 11 with a secondary combustion body 10 vertically disposed in the center opening of the inner lid 11;
is provided. The exhaust top plate 8 is provided with an outer cover 12 at its central opening, and an exhaust port 13 near the outer edge.
is provided. 14 is a combustion blower.

In this embodiment, pressure sensors 2 are installed in the combustion air passage just below the burner 2 and in the upper combustion cylinder 4, respectively.
1 and 22 are provided. The speed of the combustion blower 14 is controlled by a control section, which will be described later, based on output signals from the pressure sensors 21 and 22.

Figure 2 shows the difference ΔP (=P ₂₁ - P ₂₂ ) between the wind pressure P ₂₁ in the combustion air passage and the exhaust gas pressure P ₂₂ in the upper combustion tube 4.
(However, P ₂₁ > P ₂₂ ) is a diagram showing the relationship between combustion amount and combustion amount. As is clear from this figure, a certain amount of combustion
The optimum value of the pressure difference at K ₁ is ΔP ₁ , but in reality it may be within the range of ΔP ₂ to ΔP ₃ .

FIG. 3 is a block diagram of the combustion blower drive circuit. To explain the outline of the circuit, numeral 31 is a combustion amount setting device, and when the combustion device is set to a certain combustion amount by external operation, its output signal is input to the delay circuit 32. The delay circuit 32 is a fuel supply device, such as an electromagnetic pump (hereinafter referred to as an electromagnetic pump), when there is a sudden change in the combustion amount setter 31, for example, when switching the combustion amount setting from large combustion to small combustion.
It is provided to maintain a balance in operation with a combustion air supply device, such as a motor for a combustion blower (hereinafter referred to as the combustion motor), and to maintain a good combustion state following changes in the combustion amount set value. The output of the delay circuit 32 is input to the error amplifier 33 and is obtained from a circuit 36 that detects the standard pressure difference corresponding to the combustion amount set by the combustion amount setting device 31 and the difference signal between the two pressure sensors 21 and 22. An error signal corresponding to the difference from the actual pressure difference is output from the error amplifier 33. The motor drive circuit 34 controls the rotational speed of the combustion motor 35 so that the error signal becomes zero.

The arithmetic control section 37, the frequency output circuit 38, and the electromagnetic pump drive circuit 39 control the speed of the electromagnetic pump 40 according to the output signal of the pressure difference detection circuit 36, thereby controlling the amount of fuel oil supplied to the burner. That is,
Here, the speed of the electromagnetic pump 40 is controlled by frequency control.

Next, the operation will be explained.

For example, during combustion when the combustion amount in Fig. 2 is the set value K ₁ , a head wind is applied to the tip of the exhaust pipe outdoors, and the pressure difference between the two pressure sensors 21 and 22 decreases from ΔP ₁ to ΔP ₂ . In this case, based on the change in the output signal of the pressure difference detection circuit 36, the calculation control section 3
7. Frequency output circuit 38, electromagnetic pump drive circuit 3
9, the amount of fuel supplied from the electromagnetic pump 40 is reduced to bring the amount of combustion to _K2 . On the other hand, the error amplifier 33
increases the rotational speed of the combustion motor 35 in order to return the reduced pressure difference ΔP ₂ to the original pressure difference ΔP ₁ . As a result, the pressure difference gradually approaches the original ΔP ₁ , and accordingly, the amount of fuel supplied from the electromagnetic pump 40 gradually increases, and when the pressure difference returns to ΔP ₁ , the combustion amount returns to the original set value K. Return to ₁ .

On the other hand, if the pressure difference increases from ΔP ₁ to ΔP ₃ due to the exhaust gas in the exhaust pipe being pulled by a crosswind etc. during combustion with the combustion amount K ₁ in Figure 2, the combustion amount will become K ₃ . Become. However, at the same time, the combustion motor 3
5 decreases and the pressure difference ΔP ₃ gradually returns to ΔP ₁ , so the combustion amount also gradually returns to the set value K ₁ .

In this way, even if the pressure difference ΔP changes due to outdoor natural conditions, especially changes in wind speed and direction, the pressure difference can be returned to its original value without deteriorating the combustion state.

By the way, in the present invention, the pressure difference ΔP is maintained within a certain range not only when the outdoor natural conditions change, but also when the installation conditions of the heater, especially the exhaust pipe, such as the horizontal length of the exhaust pipe, change. For example, when the horizontal length of the exhaust pipe becomes longer, the pipe resistance increases, so conventionally the pressure difference ΔP decreases, but with the above configuration, it acts to increase the rotational speed of the combustion motor. However, the pressure difference ΔP is maintained within a certain range.

[Effect of idea]

As described above, according to the present invention, it is possible to provide a heater that can always provide a stable combustion state without being affected by the exhaust pipe installation structure or outdoor natural conditions.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, Fig. 2 is a characteristic diagram for explaining combustion characteristics in a heater, and Fig. 3 shows an example of a combustion air and fuel oil supply control circuit. Figure. In the figure, 2 is a burner, 4 is an upper combustion cylinder, 14 is a combustion blower, and 21 and 22 are pressure sensors.

Claims (1)

[Scope of utility model registration request] In a forced air heater equipped with a combustion blower, a pressure sensor is installed in each of the combustion air passage and the exhaust gas passage, and a circuit that detects the difference in pressure detected by these pressure sensors and a The output signal of the combustion amount setter for setting the standard pressure difference set by the combustion amount setting device is delayed through a delay circuit, and the output signal of the pressure difference detection circuit is input, and when the pressure difference increases due to a disturbance, the combustion amount setting device a rotation speed control circuit that reduces the rotation speed of the blower and increases the rotation speed of the combustion blower when the pressure difference decreases to maintain the pressure difference at the standard pressure difference; and an output of the pressure difference detection circuit. Take the signal as input,
A forced air heating system characterized by comprising a combustion amount control circuit that provides a combustion amount based on the standard pressure difference controlled by the rotation speed control circuit and increases or decreases the combustion amount in accordance with an increase or decrease in the pressure difference due to disturbance. Machine.