KR950005238B1 - Control circuit of exhaust fan for adverse wind check - Google Patents

Abstract

a hall sensor for generating a pulse signal by the rotation of an exhaust fan; an inverse amplifier for inverse-amplifying the output signal of the hall sensor and smoothing it by a condenser; a low-pass filter for filtering the output of the charging/discharging unit and then outputting it as a reference voltage; a reference voltage level adjusting part for lowering the reference voltage output; comparators for respectively receiving the output voltages of the inverse-amplifier and the amplifier to a non-inverse input terminal, receiving the output voltage of the low-pass filter, and comparing those signals; and a gas valve operation control for cutting off the operation control signal input of the gas valve operating unit when switching by to the outer wind entrance of the wind pressure switch.

Description

Anti-wind control circuit of exhaust fan

1 is a block diagram of a conventional anti-wind circuit of the exhaust fan.

2 is an operation timing diagram with respect to FIG.

3 is a block diagram of the anti-wind control circuit of the exhaust fan of the present invention.

4 is an operation timing diagram when there is no backwind according to FIG.

FIG. 5 is a timing diagram of an operation in the case of counterwind according to FIG. 3, and (a) is a timing diagram when the counterwind is weak. (b) is a timing chart when the strong wind is strong.

6 is a detailed circuit diagram of FIG.

* Explanation of symbols for main parts of the drawings

1 control unit 2 exhaust fan drive unit

3: gas valve driving unit 4: gas valve

5: gas pipe 6: burner

7: exhaust fan 8: wind pressure switch

9 year 10 Hall sensor

11: inverting amplifier 12: amplifier

13: charge / discharge part 14: low pass filter

15: reference voltage level adjusting unit 16: gas valve driving control unit

CS ₁ , CS ₂ : control signal OP ₁ , OP ₂ : comparator

SR ₁ : thyristor

The present invention relates to an exhaust fan control circuit of a forced exhaust boiler, and more particularly, to an anti-wind control circuit of an exhaust fan, which is suitable for preventing the system from being shut off immediately by increasing the rotational speed of the exhaust fan by a certain amount when a reverse wind occurs. will be.

As shown in FIG. 1, in the conventional anti-wind prevention circuit of the exhaust fan, the output of the control unit 1 is connected to the input side of the exhaust fan driver 2 and the gas valve driver 3 so that the exhaust fan 7 and the gas valve are (4) is driven, the gas used in the combustion flows into the burner 6 through the gas pipe 5 and the gas valve (4), the flue (9) is provided at the upper end of the burner (6) In the middle of (9), the exhaust fan 7 and the wind pressure switch 8 are connected.

The anti-wind circuit of the middle exhaust fan configured as described above is driven by the exhaust fan driver 2 in accordance with the control signal of the controller 1 to maintain the exhaust fan 7 at a constant rotational speed. The gas valve 4 is opened and ignited. The wind pressure switch 8 does not affect the gas valve driving unit 3 since the wind pressure switch 8 maintains a shut-off state during normal combustion.

On the other hand, if a reverse wind is generated outside the flue 9 at the top of the burner 6, the wind pressure switch 8 is operated to affect the gas valve driving unit 3, and as shown in FIG. 2, According to the operation, the gas valve 4 is shut off at the gas valve driving unit 3.

However, the conventional anti-wind circuit of the exhaust fan in the exhaust fan of the forced exhaust type Boeing Boiler that discharges the burned waste gas out of the flue, when the reverse wind blows from the outside of the flue, the pressure switch installed inside the flue operates the gas valve If a constant pressure difference occurs between the inlet and outlet of the wind pressure switch during combustion, the system is shut off regardless of the strength of the reverse wind, so that the gas valve shuts off even when the strength of the back wind is slightly higher than the pressure difference of the wind pressure switch. As a result, the system often becomes unavailable, making it a major factor in reducing product reliability.

In consideration of such a conventional problem, the present invention detects a pressure difference when a reverse wind is introduced from the outside, thereby increasing the rotational speed of the exhaust fan by a predetermined amount, thereby preventing backwind of the exhaust fan, which can prevent the system from being unconditionally blocked. Invented a control circuit, which will be described in detail with reference to the accompanying drawings.

3 is connected to the input side of the exhaust fan drive unit 2 and the gas valve drive unit 3 of the present invention, the output of the gas valve drive unit 3 to the gas valve 4, as a block diagram of the anti-wind control circuit of the exhaust fan As shown therein, the output of the control unit 1 is connected to the output of the exhaust fan drive unit 2 to the exhaust fan 7, and the gas used for combustion is burner through the gas pipe 5 and the gas valve 4. (6) is drawn in, the upper end of the burner (6) is connected to the flue (9) to connect the exhaust fan (7) and the wind pressure switch (8) in the middle of the flue (9), the wind pressure switch (8) is a control unit It connects to (1) and the exhaust fan drive part 2, and is comprised.

FIG. 6 is a detailed circuit diagram of FIG. 3, and as shown therein, the Hall sensor 10 which generates a pulse signal according to the rotation of the exhaust fan 7, and the output signal of the Hall sensor 10 are inverted and amplified and smoothed. An inversion amplifier 1, an amplifier 12 for amplifying and smoothing the output signal of the hall sensor 10, a charge / discharge unit 13 for charging and discharging with a pulse control signal CS ₁ , and A low pass filter 14 for filtering the output signal of the charging and discharging unit 13 and outputting it as a reference voltage, and a wind pressure switch 8 installed in the flue 9 to detect when the draft is introduced into the flue 9; A reference voltage level adjusting unit 15 for lowering the output voltage of the low pass filter 14 to a predetermined level when the wind pressure switch 8 detects the inflow of wind; and the inverting amplifier 11 and the amplifier 12. Comparing the output voltage of the low-pass filter 14 with the output voltage of the low-pass filter 14 and applying it to the exhaust fan driver 2 as an exhaust fan drive signal. Comparator (OP ₁ ), (OP ₂ 2), and the gas valve drive control unit 16 to cut off the drive control signal input of the gas valve drive unit 3 after a predetermined delay time when the wind pressure inlet of the wind pressure switch 8 is detected. Configure.

Referring to the operation and effects of the present invention configured as described above in detail.

When the output signal of the control unit 1 is input to the exhaust fan driver 2, the exhaust fan driver 2 starts to rotate at a constant speed by driving the exhaust fan driver 2. When the wind pressure switch 8 is switched from the fixed terminal b to the fixed terminal c as shown in FIG. 6 due to the rotation, at the same time, the control signal of the gas valve driving control unit 16 receives the gas valve driving unit 3. And the gas valve driving unit 3 is driven so that the gas valve 4 is opened. When the gas valve 4 is opened, gas is introduced into the burner 6 through the gas pipe 5 to ignite. At this time, when the ignition is made and the outside air flowing into the inside from the outside of the flue 9, that is, in the normal combustion state without the reverse wind, as shown in FIG. 4, the air pressure switch 8 always performs the normal combustion while maintaining the "H" state. .

On the other hand, if the draft is introduced into the interior from the outside of the year (9), that is, if the reverse wind occurs, the contact point of the wind pressure switch (8) is switched from the fixed terminal (c) to the fixed terminal (b) at the time of the reverse wind detection as shown in FIG. It is at the "H" state changes to an "L" state, and at the same time was elevated by a certain amount of the rotational speed of the exhaust fan (7) for carrying out the combustion, wherein the limited time (T ₁₎ in the check time has elapsed the fifth degree ( In the case of "Fan air flow rate> reverse wind strength" as in a), the wind pressure switch 8 is switched from the fixed terminal b to the fixed terminal c to continue combustion without interrupting the gas valve 4, After a predetermined time t ₂ has elapsed, the rotational speed of the exhaust fan 7 is also lowered by the amount raised during the operation of the wind pressure switch 8 to maintain the original speed.

However, when the check time elapses after the limited time t ₁ , as shown in (b) of FIG. 5, when the "fan air flow rate <back wind strength", the wind pressure switch 8 continues to be short-circuited to the fixed terminal b. The gas valve (4) is shut off.

That is, at this time, since the transistor Q ₈ is turned on and the charging voltage of the capacitor C ₇ is discharged through the transistor Q ₈ , the gas valve driving unit 3 is not driven and the gas valve 3 is shut off.

Here, the time limit t ₁ until the time when the reverse wind is sensed and the rotation speed of the exhaust fan 7 is increased and checked is the resistance R ₂₁ and the condenser C ₇ connected to the collector of the transistor Q ₈ . Since it is determined by the equation, it can be expressed as a time constant T ₁ = R ₂₁ × C _7, and a constant time t _{2 for} increasing the rotational speed of the exhaust fan 7 is determined by the thyristor SR ₁ . It depends on the period of the signal applied to the gate.

Referring to the detailed circuit diagram of FIG. 6, when the pulse control signal CS ₁ is not applied, the transistor Q ₇ maintains the turn-off state, and thus the power supply voltage V ₂ is connected to the capacitor R ₁₄ through the resistor R ₁₄ . (C ₃ ) is charged, and the charging voltage passes through the low pass filter 14 so that the reference voltage Vref applied to the resistor R ₁₇ has a high value, and the reference voltage Vref at this time is a comparator ( OP ₁ ) and the inverting terminal of the comparator (OP ₂ ), the output signal of the Hall sensor 10 is inverted amplified in the transistor (Q ₁₁ ) of the inverted amplifier ₁₁ and smoothed in the capacitor (C ₂ ) The non-inverting terminal of the comparator OP ₁ is applied, and the output signal of the hall sensor 10 is amplified by the transistors Q ₀ and Q ₁₀ of the amplifier 12 and smoothed by the capacitor C ₁ . It is applied to the non-inverting terminal of the comparator OP ₂ . Therefore, this time the comparator (OP _1), mood voltage (Vret) is not going to the inverting terminal of the (OP ₂₎ is higher than the voltage applied to the non-inverting terminal, the output of the comparator _{(OP 1), (OP 2} ) are all " Since the transistors Q ₁ and Q ₂ are turned off because the L ″ state is maintained, the motor M ₁ of the exhaust fan 7 does not rotate, and the motor M ₁ does not rotate, so the wind pressure switch 8 The common terminal (a) of is connected to the fixed terminal (b), the thyristor (SR ₁ ) is maintained in the off state that the power supply voltage (V ₁ ) is not applied because no signal is input to the gate terminal, the capacitor (C) ₇ ) since the charging voltage does not occur in the gas valve control signal CS ₂ , the gas valve control signal CS ₂ remains in the “L” state and thus does not affect the gas valve driving unit 3.

On the other hand, when the pulse control signal CS ₁ is applied, the transistor Q ₇ is repeatedly turned on and off, so that the charge and discharge voltage is generated in the capacitor C ₃ , and is almost constant through the low pass filter 14. The reference voltage Vref applied to the resistor R ₁₇ is lower than the first time. Accordingly, the reference voltage Vref applied to the inverting terminal of the comparator OP ₂ is connected to the capacitor connected to the collector of the transistor Q ₁₀ . Since the charge voltage generated at C ₁ ) is lowered, the output of the comparator OP ₂ is in the “H” state, which turns on the transistor Q ₂ and at the same time turns on the transistors Q ₄ and Q ₅ . Accordingly, the motor M ₁ of the exhaust fan 7 starts to rotate and the wind pressure switch 8 switches from the fixed terminal c to the fixed terminal b, and the motor M ₁ starts to rotate. repeated continues on / off transistor (Q ₉ ~Q ₁₁₎ by a pulse signal generated at the output of the Hall sensor 10, Crab, so the comparator output of the (OP ₁₎ and a comparator (OP ₂₎ outputs a high / low signals in sequence, and the transistors (Q _1, Q _2), so repeat the on / off motor (M ₁₎ is continued by a constant Keep pace.

At this time, when the outside air is blown from the outside of the year (9), that is, the reverse wind is generated, when the wind pressure switch (8) is switched from the fixed terminal (b) to the fixed terminal (c), the voltage on the gate of the die Lister (SR ₁ ) Is generated to conduct the thyristor SR ₁ so that the reference voltage Vref is lowered to increase the rotational speed of the motor M ₁ , and the transistor Q is applied from the moment when the voltage is applied to the gate of the thyristor SR ₁ . ₈ ) is turned off, and the capacitor C ₇ starts to charge the power supply voltage V ₁ through the resistor R ₂₁ .

Wind pressure during the limited time (t ₁ ) [time determined by the time constant T ₁ = R ₂₁ × C ₇ as the time when the charging voltage at the capacitor C ₇ becomes high enough to affect the gas valve driving unit 3] When the contact point of the switch 8 is changed from the fixed terminal (c) to the fixed terminal (b), since the "fan flow volume> reverse wind strength" continues normal operation, and the fixed terminal (c) to fixed terminal (b) does not change If not, the gas valve 4 is shut off at the time of check past the limit time t ₁ because the " fan air volume >

Therefore, the gas valve is not shut off immediately when the reverse air is drawn from the outside, but once the rotational speed of the exhaust fan motor is increased by a certain direction, combustion is normally performed when the fan air volume of the system can overcome the external wind. If the fan speed of the system cannot overcome the draft even after increasing the rotation speed by a certain amount, shut off the gas valve at that time.

As described in detail above, the present invention, in the exhaust fan of the forced exhaust boiler that discharges the burned waste gas out of the flue, once the reverse wind is generated, the wind pressure switch is operated, the strength of the reverse wind is the inlet and outlet of the wind pressure switch If it is slightly higher than the pressure difference generated from the side, it increases the motor's rotational speed by a certain amount so that it becomes "Fan air volume> Back wind strength" and overcomes the external pressure, so it can have higher reliability. There is an effect that can be less affected by.

Claims (3)

The Hall sensor 10 generating a pulse signal according to the rotation of the exhaust fan 7 and the output signal of the Hall sensor 10 are inverted and amplified by the transistor Q ₁₁ and smoothed by the condenser C ₂ . An inverting amplifier 11, an amplifier 12 amplifying the output signal of the Hall sensor 10 by transistors Q ₉ and Q ₁₀ and smoothing by a capacitor C ₁ , and a pulse control signal ( The charging / discharging unit 13 for charging / discharging the capacitor C ₃ by controlling the on / off of the transistor XJ (Q ₇ ) according to CS ₁ ) and filtering the output signal of the charging / discharging unit 13 to the reference voltage Vref. Low-pass filter 14 outputting through), wind pressure switch 8 installed in flue 9 to detect it by switching operation when draft is introduced into flue 9, and draft of wind pressure switch 8 A reference voltage level adjusting unit 15 for lowering the reference voltage Vref output from the low pass filter 14 to a predetermined level during switching according to the inflow; Section 11, and a comparator (OP ₁₎ for comparing the output voltage of the amplifying section 12 being applied Angular to the non-inverting input terminal receiving applied respectively the output voltage of the low-pass filter 14 to the inverting input terminal, (OP ₂ ) and on / off of the transistors Q ₁ , Q ₃ , Q ₆ , and Q ₂ , Q ₄ and Q ₅ according to the output signals of the comparators OP ₁ and OP ₂ to exhaust the gas. An exhaust fan driver 2 for driving the fan motor M ₁ , and a gas valve drive control unit for blocking input of a drive control signal of the gas valve drive unit 3 when the wind pressure switch 8 is switched in accordance with the inflow of wind. 16. An anti-wind control circuit for an exhaust fan, characterized in that it is configured as 16). The reference voltage level adjusting unit 15 is connected to the power supply voltage (V ₁ ) to be applied to the fixed terminal (C) of the wind pressure switch (8) which is short-circuited when the inflow of wind through the resistor (R ₁₉ ) The wind pressure switch 8 is connected to the gate of the resistor R ₂₀ , the capacitor C ₆ , and the thyristor SCR ₁ of the ground, and the output side of the low pass filter 14 is connected through the resistor R ₁₈ . An anti-wind control circuit for an exhaust fan, characterized in that it is connected to the anode of the thyristors (SCR ₁ ). The gas valve driving control unit 16 is connected so that the power supply voltage (V ₁ ) is applied to the fixed terminal (C) of the wind pressure switch (8) which is short-circuited when the inflow of the wind through the resistor (R ₁₉ ) The wind pressure switch 8 is connected to the ground resistor R ₂₀ , and the fixed terminal c is connected to the base of the transistor Q ₈ through the zener diode ZD, and the power supply voltage V _{1 is} connected. The exhaust fan prevents backwind of the exhaust fan, characterized in that the connection points connected to the collector and the condenser C ₇ of the transistor Q ₈ are applied to the gas valve driving unit 3 via the resistor R ₂₁ . Circuit.