JP4606601B2 - Exhaust fan air volume control system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust fan air volume control system that controls the air volume of a main exhaust duct to which a plurality of exhaust systems are connected, and is particularly suitable for use in a kitchen exhaust system of a commercial facility where there are many restaurants and tenants.
[0002]
[Prior art]
In general, in an exhaust system, a plurality of exhaust systems having terminals opened to individual tenants or the like are integrated into a main exhaust duct, and air volume control is performed by controlling rotation of an exhaust fan provided in the main exhaust duct. . Conventionally, this exhaust fan is controlled by various methods. For example, if the exhaust air is clean general air, a static pressure sensor is attached to the main exhaust duct near the exhaust fan to detect the static pressure in the main exhaust duct and drive the exhaust fan so that the static pressure is constant. Is controlled. In addition, when a VAV unit (variable air volume control unit) is provided in each exhaust system, a signal from the air volume sensor of the VAV unit is calculated, and the exhaust fan is driven so that the air volume in the main exhaust duct is constant. Is controlled. Further, a motor damper may be provided in each exhaust system, and the overall air volume may be assumed and calculated based on the opening / closing signal of the motor damper, and the drive of the exhaust fan may be controlled so that the assumed overall air volume is constant.
[0003]
However, if the exhaust air is dirty air containing a lot of oil and fat, such as kitchen exhaust, the oil and dirt will adhere to the sensor even during a short exhaust operation, and accurate detection will not be possible. Control by using an air flow sensor such as a duct static pressure sensor or a VAV unit becomes difficult.
In addition, a motor damper is provided in each exhaust system, and the method of controlling the rotation of the exhaust fan based on the opening / closing signal from this motor damper is based on the case where the air volume of each exhaust system is changed due to renovation work, etc. Is changed, it is necessary to change the parameter setting when calculating the estimated total air volume, which causes a problem that maintenance becomes complicated.
[0004]
To solve this problem, a pilot duct is connected to the main exhaust duct near the exhaust fan, a static pressure sensor is provided in the pilot duct, and the exhaust fan is installed based on the static pressure obtained by the static pressure sensor. An exhaust fan air volume control system for controlling the air volume has been proposed.
[0005]
According to this exhaust fan air volume control system, even if the exhaust air is dirty air containing a lot of oils and fats such as kitchen exhaust, it is possible to pass these clean air through the pilot duct and to the static pressure sensor. Thus, it is possible to accurately control the air volume of the exhaust fan based on the detection value of the static pressure sensor. Further, even when the air volume of each exhaust system is changed due to renovation work or the like, no complicated setting changes occur in the control system, and maintenance can be facilitated.
[0006]
[Problems to be solved by the invention]
However, in the conventional exhaust fan air volume control system described above, the pilot duct is connected to the downstream end of the main exhaust duct near the exhaust fan, and a static pressure sensor is provided in the pilot duct. It will be located downstream. For this reason, exhaust gas containing dirt such as oil and fat passes through the connection portion of the pilot duct, and there is a possibility that the oil and fat adhering in the main exhaust duct may block the connection portion of the pilot duct. Further, in the conventional system, when the total air volume is halved, the pressure loss in the duct becomes ¼. For this reason, in the conventional system that controls the downstream end of the main exhaust duct to a constant static pressure, an excess pressure is generated on the downstream side of the main exhaust duct as much as the pressure loss in the duct is reduced. That is, the static pressure on the downstream side of the main exhaust duct increases, and the air volume of the branch exhaust duct increases. Accordingly, there is a problem that the air volume of the branch exhaust duct fluctuates, and the exhaust fan is operated with excess pressure generated, so that the energy saving rate is reduced. Furthermore, since the static pressure sensor is used in the conventional system, it is difficult to detect the static pressure at the upstream end of the main exhaust duct having a small static pressure.
The present invention has been made in view of the above situation, and is capable of preventing the pilot duct connection portion from being blocked by oil or the like adhering to the main exhaust duct and the reduction of the energy saving rate and stabilizing the air volume in the branch exhaust duct. The purpose is to provide a fan air volume control system.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an exhaust fan air volume control system according to claim 1 of the present invention comprises a plurality of branch exhaust ducts for conveying contaminated air, and a plurality of branch exhaust ducts connected to downstream ends of the plurality of branch exhaust ducts. A main exhaust duct integrating the branch exhaust duct; an exhaust fan provided at a downstream end of the main exhaust duct for exhausting the contaminated air from the main exhaust duct; and an upstream end of the main exhaust duct and the plurality of branches A pilot duct connected to the upstream side of the exhaust duct and having a terminal opened to an atmosphere space free from dirt, a wind speed sensor provided in the pilot duct, and the exhaust fan based on the wind speed obtained by the wind speed sensor And a control means for controlling the air volume.
[0008]
In this exhaust fan air volume control system, when the exhaust fan is driven and the main exhaust duct becomes negative pressure, the air in the atmosphere space not containing dirt flows through the pilot duct and flows into the main exhaust duct. Accordingly, the air volume at the upstream end of the main exhaust duct can be detected by the wind speed sensor provided in the pilot duct, and the air without any dirt passes through the pilot duct, so that the air quantity sensor is not attached with dirt. As a result, even if the exhaust air is dirty air such as exhaust, it is possible to prevent the dust from adhering to the wind speed sensor and accurately control the air flow of the exhaust fan. In addition to such an action, the pilot duct is disposed upstream of the branch exhaust duct, and dirt-containing exhaust does not pass through the pilot duct connection portion of the main exhaust duct. Blocking of the pilot duct connecting portion due to is prevented. Thereby, the air volume control over a long period of time can be stably performed. In addition, since the air volume is detected at the upstream end of the main exhaust duct, excess pressure generated when detection is performed at the downstream end does not occur, fluctuations in the air volume of the branch exhaust duct are suppressed, and a reduction in the energy saving rate is prevented. Is done. Furthermore, since the detection is performed by the wind speed sensor, the control at the upstream end of the main exhaust duct, which is difficult to control by the static pressure sensor due to the small static pressure, can be performed reliably and stably.
[0009]
The exhaust fan air volume control system according to claim 2 is characterized in that the control means includes an inverter control device for increasing / decreasing the rotational speed of the exhaust fan based on a detection value of the air volume sensor.
[0010]
In this exhaust fan air volume control system, when the wind speed value in the duct is detected by the wind speed sensor and the air volume corresponding to the wind speed is calculated, the inverter control device is arranged so that the air volume value approaches a predetermined value set in advance. Thus, the exhaust fan is controlled to rotate. As a result, the air flow of the exhaust fan can be controlled steplessly, and accurate and fine air flow control that follows changes in the air flow of each exhaust system is possible.
[0011]
The exhaust fan air volume control system according to claim 3 is characterized in that the pilot duct is provided with intake resistance means for reducing an opening area to the atmosphere space.
[0012]
In this exhaust fan air volume control system, intake resistance means is provided in the pilot duct, so that the intake of a large amount of air is suppressed from the open end of the pilot duct, and the minimum necessary air can be taken in. If a damper or the like whose opening area can be adjusted is used as the intake resistance means, the optimum opening area of the pilot duct can be variably set, which is more convenient.
[0013]
The exhaust fan air volume control system according to claim 4 is characterized in that a rectifying means for rectifying intake air is provided upstream of the wind speed sensor in the pilot duct.
[0014]
In this exhaust fan air volume control system, the air drawn into the pilot duct from the atmosphere space is rectified by the rectifying means and then reaches the wind speed sensor. Accordingly, the air reaching the wind speed sensor is prevented from being reduced in wind speed due to the generation of vortices and the like. Thereby, a highly accurate speed measurement becomes possible.
[0015]
The exhaust fan air volume control system according to claim 5 is characterized in that the pilot duct is connected to a side surface or an upper surface other than the bottom surface of the main exhaust duct.
[0016]
In this exhaust fan air volume control system, the pilot duct is connected to the side or top surface other than the bottom surface of the main exhaust duct, so that oil or the like accumulates inside the main exhaust duct due to long-term use. Even when an object flows to the upstream end of the main exhaust duct, the probability that the connection part of the pilot duct is blocked by the oil deposits is reduced. Thereby, highly accurate speed measurement by a wind speed sensor can be maintained over a long period of time.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an exhaust fan air volume control system according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of an exhaust fan air volume control system according to the present invention, and FIG. 2 is a configuration diagram of a pilot duct shown in FIG.
[0018]
Branch exhaust ducts 1a, 1b, and 1c are respectively connected to a plurality of tenants (not shown), and the branch exhaust ducts 1a, 1b, and 1c include oil and fat from an end of an inlet port (not shown) opened in a kitchen room in the tenant. Delivers exhaust (contaminated air) to the downstream end. The main exhaust duct 3 is connected to the downstream end of each branch exhaust duct 1a, 1b, 1c, and the main exhaust duct 3 joins the air flowing in from the plurality of branch exhaust ducts 1a, 1b, 1c to the downstream end. And carry.
[0019]
An exhaust fan 5 is provided at the downstream end of the main exhaust duct 3, and the exhaust fan 5 exhausts the contaminated air conveyed by the main exhaust duct 3 to the outside. The exhaust fan 5 may be a separate fan connected to the downstream end of the main exhaust duct 3 or a fan built in the downstream end of the main exhaust duct 3. Therefore, when the exhaust fan 5 is driven, the exhaust from each tenant kitchen room flows into the main exhaust duct 3 via the branch exhaust ducts 1a, 1b, and 1c, joins in the main exhaust duct 3, and then is discharged to the outside. The
[0020]
A pilot duct 7 communicates with and is connected to the upstream end 3 a of the main exhaust duct 3. The opening end of the pilot duct 7 opposite to the connection portion is opened in an atmosphere space 8 such as the outside or a machine room that does not contain dirt such as oil and fat. Therefore, when the exhaust fan 5 is driven and the main exhaust duct 3 becomes negative pressure, clean air from the atmosphere space 8 such as a machine room flows into the main exhaust duct 3 into the pilot duct 7. . The air from the atmosphere space 8 that has flowed into the main exhaust duct 3 is merged with the dirty air from the branch exhaust ducts 1a, 1b, and 1c on the downstream side in the air conveyance direction, and is discharged to the outside by the exhaust fan 5. The
[0021]
A wind speed sensor 9 is provided in the pilot duct 7, and the wind speed sensor 9 can detect the wind speed in the pilot duct 7 as an electric signal. The wind speed value detected by the wind speed sensor 9 is sent to the control means described later. The control means can calculate the air volume in the main exhaust duct as a converted value based on the wind speed in the pilot duct 7. As the wind speed sensor 9, for example, an electromagnetic pickup system that detects the wind speed by rotating the magnetic rotor by the rotor 9a and detecting the magnetic flux to detect the rotational speed can be used.
[0022]
Further, instead of the wind speed sensor 9, a flow rate sensor may be used to detect the air volume of the main exhaust duct 3 from the flow rate passing through the predetermined opening cross-sectional area. The static pressure may be obtained as a converted value. As the flow sensor in this case, for example, a vane air flow meter, a Karman vortex air flow meter, a hot-wire air flow meter, or the like can be used.
[0023]
Rectifying means 11 is provided on the upstream side of the wind speed sensor 9 in the pilot duct 7, and the rectifying means 11 functions to rectify the air flowing into the wind speed sensor 9. In this embodiment, a cylindrical body in which the rectifying means 11 is continuous with a uniform cross-sectional area substantially equal to the passage opening area of the wind speed sensor 9 is used. By providing the rectifying means 11, the air drawn into the pilot duct 7 from the atmosphere space 8 is rectified and then reaches the wind speed sensor 9. The air reaching the wind speed sensor 9 is prevented from being reduced in wind speed due to the generation of vortices and the like. Thereby, highly accurate speed measurement by the wind speed sensor 9 is attained.
[0024]
The pilot duct 7 is connected to the side surface 3c or the upper surface 3d other than the bottom surface 3b of the main exhaust duct 3. That is, even when oil or the like accumulates inside the main exhaust duct 3 due to long-term use, and this oil and fat deposit flows to the upstream end 3a of the main exhaust duct 3, the connection portion of the pilot duct 7 is connected to the oil or fat. The probability of being clogged with deposits is reduced. Thereby, highly accurate speed measurement by the wind speed sensor 9 can be maintained over a long period of time.
[0025]
The pilot duct 7 is provided with intake resistance means 13 for reducing the opening area to the atmosphere space 8. In this embodiment, as the intake resistance means 13, for example, an orifice formed by an annular plate that closes a gap between the inner peripheral wall of the pilot duct 7 and the outer peripheral wall of the rectifying means 11 is used. Thus, by providing the intake resistance means 13 in the pilot duct 7, the intake of a large amount of air is suppressed from the open end of the pilot duct 7, and the minimum necessary air can be inhaled. If an opening area adjusting device (such as a damper) capable of adjusting the opening area is used as the intake resistance means, the optimum opening area of the pilot duct can be variably set, which is more convenient.
[0026]
Note that a dust collection filter (not shown) is preferably provided at the air inlet of the pilot duct 7. Thereby, the air sucked into the pilot duct 7 can be further purified, the wind speed sensor 9 can be made more difficult to be contaminated, and the detection performance can be stabilized over a long period of time.
[0027]
Control means 14 is connected to the exhaust fan 5. The control means 14 includes an inverter control device 15 and regulators 17a and 17b. The inverter control device 15 has a drive control circuit connected to the drive circuit of the exhaust fan 5. The inverter control device 15 is provided with a calculation unit (CPU) that converts a wind speed detection signal from the wind speed sensor 9 input through the regulators 17a and 17b into an air volume value. Of course, this calculation unit may be provided separately from the inverter control device 15. The inverter control device 15 is connected to the wind speed sensor 9 via the regulators 17a and 17b. The inverter control device 15 increases or decreases the rotational speed of the exhaust fan 5 so that the air volume in the pilot duct 7 matches the predetermined air volume value set by the regulators 17a and 17b. That is, the inverter control device 15 controls the air volume of the exhaust fan 5 based on the wind speed obtained by the wind speed sensor 9 (that is, the air volume converted based on the wind speed).
[0028]
As a method for controlling the air volume of the main exhaust duct 3 to be a predetermined air volume setting value set by the regulators 17a and 17b, for example, feedback control can be employed. In the feedback control, a signal from the wind speed sensor 9 representing the operation state is fed back, and the difference between the control amount and the target air volume setting value is automatically adjusted by comparing with a signal corresponding to the air volume setting value. Further, in this feedback control, cascade control may be performed in which the set value of the secondary regulator 17b is operated by the output signal of the primary regulator 17a to enable more accurate air volume control.
[0029]
Next, the operation of the exhaust fan air volume control system 19 configured as described above will be described.
When the exhaust fan 5 is driven and the main exhaust duct 3 has a negative pressure, air in an atmosphere space that does not include dirt such as oil and fat flows into the main exhaust duct 3 via the pilot duct 7. If the required air volume flowing from the branch exhaust ducts 1a, 1b, 1c to the main exhaust duct 3 changes due to the opening / closing of a motor damper provided in the branch duct due to the different business hours of each tenant, the wind speed sensor 9 of the pilot duct 7 This air volume change is detected. The inverter control device 15 controls the rotation of the exhaust fan 5 so that the air volume becomes a constant air volume set by the regulators 17a and 17b.
[0030]
A small amount of clean air always flows into the pilot duct 7 while the exhaust fan 5 is driven, and the inside of the pilot duct 7 is always kept clean. Accordingly, the wind speed sensor 9 provided in the pilot duct 7 can always detect the wind speed, and dirt-free air passes through the pilot duct 7 so that the wind speed sensor 9 is not attached with dirt. Thereby, even if the exhaust air is dirty air containing a lot of oil and fat such as kitchen exhaust, adhesion of dirt to the wind speed sensor 9 is prevented, and the air volume control of the exhaust fan 5 can be performed accurately.
[0031]
Thus, according to the exhaust fan air volume control system 17 described above, even if the exhaust air is dirty, clean air can be passed through the pilot duct 7 to prevent the wind speed sensor 9 from adhering to the dirt. Thus, the air volume control of the exhaust fan 5 can be performed accurately. Further, even when the air volume of each exhaust system is changed due to refurbishment work, etc., the exhaust fan air volume control system 19 can be used as it is, so that complicated setting changes do not occur and maintenance is facilitated. Can do.
In addition to such an action, the pilot duct 7 is positioned upstream of the branch exhaust ducts 1a, 1b, and 1c, and exhaust containing dirt such as oil does not pass through the pilot duct connection portion of the main exhaust duct 3, Blocking of the pilot duct connecting portion due to oil or the like adhering in the main exhaust duct is prevented. Thereby, the air volume control over a long period of time can be stably performed. Further, since the air volume is detected at the upstream end 3a of the main exhaust duct 3, excess pressure generated when detection is performed at the downstream end is not generated, and fluctuations in the air volume of the branch exhaust ducts 1a, 1b, 1c are suppressed, In addition, a reduction in the energy saving rate is prevented. Furthermore, since the detection is performed by the wind speed sensor 9, the control at the end of the main exhaust duct (upstream end 3a), which is difficult with the static pressure sensor due to the low static pressure, can be performed reliably and stably.
In the above-described example, the exhaust fan air volume control system of the present invention is mainly applied to a kitchen or the like. However, the present invention is not limited to this, and all exhaust air contains dirt. Needless to say, it can be applied to this case.
[0032]
【The invention's effect】
As described above in detail, according to the exhaust fan air volume control system according to the present invention, the pilot duct whose terminal is opened to the atmosphere space not containing dirt is connected to the upstream end of the main exhaust duct, and this pilot duct Since the wind speed sensor was installed inside and the exhaust fan was controlled based on the air volume obtained by this air speed sensor, the pilot duct was positioned upstream of the branch exhaust duct, and the pilot duct was connected. Contaminated exhaust does not pass through the main exhaust duct, and blockage of the pilot duct connecting portion due to oil or the like adhering to the main exhaust duct can be prevented. In addition, since the air volume is detected at the upstream end of the main exhaust duct, surplus pressure is not generated, the air volume of the branch exhaust duct can be stabilized, and the energy saving rate can be prevented from being lowered. Furthermore, since the detection is performed by the wind speed sensor, the control at the end of the main exhaust duct can be performed reliably and stably.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an exhaust fan air volume control system according to the present invention.
FIG. 2 is a configuration diagram of a pilot duct shown in FIG. 1;
[Explanation of symbols]
1a, 1b, 1c ... branch exhaust duct, 3 ... main exhaust duct, 3a ... upstream end, 3b ... bottom face, 3c ... side face, 3d ... top face, 5 ... exhaust fan, 7 ... pilot duct, 8 ... atmosphere space, 9 ... Wind speed sensor, 11 ... rectifying means, 13 ... intake resistance means, 14 ... control means, 15 ... inverter controller, 19 ... exhaust fan air volume control system

Claims (5)

Multiple branch exhaust ducts carrying contaminated air;
A main exhaust duct connected to a downstream end of the plurality of branch exhaust ducts and integrating the plurality of branch exhaust ducts;
An exhaust fan provided at the downstream end of the main exhaust duct for exhausting the contaminated air from the main exhaust duct;
A pilot duct that is an upstream end of the main exhaust duct and is connected to an upstream side of the plurality of branch exhaust ducts and opened to an atmosphere space that does not include dirt;
A wind speed sensor provided in the pilot duct;
An exhaust fan air volume control system comprising: control means for controlling the air volume of the exhaust fan based on the wind speed obtained by the wind speed sensor.   2. The exhaust fan air volume control system according to claim 1, wherein the control means includes an inverter control device for increasing or decreasing the rotation speed of the exhaust fan based on a detection value of the air volume sensor.   3. The exhaust fan air volume control system according to claim 2, wherein the pilot duct is provided with intake resistance means for reducing an opening area to the atmosphere space.   4. The exhaust fan air volume control system according to claim 3, wherein a rectifying means for rectifying intake air is provided upstream of the wind speed sensor in the pilot duct.   The exhaust fan air volume control system according to claim 4, wherein the pilot duct is connected to a side surface or an upper surface other than the bottom surface of the main exhaust duct.

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