JP2012247121A - Variable air volume control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable air volume control device that can shorten a distance between an orifice and a damper blade functioned as components for calculating an air volume.SOLUTION: The orifice 2 for throttling a pipe diameter of a duct 1 and the damper blade 53 inclinable in the duct 1 are disposed on the same position. The orifice 2 is divided into an upstream-side orifice piece 21 and a downstream-side orifice piece 22, and disposed while holding the damper blade 53 from both sides. Further, a PLC 4 stores an opening correction coefficient according to an opening of a motor damper 5 having the damper blade 53, and corrects the air volume calculated by using Torricelli's theorem with the opening correction coefficient. The PLC 4 controls the opening of the motor damper 5 on the basis of the air volume after the correction.

Description

  The present invention relates to a variable air volume control device that is mainly installed in a duct type ventilation air conditioning system and performs air volume detection by an orifice and air volume adjustment by a damper.

  The ventilation air conditioning unit is installed on the ceiling or the like of a building, has an air supply system and an exhaust system, sends air conditioned to each room through a duct, and exhausts air from each room. Ventilation air-conditioning units are used in all air supply / exhaust rooms, for example, in electronics and precision machinery factories, stores, offices, residential sanitary zones, etc. It is installed in a clean room for circuit parts, a storage room for food preservation, a laboratory animal breeding room, a biological clean room, and the like.

  Ventilation air-conditioning units often have a fan in a duct connecting indoors and outdoors in an air supply system, an exhaust system, or both, and incorporate an air volume calculator and a variable air volume control device (for example, Patent Document 1). reference).

  The air flow calculator throttles the duct pipe by providing an orifice, generates a differential pressure before and after the orifice, derives the pressure across the orifice from the pressure outlet, and uses the Torrichelli theorem from the derived differential pressure of both pressures. Is used to calculate the air volume in the duct.

  The variable air volume control device is also called a VAV (Variable Air Volume) device, and is a damper provided with a damper blade so as to block a flow path in the duct. The variable air volume control device controls the air volume supplied or exhausted by changing the opening of the damper. In a ventilation air-conditioning unit, if air supply corresponding to a large amount of exhaust air flow is performed, the temperature adjustment energy of the outside air becomes large. Therefore, it is mainstream to provide a variable air flow control device from the viewpoint of energy saving. As the variable air volume control device, many motor dampers that change the tilt rate of the damper blade by a motor have been proposed.

  In such a ventilation air conditioning unit, the air volume calculated by the air volume calculator is compared with the desired air volume, and the opening degree of the motor damper is adjusted according to the comparison result so that the calculated air volume matches the desired air volume. I have to.

JP 05-49856 A

  Here, the outline of the flow of air before and after the orifice will be explained.On the upstream side of the orifice, the air is peeled from the inner wall surface of the duct, and after passing through the orifice, the basin distribution of the air continues to shrink, and then the basin distribution expands. It is said to turn and return to the original flow.

  Therefore, if there is a physical obstacle near the orifice, a deviation in the flow velocity distribution occurs near the orifice, which affects the differential pressure before and after the orifice detected by the air volume calculator. The change in the differential pressure leads to a decrease in the air volume calculation accuracy. And the fall of the air volume calculation accuracy also affects the opening degree adjustment of the motor damper, and the desired air conditioning control becomes difficult.

  Therefore, conventionally, in order to avoid this decrease in the accuracy of air volume calculation, no physical obstacle has been installed in the vicinity of the orifice that functions as one configuration of the air volume calculation. Specifically, the damper blade of the variable airflow control device is generally installed at a location sufficiently away from the orifice.

  Therefore, when the orifice that functions as a configuration for calculating the air volume and the variable air volume control device are used in combination, it is necessary to ensure a certain duct distance, and the ventilation air conditioning unit has been enlarged. Such problems are required to be corrected from the viewpoint of increasing the installation cost of the ventilation air conditioning unit and extending the construction period.

  For example, when the pipe diameter of the duct is 200 mm, the duct length including the orifice and the damper blade is 610 mm in total length, and when the duct diameter is 400 mm, the duct length including the orifice and the damper blade is included. Becomes 910 mm in total length.

  Furthermore, depending on the ceiling height and ceiling location, the duct length as described above cannot be secured linearly from the ceiling to the room, so it is possible to install the orifice and the variable airflow control device by horizontally pulling the duct. It was necessary to secure the duct length. When the duct is pulled horizontally, an elbow that should not be necessary must be provided, which increases the pressure loss of the ventilation air conditioning system.

  The present invention has been proposed to solve the above-described problems, and provides a variable airflow control device capable of shortening the distance between an orifice and a damper blade that functions as a structure of airflow calculation. For the purpose.

  In order to achieve the above object, a variable air volume control device according to the present invention includes an orifice for restricting the inside of a duct, a damper having a damper blade in the duct and capable of changing an opening degree, and two regions separated by the orifice. A differential pressure detecting means for detecting a differential pressure of the duct, an air volume calculating means for calculating an air volume in the duct based on the differential pressure, and the opening degree of the damper based on the air volume calculated by the air volume calculating means. And an opening degree adjusting means for adjusting. The damper blade is provided at the same position as the orifice. The air volume calculating means stores in advance each air volume correction coefficient according to the opening degree of the damper, and a correction for correcting the calculated air volume with the correction coefficient according to the opening degree of the damper. Means. The opening degree adjusting means adjusts the opening degree of the damper based on the air volume corrected by the correcting means.

  The orifice may be divided into two parallel to the rotation axis of the damper blade, and may be provided so as to sandwich the damper blade.

  The differential pressure detection means includes a high pressure side pressure outlet provided upstream of the orifice, and a low pressure side pressure outlet provided downstream of the orifice, and the low pressure side pressure outlet The damper blade may be provided downstream of the tip position when the damper blade falls in parallel with the duct axis.

  In addition, the variable air volume control device according to another aspect of the present invention includes an orifice projecting into a duct, a damper having a damper blade, the opening of which can be changed, and a differential pressure between two regions separated by the orifice. A differential pressure detecting means for detecting; an air volume calculating means for calculating an air volume in the duct based on the differential pressure; and an opening for adjusting the opening of the damper based on the air volume calculated by the air volume calculating means. Degree adjusting means. The damper blade is provided at a position where the distance from the orifice is substantially the same as the inner diameter of the duct.

  In addition, the orifice may rise at a right angle from the root to the tip on both sides.

  According to the present invention, since the air volume calculation result is corrected by the correction coefficient corresponding to the opening degree of the damper, the orifice and the damper can be provided at the same position. Thereby, the installation space of an orifice and a motor damper is made compact, the duct length of a ventilation air-conditioning system can be shortened, and reduction of cost and a work period can be aimed at.

It is a perspective view which shows the variable air volume control apparatus which concerns on 1st Embodiment. It is a side view which shows the variable air volume control apparatus which concerns on 1st Embodiment. It is a block diagram which shows the structure of PLC. It is a graph which shows an opening degree correction coefficient. It is a table | surface which shows the air volume which the variable air volume control apparatus which concerns on 1st Embodiment outputs. It is a schematic diagram which shows the installation aspect of the variable air volume control apparatus which concerns on 1st Embodiment. It is a side view which shows the variable air volume control apparatus which concerns on 2nd Embodiment. It is a schematic diagram which shows an air flow in case an orifice and a damper blade exist in the same position. It is a figure which shows the example of installation to the air supply system of the variable air volume control apparatus which concerns on 3rd Embodiment. It is a figure which shows the example of installation in the exhaust system of the variable air volume control apparatus which concerns on 3rd Embodiment. It is a table | surface which shows the result of the ventilation experiment in the air supply system of the variable air volume control apparatus which concerns on 3rd Embodiment. It is a table | surface which shows the result of the ventilation experiment in the exhaust system of the variable air volume control apparatus which concerns on 3rd Embodiment. It is sectional drawing which cut the orifice of the variable air volume control apparatus which concerns on 4th Embodiment in parallel with the axis | shaft of a duct.

  Hereinafter, embodiments of a variable air volume control device according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
[1. Constitution]
The structure of the variable air volume control device according to the first embodiment is shown in FIGS. FIG. 1 is a perspective view showing a variable air volume control device according to the first embodiment. FIG. 2 is a side view showing the variable air volume control device according to the first embodiment.

  The variable air volume control device 100 is provided in a ventilation air conditioning system and constitutes a part of a duct of the ventilation air conditioning system. The variable air volume control device 100 is an apparatus in which the orifice 2 and the motor damper 5 are integrated, and has two functions of air volume detection and air volume adjustment. That is, in this embodiment, the orifice 2 and the damper blade 53 of the motor damper 5 are provided at the same position of the duct 1.

  The variable air volume control device 100 includes an orifice 2, a differential pressure detection unit 3, a PLC 4, and a motor damper 5. The variable air volume control device 100 generates a differential pressure in the duct 1 with the orifice 2 that restricts the inside of the duct 1 as a boundary, and the differential pressure detection unit 3 into which the respective static pressures before and after the orifice 2 are introduced. The pressure is detected, the air volume in the duct 1 is calculated from the differential pressure detection result by a PLC (programmable logic controller) 4, and the air volume is adjusted by varying the opening degree of the motor damper 5 based on the air volume calculation result.

  Furthermore, when the orifice 2 and the damper blade 53 exist at the same position, it was confirmed that the deviation of the flow velocity distribution generated near the orifice 2 changes according to the opening degree of the motor damper 5. Therefore, in this variable air volume control device 100, an opening degree correction coefficient corresponding to the opening degree of the motor damper 5 is stored in the PLC 4 in advance, and the calculated air volume is corrected with the opening degree correction coefficient.

[A. damper]
More specifically, the motor damper 5 includes a motor 51 that rotates the rotating shaft 52 and a damper blade 53 that can change the tilt rate. The damper blade 53 is a flat plate that is pivotally supported by the rotating shaft 52 so as to cross the inside of the duct 1.

  The opening degree of the motor damper 5 is a ratio at which the inside of the duct 1 is opened without being blocked by the damper blade 53. This opening degree is represented by a tilt rate of the damper blade 53, and the extension plane of the damper blade 53 is 0% when it is completely upright with respect to the axis of the duct 1, and the extension plane of the damper blade 53 is the axis of the duct 1 The coincidence state is expressed as 100%. That is, the opening degree of the motor damper 5 is changed by changing the tilt rate of the damper blade 53.

  The center of the damper blade 53 exists on the axis of the duct 1, and the shape and size thereof substantially coincide with the inner diameter of the duct 1. For example, if the duct 1 is a cylindrical tube, the damper blade 53 has a disk shape and is slightly smaller than the inner diameter of the duct 1 so that it can be tilted in the duct 1.

  The rotating shaft 52 is installed orthogonal to the axis of the duct 1. The rotation shaft 52 is provided so as to pass from one side of the damper blade 53 through the center to the other side, and pivotally supports the damper blade 53. In the case of the disk-shaped damper blade 53, the rotating shaft 52 is pivotally supported through the diameter of the damper blade 53.

  The motor 51 is a rotation motor capable of controlling the rotation angle of the rotation shaft 52, and is a stepping motor or a geared motor. The motor 51 generates a rotational force and rotates the rotating shaft 52 by a predetermined angle. When the rotational force of the motor 51 is transmitted to the rotation shaft 52, the damper blade 53 supported by the rotation shaft 52 is tilted in the duct 1 in accordance with the rotation angle of the rotation shaft 52. The rotation angle of the rotating shaft 52, in other words, the driving amount of the motor 51 is controlled by the PLC 4 in accordance with the calculated air volume.

[B. Orifice]
The orifice 2 is formed by dividing a ring member into two parts, and is composed of an upstream-side orifice piece 21 and a downstream-side orifice piece 22 each having a semi-doughnut shape. That is, when the duct 1 is a cylindrical tube, the upstream orifice piece 21 and the downstream orifice piece 22 are arc plates extending in a circumferential direction from the inner wall of the duct 1, and the duct 1 is a rectangular tube. In the case, it is a U-shaped board.

  The upstream orifice piece 21 and the downstream orifice piece 22 protrude at different positions in the axial direction of the duct 1. In other words, the upstream orifice piece 21 and the downstream orifice piece 22 are extended on different planes. The upstream orifice piece 21 is provided more upstream in the air blowing direction in the duct 1 than the downstream orifice piece 22. The downstream orifice piece 22 is provided more downstream in the air blowing direction in the duct 1 than the upstream orifice piece 21.

  Furthermore, when the upstream orifice piece 21 and the downstream orifice piece 22 are viewed from the axial direction of the duct 1, the upstream orifice piece 21 and the downstream orifice piece 22 form a complete or partially missing ring.

  That is, the upstream orifice piece 21 and the downstream orifice piece 22 are provided so as to be point-symmetric with respect to one point on the axis of the duct 1. If the installation position of the upstream orifice piece 21 is the upper side, the installation position of the downstream orifice piece 22 is the lower side. Further, when the upstream orifice piece 21 and the downstream orifice piece 22 are placed on the same plane, they are formed so that one closed ring is completed or a part of the ring is missing. Is formed. In other words, the ring is formed such that a part of the ring is missing when the central angle of the upstream orifice piece 21 and the downstream orifice piece 22 is less than 180 degrees.

  The orifice 2 is a plate that squeezes the inside of the duct 1, and generates a differential pressure before and after the orifice 2. The air passing through the orifice 2 is peeled off from the inner wall of the duct 1 on the upstream side of the orifice 2, and when passing through the orifice 2, the pressure increases and the wind speed increases, and the static pressure decreases on the downstream side.

  In the variable air volume control device 100, the center of the orifice 2 and the center of the damper blade 53 coincide. The center of the orifice 2 is the position of the center of gravity when the upstream orifice piece 21 and the downstream orifice piece 22 are considered as one body. That is, the orifice 2 and the damper blade 53 are attached at the same position.

  Specifically, the upstream-side orifice piece 21 and the downstream-side orifice piece 22 are installed in line symmetry with respect to the rotating shaft 53 that supports the damper blade 53, and the damper blade 53 stands upright with respect to the axis of the duct 1. In the state, the damper blade 53 is sandwiched. The upstream orifice piece 21 faces the upstream surface of the damper blade 53, and the downstream orifice piece 22 faces the downstream surface of the damper blade 53. The upstream orifice piece 21 and the downstream orifice piece 22 may contact the surface of the damper blade 53. In the installation mode of the orifice 2 and the motor damper 5, when the damper blade 53 tilts away from the upstream orifice piece 21 and the downstream orifice piece 22, the opening degree increases.

[C. Differential pressure detection means]
The differential pressure detector 3 includes a high pressure side pressure outlet 31, a low pressure side pressure outlet 32, a high pressure side tube 33, a low pressure side tube 34, and a detector 35. The differential pressure of is detected.

  The high-pressure side pressure outlet 31 and the low-pressure side pressure outlet 32 are slits or holes that penetrate the tube wall of the duct 1. The high-pressure side pressure outlet 31 and the low-pressure side pressure outlet 32 are formed by hollow terminals that conduct the inside and outside of the duct 1, and one end of the opening is provided flush with the inner wall surface of the duct 1.

  A plurality of high-pressure side pressure outlets 31 are provided in the vicinity of the upstream side of the upstream orifice piece 21 along the circumferential direction of the duct 1. A plurality of low-pressure side pressure outlets 32 are provided in the vicinity of the downstream side of the downstream orifice piece 22 along the circumferential direction of the duct 1.

  A high-pressure side tube 33 is attached to the other open end of the high-pressure side pressure outlet 31 protruding outside the duct 1, and the low-pressure side is connected to the other open end of the low-pressure side pressure outlet 32 protruding outside the duct 1. A tube 34 is attached.

  The high-pressure side tube 33 and the low-pressure side tube 34 are pressure guiding tubes that guide pressure to the detector 35, respectively. The high-pressure side tube 33 and the low-pressure side tube 34 may be replaced with a diaphragm seal and a capillary tube.

  The detector 35 is a differential pressure transmitter, to which the other ends of the high-pressure side tube 33 and the low-pressure side tube 34 are attached, and pressures before and after the orifice 2 are respectively introduced. Inside the detector 35, a pressure sensitive diaphragm, a differential capacitance and an amplifier are provided. The pressure sensitive diaphragm is provided between the openings of the high pressure side tube 33 and the low pressure side tube 34. The installation space of this pressure sensitive diaphragm is filled with the sealing liquid.

  In the detector 35, the strain amount of the pressure-sensitive diaphragm changes according to the difference between the static pressures introduced by the high-pressure side tube 33 and the low-pressure side tube 34. The amount of distortion of the pressure-sensitive diaphragm is detected by a differential capacitance and converted into an electric signal, and the electric signal is amplified by an amplifier and output. In addition to the differential capacitance, various displacement sensors such as a differential transformer method and an eddy current method can be used.

[D. Air volume calculation means]
The PLC 4 is a programmable logic controller, and serves as an air volume calculating means for calculating the air volume, a correcting means for correcting the calculated air volume, and an opening degree adjusting means for controlling the opening degree of the motor damper 5 based on the air volume obtained by the correction. As shown in FIG. 3, the PLC 4 includes an air volume calculation unit 41, a correction unit 42, and an opening degree adjustment unit 43, and the correction unit 43 includes an opening degree correction coefficient storage unit 44.

The air volume calculation unit 41 converts the differential pressure ΔP indicated by the electrical signal output from the differential pressure detection unit 3 into a digital signal, and performs an arithmetic process with the following mathematical formula (1) to perform an air volume qv (m ³ ) in the duct 1. / H).

Ｃは非圧縮性流体の流れによって決められる係数で、実際の流量と理論流量との比である。Ｌｏはオリフィス２の管内に突出した断面積（ｍ^２）である。ρは温度と圧力から算出される流体密度であり、例えば、空気２０℃１気圧の場合には１．２ｋｇ／ｍ^３である。∂は圧縮係数やレイノルズ係数を加味した絞り直径比に基づく係数である。ｋｏは可変風量制御装置１００の個体差に基づき、実験により得られる係数である。

C is a coefficient determined by the flow of the incompressible fluid, and is a ratio between the actual flow rate and the theoretical flow rate. Lo is a cross-sectional area (m ² ) protruding into the pipe of the orifice 2. ρ is a fluid density calculated from temperature and pressure, and is 1.2 kg / m ³ in the case of air at 20 ° C. and 1 atmosphere, for example. ∂ is a coefficient based on the diameter ratio of the drawing with the compression coefficient and Reynolds coefficient added. ko is a coefficient obtained by experiments based on individual differences of the variable airflow control device 100.

As shown in the above formula (1), since the static pressure drop and the air volume have square characteristics according to the Torrichelli theorem, the differential pressure Δp is calculated according to the Torrichelli theorem and using various arithmetic expressions in consideration of various coefficients. To calculate the air volume qv (m ³ / h). The coefficients C, Lo, ∂, and ko are calculated from measured values and stored in advance in the memory of the air volume calculation unit 41. The PLC 4 is provided with a user interface such as a touch panel. By operating the user interface, the coefficients C, Lo, ｋ, and ko are input and stored in the memory of the air volume calculation unit 41.

The correcting unit 42 corrects the air volume qv (m ³ / h) calculated by the air volume calculating unit 41 according to the temperature and the opening degree of the motor damper 5. The opening degree of the motor damper 5 is acquired from the opening degree adjustment unit 43. When correcting based on the opening degree of the motor damper 5, the opening degree correction coefficient km stored in the opening degree correction coefficient storage unit 44 is used.

  FIG. 4 is a graph showing the opening correction coefficient km stored in the opening correction coefficient storage unit 44. As shown in FIG. 4, the opening correction coefficient storage unit 44 stores in advance opening correction coefficients km corresponding to the respective openings of the motor damper 5.

  The correction unit 42 reads the opening degree of the motor damper 5 from the opening degree adjustment unit 43, and reads the opening degree correction coefficient km corresponding to the read opening degree from the opening degree correction coefficient storage unit 44. Then, as shown in the following formula (2), the true air volume Qv is obtained by multiplying the air volume qv by the opening correction coefficient km.

(Equation 2)
Qv = qv × km ... number (2)

  The correction unit 42 may further determine the surface wind speed γ by dividing the air volume Qv by the cross-sectional area of the duct 1.

[E. Opening adjustment means]
The opening adjustment unit 43 adjusts the opening of the motor damper 5. Specifically, the tilt rate of the damper blade 53 is changed. The opening adjustment unit 43 stores a predetermined air volume in advance. The stored air volume is determined by the balance of the air flow rates of the air supply system and the exhaust system. The opening degree adjusting unit 43 compares the air volume Qv calculated by the correcting unit 42 with the stored air volume. Then, an analog signal or a pulse signal corresponding to the comparison result is input as a drive signal to the motor damper 5 to change the tilt rate of the damper blade 53. As a result of the comparison, when the air volume Qv matches the stored air volume, the output of the drive signal is stopped.

  For example, if the air volume Qv is smaller than the stored air volume, a pulse signal is output in a direction to increase the opening degree of the motor damper 5. If the air volume Qv is larger than the stored air volume, a pulse signal is output in a direction to decrease the opening degree of the motor damper 5.

[2. Action / Effect]
The variable air volume control device 100 was installed in a ventilation air conditioning system, each air flow was blown by a fan, the motor damper 5 was opened at each opening degree, and the air flow was detected by the variable air flow control device 100. Further, in the aspect in which the conventional orifice and the motor damper are installed with a sufficient distance as the separation type, each air volume was blown in the same manner to detect the air volume. The detection result is shown in FIG.

  As shown in FIG. 5, it can be seen that the air volumes detected by the separation type and the variable air volume control device 100 according to the present embodiment are accurately matched in each air volume and each opening. That is, by correcting the air volume calculation result with the opening correction coefficient corresponding to the opening of the motor damper 5, the air volume can be detected with high accuracy, and the variable variable is integrated with the orifice 2 and the motor damper 5 installed at the same position. The air volume control device 100 can be realized.

  FIG. 6 is a schematic diagram illustrating an installation mode of the variable air volume control device 100 according to the present embodiment, where (a) illustrates a conventional installation mode, and (b) illustrates the variable air volume control device 100 according to the present embodiment. An installation aspect is shown.

  As shown in FIG. 6 (a), conventionally, when the ceiling height is low, in order to ensure a sufficient distance between the orifice and the motor damper, the duct connecting the inside and outside of the clean room is laterally drawn, Were installed with an orifice and a motor damper. As a result, the overall length of the duct has become longer and the system has become larger.

  On the other hand, as shown in FIG. 6B, when the variable air volume control device 100 according to the present embodiment is installed, the variable air volume control device 100 is made compact by integrating the orifice 2 and the motor damper 5. Therefore, it is not necessary to pull the duct sideways. Therefore, the duct length is remarkably shortened, the installation cost is reduced, and the construction period can be shortened. Moreover, since the duct length is shortened, the pressure loss of the entire ventilation air conditioning system is also reduced.

  As described above, the variable air volume control device 100 according to the present embodiment includes the orifice 2 and the motor damper 5 in the duct 1, and the differential pressure detection unit 3 that detects the differential pressure between the two regions separated by the orifice 2, and the differential pressure The air volume calculating unit 41 that calculates the air volume in the duct 1 based on the above, and the opening degree adjusting unit 43 that adjusts the opening degree of the motor damper 5 based on the air volume calculated by the air volume calculating unit 41.

  The damper blade 53 is provided at the same position as the orifice 2, and according to the opening degree of the motor damper 5, an opening degree correction coefficient storage unit 44 that stores each correction coefficient of the air quantity in advance, and the calculated air quantity of the motor damper 5. A correction unit 42 that corrects with a correction coefficient corresponding to the opening degree is provided, and the opening degree of the motor damper 5 is adjusted based on the air volume corrected by the correction unit 42.

  Thereby, the installation space of the orifice 2 and the motor damper 5 is made compact, the duct length can be shortened, and the cost and the construction period can be reduced. Moreover, the pressure loss of the whole ventilation air conditioning system also falls.

  Further, in order to provide the orifice 2 and the damper blade 53 at the same position, the orifice 2 may be divided into two parallel to the rotation shaft 52 of the damper blade 53 and the damper blade 53 may be sandwiched.

[Second Embodiment]
Next, the variable air volume control device 100 according to the second embodiment will be described. In the variable air volume control device 100, the installation position of the low pressure side pressure outlet 34 is changed in the variable air volume control device 100 according to the first embodiment.

[1. Constitution]
FIG. 7 is a side view showing the variable air volume control device 100. As shown in FIG. 7, the low-pressure-side pressure outlet 32 is installed in the vicinity of the tip position when the extension plane of the damper blade 53 falls substantially parallel to the axis of the duct 1. When the opening degree of the motor damper 5 is 100%, the damper blade 53 falls down substantially parallel to the axis of the duct 1. At this time, the tip position of the damper blade 53 and the low pressure outlet 32 coincide with each other within a range of several mm to several cm at the axial position of the duct 1.

  In the installation mode of the low pressure outlet 32, it is more desirable that the low pressure side outlet 32 is provided on the downstream side of the tip position when the damper blade 53 falls substantially parallel to the axis of the duct 1.

[2. Effect]
FIG. 8 is a schematic diagram showing an air flow when the orifice 2 and the damper blade 53 exist at the same position. As shown in FIG. 8, the air that has passed through the orifice 2 collides with the damper blade 53, and a swirling flow S is generated on the upstream surface of the damper blade 53. Therefore, the air pressure existing on the upstream surface of the damper blade 53 pulsates in a complicated manner. In addition, the swirl | vortex flow S weakens, so that the opening degree of the motor damper 5 becomes large.

  In the variable air volume control device 100 according to the second embodiment, the low pressure side pressure outlet 32 is out of the range where the influence of the swirling flow S is large when the opening degree of the motor damper 5 is small. Therefore, the pulsation of the pressure introduced into the low-pressure side outlet 32 is small. Further, when the opening degree of the motor damper 5 is increased, the swirl flow S is weak, and similarly, the pulsation of the pressure introduced into the low-pressure side outlet 32 is small. In other words, when the low pressure inlet 32 is present near the tip position when the damper blade 53 falls substantially parallel, the variation in pressure introduced from the low pressure outlet 32 to the detector 35 is reduced.

  When the low pressure outlet 32 exists downstream from the tip position when the damper blade 53 falls substantially in parallel, all the openings of the motor damper 5 are out of the influence of the swirl flow S, so that the low pressure intake The variation in pressure introduced from the outlet 32 to the detector 35 becomes smaller.

  Therefore, in the variable air volume control device 100 in which the low pressure side pressure outlet 32 is provided in the vicinity of the tip position when the damper blade 53 falls substantially parallel to the axis of the duct 1, the air volume is calculated at any timing. Variations in the calculation results are reduced. As a result, even when the orifice 2 and the damper blade 53 are installed at the same position, the air volume can be calculated with higher accuracy. For this reason, the variable air volume control device 100 can be applied even to a ventilation air conditioning system that requires more accurate air volume control.

  As described above, in the variable air flow control device 100 according to the present embodiment, the low pressure side pressure outlet 32 is located in the vicinity of the tip position when the damper blade 53 falls substantially parallel to the axis of the duct 1 in the axial direction of the duct 1. Is provided. More preferably, the low pressure side pressure outlet 32 is provided on the downstream side of the tip position when the damper blade 53 falls substantially parallel to the axis of the duct 1. Therefore, it is possible to further suppress variation in the air volume calculation result due to the swirling flow generated by the damper blade 53, and it is possible to apply the variable air volume control device 100 even to a ventilation air conditioning system that requires high air volume control. .

[Third Embodiment]
Next, the variable air volume control device 100 according to the third embodiment will be described. FIG. 9 shows an installation example of the variable air volume control device 100 according to the third embodiment in an air supply system, and FIG. 10 shows an installation example of the variable air volume control device 100 according to the third embodiment in an exhaust system. Indicates.

  As shown in FIGS. 9 and 10, the variable air volume control device 100 according to the third embodiment is provided with a damper blade 53 at a distance 1D downstream of the orifice 2. 1D is the same distance as the inner diameter of the duct 1. In this case, it is not necessary to install the orifice 2 separately.

In this installation mode, a comparative experiment was performed in which the amount of air passing through the orifice 2 and the amount of air at other positions of the duct were compared while the amount of air from the fan 200 was changed to 100 to 600 m ³ / h. A duct having a diameter of 200 mm was used.

  At other positions of the duct, a Pitot tube 300 was installed to collect the air volume. The Pitot tube 300 measures the air volume from the pressure of the air flow, and is installed so that the end faces the upstream of the duct. In the air supply system, the Pitot tube 300 is installed at a position 3D upstream from the orifice 2 and in the exhaust system, the Pitot tube 300 is installed at a position 3D upstream from the orifice 2. .

Then, 100 m ³ / h, 200 m ³ / h, 300 m ³ / h, 400 m ³ / h, 500 m ³ / h, and 600 m ³ / h are blown by the fan 200, and the amount of air that has passed through the orifice 2 (Ori air volume) Calculated by PLC4, and the ratio (%) of the orientation air volume based on the air volume collected by the Pitot tube 300 (referred to as AE air volume) was obtained.

FIG. 11 shows the experimental results in the air supply system, and FIG. 12 shows the experimental results in the exhaust system. As shown in FIG. 11 and FIG. 12, the difference between the orientation air amount passing through the orifice 2 and the AE air amount is within ± 3% in the air supply amount of 200 m ³ / h or more in both the air supply system and the exhaust system. It was. Moreover, it was confirmed that the duct can be used even when the inside of the duct has a negative pressure.

  That is, since the variable air volume control device 100 according to the present embodiment is provided with the damper blade 53 at the 1D position downstream of the orifice 2, it is possible to prevent a decrease in pressure loss due to the interaction between the damper blade 53 and the orifice 2. It is possible to achieve energy saving while achieving compactness.

[Fourth Embodiment]
Next, the variable air volume control device 100 according to the fourth embodiment will be described. FIG. 13 shows a cross section in which the orifice 2 provided in the variable air flow control device 100 is cut parallel to the axis of the duct 1.

  The protruding length of the orifice 2 shown in FIG. 13 is set to be low. In addition, the upstream and downstream surfaces of the orifice 2 rise at right angles from the root to the tip, and both the corners of the tip are formed at right angles in a cross section cut parallel to the axis of the duct 1. The orifice 2 is generally provided with a large edge on the downstream side and a small edge on the upstream side as standardized by JIS.

By setting the protruding length of the orifice 2 to be low, it is possible to prevent an increase in pressure loss of the entire system caused by the interaction between the orifice 2 and the damper blade 53. On the other hand, if the protruding length of the orifice 2 is reduced, the differential pressure is less likely to rise before and after the orifice 2. However, by forming both sides of the orifice 2 so as to rise at right angles from the root to the tip, the differential pressure can be quickly and clearly set. To stand. Therefore, adverse effects caused by bringing the orifice 2 and the damper blade 53 to the same position or close to each other can be suppressed, and the variable air volume control device 100 with higher effectiveness can be provided.
[Other embodiments]
In the present specification, a plurality of embodiments according to the present invention have been described. However, these embodiments are presented as examples, and the first to fourth embodiments may be combined with all or any one of them. Is included. Each embodiment can be variously omitted, replaced, and changed without departing from the scope of the invention, and can be implemented in various forms. The embodiments and modifications thereof are included in the scope of the invention and the gist thereof, and are also included in the invention described in the claims and the equivalent scope thereof.

DESCRIPTION OF SYMBOLS 100 Variable air volume control apparatus 1 Duct 2 Orifice 21 Upstream orifice piece 22 Downstream orifice piece 3 Differential pressure detection part 31 High pressure side pressure outlet 32 Low pressure side pressure outlet 33 High pressure side tube 34 Low pressure side tube 35 Detector 4 PLC
41 Air volume calculation unit 42 Correction unit 43 Opening adjustment unit 44 Opening correction coefficient storage unit 5 Motor damper 51 Motor 52 Rotating shaft 53 Damper blade 200 Fan 300 Pitot tube 400 Volume damper

Claims (7)

An orifice that restricts the inside of the duct;
A damper blade in the duct, and a damper capable of changing the opening;
Differential pressure detecting means for detecting a differential pressure in two regions separated by the orifice;
An air volume calculating means for calculating an air volume in the duct based on the differential pressure;
An opening degree adjusting means for adjusting the opening degree of the damper based on the air volume calculated by the air volume calculating means;
With
The damper blade is provided at the same position as the orifice,
The air volume calculating means includes
Storage means for preliminarily storing each correction coefficient of the air volume according to the opening of the damper;
Correction means for correcting the calculated air volume with the correction coefficient corresponding to the opening of the damper;
With
The opening adjustment means adjusts the opening of the damper based on the air volume corrected by the correction means;
A variable air volume control device characterized by the above. The orifice is
Divided into two in parallel with the rotation axis of the damper blade, and sandwiched between the damper blades,
The variable air volume control device according to claim 1. The differential pressure detecting means includes
A high-pressure side pressure outlet provided upstream of the orifice;
A low-pressure side pressure outlet provided downstream of the orifice;
With
The low pressure side pressure outlet is
In the axial direction of the duct, the damper blade is provided in the vicinity of the tip position when falling down substantially parallel to the axis of the duct,
The variable air volume control device according to claim 1 or 2. The low pressure side pressure outlet is
The damper blade is provided on the downstream side of the tip position when the damper blade falls substantially parallel to the axis of the duct;
The variable air volume control device according to claim 3. The orifice rises at right angles from the root to the tip on both sides;
The variable air volume control device according to any one of claims 1 to 4. An orifice protruding into the duct;
A damper having a damper blade and capable of changing the opening;
Differential pressure detecting means for detecting a differential pressure in two regions separated by the orifice;
An air volume calculating means for calculating an air volume in the duct based on the differential pressure;
An opening degree adjusting means for adjusting the opening degree of the damper based on the air volume calculated by the air volume calculating means;
With
The damper blade is provided at a position where the distance from the orifice is substantially the same as the inner diameter of the duct;
A variable air volume control device characterized by the above. The orifice rises at right angles from the root to the tip on both sides;
The variable air volume control device according to claim 6.

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