Suction device

Abstract

[Problem] To provide a suction device in which a vortex is actually generated so that whether appropriate suction is being performed can be easily confirmed and in which adjustment can be performed for suitable suction. [Solution] A suction device 100 which includes a suction fan 20 for suctioning suction target air and blower fans 40 for forming an air curtain that is blown out and swirls so as to surround the suction target air and in which the air is suctioned while a swirling suction flow (vortex) is generated by swirling of the air curtain and the rotation of the suction fan, said suction device 100 comprising a sensor (60) for determining the swirling strength of the suction flow and an output means (70) for outputting the result of determination of the swirling strength. Examples of the sensor (60) include a wind speed sensor 60, a differential pressure sensor 61, and a current sensor 63 and a rotation speed sensor 64 of a fan motor 20a of the suction fan 20.

Description

Suction device

[0001] This invention relates to a suction device that generates a swirling flow to suck air for local exhaust.

[0002] Conventionally, suction devices for local exhaust have been proposed. For example, in the device of Patent Document 1, a coaxial double - structure propeller fan with blades arranged to generate a blowing flow in the outer part and a suction flow in the inner part is used. While generating a blowing flow in the outer part to form an air curtain, the air inside is sucked in the inner part. Due to the rotation of the propeller fan, the blowing flow and the suction flow rotate in the same direction, so a swirling suction flow is generated, and effective suction can be achieved.

[0003] In the device of Patent Document 2, two sirocco fans are used. One fan blows out from the peripheral part to generate an air curtain, and the other fan sucks from the central part. At this time, inclined blades are provided in the middle of the blowing flow passage to swirl the blowing flow, thereby generating a swirling suction flow.

[0004] In the device of Patent Document 3, it includes a suction fan that generates a suction flow in the suction flow passage, a blowing flow generation chamber that introduces a blowing flow from an inlet on the opposite side of the suction target and expands it in a disc shape, a plurality of blowing fans that blow out the blowing flow in an outer direction swirling around the axis of the suction flow passage from this blowing flow generation chamber, and a blowing flow deflection guide that deflects the blowing flow in the direction of the suction target, thereby forming a large - diameter cylindrical air curtain that swirls. Due to this swirling, a swirling suction flow is generated.

[0005] Japanese Patent Application Laid - Open No. 5 - 60088, Japanese Patent Application Laid - Open No. 8 - 75208, Japanese Patent Application Laid - Open No. 2023 - 106210

[0006] In each of the above suction devices, if a suction flow (tornado) with appropriate swirling strength is generated, the object to be sucked along the axis of this suction flow can be concentrated and localized exhaust can be achieved. On the other hand, if a suction flow with appropriate swirling strength is not generated, the suction force dissipates and localized exhaust cannot be achieved. Whether or not a suction flow with appropriate swirling strength is generated is influenced by the rotation speed of the suction fan and discharge fan, the distance between the fan and the floor, etc. In conventional suction devices, in order to obtain appropriate swirling strength, the rotation speed of the fan was adjusted based on empirical rules, for example, according to the distance from the floor. However, the swirling strength also changes depending on the actual installation site conditions, such as the size of the room, the degree of openness, the arrangement of equipment, etc., so it was not always possible to obtain a suction flow with optimal swirling strength. Furthermore, in order to check whether a swirling flow (tornado) with appropriate swirling strength was being generated, it was necessary to check the flow of incense smoke or dry ice mist, which was inefficient.

[0007] This invention has been made in view of the above circumstances, and aims to provide a suction device that allows for easy confirmation of whether a suction flow with appropriate swirling strength is generated and whether appropriate suction is being performed, and that can be adjusted to achieve optimal suction.

[0008] To solve the aforementioned problems, the present invention provides a suction device comprising: a suction fan for sucking in air to be sucked in; a discharge fan that blows out so as to surround the air to be sucked in and forms a swirling air curtain; a suction device that sucks in the air while generating a swirling suction flow (tornado) by the swirling of the air curtain and the rotation of the suction fan; and further comprising: a sensor for determining the swirling intensity of the suction flow; and an output means for outputting the determination result of the swirling intensity.

[0009] This configuration includes a sensor for determining the swirling intensity of the swirling suction flow (tornado) and an output means for outputting the determination result of the swirling intensity, making it easy to confirm whether a tornado is actually being generated and whether proper suction is being performed.

[0010] The sensor may be an anemometer that measures the wind speed in the axial direction of the suction flow and determines the swirling intensity of the suction flow based on a known relationship between the wind speed and the swirling intensity of the suction flow. This configuration allows for relatively direct measurement of the swirling intensity of the suction flow, making it easier to adjust to the optimal swirl intensity of the suction flow.

[0011] The suction device may also use the wind speed sensor to rotate the suction fan motor to measure the wind speed, calculate the difference in wind speed when the outlet fan is ON and when it is OFF, and determine the swirling strength of the suction flow based on a known relationship between the difference in wind speed and the swirling strength of the suction flow.

[0012] The sensor may be a pressure sensor that measures the pressure at the central axis of the suction flow or the differential pressure, which is the difference in pressure between the central axis of the suction flow and the surrounding area, and determines the swirling intensity of the suction flow based on a known relationship between the pressure or the differential pressure and the swirling intensity of the suction flow.

[0013] This configuration allows for the measurement of the swirling intensity of the suction flow relatively directly, making it easier to adjust the swirl intensity to the optimal level.

[0014] The suction device may also use the pressure sensor to rotate the suction fan to measure the pressure or differential pressure, calculate the difference in pressure or differential pressure when the outlet fan is ON and when it is OFF, and determine the swirling strength of the suction flow based on a known relationship between the difference in pressure or differential pressure and the swirling strength of the suction flow.

[0015] The sensor may be a current sensor for the fan motor of the suction fan, which rotates the fan motor at a constant voltage, measures the current flowing through the fan motor, calculates the difference in current flowing through the fan motor when the outlet fan is ON and when it is OFF, and determines the swirling strength of the suction flow based on a known relationship between the difference in current and the swirling strength of the suction flow. This configuration makes it easy to measure the swirling strength even in locations with a lot of smoke and soot.

[0016] The sensor may be a rotation speed sensor for the suction fan, which rotates the fan motor of the suction fan at a constant voltage to measure the rotation speed of the suction fan, calculates the difference in rotation speed of the suction fan when the outlet fan is ON and when it is OFF, and determines the swirling strength of the suction flow based on a known relationship between the difference in rotation speed and the swirling strength of the suction flow. This configuration makes it easy to measure the swirling strength even in places with a lot of smoke and dust.

[0017] The output means may be an LED display that shows the result of determining the swirling intensity of the suction flow. This configuration makes it easy to intuitively grasp the swirling intensity status even from a distance.

[0018] The output means may be a flat panel display that shows the determination result of the swirling intensity of the suction flow. With this configuration, the swirling intensity of the suction flow can be grasped in detail, for example numerically, and fine adjustments can be made easily.

[0019] The output means may be a communication interface that outputs the determination result of the swirling intensity of the suction flow to a communication line. With this configuration, the swirling intensity status of the suction flow can be output to and displayed on an external terminal such as a smartphone or PC.

[0020] The suction device further includes a rotation control unit that individually controls the rotation speeds of the suction fan and the discharge fan, and the rotation control unit may be configured to adjust the rotation speed of at least one of the suction fan and the discharge fan so that the determined swirling intensity of the suction flow becomes a predetermined value. With this configuration, the swirling intensity of the suction flow can be automatically and optimally adjusted, particularly by adjusting the rotation speed of the discharge fan, thereby achieving efficient intake.

[0021] The suction device further includes an adjustment mechanism for adjusting the height of the suction device from the floor surface at the installation location, a motor for driving the adjustment mechanism, and a height control unit for controlling the motor. The height control unit may be configured to adjust the height of the suction device from the floor surface so that the determined swirling intensity of the suction flow becomes a predetermined value. With this configuration, the swirling intensity of the suction flow can be automatically and optimally adjusted, particularly by adjusting the height of the suction device from the floor surface, thereby achieving efficient air intake.

[0022] The present invention provides a suction device comprising: a suction fan for sucking in air to be sucked in; a suction duct having one or more suction ports and guiding the air to the suction fan; and a blowing fan that blows out from around each of the suction ports so as to surround the air to be sucked in, forming a swirling air curtain, wherein the suction device sucks in the air while generating a swirling suction flow at each of the suction ports by the swirling of the air curtain and the suction by the suction fan, and further comprising: a sensor for determining the swirling intensity of the suction flow at each of the suction ports; and an output means for outputting the determination result of the swirling intensity at each of the suction ports, wherein the sensor is a pressure sensor that measures the pressure at the central axis of the suction flow or the differential pressure which is the difference in pressure between the central axis of the suction flow and the surrounding area, and determines the swirling intensity of the suction flow based on a known relationship between the pressure or the differential pressure and the swirling intensity of the suction flow. This configuration makes it easier to check the status of the swirling suction flow (tornado) at each suction port, even in suction systems that draw in smoke generated at multiple tables, such as in a yakiniku restaurant, through ducts from suction ports on each table.

[0023] The suction device according to the present invention is equipped with a sensor for determining the swirling intensity of the suction flow and an output means for outputting the determination result of the swirling intensity. This makes it easy to confirm whether a tornado is actually being generated and whether appropriate suction is being performed, and provides a suction device that can be adjusted to achieve optimal suction.

[0024] Figure 1 is a schematic diagram showing a suction device according to the first embodiment of the present invention, where (a) is a longitudinal cross-sectional view and (b) is a cross-sectional view taken along line A-A. Figure 1 is a flowchart showing the operation of measuring the swirling intensity of the suction flow in the suction device. Figure 1 is a diagram showing the relationship between the wind speed of the suction flow and the swirling intensity of the suction flow in the suction device. Figure 1 is a diagram showing the reason why the wind speed of the suction flow changes with the swirling intensity of the suction flow in the suction device. Figure 5 is a schematic cross-sectional view showing a suction device according to the second embodiment of the present invention. Figure 5 is a diagram showing the relationship between the differential pressure and the swirling intensity of the suction flow in the suction device. Figure 7 is a schematic diagram conceptually showing a third embodiment of the suction device according to the present invention. Figure 7 is a diagram showing the relationship between the suction fan motor current and the swirling intensity of the suction flow in the suction device. Figure 9 is a schematic diagram conceptually showing a fifth embodiment of the suction device according to the present invention. Figure 6 is a schematic diagram conceptually showing a sixth embodiment of the suction device according to the present invention. Figure 7 is a schematic diagram conceptually showing a seventh embodiment of the suction device according to the present invention.

[0025] Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) This embodiment uses an anemometer as the sensor. Figure 1 is a schematic diagram showing a suction device 100 of the first embodiment according to the present invention, where (a) is a vertical cross-sectional view and (b) is a cross-sectional view taken along A-A. As shown in Figure 1, the suction device 100 of the first embodiment includes a suction flow passage 10, a suction fan 20, a discharge flow generation chamber 30, a plurality of discharge fans 40, a discharge flow deflection guide 50, an anemometer 60 as the sensor, an LED display device 70 as the output means, and a control unit 80. Note that in Figures 1, 5, 7, 9, 12, and 13, the power lines from the control unit 80 to the suction fan 20 and discharge fan 40 are omitted in principle to avoid complexity.

[0026] The suction flow passage 10 has a substantially circular suction port 12 at its end facing the object to be suctioned 90, and is a passage through which the suction flow passes. In this embodiment, it is formed inside the cylindrical suction duct 11.

[0027] The suction fan 20 is a fan that generates a suction flow, is driven by a motor 20a, and is positioned within the suction flow passage 10 such that its rotating shaft is coaxial with the axis 10c of the suction flow passage 10. However, in this invention, the suction fan 20 is not limited to this, and may be a centrifugal fan such as a sirocco fan.

[0028] The discharge flow generation chamber 30 is formed in a substantially disc shape that coaxially surrounds the suction flow passage 10, and is a space in which air is introduced from the inlet 31 on the opposite side of the object to be suctioned 90 and expanded into a disc shape. In this embodiment, it extends outward from the outer circumference of the suction duct 11 along a plane perpendicular to the suction duct 11 and is formed between two parallel annular discs. The inlet 31 is formed in an annular shape between the inner circumference of the upper disc and the outer circumference of the suction duct 11.

[0029] As shown in Figure 1(b), the multiple discharge fans 40 are provided at various locations on the outer periphery of the discharge flow generation chamber 30 and are fans that blow air outwards from the discharge flow generation chamber 30 in a direction that rotates around the axis 10c (see Figure 1) of the suction flow passage 10. In this embodiment, each of the multiple discharge fans 40 is an axial flow fan driven by a fan motor 40a. The multiple discharge fans 40 are provided within the discharge flow generation chamber 30 and are arranged so that their rotation axis directions are in a radial direction that rotates. As a result, air is blown out from the inside of the discharge flow generation chamber 30 in a radial direction that rotates. In this embodiment, if the suction fan 20 is provided coaxially within the suction flow passage 10, the rotation direction in the "radial direction that rotates" may be the same as or different from the rotation direction of the suction fan 20.

[0030] As shown in Figure 1, the discharge flow deflection guide 50 is provided on the outer periphery of the discharge flow generation chamber 30 and is a guide that deflects the airflow blown out in a planar manner by the plurality of discharge fans 40 toward the suction target 90. Due to this discharge flow deflection guide 50, the airflow blown out by the plurality of discharge fans 40 is deflected toward the suction target 90 while maintaining a rotation around the axis 10c of the suction flow passage 10, forming a rotating, substantially cylindrical air curtain AC. Hereinafter, the rotating air curtain AC will also be referred to as the "discharge flow". As will be described later, this discharge flow changes direction on the floor or elsewhere and becomes a suction flow that is sucked in by the suction fan 20, and the rotating suction flow among these will also be referred to as the "tornado T".

[0031] The wind speed sensor 60 is a sensor for determining the swirling strength of the suction flow. It measures the axial wind speed of the suction flow from the suction fan 20 (also simply called the "wind speed of the suction flow") and determines the swirling strength of the suction flow based on a known relationship between this wind speed and the swirling strength of the suction flow (referring to the degree of swirling when the suction flow is visualized with dry ice, etc., the same applies hereinafter). For example, a hot-wire anemometer can be used as the wind speed sensor 60. The wind speed sensor 60 can be installed in any of the suction flow paths before or after the suction fan 20, but a location above the suction fan 20 (output side) that is far enough away that the suction flow stabilizes is preferable because it clearly shows the relationship between the wind speed of the suction flow and the swirling strength of the suction flow, making it easy to determine suitability.

[0032] The LED display device 70 is an output means that outputs the intensity judgment result. This LED display device 70 has, for example, a two-stage display, where a green LED lights up when the judgment result is OK, and a red LED lights up when the judgment result is NG. This configuration makes it easy to intuitively grasp the intensity status of the swirling flow (tornado) even from a distance. The LED display device 70 may also have a multi-stage display, where a red LED lights up when the judgment result is NG, but when the judgment result is OK, the number of green LEDs lit up increases depending on the degree of OK. In addition to this LED display device 70, a flat panel display may also be used as the output means, in which case the swirling intensity status of the suction flow can be grasped in detail, for example numerically, and fine adjustments can be made. Furthermore, the output means may be a communication interface that outputs the determination result of the swirling intensity of the suction flow to a communication line, such as Wi-Fi, Bluetooth®, or a LAN interface. In this case, the swirling intensity status of the suction flow can be output to and displayed on an external terminal such as a smartphone or PC.

[0033] The control unit 80 individually controls the rotation and stopping of the suction fan 20 and each outlet fan 40, reads the measured value from the wind speed sensor 60, determines the swirling intensity of the suction flow, and outputs the determination result to an output means (LED display device 70). Any known means can be used for this unit. For example, a microcontroller with a predetermined execution program stored in it and a unit equipped with an input / output interface can be used. The control unit 80 may also have a function to control the rotation speed of the suction fan 20 and the outlet fan 40, as in the rotation control unit 81 of the fifth embodiment described later.

[0034] Next, the operation of the suction device 100 of the first embodiment formed in this manner will be described with reference to Figures 1 and 2. In Figures 1(a) and 1(b), the arrows (excluding the leader line arrows and the arrows indicating the viewing direction of the A-A cross section) indicate the flow of air. When the suction fan 20 and the plurality of discharge fans 40 are driven to rotate, air is introduced into the discharge flow generation chamber 30 from the inlet 31 by the plurality of discharge fans 40. The introduced air is spread out in a disc shape within the discharge flow generation chamber 30 and blown outwards in a swirling direction around the axis 10c of the suction flow passage 10 by the plurality of discharge fans 40 arranged on the outer circumference (see Figure 1(b)). The discharge flow deflection guide 50 deflects the air towards the suction target 90 while maintaining the swirling motion, forming a swirling, substantially cylindrical air curtain AC.

[0035] Meanwhile, the rotation of the suction fan 20 generates a suction flow, and the air inside the air curtain AC is drawn in through the suction flow passage 10 formed inside the suction duct 11. As a result, the blown-out flow that forms the air curtain AC changes direction towards the suction port 12 of the suction flow passage 10 at a point determined by its wind speed, or at a physical floor or plane, and continues to rise towards the suction port 12 of the suction flow passage 10 while swirling. At this time, because the radius of rotation becomes smaller while the rotational kinetic energy is maintained by changing direction, the rotation becomes faster, and a swirling suction flow (tornado T) is formed that reaches the object to be sucked 90. This swirling suction flow can efficiently suck in the object to be sucked 90 (for example, steam or smoke generated from a cooking range).

[0036] As shown in Figure 1, the suctioned object 90 is exhausted as a suction flow through the suction flow passage 10 formed inside the suction duct 11.

[0037] In this embodiment, it is determined and output whether a swirling suction flow is actually generated and whether appropriate suction is being performed by utilizing the fact that the axial wind speed of the suction flow changes depending on the swirling intensity of the suction flow. Specifically, as shown in the flowchart of Figure 2(a), immediately after the power of the suction device 100 is turned ON, the control unit 80 first rotates only the suction fan 20. This generates a non-swirling suction flow. In this state, the control unit 80 reads the measured value of the axial wind speed of the suction flow from the wind speed sensor 60 (let's call it wind speed V0). Next, while maintaining the rotation of the suction fan 20, the control unit 80 also rotates the discharge fan 40. This generates a rotating air curtain AC, so the suction flow also swirls in the same direction as the rotation direction of the air curtain AC, generating a swirling suction flow. In this state, the control unit 80 reads the measured value of the axial wind speed of the suction flow from the wind speed sensor 60 (let's call it wind speed V1). The control unit 80 calculates the difference in wind speed (V1-V0) when the outlet fan 40 is ON and when it is OFF, and determines the swirling strength of the suction flow based on the known relationship between this difference in wind speed (V1-V0) and the swirling strength of the suction flow.

[0038] As an example of the known relationship between this difference in wind speed (V1 - V0) and the swirling intensity of the suction flow, Figures 3(a) and 3(b) show the relationship between the wind speed of the suction flow and the swirling intensity of the suction flow. Figure 3(a) is a conceptual diagram showing the relationship when the rotation of the discharge flow and the rotation of the suction fan 20 are in the same direction, and Figure 3(b) is a conceptual diagram showing the relationship when the rotation of the discharge flow and the rotation of the suction fan 20 are in opposite directions. In both figures, the horizontal axis is the distance L between the suction fan 20 and the floor, and the vertical axis is the wind speed V. It is known that the smaller this distance L is, the stronger the swirling intensity of the suction flow, so the horizontal axis also represents the swirling intensity of the suction flow. The curve of wind speed V1 when the discharge flow is ON (i.e., when the suction flow swirls ON) with respect to this distance L is shown as a solid line, and the curve of wind speed V0 when the discharge flow is OFF (i.e., when the suction flow swirls OFF) is shown as a dashed line. First, looking at the graph in Figure 3(a) when the rotation of the discharge flow and the rotation of the suction fan 20 are in the same direction, we can see that the wind speed V1 when the discharge flow is ON is smaller than the wind speed V0 when the discharge flow is OFF, and that the smaller the distance L, that is, the stronger the swirling intensity of the suction flow, the larger the difference in wind speed (V1-V0). In this embodiment, since the rotation of the discharge flow and the rotation of the suction fan 20 are in the same direction, based on the relationship in Figure 3(a), for example, if the absolute value of the difference in wind speed (V1-V0) is greater than a predetermined value, the judgment result of the swirling intensity of the suction flow is set to OK, and if it is smaller than the predetermined value, the judgment result is set to NG.

[0039] Furthermore, when the rotation of the discharge flow and the rotation of the suction fan 20 are in opposite directions, as shown in Figure 3(b), the wind speed V1 when the discharge flow is ON is greater than the wind speed V0 when the discharge flow is OFF, and it can be seen that the smaller the distance L, that is, the stronger the swirling intensity of the suction flow, the larger the difference in wind speed (V1-V0).

[0040] Figure 4 illustrates the reason why the wind speed of the suction flow changes as described above depending on the swirling intensity of the suction flow. Assume that the suction fan 20 is an axial flow fan such as a propeller fan and is rotating at a rotational speed ωf. When there is no swirling of the suction flow, the air around the suction fan is not rotating, so the relative rotational speed of the suction fan 20 with respect to this air is ωf. The air is scraped by the suction fan 20 at an axial speed proportional to this relative rotational speed and is sucked in at an axial wind speed V0. On the other hand, when the rotation of the blown-out flow causes swirling of the suction flow at a rotational speed ωa in the same direction as the rotation of the suction fan 20, the relative rotational speed of the suction fan 20 with respect to this air becomes smaller, ωf - ωa. Therefore, the axial wind speed V1 at this time becomes smaller than V0, and the absolute value of the difference V1 - V0 increases in proportion to the rotational speed ωa of the suction flow. Furthermore, when the rotation of the blown-out flow causes the suction flow to swirl at a rotational speed ωa in the opposite direction to the rotation of the suction fan 20, the relative rotational speed of the suction fan 20 with respect to this air becomes large as ωf + ωa. Therefore, the axial wind speed V1 at this time becomes larger than V0, and the absolute value of the difference V1 - V0 increases in proportion to the rotational speed ωa of the suction flow.

[0041] Returning to the flowchart in Figure 2(a), the control unit 80 displays the result of the determination of the swirling strength of the suction flow on the LED display device 70. In this embodiment, for example, the LED display device 70 has a two-stage display, lighting up a green LED when the determination result is OK, and lighting up a red LED when the determination result is NG. When the determination result is NG, the strength of the discharge flow may be adjusted manually or automatically, for example, by adjusting the rotation speed of the discharge fan 40 so that the determination becomes OK. In the suction device 100 of this embodiment, there are multiple discharge fans 40, so for example, in an environment where there is a crosswind, the swirling flow may be stabilized by individually increasing the rotation speed of the discharge fan 40 on the windward side to strengthen the air curtain AC. Alternatively, a wind direction adjustment mechanism may be provided for each discharge fan 40 to adjust the wind direction, thereby stabilizing the air curtain AC and the swirling suction flow. With these adjustments, a stable swirling suction flow can be formed not only in a closed space where the air is still, such as a room, but also in an open space where the air is flowing. In some cases, depending on the intended use, an excessively strong swirling force of the suction flow may be problematic. In such cases, the swirling force may be adjusted to be weaker.

[0042] As long as the power is ON, the control unit 80 continues to read the measured wind speed of the suction flow from the wind speed sensor 60 (wind speed V1), determine the swirling intensity of the suction flow based on the difference in wind speed (V1 - V0), and display the result on the LED display device 70. This allows the status of the swirling intensity of the suction flow to be displayed in real time. In particular, when the distance L from the suction device 100 to the floor is long and it takes time for a tornado to form, the real-time display is useful because it allows you to know when a tornado has formed.

[0043] As shown in Figure 2(b), the swirling strength of the suction flow may be determined based only on the wind speed V1 when the outlet flow is ON, rather than on the difference in wind speed (V1-V0), by determining whether the wind speed V1 is within a predetermined range. In this case, there is the advantage of simplifying the control of the control unit 80. However, it is more preferable to determine the swirling strength of the suction flow based on the difference in wind speed (V1-V0) as shown in Figure 2(a), because measurement errors in wind speeds V1 and V0 due to the installation method of the wind speed sensor 60 do not affect the determination of the swirling strength of the suction flow.

[0044] (Second Embodiment) In this embodiment, in the first embodiment, a differential pressure sensor 61 which is a barometric pressure sensor is used instead of the wind speed sensor 60 as the sensor, and the determination is made by utilizing the fact that the atmospheric pressure on the axis of the suction flow changes according to the swirling intensity of the suction flow. Since the other configurations are the same as those in the first embodiment, common elements are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0045] FIG. 5 is a schematic longitudinal sectional view showing a suction device 200 according to a second embodiment of the present invention. As the differential pressure sensor 61, for example, a MEMS type micro differential pressure sensor that detects deformation of a diaphragm due to atmospheric pressure as a capacitance change and has a range of about ±500 Pa can be mentioned. This differential pressure sensor 61 is installed so as to measure the differential pressure (small letter p) of the atmospheric pressure at the measurement position 61a on the axis of the suction flow path with respect to the atmospheric pressure at the reference position 61b outside the suction flow path. The measurement position 61a can be any position on the axis of the suction flow path before and after the suction fan 20, but the position directly below (immediately before) the suction fan 20 is preferable because the atmospheric pressure of the suction flow is the lowest and it is easy to determine suitability.

[0046] The procedure for determining the swirling intensity of the suction flow in this embodiment is to read the measured values p0 and p1 of the differential pressure sensor 61 instead of reading the measured values V0 and V1 of the wind speed sensor 60 in the procedure shown in the flowchart of FIG. 2(a), and the swirling intensity of the suction flow is determined based on those values. That is, immediately after the power of the suction device 200 is turned on, the control unit 80 first rotates only the suction fan 20. Thereby, a non-swirling suction flow is generated. In this state, the control unit 80 reads the measured value of the differential pressure p between the inside and outside of the suction flow by the differential pressure sensor 61 (referred to as differential pressure p0). Next, while maintaining the rotation of the suction fan 20, the control unit 80 also rotates the blowing fan 40. Thereby, a swirling suction flow is generated. The control unit 80 reads the measured value of the differential pressure p between the inside and outside of the suction flow by the differential pressure sensor 61 in this state (referred to as differential pressure p1). The control unit 80 calculates the difference in differential pressure (p1 - p0) when the rotation of the blowing fan 40 is ON and OFF, and determines the swirling intensity of the suction flow based on the known relationship between the difference in differential pressure (p1 - p0) and the swirling intensity of the suction flow.

[0047] As an example of this relationship, FIG. 6 shows the relationship between the air pressure (differential pressure) of the suction flow and the swirling strength of the suction flow. FIG. 6(a) is a conceptual diagram when the blowing flow and the rotation direction of the suction fan 20 are in the same direction, and FIG. 6(b) is a conceptual diagram when the blowing flow and the rotation direction of the suction fan 20 are in the opposite direction. In the present embodiment, the relationship between the differential pressure difference (p1 - p0) and the swirling strength of the suction flow does not depend on whether the rotation direction of the blowing flow and the rotation direction of the suction fan 20 are the same or different. This is because the air pressure change on the axis of the suction flow is only due to the exhaust strength by the centrifugal force of the swirling flow, that is, only the swirling strength of the suction flow. In FIGS. 6(a) and 6(b), the horizontal axis represents the distance L between the suction fan 20 and the floor surface, and the vertical axis represents the differential pressure p. Since it is known that the smaller the distance L, the stronger the swirling strength of the suction flow, the horizontal axis also represents the swirling strength of the suction flow. The curve of the differential pressure p1 when the blowing flow is ON (that is, when the swirling of the suction flow is ON) with respect to the distance L is shown by a solid line, and the curve of the differential pressure p0 when the blowing flow is OFF (that is, when the swirling of the suction flow is OFF) is shown by a broken line. Looking at the graphs of FIGS. 6(a) and 6(b), it can be seen that the differential pressure p1 when the blowing flow is ON is lower than the differential pressure p0 when the blowing flow is OFF, and the smaller the distance L, that is, the stronger the swirling flow, the larger the differential pressure difference (p1 - p0). Based on the relationship of FIGS. 6(a) and 6(b), for example, when the absolute value of the differential pressure difference (p1 - p0) is greater than a predetermined value, the determination result of the swirling strength of the suction flow is set to OK, and when it is smaller than the predetermined value, the determination result is set to NG.

[0048] Operations such as the display of the determination result of the swirling strength of the suction flow are the same as those in the first embodiment.

[0049] Note that, similar to FIG. 2(b), the determination of the swirling strength of the suction flow may be based only on the differential pressure p1 when the blowing flow is ON, instead of the differential pressure difference (p1 - p0), by determining whether the differential pressure p1 is within a predetermined range. In that case, there is an advantage that the control of the control unit 80 becomes simpler. However, it is more preferable to determine using the differential pressure difference (p1 - p0) as in FIG. 2(a) because even if there are measurement value errors of the differential pressures p1 and p0 due to the installation method of the differential pressure sensor 61, it does not affect the determination of the swirling strength of the suction flow.

[0050] (Modified Version) This modified version is a configuration in the second embodiment in which a pressure sensor 62 (see Figure 5) is installed on the axis of the suction flow path to measure the absolute pressure (uppercase P) of the air pressure instead of the differential pressure sensor 61. Examples of the pressure sensor 62 include a MEMS-type pressure sensor that detects the deformation of a diaphragm due to air pressure as a change in capacitance. In this case, the procedure for determining the swirling strength of the suction flow is the same as in the second embodiment. That is, similar to the procedure shown in the flowchart of Figure 2(a), the measured value P0 of the pressure sensor 62 when the rotation of the discharge fan 40 is OFF and the measured value P1 of the pressure sensor 62 when the rotation of the discharge fan 40 is ON are read, the difference in air pressure (P1-P0) between when the rotation of the discharge fan 40 is ON and OFF is calculated, and the swirling strength of the suction flow is determined based on the known relationship between the difference in air pressure (P1-P0) and the swirling strength of the suction flow. However, in this modified example, determining the swirling strength of the suction flow solely by the atmospheric pressure P1 when the outlet fan 40 is turned ON, as in Figure 2(b), is undesirable because the atmospheric pressure P1 changes depending on the altitude and weather conditions of the installation site. For this reason, it is preferable to determine the swirling strength of the suction flow based on the difference in atmospheric pressure (P1 - P0), as in Figure 2(a).

[0051] (Third Embodiment) This embodiment is a configuration in which, in the first embodiment, a current sensor 63 that measures the current of the suction fan motor 20a is used as a sensor instead of the wind speed sensor 60, and the determination is made by utilizing the fact that the current value of the suction fan motor 20a changes depending on the swirling strength of the suction flow. Figure 7 is a schematic longitudinal cross-sectional view showing the suction device 300 of the third embodiment according to the present invention. As the current sensor 63, for example, one using a magnetic core and a Hall element that surrounds the power line to the suction fan motor 20a can be used. Alternatively, as the current sensor 63, a small resistor may be provided on the power line, and the current value may be calculated from the voltage applied to it. The other configurations are the same as in the first embodiment, so the same reference numerals are used for common elements, and their detailed explanation is omitted.

[0052] In this embodiment, the determination of the swirling strength of the suction flow is performed by reading the measured values ​​I0 and I1 from the current sensor 63 instead of the measured values ​​V0 and V1 from the wind speed sensor 60, in the procedure shown in the flowchart of Figure 2(a), and based on those values. That is, immediately after the power of the suction device 300 is turned ON, the control unit 80 first rotates only the suction fan 20. This generates a non-swirling suction flow. In this state, the control unit 80 reads the measured current of the suction fan motor 20a from the current sensor 63 (referred to as current I0). Next, the control unit 80 rotates the discharge fan 40 while maintaining the rotation of the suction fan 20. This generates a swirling suction flow. In this state, the control unit 80 reads the measured current of the fan motor 20a of the suction fan 20 from the current sensor 63 (referred to as current I1). The control unit 80 calculates the difference in current values ​​(I1 - I0) when the outlet fan 40 is ON and when it is OFF, and determines the swirling strength of the suction flow based on the known relationship between this difference in current values ​​(I1 - I0) and the swirling strength of the suction flow.

[0053] As an example of this relationship, Figure 8 shows the relationship between the current I of the fan motor 20a and the swirling strength of the suction flow. Figure 8(a) is a conceptual diagram when the rotation of the discharge flow and the rotation of the suction fan 20 are in the same direction, and Figure 8(b) is a conceptual diagram when the rotation of the discharge flow and the rotation of the suction fan 20 are in opposite directions. In both cases, the horizontal axis is the distance L between the suction fan 20 and the floor, and the vertical axis is the current I. It is known that the smaller this distance L is, the stronger the swirling strength of the suction flow. In both cases, the curve of the current I1 when the discharge flow is ON (i.e., when the suction flow is swirling ON) is shown as a solid line with respect to the distance L, and the curve of the current I0 when the discharge flow is OFF (i.e., when the suction flow is swirling OFF) is shown as a dashed line.

[0054] The reason why the current I of the fan motor 20a of the suction fan 20 changes depending on the swirling intensity of the suction flow is as follows. That is, as explained with reference to Figure 4 in the first embodiment, when a swirling suction flow occurs with a rotational speed ωa in the same direction as the rotation of the suction fan 20, the relative rotational speed of the suction fan 20 with respect to this air becomes small, ωf - ωa. In this case, the load on the fan motor 20a of the suction fan 20 is lighter than when there is no swirling, so the current I1 when the blow-out flow is ON becomes smaller than the current I0 when the blow-out flow is OFF, and the absolute value of the difference I1 - I0 increases in proportion to the swirling speed ωa of the suction flow. On the other hand, when a swirling suction flow occurs with a rotational speed ωa in the opposite direction to the rotation of the suction fan 20 due to the rotation of the blow-out flow, the relative rotational speed of the suction fan 20 with respect to this air becomes large, ωf + ωa. In this case, the load on the fan motor 20a becomes heavier compared to when there is no swirling, so the current I1 when the outlet flow is ON is greater than the current I0 when the outlet flow is OFF, and the absolute value of the difference I1 - I0 increases in proportion to the swirling speed ωa of the outlet flow.

[0055] Returning to the procedure for determining the swirling strength of the suction flow, in this embodiment, since the rotation of the blown-out flow and the rotation of the suction fan 20 are in the same direction, based on the relationship in Figure 8(a), for example, if the absolute value of the difference in current (I1 - I0) is greater than a predetermined value, the determination result of the swirling strength of the suction flow is set to OK, and if it is less than the predetermined value, the determination result is set to NG. The operation of displaying the determination result of the swirling strength of the suction flow is the same as in the first embodiment.

[0056] Furthermore, similar to Figure 2(b), the swirling strength of the suction flow may be determined not by the difference in current (I1-I0), but by determining whether the current I1 is within a predetermined range when the blow-out flow is ON, based only on the current I1. However, determining the strength by the difference in current (I1-I0), similar to Figure 2(a), is more preferable because differences in the suction fan motor 20a do not affect the determination of the swirling strength of the suction flow.

[0057] (Fourth Embodiment) This embodiment is a configuration in which, in the first embodiment, a rotational speed sensor 64 is used as the sensor instead of the wind speed sensor 60, and the determination is made by utilizing the fact that the rotational speed of the suction fan 20 changes depending on the swirling strength of the suction flow. Figure 9 is a schematic longitudinal cross-sectional view showing a suction device 400 of the third embodiment according to the present invention. As the rotational speed sensor 64, for example, a rotary encoder attached to the fan motor 20a can be used, and the rotational speed may be detected by counting the number of pulses generated per unit time that are synchronized with the rotation. The other configurations are the same as in the first embodiment, so the same reference numerals are used for common elements, and their detailed explanation is omitted.

[0058] In this embodiment, the determination of the swirling strength of the suction flow is performed by reading the measured values ​​ω0 and ω1 from the rotational speed sensor 64 instead of the measured values ​​V0 and V1 from the wind speed sensor 60, in the procedure shown in the flowchart of Figure 2(a), and is based on those values. That is, immediately after the power of the suction device 400 is turned ON, the control unit 80 first rotates only the suction fan 20. This generates a suction flow that does not swirl. In this state, the control unit 80 reads the rotational speed measurement of the suction fan 20 from the rotational speed sensor 64 (let's call it rotational speed ω0). Next, the control unit 80 rotates the discharge fan 40 while maintaining the rotation of the suction fan 20. This generates a swirling suction flow. In this state, the control unit 80 reads the rotational speed measurement of the suction fan 20 from the rotational speed sensor 64 (let's call it rotational speed ω1). The control unit 80 calculates the difference in rotational speed (ω1 - ω0) when the outlet fan 40 is ON and when it is OFF, and determines the swirling strength of the suction flow based on the known relationship between this difference in rotational speed (ω1 - ω0) and the swirling strength of the suction flow.

[0059] As an example of this relationship, Figure 10 shows the relationship between the rotational speed ω of the suction fan 20 and the swirling strength of the suction flow. Figure 10(a) is a conceptual diagram when the rotation of the discharge flow and the rotation of the suction fan 20 are in the same direction, and Figure 10(b) is a conceptual diagram when the rotation of the discharge flow and the rotation of the suction fan 20 are in opposite directions. In both cases, the horizontal axis is the distance L between the suction fan 20 and the floor, and the vertical axis is the rotational speed ω. It is known that the smaller this distance L is, the stronger the swirling strength of the suction flow. In both cases, the curve of the rotational speed ω1 when the discharge flow is ON is shown as a solid line with respect to the distance L, and the curve of the rotational speed ω0 when the discharge flow is OFF is shown as a dashed line.

[0060] The reason why the rotational speed ω of the suction fan 20 changes depending on the swirling intensity of the suction flow is as follows. That is, as explained with reference to Figure 4 in the first embodiment, when a swirling suction flow occurs with a rotational speed ωa in the same direction as the rotation of the suction fan 20, the relative rotational speed of the suction fan 20 with respect to this air becomes small, ωf - ωa. In this case, the load on the fan motor 20a of the suction fan 20 is lighter than when there is no swirling, so the rotational speed ω1 when the discharge flow is ON is slightly faster than the rotational speed ω0 when the discharge flow is OFF, and the absolute value of the difference ω1 - ω0 increases in proportion to the swirling speed ωa of the suction flow. On the other hand, when a swirling suction flow occurs with a rotational speed ωa in the opposite direction to the rotation of the suction fan 20 due to the rotation of the discharge flow, the relative rotational speed of the suction fan 20 with respect to this air becomes large, ωf + ωa. In this case, the load on the fan motor 20a of the suction fan 20 becomes heavier compared to when there is no swirling motion. Therefore, the rotational speed ω1 when the discharge flow is ON is slightly slower than the rotational speed ω0 when the discharge flow is OFF, and the absolute value of the difference ω1 - ω0 increases in proportion to the swirling speed ωa of the suction flow.

[0061] Returning to the procedure for determining the swirling strength of the suction flow, in this embodiment, since the rotation of the discharge flow and the rotation of the suction fan 20 are in the same direction, based on the relationship in Figure 10(a), for example, if the absolute value of the difference in rotational speed of the suction fan 20 (ω1 - ω0) is greater than a predetermined value, the determination result of the swirling strength of the suction flow is set to OK, and if it is less than the predetermined value, the determination result is set to NG. The operation of displaying the determination result of the swirling strength of the suction flow is the same as in the first embodiment.

[0062] Furthermore, similar to Figure 2(b), the strength of the swirling flow may be determined based only on the rotational speed ω1 when the blow-out flow is ON, rather than the difference in rotational speed (ω1 - ω0), by determining whether the rotational speed ω1 is within a predetermined range. However, it is more preferable to determine the strength of the suction flow based on the difference in rotational speed (ω1 - ω0), similar to Figure 2(a), because differences in the suction fan motor 20a do not affect the determination of the swirling strength of the suction flow.

[0063] (Fifth Embodiment) This embodiment further includes a rotation control unit 81 that individually controls the rotation speeds of the suction fan 20 and the discharge fan 40, in the first embodiment, and the rotation control unit 81 adjusts the rotation speed of the discharge fan 40 or the suction fan 20 so that the determined swirling intensity of the suction flow becomes a predetermined value. Figure 11 is a schematic longitudinal cross-sectional view showing a suction device 500 of the sixth embodiment according to the present invention. For example, if AC motors are used as the fan motors 20a and 40a that drive the fans, a rotation control unit 81 that controls the drive frequency of the fan motors 20a and 40a using an inverter circuit can be used. If DC motors are used as the fan motors 20a and 40a that drive the fans, the rotation control unit 81 may alternatively perform level control or PWM control of the drive voltage of the fan motors 20a and 40a. This rotation control unit 81 is provided as part of the control unit 80 and is controlled by a microcontroller or the like of the control unit 80. The overall configuration of the suction device 500 in this embodiment is the same as, for example, the suction device 100 of the first embodiment shown in Figure 1, and includes, for example, a wind speed sensor 60 as a sensor for determining the swirling strength of the suction flow. However, it is not limited to this, and any device configuration having a sensor for determining the swirling strength of the suction flow, such as in the second to fourth embodiments, may be used.

[0064] In this embodiment, the operation of the suction device 500 is as shown in the operation sequence in Figure 2(a). When the determination result of the swirling strength of the suction flow is NG, the control unit 80 automatically adjusts the rotation speed of the discharge fan 40, for example, so that the strength determination result becomes OK. While the rotation speed of the suction fan 20 could also be adjusted at this time, in that case, not only the wind speed V1 when the discharge flow is ON but also the wind speed V0 when the discharge flow is OFF would change, requiring the wind speed V0 when the discharge flow is OFF to be measured again, thus complicating the operation sequence. According to this embodiment, the swirling strength of the suction flow can be automatically adjusted, enabling efficient intake.

[0065] (Sixth Embodiment) Figure 12 is a schematic longitudinal cross-sectional view showing a suction device 600 according to the sixth embodiment of the present invention. This embodiment is a modified version of the first embodiment, further comprising an adjustment mechanism 83 for adjusting the height of the suction device 600 from the floor surface at the installation location, a motor 83a for driving the adjustment mechanism, and a height control unit 82 for controlling the motor 83a. The height control unit 82 is configured to adjust the height (distance L) of the suction device 600 from the floor surface so that the determined swirling intensity of the suction flow becomes a predetermined value. The other configurations are the same as in the first embodiment, so the same reference numerals are used for common elements, and their detailed descriptions are omitted.

[0066] In this embodiment, the adjustment mechanism 83 uses a feed screw mechanism driven by a motor 83a. However, the adjustment mechanism 83 is not limited to this, and any mechanism that can raise and lower the suction device 600 may be used. The height control unit 82 is a drive circuit that drives the motor 83a, and in this embodiment, it is provided in the control unit 80 and controlled by a microcomputer in the control unit 80. The overall configuration of the suction device 600 in this embodiment is the same as, for example, the suction device 100 of the first embodiment shown in Figure 1, and includes, for example, a wind speed sensor 60 as a sensor for determining the swirling strength of the suction flow. However, it is not limited to this, and any device configuration having a sensor for determining the swirling strength of the suction flow may be used, such as in the second to fourth embodiments.

[0067] In this embodiment, the operation of the suction device 600 is as follows: In the operation sequence shown in Figure 2(a), if the determination result of the swirling strength of the suction flow is NG, the control unit 80 automatically controls the height control unit 82 to adjust the height of the suction device 600 by moving the adjustment mechanism 83 with the motor 83a so that the determination result of the swirling strength becomes OK. For example, when the swirling strength of the suction flow is small, the height of the suction device 600 is lowered to reduce the distance L from the floor, thereby raising the swirling strength of the suction flow to an appropriate level. With this embodiment as well, the swirling strength of the suction flow can be automatically adjusted, enabling efficient air intake.

[0068] (Seventh Embodiment) Figure 13 is a schematic longitudinal cross-sectional view showing a suction device 700 according to the seventh embodiment of the present invention. The suction device 700 includes a large suction fan 720 for drawing in air and a suction duct 711 having one or more suction ports 12 and guiding the air to the suction fan 720. Around each suction port 12, there is a blow-out flow generation chamber 30, a blow-out fan 40, a blow-out flow deflection guide 50, a differential pressure sensor 61, a control unit 80, and an LED display device 70 as an output means. That is, around each suction port 12, the components of the suction device 200 of the second embodiment, excluding the suction fan 20 (also called a "suction unit 730") are arranged. Each suction unit 730 is provided with a shutter 731 for closing the suction port 12 when the suction unit 730 is not in use. The shutter 731 is structured so as not to obstruct the swirling of the suction flow when open.

[0069] In this embodiment, the operation of the suction device 700 is such that the ON / OFF of the suction fan 720 is performed as an operation of the entire suction device 700 in the flowcharts of Figures 2(a) and 2(b), but other operations are performed as independent operations of the individual suction units 730. The operation of these individual suction units 730 is the same as that of the suction device 200 in the second embodiment, except that the shutters 731 are opened and closed instead of the ON / OFF of the suction fan 720. That is, each suction unit 730 opens its respective shutter 731, forms an air curtain rotated by its respective blowing fan 40, determines the swirling intensity of the suction flow at its respective suction port 12, and displays the determination result on its respective LED display device.

[0070] In this embodiment, one large suction fan 720 is used to draw air from each suction port 12, while a discharge fan 40 is provided for each suction unit 730. However, it is also possible to use one large discharge fan 40, provide a discharge duct to send air to each suction unit 730, and generate an air curtain with its swirling blades. In that case, the air curtain can be adjusted using its swirling blades or aperture. In this embodiment, a control unit 80 is provided for each suction unit 730, but a single control unit 80 may collectively perform sensor readings, control of the discharge fan 40 and output means (70) for each suction unit 730. In this embodiment, the number of suction units 730 is set to two, but it may be one or three or more. Furthermore, the output of the suction fan 720 may be controlled by the number of operating suction units 730, i.e., the number of units that have opened the shutter 731 and are performing suction.

[0071] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. Those skilled in the art can make various additions and modifications within the scope of the present invention. For example, the suction device in each of the above embodiments includes a disc-shaped discharge flow generation chamber 30 and a discharge flow deflection guide 50 as shown in Figure 1, and is configured to have multiple discharge fans 40, but the suction device of the present invention is not limited to this, and may include a suction fan 20 and one or more discharge fans 40, as long as it can form a swirling air curtain AC and a swirling suction flow.

[0072] Furthermore, in the suction devices of each embodiment described above, the flow for determining the swirling strength of the suction flow is configured to first read the measured values ​​of each sensor when the discharge flow is OFF, and then to continuously read the measured values ​​of each sensor when the discharge flow is ON. However, the present invention is not limited to this, and the order of reading the measured values ​​of each sensor when the discharge flow is OFF and reading the measured values ​​of each sensor when the discharge flow is ON may be either. Also, the reading of the measured values ​​of each sensor when the discharge flow is ON and the display of the determination results do not necessarily have to be performed continuously for the duration that the power is ON, but may be performed only once, intermittently, or continuously for a predetermined period of time.

[0073] Furthermore, while the suction devices of each of the above embodiments are provided with a control unit 80 that controls the ON / OFF status of at least the suction fan 20 and the discharge fan 40, the present invention is not limited to this. The control unit 80 is not essential as long as a sensor for determining the swirling strength of the suction flow and an output means for outputting the determination result of the swirling strength are provided. For example, in the second embodiment, when determining using only the differential pressure p1 when the discharge fan is ON and a differential pressure sensor 61 is used, the analog output of the differential pressure sensor 61 may be determined by an analog comparator and the result output to the LED display device 70.

[0074] 10 Suction flow path 10c Axis 11 Suction duct 12 Suction port 20 Suction fan 20a Fan motor 30 Outlet flow generation chamber 31 Inlet 40 Outlet fan 40a Fan motor 50 Outlet flow deflection guide 60 Wind speed sensor 61 Differential pressure sensor 61a Measurement position 61b Reference position 62 Barometric pressure sensor 63 Current sensor 64 Rotation speed sensor 70 LED display device 80 Control unit 81 Rotation control unit 82 Height control unit 83 Adjustment mechanism 83a Motor 90 Suction target 100, 200, 300, 400, 500, 600, 700 Suction device 711 Suction duct 720 Suction fan 730 Suction unit 731 Shutter AC Air curtain T Tornado

Claims

1. A suction device comprising: a suction fan for sucking in air to be sucked in; and a discharge fan that blows out so as to surround the air to be sucked in and forms a swirling air curtain, wherein the suction device sucks in the air while generating a swirling suction flow by the swirling of the air curtain and the rotation of the suction fan, and further comprising: a sensor for determining the swirling intensity of the suction flow; and an output means for outputting the determination result of the swirling intensity.

2. The suction device according to claim 1, characterized in that the sensor is an anemometer, which measures the anemometer velocity in the axial direction of the suction flow and determines the swirling intensity of the suction flow based on a known relationship between the anemometer velocity and the swirling intensity of the suction flow.

3. The suction device according to claim 2, characterized in that the wind speed sensor is used to rotate the suction fan and measure the wind speed, the difference in wind speed when the outlet fan is ON and when it is OFF is calculated, and the swirling strength of the suction flow is determined based on a known relationship between the difference in wind speed and the swirling strength of the suction flow.

4. The suction device according to claim 1, characterized in that the sensor is a pressure sensor that measures the pressure at the central axis of the suction flow or the differential pressure which is the difference in pressure between the central axis of the suction flow and the surrounding area, and determines the swirling strength of the suction flow based on a known relationship between the pressure or the differential pressure and the swirling strength of the suction flow.

5. The suction device according to claim 4, characterized in that the pressure sensor is used to rotate the suction fan to measure the pressure or differential pressure, the difference in pressure or differential pressure when the rotation of the outlet fan is ON and when it is OFF is calculated, and the swirling strength of the suction flow is determined based on a known relationship between the difference in pressure or differential pressure and the swirling strength of the suction flow.

6. The suction device according to claim 1, wherein the sensor is a current sensor for the fan motor of the suction fan, and the sensor rotates the fan motor at a constant voltage to measure the current flowing through the fan motor, calculates the difference in current flowing through the fan motor when the rotation of the outlet fan is ON and when it is OFF, and determines the swirling strength of the suction flow based on a known relationship between the difference in current and the swirling strength of the suction flow.

7. The suction device according to claim 1, wherein the sensor is a rotation speed sensor for the suction fan, and it measures the rotation speed of the suction fan by rotating the fan motor of the suction fan at a constant voltage, calculates the difference in rotation speed of the suction fan when the rotation of the discharge fan is ON and when it is OFF, and determines the swirling strength of the suction flow based on a known relationship between the difference in rotation speed and the swirling strength of the suction flow.

8. The suction device according to claim 1, characterized in that the output means is an LED display that displays the determination result of the rotation strength.

9. The suction device according to claim 1, characterized in that the output means is a flat panel display that displays the determination result of the rotation strength.

10. The suction device according to claim 1, characterized in that the output means is a communication interface that outputs the determination result of the rotation strength to a communication line.

11. The suction device according to claim 1, further comprising a rotation control unit that individually controls the rotation speed of the suction fan and the discharge fan, wherein the rotation control unit is configured to adjust the rotation speed of at least one of the suction fan and the discharge fan so that the determined swirling intensity of the suction flow is a predetermined value.

12. The suction device according to claim 1, further comprising an adjustment mechanism for adjusting the height of the suction device from the floor surface at the installation location of the suction device, a motor for driving the adjustment mechanism, and a height control unit for controlling the motor, wherein the height control unit is configured to adjust the height of the suction device from the floor surface so that the determined swirling intensity of the suction flow becomes a predetermined value.

13. A suction device comprising: a suction fan for sucking in air to be sucked in; a suction duct having one or more suction ports and guiding the air to the suction fan; and a blowing fan that blows out from around each of the suction ports so as to surround the air to be sucked in, forming a swirling air curtain, wherein at each of the suction ports, a swirling suction flow is generated by the swirling of the air curtain and the suction by the suction fan while sucking in the air, further comprising: a sensor for determining the swirling intensity of the suction flow at each of the suction ports; and an output means for outputting the determination result of the swirling intensity at each of the suction ports, wherein the sensor is a pressure sensor that measures the pressure at the central axis of the suction flow or the differential pressure which is the difference in pressure between the central axis of the suction flow and the surrounding area, and determines the swirling intensity of the suction flow based on a known relationship between the pressure or the differential pressure and the swirling intensity of the suction flow.

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