JP6351378B2 - Low airflow draft chamber - Google Patents

Description

  The present invention relates to a low air flow draft chamber that allows air to pass through a low air flow draft when an experiment or work is performed using a work space.

  The draft chamber is used for performing experiments and work by using tools in the work space in the warehouse. The draft chamber can be adjusted to increase or decrease the opening height of the work surface opening on the front side by adjusting the opening degree of the sash on the front side. A draft chamber of this type is disclosed in Patent Document 1.

  In recent years, a draft chamber that can be operated with an exhaust air volume smaller than a conventional air volume is required from the viewpoint of energy saving. Such a draft chamber is generally called a “low airflow draft chamber” or a “low airflow fume hood”. This draft chamber can contain toxic gases and the like in the draft chamber with an air volume of 50% to 60% compared to the conventional air volume.

  However, because this draft chamber is a constant air volume draft chamber where the exhaust air volume is always constant (CAV: constant air volume control), the opening height of the work surface opening can be adjusted by adjusting the opening of the sash on the front side. However, the exhaust air volume is constant. For this reason, from the viewpoint of further energy saving, there are increasing market demands and examples of combining this VAV (variable air volume control) system with this low air volume draft chamber.

  Here, based on general examples of the exhaust air volume of the standard air volume draft chamber incorporating the CAV control system, the low air volume draft chamber incorporating the CAV control system, and the low air volume draft chamber incorporating the VAV control system, respectively. I will explain.

(1) Standard air volume draft chamber (CAV control system)
In a draft chamber with a standard air volume having a frontage size of 1800 mm, the exhaust air volume when the front side sash is opened to maximize the work opening height is about 20 · / min. Further, since the exhaust control method is CAV control (constant air flow control), this exhaust air flow is constant regardless of the increase or decrease in the work surface opening height.

(2) Low airflow draft chamber (CAV control system)
In the case of a low airflow draft chamber in which the standard airflow draft chamber is reduced, the exhaust airflow is 60% of 20 · / min, and the airflow is about 12 · / min. However, in the case of CAV control in this low airflow draft chamber, the exhaust airflow is always constant despite the increase or decrease adjustment of the work surface opening height by adjusting the opening of the sash on the front side. The air volume is about 12 · / min.

(3) Low air volume draft chamber (VAV control system)
When VAV control (variable air volume control) is incorporated in the low air volume draft chamber, for example, the air volume is generally as follows.

Maximum working surface opening height: approx. 12 · / min (Example: Working surface opening height 500 mm)
Minimum working surface opening height: Approx. 5 · / min (Example: Working surface opening height 75 mm)
From the characteristic that the VAV control method increases or decreases the exhaust air volume by increasing or decreasing the work surface opening height, the above-described fluctuation of the air volume occurs.

JP 2005-288241 A

  However, as described above, the low air volume draft chamber equipped with the VAV control system has a small amount of air entering from the work surface opening when the work surface opening height is minimum by adjusting the opening degree of the sash on the front side. Since the amount is small, the amount of exhaust air discharged from the interior to the outside is very small. For this reason, in a low airflow draft chamber equipped with a VAV control method, for example, when a heating apparatus is placed in a warehouse and an experiment object is placed on the heater, a harmful gas is generated from the experiment object by heating. Etc. occur. In this way, if the generation of toxic gases, etc., when the work surface opening height is lowered, the exhaust air volume will also decrease, and as the exhaust air volume decreases, the inside of the low air volume draft chamber is reduced. The gas concentration becomes high.

  As described above, in the low air volume draft chamber equipped with the VAV control system, the exhaust air volume of the draft chamber is determined by the opening of the sash, so that the heating experiment is performed in the draft chamber and the air in the chamber is warmed. Thus, when the air capacity is increased according to Boyle-Charles' law, there may be a case where harmful gas or the like cannot be exhausted with the exhaust air volume calculated from the opening of the sash. For this reason, there exists a possibility that the atmosphere in a store | warehouse | chamber may leak outside from the clearance gap etc. of the body of a draft chamber. As a result, safety that is most important for a local exhaust apparatus such as a draft chamber may be hindered.

  Therefore, it is common not to apply the VAV control method in the conventional draft chamber for heating experiments, and the draft chamber is always operated with a large displacement, which has been an obstacle to reduction of energy costs.

  The present invention has been made in view of the above. The object of the present invention is to apply a VAV control method to a heating experiment, and always keep a safe state, energy saving and gas leakage. An object of the present invention is to provide a low air volume draft chamber capable of achieving both reduction in concentration.

  In order to achieve the above object, the low airflow draft chamber according to claim 1 is a variable airflow control type low airflow draft chamber that sends air of low airflow through the opening into the chamber and exhausts it from the inside to the outside. An opening / closing shutter that opens and closes the opening, a fan that feeds the air into the warehouse, an exhaust damper that adjusts an amount of the exhaust air when exhausting the air in the warehouse, and the warehouse A first temperature sensor that is disposed in the chamber and detects a temperature in the chamber; a second temperature sensor that detects a temperature of exhaust air from the chamber; and a temperature in the chamber that is obtained by the first temperature sensor. A first required exhaust amount that needs to be exhausted from the interior, a second required exhaust amount that needs to be exhausted from the interior based on the temperature of the exhaust air obtained by the second temperature sensor, and a front end in the opening. A control unit that obtains a required third required exhaust amount obtained from a work surface opening area obtained from an opening amount of the opening / closing shutter and a predetermined front wind speed, and the control unit includes the opening / closing shutter. Depending on the size of the opening amount, any one of the first required exhaust amount, the second required exhaust amount, and the third required exhaust amount is selected to be necessary for the actual exhaust in the warehouse. It is characterized in that it is set as a set required exhaust amount, and the amount of the exhaust air by the exhaust damper is changed.

  In the low air volume draft chamber according to claim 1, any one of the first required exhaust amount, the second required exhaust amount, and the third required exhaust amount is set according to a magnitude of an opening amount of the opening / closing shutter. Select and set to a set required exhaust amount required for exhaust in the warehouse, and change the amount of exhaust air by the exhaust damper. For this reason, even if the VAV control method is applied to the low airflow draft chamber or the heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust according to the size of the opening / closing shutter. The amount can be set to reliably discharge the heated air in the cabinet. Therefore, even if the VAV control method is applied to a low airflow draft chamber, it can be applied to a heating experiment, and it is possible to always maintain a safe state and achieve both energy saving and reduction of gas leakage concentration.

  In the low air volume draft chamber according to claim 2, the opening amount of the open / close shutter is divided into a predetermined small value, a predetermined intermediate value, and a predetermined large value, and the control is performed. When the opening amount of the opening / closing shutter is set to the predetermined small value, the unit selects the larger one of the first required exhaust amount and the second required exhaust amount, and the setting required It is characterized by setting the displacement.

  In the low air volume draft chamber according to claim 2, when the opening degree of the opening / closing shutter is set to a predetermined small value, the larger one of the first required exhaust amount and the second required exhaust amount is selected. To set the required exhaust volume. For this reason, even if a heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust amount is set according to the opening degree of the open / close shutter, and the heated air in the chamber is changed. It can be discharged safely and reliably.

In the low air flow draft chamber according to claim 3, the opening amount of the open / close shutter is divided into a predetermined small value, a predetermined intermediate value, and a predetermined large value.
When the opening amount of the opening / closing shutter is set to the predetermined intermediate value, the control unit selects the first required exhaust amount and sets the first required exhaust amount to the set required exhaust amount. It is characterized by being set to a quantity.

  In the low air volume draft chamber according to claim 3, when the opening degree of the opening / closing shutter is set to a predetermined medium value, the first required exhaust gas that can directly detect the heated air in the warehouse. The amount is selected, and the first required exhaust amount is set to the set required exhaust amount. For this reason, even if a heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust amount is set according to the opening degree of the open / close shutter, and the heated air in the chamber is changed. It can be discharged safely and reliably.

  The low air volume draft chamber according to claim 4, wherein the opening / closing amount of the open / close shutter is divided into a predetermined small value, a predetermined intermediate value, and a predetermined large value. When the opening amount of the open / close shutter is set to the predetermined large value, the unit selects the third required exhaust amount and sets the third required exhaust amount to the set required exhaust amount. It is characterized by that.

  In the low air volume draft chamber according to claim 4, when the opening degree of the opening / closing shutter is set to a predetermined large value, the third required exhaust amount set according to the opening degree of the opening / closing shutter is set. Set to displacement. For this reason, even if a heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust amount is set according to the opening degree of the open / close shutter, and the heated air in the chamber is changed. It can be discharged safely and reliably.

  According to the present invention, even if the VAV control method is applied, it can be applied to a heating experiment, and it is possible to provide a low airflow draft chamber that can always maintain a safe state and achieve both energy saving and reduction of gas leakage concentration. .

It is a front view which shows embodiment of the low air volume draft chamber of this invention. It is sectional drawing which shows the example of an internal structure in the AA line of the low air volume draft chamber shown in FIG. In the example of the internal structure of the low airflow draft chamber shown in FIG. 2 along the line AA, the airflow indicated by the arrow L indicating the air supply with a lower airflow, the airflow of the homogenized air indicated by the arrow LL, the airflow indicated by the arrow M, It is sectional drawing which adds and shows the airflow of N exhaust gas. It is sectional drawing which expands and shows the area | region R shown in FIG. It is a block diagram which shows the example of the control system of a low air volume draft chamber. It is a figure which shows the example in case the opening degree (opening amount K1) of an opening-and-closing shutter is small. It is a figure which shows the example in case the opening degree of an opening-and-closing shutter is middle (opening amount K2). It is a figure which shows the example in case the opening degree of an opening-and-closing shutter is large (opening amount K3). It is a flowchart which shows the operation example of the low air volume draft chamber at the time of carrying out the heating experiment of the test object using a heater. FIG. 10 is a diagram showing a first required exhaust amount AR1, a second required exhaust amount AR2, a third required exhaust amount AR3, and a set required exhaust amount HR appearing in the flowchart of FIG. It is a figure which shows the opening degree K1, K2, K3 of the opening-and-closing shutter which comes out in the flowchart of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a front view showing an embodiment of a low airflow draft chamber of the present invention. 2 is a longitudinal sectional view showing an example of the internal structure of the low airflow draft chamber 1 shown in FIG.

  A low air volume draft chamber 1 shown in FIGS. 1 and 2 is a low air volume draft chamber equipped with a VAV control (variable air volume control) system.

  This low airflow draft chamber 1 is used by an operator such as a researcher or an experimenter to perform an experiment or work such as a heating experiment or a heating work using instruments such as an aseptic operation of a sample such as a microorganism or a chemical experiment. Used to do. The low airflow draft chamber 1 has an internal work space so that an operator is not affected by the object to be processed when an experiment object (object to be processed) in the heating experiment or heating operation is processed in the internal work space. The atmosphere is isolated from the outside.

  This low airflow draft chamber 1 is a local exhaust device for the purpose of protecting the worker from harmful substances, and has an enclosed work space with a containment function for dangerous substances and harmful substances and an exhaust function. Yes.

  In general, the draft chamber refers to a local exhaust device that protects a worker who performs a chemical experiment or the like from a harmful atmosphere, and some laws and regulations are applied depending on the chemical used and the application. Laws and regulations are generally satisfied by ensuring the wind speed of the opening part where the experiment is performed, and a harmful atmosphere can be operated from the local exhaust system (draft chamber) by maintaining the specified exhaust air speed. It will not leak to the person's side.

  In particular, the definition of a low airflow draft chamber is as follows. In recent years, for the purpose of reducing energy costs, it has been desired that the local exhaust device (draft chamber) can be operated at a low running cost. In response to such market needs, we are developing products that reduce the amount of exhaust air and prevent leakage of harmful atmospheres at a lower front wind speed than a general draft chamber. For this purpose, efficient exhaust path formation and smooth airflow control technology are required so that harmful atmosphere does not leak from the local exhaust device (draft chamber) even at low front wind speeds. A product classified as a low airflow draft chamber is established as a product with an exhaust airflow reduced by 40 to 60% compared to a general draft chamber.

  Therefore, the low airflow draft chamber 1 of FIGS. 1 and 2 sends a low airflow draft of air into the internal working space as compared with a so-called standard airflow draft chamber that sends a normal airflow draft of air into the working space. be able to. As a result, the low air volume draft chamber 1 can be operated with a smaller air volume draft than the conventional normal draft to ensure safety. This safety means that a dangerous atmosphere in the draft store does not leak from the draft store to the outside.

  In this way, by sending air with a low airflow draft into the work space 20 in the draft chamber 19 of the low airflow draft chamber 1, a low airflow draft is compared to when sending a normal standard airflow draft into the work space 20. Energy saving (eco-friendly) during operation of the chamber 1 and low noise can be achieved. That is, the low airflow draft chamber 1 is designed to reduce the airflow draft operating energy, and the low airflow draft results from a low airflow draft, so that a low running cost is obtained.

  Under a low air velocity, the atmosphere in the work space in the low airflow draft chamber 1 is likely to leak out of the low airflow draft chamber 1 due to disturbance or the like. In such a situation, the amount of leakage of the working space in the low airflow draft chamber 1, particularly the atmosphere (for example, harmful gas) staying on the work surface, to the outside of the low airflow draft chamber 1 is in the low airflow draft chamber 1. Depends on the quality of the push air pushed into the working space. The quality of this push air refers to the extent that air can be uniformly dispersed in the work space and sent as a homogeneous flow.

  When the push air pushed into the work space 20 in the draft chamber 19 in the low air flow draft chamber 1 is reduced in air volume, the push air pushed into the work space 20 and the work space 20 are placed in the draft chamber 19. It is necessary to form a pull air that is pushed out from the inside. For this reason, the low air volume draft chamber 1 requires a mechanism for sending push air into the work space 20 in the draft cabinet 19. Therefore, the quality of the push air, that is, the feeding of the homogeneous push air greatly affects the performance of the low air volume draft chamber.

  Next, with reference to FIG. 1 and FIG. 2, the structural example of the low air volume draft chamber 1 is demonstrated in detail.

  The low air volume draft chamber 1 shown in FIGS. 1 and 2 is equipped with a VAV control (variable air volume control) system. This VAV control (Variable Air Volume: variable air volume control) is to control the load by controlling the air flow rate when air is taken into the draft chamber 19 of the low air volume draft chamber 1 and then exhausted. In order to prevent the airflow distribution in the draft chamber 19 of the low airflow draft chamber 1 from being deteriorated even when the airflow is reduced, the necessary air supply amount is secured and the air supply amount and the exhaust amount are maintained. To maintain the balance.

  As shown in FIGS. 1 and 2, the low airflow draft chamber 1 has a main body 2 that is a box-shaped enclosure, and a front opening 3 (an example of an opening) is formed on a front surface 3 of the main body 2. ) 4 is provided. The effective volume of the draft cabinet 19 is, for example, 1 cubic meter. However, the effective volume of the draft storage 19 is not particularly limited to 1 cubic meter, and can be arbitrarily set.

  An opening / closing shutter 5 is provided in the front opening 4 of the front surface 3 of the main body 2. The open / close shutter 5 is a transparent plate so that the inside of the front opening 4 can be seen, and is also called a sash.

  As illustrated in FIG. 2, the upper end portion 5A of the open / close shutter 5 is connected to one end portion of the wire 5C, and the other end portion of the wire 5C is connected to the winding portion of the drive shaft of the motor MT of the drive portion. It is attached. The wire 5C is movably held by pulleys 5A and 5B.

  As a result, the motor MT is driven by the command of the control unit 100 to wind up the wire 5C, so that the open / close shutter 5 can be positioned in the Z1 direction (upward) and can be positioned in the Z2 direction (downward). The direction can be lowered. Accordingly, the opening / closing shutter 5 can close or fully open the front opening 4, and the opening / closing shutter 5 can adjust the amount of opening in a plurality of stages to arbitrarily set the opening area of the front opening 4. Can be adjusted.

  As shown in FIG. 2, an opening / closing shutter opening sensor 150 for detecting the opening degree of the opening / closing shutter 5 is arranged. The opening / closing shutter opening sensor 150 is, for example, an optical sensor that detects the amount of movement of the wire 5C. The opening / closing shutter opening sensor 150 detects the amount of movement of the wire 5C in the Y direction, and controls the control unit 100. Is notified of the opening signal PS. Thus, the control unit 100 obtains information on the opening amount of the opening / closing shutter 5, that is, the opening area of the front opening 4, based on the opening signal PS from the opening / closing shutter opening sensor 150. Can do.

  However, preferably, the opening / closing shutter 5 does not completely close the front opening 4 but adopts a structure that maintains a slight gap even when the opening / closing shutter 5 is closed. The size of the gap varies depending on the type of the low airflow draft chamber 1, but is, for example, about 50 mm to 100 mm. If the front opening 4 is completely closed by the opening / closing shutter 5, the inside (inside) of the low airflow draft chamber 1 becomes too negative, or a wind noise is generated by the airflow flowing into the inside from the gap. Inconvenience arises. Therefore, the structure for keeping the gap is for preventing these disadvantages.

  With reference to FIG. 1 and FIG. 2, the structural example of the main-body part 2 of the low air volume draft chamber 1 is demonstrated.

  As shown in FIGS. 1 and 2, the main body 2 has a front surface portion 3, left and right wall surfaces 6, 7, a back surface portion 8, a ceiling surface 9, and a bottom surface 10. As shown in FIG. 1, the ceiling surface 9 of the main body 2 is connected to an exhaust duct D, for example.

  As will be described later in the draft storage room 19 of the main body 2, the experiment object may be subjected to a heating experiment using a heater. In such a heating experiment, air that is heated and contains toxic gas or the like is guided from the inside of the draft cabinet 19 to the exhaust duct D shown in FIG. The guided heated air can be exhausted while being purified through a purification device G having, for example, a HEPA filter (high performance filter) for removing fine particles. That is, the heated air to be discharged with a low air volume is exhausted from the inside of the main body 2 through the front opening 4 to the outside through the exhaust duct D and the purification device G.

  As shown in FIG. 1, an exhaust damper 160 is disposed in the passage 159 of the exhaust duct D. The exhaust damper 160 operates the actuator 161 in response to the exhaust command signal OS from the control unit 100 to rotate the actuator 161 by a predetermined angle as appropriate, thereby adjusting the degree of opening of the passage 159 in the exhaust duct D, and thereby adjusting the exhaust duct. The value of the exhaust area in D can be adjusted.

  As shown in FIGS. 1 and 2, the above-described cuboid-shaped draft chamber 19 is formed inside the main body 2. The draft cabinet 19 has a work space 20. The work space 20 has a work surface 21. In the work space 20, for example, a lighting fixture is attached to the inner surface of the ceiling surface 9.

  As shown in FIG. 1, the work space 20 in the draft cabinet 19 is formed along the left-right width direction (X direction) and the up-down direction (Z direction) of the main body 2, and as shown in FIG. 2, It is a closed space formed along the front-rear width direction (Y direction) of the portion 2. As shown in FIG. 2, the work surface 21 of the work space 20 is a lower surface portion of the work space 20, and is provided at a height at which an operator can put a finger and work while sitting on a work chair. .

  As shown in FIGS. 1 and 2, a draft apron portion (air foil portion) 22 is provided along the X direction on the front surface portion 3 of the main body portion 2 at a position below the work surface 21. The apron portion 22 is a closed passage for sending the push air produced by the fan 30 to the work surface 21 side so as not to leak to the outside of the main body portion 2. A space SP is provided below the apron portion 22. In this space SP, the knees of the worker sitting on the work chair are put.

  FIG. 3 shows an example of the internal structure of the low airflow draft chamber 1 shown in FIG. 2 along the line AA. Further, the airflow indicated by an arrow L indicating air supply with a low airflow, and the airflow of homogenized air indicated by an arrow LL. FIG. 6 is a cross-sectional view showing an air flow indicated by an arrow M and an exhaust air flow indicated by an arrow N. FIG.

  The air flow of the arrow L and the air flow of the homogenized air shown by the arrow LL shown in FIG. 3 are artificially generated on the work surface 21 of the work space 20 in the draft cabinet 19 to create a laminar air flow. It is a push air stream. An arrow M indicates an air current of push air that takes in external air into the inside 19 of the draft cabinet through the front opening 4. Further, an arrow N indicates a pull air flow exhausted from the inside 19 of the draft warehouse.

  Thus, in the draft chamber 19, the air flow indicated by the arrow L, the air flow of the homogenized air indicated by the arrow LL, and the air flow indicated by the arrow M are push air, and the air flow of the exhaust indicated by the arrow N is pull air. . The airflow indicated by the arrow M enters the inside of the draft cabinet 19 from the front opening 4, and then passes through the air exhaust passages 44, 45, 46 inside the rear surface 8 as the pull airflow indicated by the arrow N in FIG. The exhaust gas is exhausted to the outside through the passage 159 and the purification device G of the exhaust duct D shown.

  With reference to FIG. 3 and FIG. 4, an example of the structure in the vicinity of the draft chamber 19 of the low airflow draft chamber 1 will be described.

  As shown in FIG. 3, a working space 20 is formed between the front surface portion 3, the back surface portion 8, and the left and right side surface portions 6, 7 in the draft chamber 19 of the main body portion 2. A lower surface portion of the work space 20 is a work surface 21. As shown in FIG. 4, the worker can perform a necessary experiment, for example, a heater 300 on the work surface 21, and perform a heating experiment by placing the test object 400 on the heater 300. it can.

  As shown in FIGS. 1 and 3, a plurality of fans 30 are provided below the work surface 21. As shown in FIG. 3, these fans 30 are rotated by the operation of the fan motor FM according to a command from the control unit 100. A fan 30 and a fan motor FM shown in FIG. 3, an exhaust damper 160 and an actuator 161 shown in FIG. 1 generate and send an air flow to create a laminar flow of air on the work surface 21, and the inside of the draft warehouse 19 The air supply exhaust means for exhausting the air which should be discarded from is comprised.

  4 is an enlarged cross-sectional view of the region R shown in FIG.

  As shown in FIG. 4, an air branching portion 55 is formed above the apron portion 22 at a position below the front surface portion 3. When the air branching portion 55 is provided in the apron portion 22, the airflow indicated by the arrow L sent from the fan 30 is rectified by the rectifying member 40, and the homogenized airflow indicated by the arrow LL (laminar flow) A part after the air flow) can be branched. Thereby, the air flow of the homogenized air (laminar air flow) shown by the arrow LL is the same as the air flow of the homogenized air shown by the arrow LL forming the laminar flow on the work surface 21 and the center of the draft chamber 19. The air can be branched into an air stream of push air to the vicinity.

  The air branching portion 55 shown in FIG. 4 branches the generated push air to reduce the airflow that forms a laminar flow on the work surface 21. By pushing the push air obliquely upward to the vicinity of the center, there is an effect of suppressing the atmosphere in the draft cabinet 19 from leaking to the outside. That is, the supply of push air obliquely upward plays a role in ensuring the performance of suppressing leakage of the atmosphere to the outside in the low airflow draft chamber 1.

  Next, FIG. 5 is a block diagram illustrating an example of a control system of the low airflow draft chamber 1.

  As shown in FIG. 5, the control unit 100 of the low airflow draft chamber 1 can vary the rotation speed of each fan 30 by variably controlling the operation of the fan motor 31 by the command signal RS.

  The exhaust damper 160 shown in FIG. 5 is connected to the actuator 161. The exhaust damper 160 can be rotated by operating the actuator 161 in response to an exhaust command signal OS from the control unit 100 to adjust the area of the passage 159 in the exhaust duct D shown in FIG.

  The motor MT shown in FIG. 5 is also shown in FIG. When the motor MT is driven by the command of the control unit 100 to wind up the wire 5C, the opening / closing shutter 5 can be moved and positioned in the Z1 direction (upward), and when the wire 5C is wound down, the opening / closing shutter 5 is moved in the Z2 direction. Can move (downward) for positioning.

  The opening sensor 150 of the open / close shutter 5 shown in FIG. 5 is also shown in FIG. The opening sensor 150 of the open / close shutter 5 is an optical sensor that detects the amount of movement of the wire 5C in the Y direction, for example, detects the amount of movement of the wire 5C in the Y direction, and notifies the control unit 100 of it. Thereby, based on the opening signal PS from the opening / closing shutter opening sensor 150, the control unit 100 determines the opening area of the front opening 4 shown in FIG. 2 corresponding to the opening amount of the opening / closing shutter 5. Information can be obtained.

  The infrared sensor 180 shown in FIG. 5 is a first temperature sensor that directly detects the temperature of the heated air in the draft chamber 19. The infrared sensor 180 serving as the first temperature sensor is configured to send a temperature information signal H of heated air in the draft cabinet 19 to the control unit 100. The first temperature sensor is not limited to the infrared sensor, but may be other types of sensors.

  The temperature sensor 170 shown in FIG. 5 is preferably a second temperature sensor arranged in the exhaust duct D as shown in FIG. The temperature sensor 170 as the second temperature sensor detects the temperature of the heated exhaust air when passing the heated exhaust air into the exhaust duct D, and temperature information of the exhaust air in the exhaust duct D is detected. A signal G is sent to the control unit 100. These temperature sensor 170 and infrared sensor 180 constitute a temperature detection unit 190 of the low airflow draft chamber 1.

  In FIG. 5, the control unit 100 calculates the first required exhaust amount AR <b> 1 that needs to be exhausted from the draft chamber 19 based on the temperature information signal H of the heated air in the draft chamber 19 from the infrared sensor 180. . Further, the control unit 100 calculates the second required exhaust amount AR2 that needs to be exhausted from the inside of the draft warehouse 19 based on the temperature information signal G of the exhaust air in the exhaust duct D from the temperature sensor 170.

  In FIG. 5, the control unit 100 also calculates the third required exhaust amount AR3 necessary for exhausting in parallel with calculating the first required exhaust amount AR1 and the second required exhaust amount AR2. That is, the control unit 100 determines the work surface opening area of the front opening 4 obtained from the opening amount of the open / close shutter 5 and a predetermined front wind speed (generally preferably 0.4 m / s or 0.5 m). / s) and the third required exhaust amount AR3 required for the exhaust gas obtained from the calculation is also performed. In the following, from the opening area of the work surface of the front opening 4 shown in FIG. 1 obtained from the opening amount of the open / close shutter 5 and the predetermined front wind speed (0.4 m / s as an example), The third required exhaust amount AR3 required for the required exhaust is abbreviated as a third required exhaust amount AR3 required for exhaust based on the opening amount K3 (or the opening amount K2) of the open / close shutter 5, as shown in FIG. Show.

  Then, the control unit 100 in FIG. 5 determines the first required exhaust amount AR1 that needs to be exhausted based on the temperature information signal H of the heated air in the draft chamber 19 and the temperature of the exhaust air in the exhaust duct D. Comparing the second required exhaust amount AR2 that requires exhaust based on the information signal G, the larger one of the first required exhaust amount AR1 and the second required exhaust amount AR2 is determined from the interior 19 of the draft warehouse. It can be selected as a required set required exhaust amount HR to be exhausted.

  As a result, as shown in FIG. 4, in the draft chamber 19, the control unit 100 performs a heating experiment on the test object 400 using the heater 300 and the air in the draft chamber 19 is expanded. The larger one of the first required exhaust amount AR1 and the second required exhaust amount AR2 is selected and secured as the required set required exhaust amount HR to be exhausted from the draft store room 19, thereby being in the draft store room 19. Heated air containing harmful gas and the like is more reliably discharged from the draft chamber 19.

  In FIG. 5, the control unit 100 controls the actuator 161 of the exhaust damper 160 so that it can discharge from the exhaust duct D shown in FIG. An exhaust command signal OS is issued to control the opening degree of the exhaust damper 160.

  The infrared sensor 180 in the draft chamber 19 directly detects the temperature of the heated air in the draft chamber 19, while the temperature sensor 170 detects the temperature of the exhaust air in the exhaust duct D. Yes. For this reason, the infrared sensor 180 in the draft chamber 19 detects the temperature of the air earlier than the temperature sensor 170 in the exhaust duct D, and the temperature of the exhaust air by the temperature sensor 170 in the exhaust duct D is detected. The detection timing is delayed with a time lag compared to the detection timing of the temperature of the air in the draft chamber 19 by the infrared sensor 180 in the draft chamber 19.

  By the way, as illustrated in FIG. 4, when the experiment object 400 is heated in the draft chamber 19 using the heater 300, the air in the draft chamber 19 expands. For this purpose, the required amount of exhaust required for the exhaust determined from the front wind speed (generally 0.4 m / s or 0.5 m / s) determined in advance through the front opening 4 is stored in the draft chamber 19. It cannot be introduced through the front opening 4. For example, the state in which external air is introduced into the draft cabinet 19 at a front wind speed of 0.4 m / s through the front opening 4 cannot be maintained, and the front wind speed is, for example, less than 0.4 m / s. It is necessary to maintain the front wind speed of 0.4 m / s when air is introduced into the draft chamber 19 through the front opening 4.

  Therefore, when setting the required exhaust amount HR shown in FIG. 5, the control unit 100 normally obtains the exhaust gas obtained based on the temperature of the air in the draft chamber 19 by the infrared sensor 180 in the draft chamber 19. Is given priority to the first required displacement AR1. However, just in case, the control unit 100 does not only have the first required exhaust amount AR1 obtained based on the temperature of the air in the draft chamber 19 by the infrared sensor 180 in the draft chamber 19, but also in the exhaust duct D. The second required exhaust amount AR2 that requires exhaust obtained based on the temperature of the exhaust air by the temperature sensor 170 is also obtained, and the first required exhaust amount AR1 and the second required exhaust amount AR2 are compared, and the larger one is obtained. Is adopted as a set required exhaust amount HR required for exhausting from the draft chamber 19.

  Thus, as described above, in the draft chamber 19, the control unit 100 performs the first experiment in which the test object 400 is heated using the heater 300 and the air in the draft chamber 19 is expanded. By selecting and securing the larger one of the required exhaust amount AR1 and the second required exhaust amount AR2 as a required set required exhaust amount HR to be exhausted from the draft chamber 19, a harmful gas in the draft chamber 19 The heated air containing etc. is discharged | emitted more safely and reliably from the inside 19 of a draft store | warehouse | chamber.

  6 shows an example when the opening / closing shutter 5 has a small opening (opening amount K1), and FIG. 7 shows an example when the opening / closing shutter 5 has an intermediate opening (opening amount K2). 8 shows an example in which the opening degree of the opening / closing shutter 5 is large (opening amount K3). As shown in FIGS. 6 to 8, a heater 300 is installed in the draft chamber 19 of the low airflow draft chamber 1, and an experimental object 400 to be subjected to a heating experiment is placed on the heater 300. Is placed. The opening amounts K1, K2, and K3 of the open / close shutter 5 have a magnitude relationship of K1 <K2 <K3. The wind speed at the time of taking in the outside air to be maintained at the opening 4 is 0.4 m / s as an example. The heater 300 is, for example, an electrothermal hot plate.

  When the opening degree of the opening / closing shutter 5 shown in FIG. 6 is small (opening amount K1), the flow rate of air flowing from the front opening 4 into the draft chamber 19 is, for example, 2 · / s. In this case, when the required exhaust amount to be exhausted from the draft chamber 19 is calculated from the opening amount K1 of the opening / closing shutter 5, the required exhaust amount to be exhausted from the draft chamber 19 is reduced due to the characteristics of the VAV control. End up.

  In this way, since the required amount of exhaust air to be exhausted is small from the inside of the draft chamber 19, the heating experiment of the test object 400 is performed using the heater 300 in the draft chamber 19 of the low air volume draft chamber 1. When this is done, the air in the draft chamber 19 is heated and expanded due to the presence of the heating source, so that the air capacity of the draft chamber 19 increases due to Boyle-Charle's law. When the air capacity in the draft warehouse 19 increases, there is a possibility that the exhaust of the air in the draft warehouse 19 will not be in time with the exhaust amount reduced by the VAV control. In this state, the control unit 100 uses the first required exhaust amount AR1 obtained based on the temperature information signal H of the air in the draft chamber 19 in the heated state and the temperature information signal G of the exhaust air in the exhaust duct D. The larger one of the second required displacements AR2 obtained based on this is set as the set required displacement HR required for exhaust, and the low airflow draft chamber 1 is operated.

  Further, FIG. 7 shows that when the opening degree (opening amount K2) of the opening / closing shutter 5 is middle (nearly half-open), the flow rate of air flowing from the opening 4 into the draft chamber 19 is, for example, 6 · / s. When a heating experiment of the test object 400 is performed using the heater 300, the air capacity in the draft chamber 19 increases.

  In this case, it is obtained on the basis of the third required exhaust amount AR3 (K2) required for the exhaust calculated from the opening amount K2 of the open / close shutter 5 and the temperature information signal H of the air in the draft chamber 19 in the heated state. When the first required exhaust amount AR1 is close, the control unit 100 obtains the first information obtained based on the temperature information signal H of the air in the heated draft cabinet 19 for the purpose of ensuring the safety of the operator. The first required exhaust amount AR1 is selected, the first required exhaust amount AR1 is set as the set required exhaust amount HR required for exhaust, and the low air volume draft chamber 1 is operated. That is, the control unit 100 preferentially sets the first required exhaust amount AR1 as the set required exhaust amount HR required for exhaust so as to be safer, and always sets the exhaust amount from the draft chamber 19 for control. Control is given priority.

  Furthermore, when the opening degree of the opening / closing shutter 5 (opening amount K3) is large, the flow rate of the air flowing into the draft chamber 19 from the opening 4 is, for example, 10 · / s. When a heating experiment of the test object 400 is performed using the heater 300, the air capacity in the draft chamber 19 increases. In this case, the third required exhaust amount AR3 (K3) required for the exhaust calculated from the opening amount K3 of the opening / closing shutter 5 is in a state of a large exhaust amount from the inside of the draft cabinet 19 due to the characteristics of the VAV control. . Since the third required exhaust amount AR3 (K3) required for the exhaust calculated from the opening degree K3 of the open / close shutter 5 is in a large state, there is little possibility that the required exhaust amount from the draft chamber 19 is insufficient. Therefore, in this case, the control unit 100 calculates the opening amount K3 of the open / close shutter 5 from the first required exhaust amount AR1 obtained based on the temperature information signal H of the air in the draft chamber 19 in the heated state. The third required exhaust amount AR3 (K3) necessary for the exhausted air is selected. Then, the control unit 100 sets the third required exhaust amount AR3 (K3) required for exhaust as the set required exhaust amount HR required for exhausting the draft chamber 19 actually required, and sets the low airflow draft chamber 1 It comes to work. That is, the control unit 100 sets the third required exhaust amount AR3 (K3) required for exhaust as the set required exhaust amount HR required for exhaust so that the exhaust can be performed more safely and reliably.

  Next, an operation example of the above-described low air volume draft chamber 1 will be described.

  First, the control unit 100 shown in FIG. 5 drives the fan motor FM of, for example, three fans 30 shown in FIGS. As a result, as shown in FIG. 4, the air flow indicated by the arrow L generated by the three fans 30 is once accumulated in the air reservoir from the rear end portion 32 to the intermediate portion 34 of the air guide member 31. Since the flow path has a tapered cross-sectional shape from the rear end portion 32 and the intermediate portion 34 to the front end portion 33, the accumulated airflow indicated by the arrow L is directed toward the rectifying member 40 of the front end portion 33. The flow rate of air can be increased and the air flow shown by the arrow L with the increased flow rate can be passed through the rectifying member 40.

  As a result, the rectifying member 40 converts the air indicated by the arrow L increased in flow rate sent from the fan 30 into a uniform (homogeneous) air flow, and the air flow of the homogenized air indicated by the arrow LL It can be supplied in the direction (X direction). Thereafter, the air flow of the homogenized air indicated by the arrow LL passes through the draft apron portion 22 of the front surface portion 3 of the main body portion 2 and reaches the upper air branch portion 55.

  As shown in FIG. 4, the air branching portion 55 rectifies by the rectifying member 40 and branches a part of the homogenized air current (laminar airflow) indicated by the arrow LL to Branching into an airflow forming a laminar flow indicated by an arrow LL and an airflow of push air to the vicinity of the center of the draft chamber 19. In this way, in FIG. 4, the air flow (laminar flow) rectified by the rectifying member 40 can be sent as push air that forms a laminar flow on the work surface 21 as indicated by the arrow LL. As a result, air can be passed through the work space for the operator to perform experiments and work with a low airflow draft so that the atmosphere in the low airflow draft chamber 1 does not leak outside.

  As shown in FIG. 4, since the opening / closing shutter 5 is open in the Z1 direction, the front opening 4 of the main body 2 is externally exposed from the front opening 4 of the main body 2 as indicated by the air flow indicated by the arrow M. The air is taken into the draft chamber 19. At this time, air is taken in at a low air volume at the front opening 4. Then, the air flow of the homogenized air indicated by the arrow LL that has passed along the work surface 21 and the air current of the air indicated by the arrow M that has passed through the inside of the draft cabinet 19 are shown in FIG. The air flow can be pulled to the outside of the main body 2 through the air exhaust path portions 44, 45, 46 and the exhaust duct D shown in FIG.

  As illustrated in FIGS. 6 to 8, the low air flow draft chamber 1 opens the open / close shutter 5 shown in FIG. 6 when the experiment object 400 is heated in the draft chamber 19 using the heater 300. VAV control (variable air volume control) is performed in accordance with the amount K1, the opening amount K2 of the opening / closing shutter 5 shown in FIG. 7, and the opening amount K3 of the opening / closing shutter 5 shown in FIG.

  Thereby, in the low air volume draft chamber 1, the exhaust air volume is adjusted from the draft chamber 19 according to the opening amounts K1, K2, and K3 of the open / close shutter 5, and the wind speed at the work opening surface of the safe work opening 4 is For example, 0.4 m / s is secured. Accordingly, since the air flow rate of the low airflow draft chamber 1 is stabilized, even if toxic gas or the like is generated in the draft chamber 19 when the test object 400 is heated, the toxic gas or the like in the draft chamber 19 is surely generated. Moreover, it can be stably exhausted to the outside.

  Next, referring to FIGS. 9, 10, and 11, an example of the operation of the low air volume draft chamber 1 when the experiment object 400 is heated using the heater 300 as illustrated in FIG. 4 will be described. .

  FIG. 9 is a flowchart showing an operation example of the low airflow draft chamber 1 when the experiment object 400 is heated using the heater 300. FIG. 10 shows the first required exhaust amount AR1, the second required exhaust amount AR2, the third required exhaust amount AR3 (K3), the third required exhaust amount AR3 (K2), and the third required exhaust amount AR3 (K2), which appear in the flowchart of FIG. The set required exhaust amount HR is shown. FIG. 11 shows opening amounts K1, K2, and K3 of the open / close shutter 19 that appear in the flowchart of FIG.

  As already described, from the opening area of the work surface of the front opening 4 shown in FIG. 1 obtained from the opening amount of the open / close shutter 5, and a predetermined front wind speed (0.4 m / s as an example), The third required exhaust amount AR3 required for the required exhaust is abbreviated as a third required exhaust amount AR3 required for exhaust based on the opening amount K3 (or the opening amount K2) of the open / close shutter 5, as shown in FIG. Show.

  In step S1 of FIG. 9, as shown in FIG. 4, from the front opening 4 of the main body 2, as indicated by the air flow indicated by the arrow M, external air is taken into the draft chamber 19. At this time, air is taken in at a low air volume at the front opening 4. Then, the air flow of the homogenized air indicated by the arrow LL that has passed along the work surface 21 and the air current of the air indicated by the arrow M that has passed through the inside of the draft cabinet 19 are shown in FIG. The airflow is pulled to the outside of the main body 2 through the air exhaust passages 44, 45, and 46 as pull air.

  Then, the control unit 100 shown in FIG. 5 gives an opening degree instruction signal VR to the motor MT, and opens the opening / closing shutter 5 in the Z1 direction. Then, the worker places the test object 400 on the heater 300 and starts the heating experiment. The operator sets the opening amount of the opening / closing shutter 5 to, for example, the opening amount K1 shown in FIG. 6, the opening amount K2 shown in FIG. 7, and the opening amount K3 shown in FIG. 8 according to the type of heating experiment. Can do.

  In step S2 of FIG. 9, the control unit 100 determines whether or not the opening amount of the open / close shutter 5 is a predetermined small opening amount K1, as illustrated in FIG. In step S2, as illustrated in FIG. 6, if the opening amount K1 of the opening / closing shutter 5 is small (YES), the process proceeds to step S3.

  In step S3 of FIG. 9, when the control unit 100 calculates the required exhaust amount to be exhausted from the draft chamber 19 from the opening degree K1 of the opening / closing shutter 5, a small exhaust amount from the draft chamber 19 due to the characteristics of VAV control. It will be in the state of. As described above, when the heating capacity of the test object is increased in the draft chamber 19 using the heater 300 in a state where the exhaust amount is small from the draft chamber 19, the VAV control is performed. With the exhaust amount reduced by the above, there is a possibility that the exhaust of the air in the draft warehouse 19 will not be in time.

  Therefore, in the state of the opening amount K1 of the open / close shutter 5, in step S3, the controller 100 obtains the first required exhaust gas obtained based on the temperature information signal H of the air in the draft chamber 19 in the heating state shown in FIG. The amount AR1 is compared with the second required exhaust amount AR2 obtained based on the temperature information signal G of the exhaust air in the exhaust duct D.

  In step S3 of FIG. 9, as a result of the control unit 100 comparing the first required exhaust amount AR1 and the second required exhaust amount AR2 in FIG. 5, the control unit 100 determines that the first required exhaust amount AR1 and the second required exhaust amount. The larger one of AR2 is selected, and the required exhaust amount of the selected one is set as the actually required set required exhaust amount HR as described below.

  That is, in step S3, when it is determined that the first required exhaust amount AR1 is larger than the second required exhaust amount AR2, the control unit 100 proceeds to step S4. In step S4, the control unit 100 sets the first required exhaust amount AR1 as the set required exhaust amount HR necessary for actual exhaust. In this state, the control unit 100 shown in FIG. 5 gives the exhaust command signal OS corresponding to the set required exhaust amount HR required for actual exhaust to the actuator 161 to change the amount of exhaust air by the exhaust damper 160. The heated air containing the toxic gas and the like in the draft chamber 19 can be discharged safely and reliably.

  Instead, as a result of the control unit 100 comparing the first required exhaust amount AR1 and the second required exhaust amount AR2 in step S3 of FIG. 9, the control unit 100 determines that the second required exhaust amount AR2 is the first required exhaust amount. If it is determined that it is larger than AR1, the process proceeds to step S5. In step S5, the control unit 100 sets the second required exhaust amount AR2 as a set required exhaust amount HR necessary for actual exhaust. In this state, the control unit 100 shown in FIG. 5 gives the exhaust command signal OS corresponding to the set required exhaust amount HR required for actual exhaust to the actuator 161 to change the amount of exhaust air by the exhaust damper 160. The heated air containing the toxic gas and the like in the draft chamber 19 can be discharged safely and reliably.

  In step S4 or step S5, the control unit 100 sets a set required exhaust amount HR required for actual exhaust, operates the low air volume draft chamber 1 and removes toxic gas and the like generated during heating in the draft chamber 19 A heating experiment of the test object 400 is performed while discharging safely and reliably. And in step S6, when a heating experiment is complete | finished, the heating of the test object 400 by the heater 300 is complete | finished.

  Returning to step S2 of FIG. 9, if the control unit 100 determines that the opening amount of the open / close shutter 5 is not the smallest K1 (NO), the control unit 100 proceeds to step S7. In step S7, the control unit 100 further determines that the opening degree of the opening / closing shutter 5 is medium K2 as shown in FIG. 7, or K3 where the opening degree of the opening / closing shutter 5 is large as shown in FIG. It is judged whether it is. In step S7, when the control unit 100 determines that the opening amount of the open / close shutter 5 is the middle K2, the process proceeds to step S8. When a heating experiment of the test object 400 is performed in the draft chamber 19 using the heater 300, the air capacity increases.

  In step S8, as shown in FIGS. 10 and 11, since the opening degree K2 of the opening / closing shutter 5 is reached, the control unit 100 requires the required exhaust amount AR3 (K2) required for the exhaust gas calculated from the opening degree amount K2 of the opening / closing shutter 5. ) And the first required exhaust amount AR1 obtained based on the temperature information signal H of the air in the draft chamber 19 in the heated state are close to each other, the control unit 100 ensures the safety of the worker. For the purpose, priority is given to the first required exhaust amount AR1 obtained on the basis of the temperature information signal H of the air in the draft chamber 19 in the heated state, and this first required exhaust amount AR1 is set necessary for the actual exhaust. Set as the required displacement HR.

  In this state, the control unit 100 shown in FIG. 5 changes the amount of exhaust air by the exhaust damper 160 by giving the exhaust command signal OS corresponding to the set required exhaust amount HR required for exhaust to the actuator 161 to change the draft. A heating experiment is performed safely and reliably while discharging heated air containing toxic gas or the like in the chamber 19. And in step S6, when a heating experiment is complete | finished, the heating of the test object 400 by the heater 300 is complete | finished.

  Returning to step S7 in FIG. 9, in step S7, when the control unit 100 determines that the opening degree of the open / close shutter 5 is K3 as shown in FIG. 10, the process proceeds to step S9.

  In step S9, if the opening degree of the opening / closing shutter 5 is K3, the opening degree of the opening / closing shutter 5 is the largest, so that the control unit 100 requires the required exhaust amount AR3 ( K3) has a large displacement from the inside of the draft cabinet 19 due to the characteristics of the VAV control. When a heating experiment of the test object 400 is performed in the draft chamber 19 using the heater 300, the air capacity increases.

  However, since the required exhaust amount AR3 (K3) required for exhaustion calculated from the opening amount K3 of the open / close shutter 5 is large as described above, there is a possibility that the required exhaust amount from the draft chamber 19 is insufficient. Few. Accordingly, in this case, the control unit 100 calculates the opening amount K3 of the shutter 5 instead of the first required exhaust amount AR1 obtained based on the temperature information signal H of the air in the draft chamber 19 in the heated state. The third required exhaust amount AR3 (K3) required for exhaust is selected, and the third required exhaust amount AR3 (K3) required for exhaust is set as the required required exhaust amount for exhausting the draft chamber 19 that is actually required. Set as HR.

  In this state, the control unit 100 shown in FIG. 5 changes the amount of exhaust air by the exhaust damper 160 by giving the exhaust command signal OS corresponding to the set required exhaust amount HR required for exhaust to the actuator 161 to change the draft. A heating experiment is performed safely and reliably while discharging heated air containing toxic gas or the like in the chamber 19. And in step S6, when a heating experiment is complete | finished, the heating of the test object 400 by the heater 300 is complete | finished. Thereby, the toxic gas etc. which arise at the time of the heating in the draft store | warehouse | chamber 19 can be discharged | emitted safely and reliably.

  In step S9, the control unit 100 sets the third required exhaust amount AR3 (K3) based on the opening amount K3 as the set required exhaust amount HR necessary for exhaust, and in this state, the control unit 100 shown in FIG. Applies an exhaust command signal OS corresponding to a set required exhaust amount HR required for exhaust to the actuator 161, changes the amount of exhaust air by the exhaust damper 160, and heats including toxic gas or the like in the draft chamber 19 The heating experiment is performed safely and reliably while discharging the generated air. And in step S6, when a heating experiment is complete | finished, the heating of the test object 400 by the heater 300 is complete | finished. Thereby, the toxic gas etc. which arise at the time of the heating in the draft store | warehouse | chamber 19 can be discharged | emitted safely and reliably.

  As described above, the heater 300 is installed in the draft chamber 19 as illustrated in FIGS. 6 to 8 using the VAV control type low air volume draft chamber 1, and the heater 300 has an experiment. When performing the heating experiment with the object 400 mounted, as shown in FIGS. 10 and 11, the front opening 4 is opened at each stage according to each stage of the opening amounts K 1, K 2, K 3 of the opening / closing shutter 5. For example, the set required exhaust amount HR necessary for exhaust can be adjusted so that a predetermined front wind speed of 0.4 m / s can be maintained.

  Thereby, even if a heating experiment is performed in the draft chamber 19 and toxic gas or the like is generated from the test object, the toxic gas or the like is discharged from the draft chamber 19 to the outside through the exhaust duct D and the purification device G shown in FIG. Safe and reliable exhaust. Therefore, the VAV control type low air volume draft chamber 1 can be applied not only to an experiment not involving heating but also to a heating experiment in which the experimental object 400 is heated using the heater 300. The low air volume draft chamber 1 of the VAV control system can be operated while always maintaining a safe state, and both energy saving of the low air volume draft chamber 1 and reduction of gas leakage concentration can be achieved.

  A low air volume draft chamber 1 according to an embodiment of the present invention is a variable air volume control type low air volume draft chamber that sends air of a low air volume into an interior through an opening 4 and exhausts the air from the interior to the outside. The low air volume draft chamber 1 includes an opening / closing shutter 5 that opens and closes the opening 4, a fan 30 that sends air into the draft chamber 19, and an exhaust that adjusts the amount of exhaust air when exhausting the air inside the draft chamber 19. A damper 160, an infrared sensor 180 as a first temperature sensor that is disposed in the draft chamber 19 and detects the temperature in the cabinet, and a temperature sensor as a second temperature sensor that detects the temperature of exhaust air from the draft chamber 19 170, the first required exhaust amount AR1 that needs to be exhausted from the interior based on the temperature in the interior obtained by the first temperature sensor, and the first exhaust amount that requires exhaust from the interior from the temperature of the exhaust air obtained by the second temperature sensor. 2 Based on the required exhaust amount AR2 and the work surface opening area determined from the opening amounts (K1, K2, K3) of the opening / closing shutter 5 at the opening 4 and a predetermined front wind speed. And a third required exhaust volume AR3 needed sought, and the control section 100 to obtain, the. The control unit 100 selects any one of the first required exhaust amount AR1, the second required exhaust amount AR2, and the third required exhaust amount AR3 according to the opening degree (K1, K2, K3) of the open / close shutter 5. This is a configuration in which the amount of exhaust air by the exhaust damper 160 is changed by setting the required exhaust amount HR required for exhaust in the warehouse.

  Thus, one of the first required exhaust amount AR1, the second required exhaust amount AR2, and the third required exhaust amount AR3 is selected according to the magnitude of the opening amount (K1, K2, K3) of the opening / closing shutter 5. Then, since the amount of exhaust air by the exhaust damper 160 is changed by setting the required required exhaust amount HR for the exhaust in the chamber, even if the VAV control method is applied in the low air volume draft chamber, the heating experiment is performed in the chamber Even if the air in the storage chamber expands, an appropriate required exhaust amount is set according to the size of the opening / closing shutter, and the heated storage air is discharged safely and reliably. be able to. Therefore, even if the VAV control method is applied to the low airflow draft chamber 1, it can also be applied to a heating experiment, so that a safe state can always be maintained, and both energy saving and gas leakage concentration reduction can be achieved.

  The opening amount of the opening / closing shutter 5 is divided into a predetermined small value K1, a predetermined intermediate value K2, and a predetermined large value K3, and the control unit 100 determines the opening amount of the opening / closing shutter 5. Is set to a predetermined small value, the larger one of the first required exhaust amount AR1 and the second required exhaust amount AR2 is selected and set to the set required exhaust amount HR. Thereby, when the opening amount of the opening / closing shutter 5 is set to a predetermined small value K1, the larger one of the first required exhaust amount AR1 and the second required exhaust amount AR2 is selected, and the set required exhaust amount is selected. Set to amount HR. For this reason, even if the heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust amount is set according to the opening degree K1 of the open / close shutter 5, and the heated draft chamber 19 air can be discharged safely and reliably.

  The opening amount of the opening / closing shutter 5 is divided into a predetermined small value K1, a predetermined intermediate value K2, and a predetermined large value K3, and the control unit 100 determines the opening amount of the opening / closing shutter 5. Is set to a predetermined intermediate value K2, the first required exhaust amount AR1 is selected, and the first required exhaust amount AR1 is set to the set required exhaust amount HR. Thereby, when the opening amount of the opening / closing shutter 5 is set to a predetermined intermediate value K2, the first required exhaust amount AR1 that can directly detect the heated air in the warehouse is selected, The first required exhaust amount AR1 is set to the set required exhaust amount HR. For this reason, even if the heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust amount is set according to the opening amount K2 of the open / close shutter 5, and the inside of the heated chamber Air can be discharged safely and reliably.

  The opening / closing amount of the opening / closing shutter is divided into a predetermined small value K1, a predetermined intermediate value K2, and a predetermined large value K3. The control unit 100 determines whether the opening / closing shutter 5 has an opening amount. When the predetermined large value K3 is set, the third required exhaust amount AR3 is selected, and the third required exhaust amount AR3 is set to the set required exhaust amount HR. Thereby, when the opening amount of the opening / closing shutter 5 is set to a predetermined large value K3, the third required exhaust amount AR3 set according to the opening amount K3 of the opening / closing shutter is set to the set required exhaust amount HR. To do. For this reason, even if the heating experiment is performed in the chamber and the air in the chamber expands, an appropriate required exhaust amount is set according to the opening degree K3 of the open / close shutter 5, and the inside of the heated chamber Air can be discharged safely and reliably.

  The present invention has been described with reference to the embodiments. However, each embodiment is an example, and the scope of the invention described in the claims can be variously modified without departing from the scope of the invention. .

  As the heater 300 installed in the draft cabinet 19, for example, in addition to a hot plate using a heating wire, an IH hot plate, an alcohol lamp, a gas burner such as city gas or propane gas, and the like for irradiating heat from above An infrared lamp or the like can be employed, and the heater 300 can be used, for example, for ashing excess from the experimental object 400 by heating the experimental object 400.

  As illustrated in FIG. 1, the attachment position of the infrared sensor 180 as the first temperature sensor is not limited to the upper part of the draft chamber 19, and may be the left and right side surfaces and the rear surface portion of the draft chamber 19. The attachment position of the temperature sensor 170 as the second temperature sensor is in the vicinity of the exhaust damper 160 of the exhaust duct D as illustrated in FIG. 1, but may be another position of the exhaust duct D.

  In the above-described embodiment of the present invention, the opening / closing shutter opening amount K1 is set to a predetermined small value, and the opening / closing shutter opening amount K2 is set to a predetermined intermediate value. The opening / closing amount K3 of the opening / closing shutter is set in three steps as a predetermined large value, but is not limited thereto, and may be set in two steps or four or more steps.

1 Low airflow draft chamber 2 Main body 4 Front opening (example of opening)
5 Opening / closing shutter 19 Draft chamber 30 Fan 31 Fan motor 100 Control unit 150 Opening / closing shutter opening sensor 160 Exhaust damper 161 Exhaust damper actuator 170 Temperature sensor (second temperature sensor)
180 Infrared sensor (first temperature sensor)
300 Heater 400 Test object (Heating object)
AR1 First required exhaust amount AR2 obtained based on the temperature information signal H of the air in the draft chamber in the heated state Second required exhaust amount AR3 (based on the temperature information signal G of the exhaust air in the exhaust duct D) K2) Third required exhaust amount AR3 (K3) required for exhaust gas calculated from opening / closing shutter opening amount K2 Third required exhaust gas amount HR required for exhaust gas calculated from opening / closing shutter opening amount K3 Necessary for exhaust in draft chamber Necessary setting required exhaust amount D Exhaust duct K1 Predetermined small value K2 of opening / closing shutter opening amount Predetermined intermediate value K3 of opening / closing shutter opening amount Predetermined large value OS opening / closing shutter opening amount OS Exhaust command signal VR Opening instruction signal PS Opening signal RS Command signal

Claims (3)

A low air volume draft chamber of a variable air volume control system that sends air of a low air volume into the chamber through an opening and exhausts the air from the interior to the outside,
An opening and closing shutter for opening and closing the opening;
A fan for sending the air into the cabinet;
An exhaust damper that adjusts the amount of the exhaust air when exhausting the air in the chamber;
A first temperature sensor that is arranged in the storage and detects the temperature in the storage;
A second temperature sensor for detecting the temperature of the exhaust air from the interior;
Exhaust from the interior is required from the first required exhaust amount that requires exhaust from the interior based on the temperature in the interior obtained by the first temperature sensor and the temperature of the exhaust air obtained by the second temperature sensor. A control unit for obtaining a second required exhaust amount, and a required third required exhaust amount obtained from a work surface opening area obtained from an opening amount of the opening / closing shutter in the opening and a predetermined front wind speed. And having
The control unit selects one of the first required exhaust amount, the second required exhaust amount, and the third required exhaust amount according to the magnitude of the opening amount of the opening / closing shutter, and It is set as a set required exhaust amount required for the actual exhaust in the engine, and the exhaust air amount by the exhaust damper is changed ,
The opening amount of the opening / closing shutter is divided into a predetermined small value, a predetermined intermediate value, and a predetermined large value,
When the opening amount of the opening / closing shutter is set to the predetermined small value, the control unit selects the larger one of the first required exhaust amount and the second required exhaust amount, and A low air volume draft chamber that is set to the required displacement . Before SL control unit, when opening degree of the opening and closing shutter is set to a value of the predetermined medium, select the first desired air volume, the set required the first required exhaust volume 2. The low air volume draft chamber according to claim 1, wherein the exhaust volume is set to an exhaust amount. Before SL control unit, when opening degree of the opening and closing shutter is set to a larger value the predetermined, select the third required exhaust volume, the set required air volume the third required exhaust volume The low air volume draft chamber according to claim 1, wherein

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