JP6323859B1 - Yin positive pressure work hood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive / negative pressure working hood capable of preventing harmful substances generated when using a negative pressure mode from being mixed into the air supplied into the working chamber when using the positive pressure mode. Only the intake fan 10 is driven in the positive pressure mode, the exhaust fan 29 is driven in the negative pressure mode, and the intake fan 10 is driven at a lower speed than in the positive pressure mode, so that clean air blown out from the rectifying grid 16 is achieved. The air flow prevents air containing harmful substances in the working chamber 5 from entering the rectifying grid 16 and the plenum chamber 14. [Selection] Figure 8

Description

  The present invention includes a positive pressure mode for holding a work chamber in a positive pressure state and preventing outside air from entering the work chamber, and holding the work chamber in a negative pressure state from the work chamber. The present invention relates to a negative and positive pressure working hood that can be used by switching between two modes of a negative pressure mode for preventing leakage of air containing harmful substances to the outside.

  Conventionally, in research fields such as medicine and medicine, for example, when performing work such as bacterial culture for experimental research and sealing of vials in aseptic conditions, clean air in the work space (work room) Is used to maintain a positive pressure so that air does not enter from the outside.

  On the other hand, when handling harmful substances such as pathogenic bacteria and toxic chemicals, negative pressure working equipment that keeps the inside of the work space (work room) at negative pressure and prevents leakage of harmful substances to the outside. Is used.

  However, in order to introduce such positive pressure and negative pressure work facilities, a large installation space is required. Therefore, in Patent Document 1, a clean air is supplied to the work space inside the box, and a positive pressure mode for maintaining a clean environment by keeping the space at a positive pressure, and a negative pressure within the space. A working facility for both negative and positive pressures has been proposed that can be used by switching the negative pressure mode that prevents harmful substances generated in this space from leaking outside.

  In the work facility described in Patent Document 1 (name of invention “clean bench”), in the positive pressure mode (positive pressure normal operation mode in the same document), the damper provided in the vent is opened to operate the motor. External air is taken into the air passage from the vent through a fan, and air purified through a filter is introduced into the work space to maintain a positive pressure in the work space.

  On the other hand, in the negative pressure mode (negative pressure normal operation mode in the same document), the damper is closed and the vent is closed, the air in the work space is sucked into the vent passage by the electric fan, and is passed through the filter to the outside. The work space is maintained at a negative pressure by exhausting.

Japanese Patent No. 4518524

  However, in the “clean bench” described in Patent Document 1 described above, in the negative pressure normal operation mode, the air in the work space is directly sucked into the air passage by the electric fan without passing through the filter. If harmful substances are mixed in the air in the working space, this will enter the air passage.

  For this reason, when the clean bench is operated in the negative pressure normal operation mode and then used in the normal positive pressure operation mode, air containing harmful substances remaining in the air passage is provided at the opening of the box. There is a possibility that the air is blown out from the gap between the shutters and is mixed into the work space or flows out.

  Therefore, the present invention eliminates the problems in the prior art as described above, and allows harmful substances generated when using the negative pressure mode to be mixed into the air supplied into the working room (work space) when using the positive pressure mode. An object of the present invention is to provide a positive and negative pressure working hood that can be prevented.

For this purpose, the first one of the positive and negative pressure working hoods of the present invention is provided with a working chamber on the inner side for performing a desired work by switching between the positive pressure mode and the negative pressure mode. A plenum chamber having an opening formed on the lower surface, to which a rectifying grid is attached, is provided above the working chamber, and an intake fan that takes in air from the outside through a first intake filter; There is an intake passage that communicates with the outlet side of the fan and the other end communicates with the inside of the plenum chamber through the second intake filter, and maintains the working chamber at a positive pressure with respect to the outside in the positive pressure mode. A positive pressure generating unit, an exhaust fan for exhausting the air in the working chamber to the outside, an exhaust passage having one end communicating with the inlet side of the exhaust fan through an exhaust filter and the other end communicating with the working chamber Have A negative pressure generator to maintain a negative pressure to the working chamber in a negative pressure mode to the external, a first differential pressure detecting means for detecting a differential pressure between the working chamber and the outside, the working chamber and the plenum A second differential pressure detecting means for detecting a differential pressure within the chamber; a first differential pressure displaying means for displaying the differential pressure detected by the first differential pressure detecting means; and a second differential pressure detecting means. Second differential pressure display means for displaying the detected differential pressure, and only the intake fan is driven in the positive pressure mode, the exhaust fan is driven in the negative pressure mode, and the intake fan is driven at a lower speed than in the positive pressure mode. In the positive pressure mode, the drive control unit can manually set the rotation speed of the intake fan, and in the negative pressure mode, the rotation speed of the intake fan and the exhaust fan can be manually set. And the rotation of the intake fan The number, as plenum chamber to the working chamber is maintained at a negative pressure and the working chamber to the outside is maintained in a positive pressure, blow clean air to the working chamber through said flow control grid The first differential pressure detection means and the second differential pressure detection means have a function of limiting a settable range based on the detection values of the first differential pressure detection means and the second differential pressure detection means .

The second one of the positive and negative pressure working hoods of the present invention is provided with a working chamber on the inner side for switching to either the positive pressure mode or the negative pressure mode, and a rectifying grid is attached. A plenum chamber having an opening formed on the lower surface is provided above the working chamber, and an intake fan that takes in air from the outside through a first intake filter, and one end on the outlet side of the intake fan A positive pressure generating portion that has an intake passage that communicates with the inside of the plenum chamber through the second intake filter at the other end, and that maintains the work chamber at a positive pressure with respect to the outside in the positive pressure mode; And an exhaust fan for exhausting the air in the working chamber to the outside, an exhaust passage that has one end communicating with the inlet side of the exhaust fan through an exhaust filter and the other end communicating with the working chamber. In pressure mode A negative pressure generating unit for maintaining a negative pressure a serial working chamber to the outside, a first differential pressure detecting means for detecting a differential pressure between the working chamber and the outside, between the working chamber and the plenum chamber Second differential pressure detecting means for detecting a differential pressure, differential pressure setting means for setting a differential pressure between the working chamber and the outside, and only the intake fan is driven in the positive pressure mode, and the exhaust gas in the negative pressure mode. A drive control unit that drives the fan and drives the intake fan at a lower speed than in the positive pressure mode, and the drive control unit detects a set value of the differential pressure setting means and a first differential pressure detection in the positive pressure mode Based on the detected value of the means, the rotational speed of the intake fan is automatically adjusted so that the differential pressure between the working chamber and the outside becomes the set value set by the differential pressure setting means. Setting value of setting means and first differential pressure detecting means Based on the detected value, the rotational speed of the exhaust fan is automatically adjusted so that the differential pressure between the working chamber and the outside becomes the set value set by the differential pressure setting means, and the second differential pressure detecting means Based on the detected value, the pressure difference between the working chamber and the plenum chamber is maintained at a predetermined value, and the rotation speed of the intake fan is automatically adjusted so that clean air is blown into the working chamber through the rectifying grid. It is characterized by having a function of.

According to the positive and negative pressure working hood according to the first and second aspects of the invention, in the negative pressure mode, the intake fan is driven at a lower speed than in the positive pressure mode together with the exhaust fan, and from the inside of the plenum chamber. Since clean air is blown out into the working chamber through the rectifying grid, the rising air containing harmful substances generated in the working chamber contacts the rectifying grid or enters the plenum chamber through the rectifying grid. Therefore, when used in the positive pressure mode, harmful substances can be prevented from being mixed into the air supplied to the working chamber through the plenum chamber.

According to the first aspect of the present invention, the rotational speed of the intake fan is set manually in the positive pressure mode, and the rotational speeds of the intake fan and the exhaust fan are manually set in the negative pressure mode. The atmospheric pressure difference and the atmospheric pressure difference between the working chamber and the plenum chamber can be individually adjusted according to the work contents.

  Further, the rotation speed of the intake fan in the negative pressure mode can be set so that the work chamber is maintained at a negative pressure with respect to the outside and the plenum chamber is maintained at a positive pressure with respect to the work chamber. Because the range is limited, the negative pressure in the work chamber is weakened due to a mistake in the setting of the rotation speed of the intake fan, causing harmful substances to leak to the outside, or harmful substances in the work chamber have entered the rectifying grid or plenum chamber. The situation where air enters can be prevented.

Further, according to the invention described in claim 2, in any mode of the positive pressure mode and the negative pressure mode, by simply setting the differential pressure between the working chamber and the outside in advance, during work in each mode, The set differential pressure can be automatically maintained.

It is a perspective view which shows one Embodiment of the positive and negative pressure working hood which concerns on this invention. It is a back side internal structure figure of the positive / negative pressure work hood shown in FIG. It is AA sectional drawing of FIG. It is a front view of the rear wall part of a working chamber. It is a perspective sectional view showing the partial structure of an exhaust slit. It is a cross-sectional view showing a partial structure of the exhaust slit. It is a figure which shows typically the supply route of the air to a working room at the time of positive pressure mode operation | work, and the flow state of the air in the said working room. It is a figure which shows typically the air exhaust route and supply path with respect to a working chamber at the time of negative pressure mode operation | work, and the flow state of the air in the said working chamber.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a positive / negative pressure working hood 1 according to the present invention. The positive / negative pressure working hood 1 (hereinafter simply referred to as a work hood) shown in FIG. The caster wheels 2 attached to the four corners of the lower surface of the machine casing 1A can be easily moved to a desired place of use.

  An opening 4 provided with a transparent glass door 3 that can be opened and closed in the vertical direction is formed on the front surface of the working hood 1, and various test and research biological tissues and pathogens are formed on the inside thereof. A working chamber 5 for handling chemical substances and the like is provided.

  The working hood 1 can be used by switching between a positive pressure mode in which the air pressure in the work chamber 5 is maintained higher than the external air pressure and a negative pressure mode in which the air pressure is maintained low according to the purpose of use. Yes.

  In the positive pressure mode, by increasing the air pressure in the work chamber 5, the outside air can be prevented from entering from the opening 4 and the work chamber 5 can be maintained in a clean environment from dust and germs mixed in the outside air. Isolate the inside of the work room 5.

  On the other hand, in the negative pressure mode, when handling harmful substances such as toxic chemical substances and pathogenic bacteria for pathological research in the work room 5, the pressure in the work room 5 is lowered from the outside. Prevent harmful substances from leaking out.

  In any of the above modes, the operator raises the glass door 3 to the minimum necessary level, and only the forearms of both arms wearing work gloves are opened from the opening 4 opened below the work door. Put in 5 and work.

  In the present embodiment, the glass door 3 is formed of transparent tempered glass, and can be opened and closed up and down by a button operation of the operation panel 6 and can be stopped at a desired opening degree. Further, the glass door 3 can be manually opened and closed by holding a handle 3A provided in the vicinity of the lower end of the front surface in an emergency such as a power failure. In addition, you may use for the said glass door 3 what was formed with organic glass, such as a transparent polycarbonate and an acryl.

  In addition to the operation buttons for opening and closing the glass door 3, the operation panel 6 is provided with various operation buttons built in the work hood 1 for operating an intake fan and an exhaust fan, which will be described later. It has been.

  FIG. 2 is an internal structural view of the back side of the work hood 1. A filter chamber 7 is disposed on the left side of the bottom inside the machine casing 1A, and a first intake filter is provided in the filter chamber 7. HEPA filter 7A (shown by a broken line) is incorporated.

  Further, the inlet side of the filter chamber 7 communicates with an intake port 8 opened at the lower portion of the outer side wall on the left side of FIG. The outlet side of the filter chamber 7 is connected to the inlet side (suction side) of the intake fan 10 via a connecting duct 9.

  The intake fan 10 is capable of continuous air volume adjustment by controlling the rotation speed of the motor 10A with an inverter. In addition, an outlet side (blow-out side) of the intake fan 10 is connected to a lower end inlet of the branch chamber 12 via a short cylindrical connecting duct 11 arranged vertically.

  The upper part of the branch chamber 12 is divided into left and right sides, and the left and right outlets are connected to the respective inlets of a pair of curved ducts 13 that are curved symmetrically upward. The outlets of the curved ducts 13 are connected to the lower surface inlets of the pair of rectangular parallelepiped relay chambers 15 communicating with the pair of left and right plenum chambers 14, respectively.

  FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2. As shown in FIG. 3, these relay chambers 15 communicate with the rear end portions of the corresponding plenum chambers 14. Further, the pair of plenum chambers 14 are installed symmetrically above the work chamber 5.

  Openings communicating with the inside of the work chamber 5 are formed on the lower surfaces of the respective plenum chambers 14, and rectifying grids 16 are detachably attached to these openings. A HEPA filter 17 as a second intake filter is incorporated in the vicinity of the rear wall inside each plenum chamber 14.

  In the present embodiment, the HEPA filter 17 can be removed from the opening of the plenum chamber 14 and taken out to the working chamber 5 side when inspecting or replacing. .

  The glass door 3 provided in the opening 4 of the working chamber 5 has a pair of guide rails 18 (only a part on the left side in FIG. 1) provided on the left and right side edges of the opening 4 respectively. ) Is guided and supported so as to be movable up and down.

  Further, as shown in FIG. 3, the upper end of the glass door 3 is connected to a door drive mechanism 19 provided on the upper part of the machine casing 1A by a chain 20, and the chain 20 is wound up by the door drive mechanism 19 or It is structured to be opened and closed in the vertical direction along the pair of guide rails 18 by the feeding operation.

  The outer portion above the position slightly below the upper end of the glass door 3 with the opening 4 completely closed is covered with a shielding plate 21. The lower end portion of the shielding plate 21 is curved toward the outer surface of the glass door 3 and is not shown in the figure, but the lower end edge thereof is flexible for closing a gap with the surface of the glass door 3. A suitable sealing member is attached.

  The bottom of the work chamber 5 is a work surface 22 for carrying out a desired work by placing an inspection sample or the like. Further, a plurality of exhaust slits 24 for exhausting air from the inside of the work chamber 5 are formed in the rear wall 23 of the work chamber 5.

  FIG. 4 is a front view showing the rear wall 23 portion, and in this embodiment, as shown in the figure, the exhaust slits 24 are paired on the left and right sides of the rear wall 23 in three upper and lower stages. A total of six places are formed.

  Each of the exhaust slits 24 is provided with a pair of shielding plates 25 that can be opened and closed on both the left and right sides. As shown in FIGS. 5 and 6, these shielding plates 25 engage with a pair of upper and lower guide pieces 26 fixed to the back sides of the upper and lower edges of the exhaust slit 24, and are slidable in the horizontal direction. The opening position and the opening area of each exhaust slit 24 can be individually adjusted by moving the open / close tab 25A protruding from the front side of each shielding plate 25 to the left and right with a finger. ing.

  As shown in FIGS. 3 and 4, an illumination unit 27 is incorporated in the upper portion of the rear wall 23. The illumination unit 27 includes an illumination lamp for illuminating the inside of the work chamber 5 and an ultraviolet lamp for sterilizing the work chamber 5 when not in use.

  In addition, a display unit 28 is provided on the rear wall 23. Here, although not shown in detail, the display unit 28 includes a lamp that displays positive pressure work availability, a lamp that displays negative pressure work availability, and a differential pressure that indicates the differential pressure between the working chamber 5 and the outside. An instruction section (first differential pressure display means) and a differential pressure instruction section (second differential pressure display means) for instructing the differential pressure between the working chamber 5 and the plenum chamber are arranged. The glass door 3 allows visual confirmation from the outside of the work hood 1.

  On the other hand, as shown in FIG. 2, an exhaust fan 29 is provided on the right side of the bottom portion inside the machine casing 1 </ b> A of the work hood 1. As with the intake fan 10 described above, the exhaust fan 29 is capable of continuous air volume adjustment by controlling the rotational speed of the motor 29A with an inverter.

  The outlet side (outlet side) of the exhaust fan 29 communicates with an exhaust port 30 formed in the lower portion of the right side wall outer surface of the machine casing 1A. Further, the inlet side (suction side) of the exhaust fan 29 is connected to the outlet side of the filter chamber 31 disposed in the back of the exhaust fan 29.

  The filter chamber 31 contains a HEPA filter 31A (see FIGS. 7 and 8 described later) as an exhaust filter, similar to the filter chamber 7 described above. The outlet side of the merging duct 32 is connected to the inlet side of the filter chamber 31.

  The merging duct 32 is bifurcated into the left and right sides of the inlet duct 32 and communicates with the inside of a pair of left and right exhaust chambers 33 disposed below the rear portion of the work surface 22 shown in FIG. Yes.

  Each of these exhaust chambers 33 communicates with a lower end of an exhaust passage 34 formed on the back side of the rear wall 23 of the work chamber 5. A pair of left and right exhaust passages 34 are provided corresponding to the respective exhaust chambers 33, and communicate with the work chamber 5 through the exhaust slits 24.

  In addition, as shown in FIG. 3, the work chamber 5 is provided with a pressure detection unit 35 that detects the internal atmospheric pressure. In addition, a pressure detection unit 36 that detects an external atmospheric pressure is provided on the rear side outside the plenum chamber 14 inside the machine casing 1A. Further, a pressure detector 37 that detects the atmospheric pressure inside the plenum chamber 14 is provided in the vicinity of the rectifying grid 16 inside the plenum chamber 14.

  Although not shown, a first differential pressure detection means for detecting a differential pressure between the inside and outside of the working chamber 5 based on the detection values of the pressure detection unit 35 and the pressure detection unit 36 is provided in the machine casing 1A. And a second differential pressure detecting means for detecting a differential pressure between the inside of the working chamber 5 and the inside of the plenum chamber 14 based on the detection values of the pressure detector 35 and the pressure detector 37.

  In the present embodiment, the pressure detection unit 35 in the work chamber 5 is shared by the first differential pressure detection unit and the second differential pressure detection unit, but the pressure detection unit 35 is configured as described above. You may provide for each differential pressure | voltage detection means separately.

  As shown in FIG. 3, in the present embodiment, a wind speed sensor that detects the strength of the air flow blown out from the plenum chamber 14 through the rectifying grid 16 at a position near the rectifying grid 16 in the work chamber 5. 38 is provided.

  As shown in FIG. 1 and FIG. 3, a pair of left and right openings each having a double-open maintenance door 39 is provided at the lower portion of the work hood 1. A HEPA filter 7A as a first intake filter built into the filter chamber 7 on the intake side, and a HEPA filter 31A as an exhaust filter built into the filter chamber 31 on the exhaust side shown in FIG. The filter chambers 7 and 31 can be cleaned and inspected.

  Although not shown in the present embodiment, each of the filter chambers 7 and 31 includes a differential pressure gauge that detects a differential pressure before and after the aeration direction of the built-in HEPA filter, and a detection by the differential pressure gauge. A differential pressure switch that operates when the differential pressure exceeds a predetermined value is provided. When these differential pressures increase due to clogging of the HEPA filter and the differential pressure switch operates, an alarm means (not shown) issues an alarm and the filter The time for replacement is announced.

  Next, a method of using the work hood 1 of the present invention configured as described above will be described. When the work hood 1 is used in the positive pressure mode, after the main power supply of the work hood 1 is turned on, the operation mode is set to the positive pressure mode. The main power ON / OFF and the switching operation between the positive pressure mode and the negative pressure mode can be performed with the operation panel 6 shown in FIGS.

  When the positive pressure mode is set, a display lamp indicating that positive pressure work is possible on the display section 28 (see FIG. 4) provided on the rear wall 23 of the work chamber 5 described above is turned on, and the exhaust fan 29 is in a stopped state. In this state, only the intake fan 10 is driven.

  Further, since the display unit 28 displays the differential pressure (positive pressure) between the working chamber 5 and the outside detected by the first differential pressure detecting means described above, the rotational speed of the intake fan 10 is It is set manually from the operation panel 6 while checking the differential pressure.

  FIG. 7 is a diagram schematically showing the air supply path to the working chamber 5 and the flow state of air in the working chamber 5 during the positive pressure mode operation. As shown in FIG. Passes through the HEPA filter 7A as a first intake filter built in the filter chamber 7 and is taken in by the intake fan 10 and further sent to the plenum chamber 14 via the intake passage 40.

  The intake passage 40 means a series of air passage paths including the connecting duct 11, the branch chamber 12, the curved duct 13, and the relay chamber 15 described above, and HEPA as a first intake filter. The positive pressure generator is configured by the filter 7A, the intake fan 10, the intake passage 40, and the HEPA filter 17 as the second intake filter.

  The air introduced into the plenum chamber 14 from the intake passage 40 passes through the rectifying grid 16 attached to the lower surface opening of the plenum chamber 14 after passing through the HEPA filter 17 as the second intake filter. Then, it is introduced into the working chamber 5.

  Here, the HEPA filter 17 has a role to further reinforce the air cleaning effect by the upstream HEPA filter 7A, and the flow velocity distribution of the air introduced into the plenum chamber 14 is changed. It has the role which equalizes the whole cross section of. The air flow having a uniform flow velocity is further blown out into the working chamber 5 in a state of being uniformly deflected downward through the rectifying grid 16 provided in the lower surface opening.

  At the time of the positive pressure mode operation, the desired operation is performed on the work surface 22 in the work chamber 5 with the opening degree of the glass door 3 being minimized. At this time, since the air in the work chamber 5 flows out from the opening 4 and other gaps narrowed by the glass door 3 to the outside, entry of dust, germs, and the like from the outside is prevented, and the work chamber 5 The interior is maintained in a clean environment.

  During the positive pressure mode operation, all the shielding plate 25 of the exhaust slit 4 formed on the rear wall 23 is closed, so that the power consumption necessary for maintaining the positive pressure in the work chamber 5 can be reduced. .

  Next, the case where the work hood 1 is used in the negative pressure mode will be described. In this case, after the main power supply of the work hood 1 is turned on, the operation mode is set to the negative pressure mode. When the negative pressure mode is set, the above-described display lamp for displaying the negative pressure work possible on the display unit 28 shown in FIG. 4 is turned on, and both the exhaust fan 29 and the intake fan 10 are driven.

  The display unit 28 displays a differential pressure (negative pressure) between the work chamber 5 and the outside, and a differential pressure in the work chamber 5 and the plenum chamber 14. In the negative pressure mode, the rotational speeds of both the exhaust fan 29 and the intake fan 10 are set on the operation panel 6 while confirming the respective differential pressures displayed on the display unit 28.

  In the negative pressure mode, the intake fan 10 is positive so that the inside of the working chamber 5 is maintained at a negative pressure with respect to the outside and the inside of the plenum chamber 14 is maintained at a positive pressure with respect to the inside of the working chamber 5. It is necessary to drive at a lower speed than in the pressure mode.

  Therefore, in the present embodiment, the range in which the rotational speed of the intake fan 10 can be manually set is determined by the detection values of the first differential pressure detection means and the second differential pressure detection means described above by the drive control unit (not shown). Restrict based on.

  FIG. 8 is a diagram schematically showing the air exhaust / supply path to the work chamber 5 and the air flow state in the work chamber 5 during the negative pressure mode operation. As shown in FIG. When the motor 29 is driven, the air in the working chamber 5 is sucked from the exhaust slit 24 of the rear wall 23, passes through the exhaust passage 41, and passes through the HEPA filter 31 </ b> A as an exhaust filter built in the filter chamber 31. It passes through and is exhausted to the outside by the exhaust fan 29.

  The exhaust passage 41 means a series of air passage paths including the exhaust passage 34, the exhaust chamber 33, and the merging duct 32 described above, and is defined by the exhaust fan 29, the HEPA filter 31A, and the exhaust passage 41. The negative pressure generating unit is configured.

  At the time of the negative pressure mode work, the desired work is performed on the work surface 22 in the work chamber 5 with the opening degree of the glass door 3 being a necessary minimum as in the case of the positive pressure mode work described above. At this time, outside air flows into the working chamber 5 from the opening 4 narrowed by the glass door 3 to prevent leakage of harmful substances in the working chamber 5 to the outside.

  In the negative pressure mode, the intake fan 10 is driven at a low speed together with the exhaust fan 29, and clean air is supplied into the plenum chamber 14 through the intake passage 40, and the inside of the plenum chamber 14 is slightly smaller than the inside of the work chamber 5. The atmospheric pressure is kept high.

  As a result, a weak air flow that blows down from the rectifying grid 16 into the work chamber 5 is generated, and this air flow includes a harmful substance in the work chamber 5 and rises to the vicinity of the rectifying grid 16 downward. By pushing back, contamination inside the rectifying grid 16 and the plenum chamber 14 due to the harmful substances is prevented.

  In addition, the opening area and opening position of the shielding plate 25 of each exhaust slit 24 are set such as a container placed on the work surface 22 or an inspection device so that the air in the work chamber 5 is exhausted from the exhaust slit 24 without stagnation. It adjusts suitably according to the shape and arrangement.

  Further, in the present embodiment, when the wind speed sensor 38 shown in FIG. 3 described above detects the strength of the air flow blown out from the rectifying grid 16 into the work chamber 5 and the wind speed of a predetermined value or more is not detected. Is supposed to issue an alarm.

  In the positive pressure mode, the drive control unit described above sets the set value of the differential pressure (positive pressure) between the work chamber 5 and the outside, which is set on the operation panel 6, and the first differential pressure detection unit described above. It is desirable to have a function of automatically adjusting the rotational speed of the intake fan 10 based on the detected value so that the differential pressure (positive pressure) between the inside and outside of the working chamber 5 becomes the set value. .

  In addition, the drive control unit, in the negative pressure mode, the set value of the differential pressure (negative pressure) between the work chamber 5 and the outside set on the operation panel 6 and the first differential pressure detecting means described above. Based on the detected value, the rotational speed of the exhaust fan 29 is automatically adjusted so that the differential pressure between the inside and outside of the working chamber 5 becomes the set value, and based on the detected value of the second differential pressure detecting means described above. Thus, it has a function of automatically adjusting the rotation speed of the intake fan 10 so that the differential pressure in the working chamber 5 and the plenum chamber 14 (positive pressure on the plenum chamber 14 side) is maintained at a predetermined value. Is desirable.

  The drive control unit replaces the rotation speed of the intake fan 10 in the negative pressure mode with the detection value (wind speed) of the wind speed sensor 38 described above, instead of the detection value (differential pressure) of the second differential pressure detection means. You may make it adjust automatically based on.

  In this case, the drive control unit compares the wind speed value detected by the wind speed sensor 38 with a preset reference wind speed value, and automatically adjusts the rotational speed of the intake fan 10 so that they match. it can.

  The rectifying grid 16 is made of a metal or ceramic grid whose surface is coated with an antibacterial / antifouling substance such as titanium oxide in order to make it difficult for harmful substances and germs to be handled in the work chamber 5 to adhere. Also good.

  When a rectifying grid 16 coated with titanium oxide is used, an ultraviolet light source is incorporated in the plenum chamber 14 and the rectifying grid 16 is turned on when the work hood 1 is not used. The antibacterial and antifouling effects due to the photocatalytic action of titanium oxide may be enhanced by irradiating with UV light.

DESCRIPTION OF SYMBOLS 1 Work hood 1A Machine frame 2 Caster wheel 3 Glass door 3A Handle 4 Opening part 5 Work room 6 Operation panel 7 Filter chamber 7A HEPA filter (first intake filter)
8 Intake port 9 Connection duct 10 Intake fan 10A Motor 11 Connection duct 12 Branch chamber 13 Curved duct 14 Plenum chamber 15 Relay chamber 16 Rectification grid 17 HEPA filter (second intake filter)
18 Guide rail 19 Door drive mechanism 20 Chain 21 Shield plate 22 Work surface 23 Rear wall 24 Exhaust slit 25 Shield plate 25A Open / close tab 26 Guide piece 27 Illumination unit 28 Display unit 29 Exhaust fan 29A Motor 30 Exhaust port 31 Filter chamber 31A HEPA filter (Exhaust filter)
32 Junction duct 33 Exhaust chamber 34 Exhaust passages 35, 36, 37 Pressure detector 38 Wind speed sensor 39 Maintenance door 40 Intake passage 41 Exhaust passage

Claims (2)

A plenum chamber in which a working chamber for performing a desired work by switching to either the positive pressure mode or the negative pressure mode is provided on the inner side, and an opening to which a rectifying grid is attached is formed on the lower surface. Provided above the working room,
An intake fan that takes in air from the outside through a first intake filter and intake air that has one end communicating with the outlet side of the intake fan and the other end communicating with the inside of the plenum chamber through a second intake filter A positive pressure generator having a path and maintaining the work chamber at a positive pressure with respect to the outside during the positive pressure mode;
An exhaust fan that exhausts the air in the working chamber to the outside; an exhaust passage that has one end communicating with the inlet side of the exhaust fan through an exhaust filter and the other end communicating with the working chamber; A negative pressure generating section for maintaining the work chamber at a negative pressure with respect to the outside during the mode;
First differential pressure detecting means for detecting a differential pressure between the working chamber and the outside ;
Second differential pressure detecting means for detecting a differential pressure between the working chamber and the plenum chamber ;
First differential pressure display means for displaying the differential pressure detected by the first differential pressure detection means ;
Second differential pressure display means for displaying the differential pressure detected by the second differential pressure detection means ;
A drive control unit that drives only the intake fan in the positive pressure mode, drives the exhaust fan in the negative pressure mode and drives the intake fan at a lower speed than in the positive pressure mode,
The drive control unit can manually set the rotation speed of the intake fan in the positive pressure mode, and can manually set the rotation speeds of the intake fan and the exhaust fan in the negative pressure mode, and the rotation of the intake fan. As for the number, the working chamber is maintained at a negative pressure with respect to the outside, and the plenum chamber is maintained at a positive pressure with respect to the working chamber so that clean air is blown into the working chamber through the rectifying grid. A negative / positive pressure working hood characterized by having a function of limiting a settable range based on the detection values of the first differential pressure detection means and the second differential pressure detection means . A plenum chamber in which a working chamber for performing a desired work by switching to either the positive pressure mode or the negative pressure mode is provided on the inner side, and an opening to which a rectifying grid is attached is formed on the lower surface. Provided above the working room ,
An intake fan that takes in air from the outside through a first intake filter and intake air that has one end communicating with the outlet side of the intake fan and the other end communicating with the inside of the plenum chamber through a second intake filter A positive pressure generator having a path and maintaining the work chamber at a positive pressure with respect to the outside during the positive pressure mode;
An exhaust fan that exhausts the air in the working chamber to the outside; an exhaust passage that has one end communicating with the inlet side of the exhaust fan through an exhaust filter and the other end communicating with the working chamber; A negative pressure generating section for maintaining the work chamber at a negative pressure with respect to the outside during the mode ;
First differential pressure detecting means for detecting a differential pressure between the working chamber and the outside ;
Second differential pressure detecting means for detecting a differential pressure between the working chamber and the plenum chamber ;
Differential pressure setting means for setting a differential pressure between the working chamber and the outside ;
A drive control unit that drives only the intake fan in the positive pressure mode, drives the exhaust fan in the negative pressure mode and drives the intake fan at a lower speed than in the positive pressure mode ,
In the positive pressure mode, the drive control unit sets the differential pressure between the working chamber and the outside by the differential pressure setting unit based on the set value of the differential pressure setting unit and the detection value of the first differential pressure detection unit. The rotational speed of the intake fan is automatically adjusted so as to obtain the set value, and in the negative pressure mode, based on the set value of the differential pressure setting means and the detected value of the first differential pressure detection means, The rotational speed of the exhaust fan is automatically adjusted so that the differential pressure with the differential pressure setting means becomes the set value set by the differential pressure setting means, and based on the detection value of the second differential pressure detection means, The differential pressure in the num chamber is maintained at a predetermined value, and the rotational speed of the intake fan is automatically adjusted so that clean air is blown into the working chamber through the rectifying grid. Yin positive pressure working hood.

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