JP5069535B2 - Fume hood - Google Patents

Description

  The present invention relates to a fume hood (also referred to as a draft chamber) used when a chemical experiment or the like is performed in a laboratory or a laboratory.

  In laboratories, laboratories, etc., it is usual to conduct experiments such as chemical reaction using chemicals, heat treatment, decomposition or extraction using a fume hood.

  The fume hood is designed so that the chemical environment in the laboratory is not damaged by pollutant gases such as harmful gases and odorous gases generated during the experiment, and the health and safety of the experimenter are not harmed. An experimental space (work space) on the work table is enclosed from outside air, and generally includes an intake hood body (chamber body) whose internal space is a work space for experiments, etc. An open / close sliding door is provided at the front opening. The hood can be opened from the front opening by opening and closing the door and sucking and discharging the air in the hood body through the exhaust duct at the top of the hood body while allowing the operator to insert a hand into the hood body. Outside air is allowed to flow into the main body to prevent the contaminated gas in the hood body from being diffused from the front opening into the laboratory.

  In recent years, such a fume hood has been developed as shown in Patent Document 1 below. The variable air volume fume hood keeps the surface velocity of air at the opening portion constant regardless of the opening degree of the open / close door (front opening). With this fume hood, the exhaust volume can be reduced when the door opening is small, while ensuring the specified exhaust performance, so the total amount of air discharged is reduced and the load on the exhaust drive mechanism is reduced. Thus, effective use of energy (energy saving) can be achieved.

  The variable air volume fume hood described in the same document includes a human sensor for detecting whether or not an operator is present in the vicinity, and door driving means such as an electric motor for lowering the door to drive the door downward. Is provided. When it is determined that there is no worker (experimental person) in the vicinity in the state where the door is opened, the electric motor is driven to automatically lower the door. . By closing the front opening in this way, the amount of exhausted air is reduced as described above to save energy. Furthermore, by closing the open / close door when not working, the experimental space (inside the hood body) can be physically blocked from the outside (in the laboratory), effectively preventing leakage of contaminated gases, etc. Yes.

Further, in the fume hood disclosed in Patent Document 1, a pressure-sensitive tape switch is provided on a portion (door contact portion) where the open / close door contacts when fully closed on the air wheel in front of the work table. If it is confirmed that there is an obstacle on the door contact part, the door lowering electric motor is stopped by stopping the drive of the door lowering electric motor even when the worker is absent. Preventing collision with obstacles.
JP-A-8-24673 (Claim 2, FIGS. 1 and 3)

  However, in the conventional fume hood shown in Patent Document 1 described above, the opening / closing door opening is controlled based on information from a tape switch provided on the base, so that the opening / closing operation of the opening / closing door is controlled. Regardless, if there is an obstacle, the door will not be closed. In other words, even if the open / close door is in the fully open state, if there is an obstacle, the open / close door is not closed at all, and the state where the front opening remains largely open is maintained. For this reason, since a large amount of air is sucked and discharged from the front opening, not only is the energy necessary for this intake / exhaust wasted, but the front opening cannot be blocked at all, and there is a slight leakage of pollutant gases. Anxiety remains.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a fume hood that can effectively prevent leakage of pollutant gases and can save energy in the case of a variable air volume. To do.

  In order to achieve the above object, the present invention is summarized as follows.

[1] A fume hood provided with a hood main body provided with a work space inside, and a vertically slidable open / close door that opens and closes the front opening of the hood main body so as to be stopped at an arbitrary slide position. ,
Door driving means for driving the open / close door in a descending direction;
In the state where the open / close door is opened, when there is no worker in the vicinity, forced lowering means for forcibly lowering the open / close door by driving the door driving means,
Obstacle detection means configured to detect an obstacle that is configured by a photoelectric switch provided at a lower end of the opening and closing door and is disposed at a lowering destination when the opening and closing door is forcibly lowered;
An emergency stop means for urgently stopping the open / close door by stopping driving of the door drive means when an obstacle is detected based on information from the obstacle detection means during the forced lowering of the open / close door; , equipped with a,
The obstacle detection means is provided on the opening / closing door so as to protrude downward,
An airfoil is provided with which the lower end of the door in the fully closed state comes into contact;
The fume hood characterized in that the obstacle detecting means is stored below a contact surface of the air wheel with the lower end of the open / close door when the open / close door is fully closed .

  [2] The obstacle detection means includes a projector provided on one side of the lower end of the door and a light receiver provided on the other side of the lower end, and is projected from the projector to the light receiver. 2. The fume hood according to item 1, comprising a transmission photoelectric sensor configured to detect an obstacle by blocking the detected beam.

[3] It is configured to be switchable between a connection state in which the driving force from the door driving means is transmitted to the opening / closing door and a blocking state in which the transmission is blocked, and is set to a connection state when the opening / closing door is forcibly lowered. Provided with a clutch mechanism,
3. The fume hood according to claim 1 or 2, wherein the emergency stop means switches the clutch mechanism to a disengaged state after stopping the driving of the door driving means when the door is emergency stopped.

[4] A pulley that is rotatably provided on an upper portion of the hood main body and that is rotated by a driving force of the door driving means;
A wire erected on the pulley, and the opening / closing door is suspended at one end;
A balance weight that is suspended at the other end of the wire and that balances the weight of the open / close door and stops the open / close door at an arbitrary slide position,
While the wire and the pulley are configured to be interlocked by frictional force,
4. The structure according to any one of the preceding items 1 to 3, wherein the balance weight is lifted through the wire and the opening / closing door is lowered when the pulley is rotated by a driving force of the door driving means. Fume hood.

  [5] The fume according to any one of the preceding items 1 to 4, wherein a surface velocity of air introduced from an opening portion of the front opening is kept constant regardless of an opening degree of the front opening by the opening / closing door. hood.

[6] Forced lowering prohibiting means for prohibiting forced lowering of the door by the forced lowering means after the emergency stop means emergency stop the door.
The fume according to any one of the preceding items 1 to 5, further comprising: a return switch that releases a state in which forced descent is prohibited by the forced descent prohibiting unit and returns to a state in which an emergency stop can be performed by the emergency stop unit. hood.

[ 7 ] An alarm sound generator for generating an alarm sound;
If the obstacle based on the information from the obstacle detecting means is detected, according to any one of items 1-6 in which and a warning sound generating means for generating an alarm sound by the warning sound generator Fume hood.

  According to the fume hood in the above invention [1], when the obstacle is detected by the non-contact obstacle detecting means at the lower end of the door when the door is forcibly lowered, the door is emergency-stopped. The door can be closed to a position near the obstacle. Therefore, even if there is an obstacle, the open / close door can be closed to some extent, so that leakage of contaminated gas can be effectively prevented, and energy saving can be achieved in the case of the variable air volume type.

Also, when the door is fully closed, the obstacle detection means at the lower end of the door is housed inside the air wheel, so that when the door is fully closed, the entire lower end of the door can be securely joined to the air wheel, and the front opening is securely closed. can do.

  According to the fume hood in the above invention [2], since the transmission photoelectric sensor composed of the projector and the light receiver is used as the obstacle detection means, the obstacle below the door is detected more quickly and accurately. Thus, the operation reliability can be further improved.

  According to the fume hood in the above invention [3], when stopping the door that is forcibly lowered, after stopping the drive of the door driving means, the transmission of power is interrupted by the clutch mechanism. Immediately after the door driving means stops, the door driving means and the open / close door are linked. Therefore, the door can be prevented from lowering due to inertia, the door can be quickly stopped, and the door can be more reliably prevented from colliding with an obstacle.

  According to the fume hood in the above invention [4], since the door-suspending wire and the pulley on which the wire is erected are interlocked by frictional force, the opening / closing door should collide with an obstacle. Even if there is something wrong, the wire slides against the pulley and the pulley runs idle, so that the load on the door that is applied to the obstacle is reduced and the impact is reduced.

  According to the fume hood in the above invention [5], since the surface velocity of the air introduced from the open portion is kept constant regardless of the opening degree of the front opening, for example, the opening degree When is small, the air volume can be reduced. For this reason, the load on the exhaust mechanism can be reduced and energy can be used effectively.

  According to the fume hood in the above invention [6], after the door is urgently stopped by the obstacle detection, the emergency descent is prohibited, so that the door automatically descends while the obstacle is left unattended. Such a malfunction can be surely prevented. If the return switch is pushed, the normal state (emergency descent possible state) can be restored, so that the fume hood can be used without any trouble.

According to the fume hood of the above invention [ 7 ], an alarm sound is generated when an obstacle is detected when the door is forcibly lowered. Therefore, the operator has a problem with the alarm sound. This can be quickly and accurately grasped, and a measure for the defect can be quickly performed.

  1-3 is a figure which shows the fume hood which is embodiment of this invention. As shown in these drawings, the fume hood includes a base (1) as a lower base and a hood main body (2) provided on the base (1).

  The hood body (2) has a substantially box-like shape in which an experimental space as a work space is provided. An opening (21) is provided in the front surface of the hood body (2), and a louver plate (22) made of a transparent plate is fixed to an upper edge portion of the front opening (21).

  Further, door guide grooves (23) are provided along the vertical direction on both side edges of the front opening (21) inside the both side walls of the hood body (2). In the door guide grooves (23) on both sides, both side edges of the open / close door (3) made of a transparent plate are slidably accommodated, and the open / close door (3) is attached so as to be movable up and down. When the open / close door (3) is raised, the front opening (21) is opened, and when the open / close door (3) is lowered, the front opening (21) is closed. The open / close door (3) is supported so as to be stopped at an arbitrary slide position (open position) as will be described later.

  As shown in FIG. 1, an exhaust port (24) is provided on the upper wall of the hood body (2). The air in the hood body (2) is discharged by an exhaust mechanism such as an exhaust duct (not shown) connected to the exhaust port (24), and the inside of the hood (experiment space) is set to a negative pressure. The negative pressure introduces external air (A) from the front opening (21) into the hood so that the gas in the experimental space does not leak to the outside.

  A work table (25) is provided inside the hood body (2). Further, an air foil (26) is provided at the front edge of the work table (25) so as to protrude forward from the front opening (21). As will be described later, when the opening / closing door (3) is lowered to the lowermost position and the front opening (21) is fully closed, the lower end of the opening / closing door (3) is brought into contact with the upper surface of the air foil (26). It has become.

  The fume hood of the present embodiment is of the VAV type (variable air volume type), and regardless of the opening degree of the front opening (21) by the open / close door (3), from the opening portion of the front opening (21). The surface velocity of the introduced air is kept constant. Therefore, when many parts of the front opening (21) are closed and the open part is small, the air volume is reduced, so that the total amount of air sucked and exhausted is kept small while maintaining a predetermined suction exhaust performance. It is possible to save energy.

  As shown in FIGS. 2 to 5, on both sides of the front portion of the upper portion of the hood body (2), hard synthetic resin wire pulleys (41) and (41) are rotatably mounted around the same axis. On both sides of the rear part, wire pulleys (42) (42) also made of hard synthetic resin are attached so as to be rotatable around the same axis.

  The wire pulleys (42) and (42) on both sides of the rear part are connected by a connecting shaft (43) and rotate in synchronization with each other.

  In addition, on both upper sides of the hood main body (2), resin-coated wires (44) are respectively installed on the front and rear wire pulleys (41) and (42).

  One end (front end) of each wire (44) (44) is attached to both sides of the door (3), and the other end (rear end) of each wire (44) (44) is a balance weight (45). (45) are attached respectively. As a result, the open / close door (3) is suspended at one end of the wires (44) (44), and the balance weights (45) (45) are suspended at the other end (rear end) of the wires (44) (44). Is done.

  Furthermore, the total weight of the two balance weights (45) (45) on both sides is adjusted to be substantially equal to the weight of the open / close door (3). As a result, the weight balance between the opening / closing door (3) and the balance weight (45) (45) is achieved, and when the opening / closing door (3) is slid, the opening / closing door (3) is moved to an arbitrary sliding position (opened). Position). Therefore, the open / close door (3) can be maintained in a fully open state, a half open state, or a small amount open state as required.

  In addition, the wire contact surface in each wire pulley (41) (42) is not formed with irregularities such as an engaging portion (meshing portion) for engaging the wire (44), and the wire pulley (41) ( 42) and the wire (44) are configured to be interlocked by a frictional force.

  On the upper side of the hood body (2), an electric motor (5) that constitutes a door drive means is provided so that its rotational drive shaft is arranged in parallel to the connecting shaft (43). Yes. A motor side belt pulley (51) is fixed to the rotational drive shaft of the electric motor (5), and a clutch side belt pulley (in the position corresponding to the motor side belt pulley (51) on the connecting shaft (43) is provided. 52) is rotatably attached to the connecting shaft (43). Further, a belt (54) is bridged between the belt pulleys (51) and (52). When the electric motor (5) is rotationally driven, the rotational driving force is transmitted to the clutch side belt pulley (52) via the motor side belt pulley (51) and the belt (54), and the clutch side belt pulley (52) is It is designed to rotate.

  A clutch mechanism (6) is provided in the vicinity of the clutch side belt pulley (52) on the connecting shaft (43). The clutch mechanism (6) includes a clutch main body (61) fixed to the coupling shaft (43), and a clutch plate (63) provided on the clutch main body (61) and capable of moving forward and backward toward the clutch side belt pulley (52). ) And a joining plate (62) provided on the clutch-side belt pulley (52) so as to face the clutch plate (63).

  As shown in FIG. 5, the clutch mechanism (6) is in a state where the clutch plate (63) of the clutch mechanism (6) is retracted and separated from the joining plate (62), and the arrow in FIG. As shown, the clutch plate (63) is configured to be switchable between a state where the clutch plate (63) is advanced and joined to the joining plate (62) (connected state).

  When the clutch mechanism (6) is set to the connected state, when the electric motor (5) is rotationally driven, the clutch-side belt pulley (52) rotates as described above, and the rotational driving force is applied to the joining plate ( 62), the clutch plate (63), the clutch body (61), and the connecting shaft (43) are transmitted to the rear side wire pulleys (42) and (42), and both pulleys (42) and (42) rotate. It is like that. The rotation direction of the pulleys (42) and (42) corresponds to the direction in which the balance weights (45) and (45) are wound up via the wires (44) and (44). Therefore, when the clutch mechanism (5) is set to the connected state and the electric motor (5) is driven, the balance weights (45) and (45) are lifted and the door (3) is lowered. Yes.

  Needless to say, as shown in FIG. 5, when the clutch mechanism (6) is switched to the disengaged state (the state of FIG. 5), the rotational driving force of the joining plate (62) is not transmitted to the clutch plate (63), and the electric motor The door (3) cannot be lowered by (5). Note that the clutch mechanism (6) is set to the disconnected state in the normal state (always), and is switched to the connected state when the forcible lowering of the open / close door (3) is started as will be described in detail later. ing.

  As shown in FIGS. 2 and 3, a human sensor (27) is provided in the center of the upper front portion of the hood body (2). The human sensor (27) detects whether or not an operator is present in front of the work table (27). In the present embodiment, as the human sensor (27), for example, a visible light type sensor such as a photo sensor, a magnetic sensor, or the like can be used in addition to an infrared sensor that detects heat generated by the human body. In FIG. 2, broken arrows indicate the worker detection range of the human sensor (27).

  On the other hand, as shown in FIGS. 6 and 7, a handle (31) is attached along the lower end of the open / close door (3). Further, sensor attachment pieces (32) and (32) are attached to both ends of the handle (31) so as to protrude downward. A light projector (71) and a light receiver (72) are attached to both sensor attachment pieces (32) so as to face each other.

  The projector (72) projects a detection beam (laser light L), and the projected detection beam L passes below the handle (31) of the open / close door (3). The light receiver (72) receives the light. Accordingly, when an obstacle is placed on the descending path (descent destination) when the open / close door (3) is lowered, the detection beam (L) is blocked by the obstacle. By blocking, the presence of the obstacle can be detected before the open / close door (3) collides with the obstacle.

  In the present embodiment, the obstacle detection sensor (7) is not normally activated in an off state, and is activated in an on state when the door (3) is automatically lowered as will be described later. It has become. However, in the present invention, the obstacle detection sensor (7) may be always set to the on state. In this case, for example, in the normal state, the output information from the obstacle detection sensor (7) is not referred to, and the presence or absence of the obstacle is not judged, and the open / close door (3) is automatically lowered (forced drop). Only when this is done, the presence or absence of an obstacle may be determined based on the output information from the obstacle detection sensor (7).

  In the present embodiment, a transmissive photoelectric sensor is constituted by the projector (71) and the light receiver (72), and the transmissive photoelectric sensor constitutes an obstacle detection sensor (7) as an obstacle detection means. .

  As shown in FIGS. 8 and 9, when the open / close door (3) is lowered to the lowermost position, the lower end of the open / close door (3), that is, the handle (31) contacts the upper surface of the air foil (26). At the same time, the light projector (71) and the light receiver (72) at both ends can enter the inside of the air foil (26), and the light projector (71) and the light receiver (72) are opened and closed doors of the air foil (26). It is configured to be stored below the contact surface with the lower end.

  A light shielding plate (75) is provided inside the air foil (26) (projector storage) corresponding to the projector (71). Further, a limit switch (76) is provided in the air wheel (26) corresponding to the sensor mounting piece (32). When the open / close door (3) moves to the lowermost position by forced lowering, the detection beam (L) from the projector (71) is blocked by the light shielding plate (75), and the open / close door (3) is opened. Simultaneously with the stop, the limit switch (76) is pushed by the lower end of the sensor mounting piece (32).

  The limit switch (76) is a return switch for releasing the forced lowering prohibition state as will be described later, in addition to detection means for confirming that the open / close door (3) has been lowered to the lowermost position (fully closed position). Also functions as a (reset switch).

  Although not shown, the fume hood of the present embodiment is provided with an alarm sound generator that generates an alarm sound such as a buzzer sound.

  As shown in FIG. 4, a control device (8) is provided on the upper portion of the hood body (2). The control device (8) includes a human sensor (27) and an obstacle detection sensor (7). , And a detection unit such as a limit switch (76), and a drive unit such as an electric motor (5), a clutch mechanism (6), and an alarm sound generator (not shown). Based on the output information from the detection unit such as the human sensor (27), the obstacle detection sensor (7), the limit switch (76), etc., the control device (8) is provided with the electric motor (5), the clutch mechanism (6). ) Controlling the driving of the above-mentioned alarm sound generator and the like, the automatic descent operation when the worker is absent and the forced descent stop operation when the obstacle is detected are automatically performed and the obstacle detection Sometimes an audible alarm is automatically generated.

  In the fume hood configured as described above, when the open / close door (3) is manually slid, as described above, the open / close door (3) is stopped at an arbitrary slide position. Therefore, the operator can perform work such as experiments on the work table (25) through the front opening (21) with the open / close door (3) arranged at a desired slide position.

  On the other hand, in the fume hood of the present embodiment, as shown in FIG. 2, it is detected by the human sensor (27) whether or not an operator is present in front (periphery) of the work table (25). If the presence of the operator is not detected, information to that effect (worker absence information) is transmitted to the control device (8).

  The control device (8) that has received the worker absence information indicates the elapsed time in the absence of the worker when the open / close door (3) is opened (not in the fully closed state). Measured with a built-in timer.

  Whether the door (3) is fully closed can be determined based on the information from the limit switch (76). That is, in a state where the limit switch (76) is pushed by the sensor mounting piece (32) of the opening / closing door (3), it is determined that the opening / closing door (3) is fully closed and is not pushed. Then, it is determined that the open / close door (3) is not fully closed (opened).

  Then, when the absence of the worker reaches a predetermined time set in advance, the control device (8) starts the forced lowering operation. That is, based on a command from the control device (8), the clutch mechanism (6) is switched to the connected state and the electric motor (5) starts to rotate.

  As a result, the rotational driving force of the electric motor (5) is applied to the rear wire pulley via the belt pulleys (51) and (52), the belt (54), the clutch mechanism (6) and the connecting shaft (43) as described above. (42) transmitted to (42), the pulley (42) (42) rotates in the direction of lifting the balance weight (45) (45) via the wire (44) (44). When the balance weights (45) and (45) are lifted in this way, the open / close door (3) is automatically lowered (forced lowering operation).

  In the present embodiment, the control device (8) that controls each operation unit so as to perform the forced lowering operation functions as the forced lowering means.

  At the same time as the forced descent operation is started, the operation of the obstacle detection sensor (7) is started based on a command from the control device (8). That is, the detection beam (L) is projected from the projector (71), and the detection beam (L) is received by the light receiver (72).

  Thus, the open / close door (3) is automatically lowered in the state where the obstacle detection sensor (7) is activated.

  When there is no obstacle that prevents the door (3) from descending, that is, when no obstacle is detected by the obstacle detection sensor (7), the door (3) continues to descend, and finally As shown in 8 and 9, it descends to the lowest end position and becomes a fully closed state.

  When the open / close door (3) is lowered to the lowermost position, the projector (71) and the light receiver (72) enter the inside of the air wheel (26), and the detection beam (L) from the projector (71) is generated. It is interrupted by the light shielding plate (75), and the forced lowering of the open / close door (3) is completed. Specifically, when the detection beam (L) is blocked, information to that effect (beam blocking information) is transmitted to the control device (8). Further, the control device (8) that has received the beam cutoff information switches the clutch mechanism (6) to the cutoff state after stopping the drive of the electric motor (5). Thereby, the rotational driving of the rear wire pulleys (42) and (42) is stopped, and the raising of the balance weights (45) and (45) and the lowering of the open / close door (3) are finished.

  Further, when the operator returns to the front of the work table (25) while the door (3) is forcibly lowered, the forced drop of the door (3) is interrupted. That is, when the presence of the worker is confirmed by the information from the human sensor (27), information to that effect (worker presence information) is transmitted to the control device (8), and the control device (8 receiving the information) ) Stops driving the electric motor (5) and switches the clutch (6) to the disconnected state. As a result, the forced lowering of the open / close door (3) is interrupted.

  Further, in the state where the forced lowering of the open / close door (3) is interrupted, when the operator is absent for a predetermined time, the forced lowering (automatic lowering) of the open / close door (3) is started again. Yes. In this way, when the forced lowering of the open / close door (3) is interrupted due to the absence of the worker, the forced lowering possible state is maintained, and every time the worker is absent, the open / close door (3) is forced down. To be done.

  On the other hand, as shown in FIG. 2, during the forced lowering of the open / close door (3), for example, an obstacle (X) such as a laboratory instrument is on the lowering path (descent destination) of the open / close door (3) on the air wheel (31). ) Until the obstacle (X) is detected by the obstacle detection sensor (7), that is, before the obstacle (X), the open / close door (3) is lowered. Go. 3 and 7, when the detection beam (L) of the obstacle detection sensor (7) is interrupted by the obstacle (X) and the obstacle (X) is detected, information to that effect (beam interruption) Information) is transmitted to the control device (8). The control device (8) that has received the beam cutoff information stops the drive of the electric motor (5), then switches the clutch mechanism (6) to the cutoff state, and urgently stops the open / close door (3) (emergency stop). Operation).

  When the obstacle (X) is detected by the obstacle detection sensor (7), the control device (8) operates the alarm sound generator to generate an alarm sound such as a buzzer sound. I am trying to inform you.

  In the present embodiment, the control device (8) that controls each operation unit so as to perform an emergency stop operation functions as an emergency stop means. Further, a control device that controls the driving of the alarm sound generator so as to generate an alarm sound when an obstacle is detected functions as an alarm sound generating means.

  Here, in the present embodiment, when the door (3) is urgently stopped by detecting the obstacle (X), the drive of the electric motor (5) is stopped, and a predetermined time (for example, After about 2 seconds), the clutch mechanism (6) is switched to the disconnected state.

  That is, when the drive stop of the electric motor (5) and the switching of the clutch mechanism (6) to the shut-off state are performed simultaneously or before the drive stop of the electric motor (5), the clutch mechanism (6) is shut off. When switching to the state, the clutch is disengaged while the door (3) is not completely stopped, and the door (3) does not stop immediately but falls slightly due to inertia. There is. Thus, when the opening / closing door (3) does not stop immediately and falls a little while detecting an obstacle, the possibility that the opening / closing door (3) collides with the obstacle (X) increases.

  Therefore, in the present embodiment, the driving of the electric motor (5) is stopped when an obstacle is detected, and the clutch is disengaged after a predetermined time has elapsed. Therefore, even after the motor is stopped, the electric motor (5) rotates. Since the drive shaft and the wire pulley (42) are linked, rotation due to the inertia of the wire pulley (42) can be prevented by the rotational resistance of the motor rotation drive shaft, and the door (3) can be stopped immediately. . Since the door (3) can be stopped immediately after detecting the obstacle (X) in this way, the door (3) can be reliably prevented from colliding with the obstacle (X). .

  Further, after the door (3) is urgently stopped by detecting the obstacle (X), the control device (8) performs control so that the stopped state is maintained. For example, if the operator returns to the front of the work table (25) in a state where the open / close door (3) is urgently stopped, that is, the presence of the worker is confirmed by the human sensor (27). Moreover, the control device (8) maintains this state (forced descent prohibited state) without performing the emergency descent of the open / close door (3).

  In the present embodiment, the control device (8) that controls to shift to the forced descent prohibition state after the emergency stop functions as the forced descent prohibition means.

  When the door (3) is manually lowered to the lowermost position after removing the obstacle (X) in the emergency stop state, the limit switch (76) is pushed by the sensor mounting piece (32) at the lower end of the door. Since it is operated, the control device (8) releases the forced lowering prohibition state in response to the pressing operation. That is, the control device (8) is in the initial state (normal state) from the forced descent prohibited state, that is, the state where the forced descent is started when the operator is absent with the open / close door (3) opened (forced descent possible state). ) Are transferred (returned).

  As described above, according to the fume hood of the present embodiment, the obstacle (X) is detected by the non-contact obstacle detection sensor (7) provided at the lower end of the door when the open / close door (3) is forcibly lowered. Then, since the door (3) is urgently stopped, the door (3) can be closed to a position near the obstacle (X) as shown in FIGS. Thus, when the door (3) is forcibly lowered, even if there is an obstacle (X), the door (3) can be closed to a permissible position, so the open area of the front opening (21) Can be made as small as possible. Accordingly, the amount of air sucked and discharged can be reduced, and energy saving can be achieved.

  Furthermore, even if there is an obstacle (X), the front opening (21) can be closed within the allowable range by the open / close door (3), so that leakage of contaminated gas can be effectively prevented.

  Needless to say, since the opening / closing door (3) stops when the obstacle (X) is detected, it is possible to reliably prevent the opening / closing door (3) from colliding with the obstacle (X).

  In particular, in this embodiment, since the transmission light beam sensor constituted by the projector (71) and the light receiver (72) is used as the obstacle detection sensor (7), the obstacle (X) below the door. Can be detected more quickly and accurately, and the operational reliability can be further improved.

  In this embodiment, when the door (3) to be forcibly lowered is stopped, the drive of the electric motor (5) is stopped and the power transmission by the clutch mechanism (6) is cut off after a predetermined time has elapsed. Therefore, immediately after the motor is stopped, the rotation drive shaft of the electric motor (5) and the wire pulley (42) on which the door-suspending wire (44) is installed are linked. For this reason, rotation due to the inertia of the wire pulley (42) can be prevented by the rotational resistance of the motor rotation drive shaft, the open / close door (3) can be quickly stopped, and the open / close door (3) becomes an obstacle (X). It is possible to more reliably prevent the collision.

  Furthermore, in this embodiment, since the door suspension wire (44) and the wire pulley (42) on which the wire (44) is erected are linked by frictional force, an obstacle detection sensor ( 7) Even if there is an obstacle (X) and the emergency stop cannot be performed when the door (3) is forcibly lowered due to a failure of 7), the door (3) is not obstructed (X) The impact at the time of collision can be reduced. In other words, even if the open / close door (3) descends and collides with the obstacle (X), the wire (44) slides against the wire pulley (42) and the wire pulley (42) is idled. It is possible to prevent all of the load of the door (3) from being applied to the obstacle (X), and a part of the load can be received by the balance weight (45). For this reason, the impact at the time of a door collision can be relieved and damage to the obstruction (X), the opening / closing door (3), etc. by the collision can be prevented effectively.

  For reference, for example, in the case of using a chain instead of the wire (44) and using a toothed sprocket instead of the wire pulley (42) and engaging the chain with the sprocket, If the forcibly descending opening / closing door collides with an obstacle, the sprocket will not slide against the chain and the chain will be sent out by the rotation of the sprocket, so the full load of the opening / closing door suspended on the chain will be applied to the obstacle. Therefore, a great impact is given, which is not preferable.

  Moreover, in this embodiment, since the clutch mechanism (6) is incorporated in the connecting shaft (43) that connects the wire pulleys (42) and (42) on both sides, for example, the clutch mechanism (6) and the wire pulley (42) ), The power transmission mechanism such as a chain or a sprocket can be omitted, the number of parts can be reduced, the structure can be simplified, and the cost can be reduced.

  Further, in this embodiment, after the door (3) is urgently stopped by the obstacle detection, the emergency descent is prohibited, so that the door (3) is automatically operated while the obstacle is left unattended. It is possible to reliably prevent a deficiency such as a descent. Furthermore, if the open / close door (3) is lowered manually to the lowest end and the limit switch (76) is pushed, the emergency descent prohibited state can be canceled and the normal state (emergency descent possible state) can be restored. A fume hood can be used. In the present embodiment, a return switch (reset switch) may be provided in the hood body (2) or the like, and the emergency descent prohibited state may be canceled by pressing the switch.

  In the present embodiment, when the obstacle (X) is detected when the open / close door (3) is forcibly lowered, an alarm sound is generated. Can grasp that there is a defect such as carelessly leaving the obstacle (X), and can quickly and accurately take measures against the defect such as removal of the obstacle (X).

  Furthermore, in this embodiment, when the open / close door (3) is fully closed, the projector (71) and the light receiver (72) projecting from the lower end of the door are stored inside the air foil (26), and the door Since the entire lower end is securely joined to the surface (upper surface) of the air foil (26), the front opening (21) can be reliably closed by the open / close door (3) when fully closed, resulting in problems such as leakage of polluted gases. Can be more reliably prevented.

  In the above embodiment, the obstacle detection means is constituted by a transmissive light beam sensor constituted by a projector and a light receiver. However, the present invention is not limited to this, and in the present invention, as the obstacle detection means, For example, a photoelectric switch such as a mirror reflective photoelectric sensor that detects an obstacle using reflected light from a mirror, a direct reflection photoelectric sensor that detects an obstacle using reflected light from an obstacle, or the like may be used. good.

  The fume hood of the present invention can be used when an experiment or the like is performed in a laboratory or a laboratory.

It is a perspective view which shows the fume hood which is embodiment of this invention. It is a perspective view for demonstrating the forced fall operation | movement of the door in the fume hood of embodiment. It is a perspective view for demonstrating the emergency stop operation | movement of the door in the fume hood of embodiment. It is a top view which shows the fume hood of embodiment. It is a top view which expands and shows the drive part of the fume hood of embodiment. It is a front view which shows the door lower end part in the fume hood of embodiment. It is a front view which expands and shows the obstacle detection sensor periphery of the door lower end part in the fume hood of embodiment. It is a front view which expands and shows the one side of the door lower end part in the door fully closed state in the fume hood of embodiment. It is a side view which expands and shows the door lower end part in the door fully closed state in the fume hood of embodiment.

Explanation of symbols

2 Hood body 21 Front opening 26 Air wheel 3 Open / close door 41 Wire pulley 42 Wire pulley 43 Connection shaft 44 Wire 45 Balance weight 5 Electric motor (door drive means)
6 Clutch mechanism 7 Obstacle detection sensor (obstacle detection means)
71 Emitter 72 Receiver 76 Limit switch (return switch)
X obstacle

Claims (7)

A fume hood provided with a hood main body provided with a work space inside, and a vertical sliding door that opens and closes the front opening of the hood main body, which can be stopped at any sliding position,
Door driving means for driving the open / close door in a descending direction;
In the state where the open / close door is opened, when there is no worker in the vicinity, forced lowering means for forcibly lowering the open / close door by driving the door driving means,
Obstacle detection means configured to detect an obstacle that is configured by a photoelectric switch provided at a lower end of the opening and closing door and is disposed at a lowering destination when the opening and closing door is forcibly lowered;
An emergency stop means for urgently stopping the open / close door by stopping driving of the door drive means when an obstacle is detected based on information from the obstacle detection means during the forced lowering of the open / close door; With
The obstacle detection means is provided on the opening / closing door so as to protrude downward,
An airfoil is provided with which the lower end of the door in the fully closed state comes into contact;
The fume hood characterized in that the obstacle detecting means is stored below a contact surface of the air wheel with the lower end of the open / close door when the open / close door is fully closed .   The obstacle detecting means includes a projector provided on one side of the lower end of the door and a light receiver provided on the other side of the lower end, and a detection beam projected from the projector to the light receiver. The fume hood according to claim 1, wherein the fume hood is configured by a transmission type photoelectric sensor configured to detect an obstacle by blocking. A clutch configured to be switchable between a connected state in which the driving force from the door driving means is transmitted to the open / close door and a cut-off state in which the transmission is blocked, and is set to a connected state when the open / close door is forcibly lowered. Equipped with a mechanism
3. The fume hood according to claim 1, wherein the emergency stop unit is configured to switch the clutch mechanism to a disengaged state after stopping the driving of the door driving unit when the door is emergency stopped. 4. A pulley rotatably provided on the upper portion of the hood main body and rotated by a driving force of the door driving means;
A wire erected on the pulley, and the opening / closing door is suspended at one end;
A balance weight that is suspended at the other end of the wire and that balances the weight of the open / close door and stops the open / close door at an arbitrary slide position,
While the wire and the pulley are configured to be interlocked by frictional force,
4. The structure according to claim 1, wherein when the pulley is rotated by a driving force of the door driving unit, the balance weight is lifted through the wire and the opening / closing door is lowered. 5. Fume hood.   The fume hood according to any one of claims 1 to 4, wherein a surface velocity of air introduced from an opening portion of the front opening is kept constant regardless of an opening degree of the front opening by the opening / closing door. A forced lowering prohibiting means for prohibiting the forced lowering of the open / close door by the forced lowering means after the emergency stop means emergency stop the openable door;
The return switch which cancels the state where forced descent was prohibited by the forced descent prohibition means, and returns to the state where an emergency stop by the emergency stop means is possible is provided. Fume hood. An alarm sound generator for generating an alarm sound,
If the obstacle based on the information from the obstacle detecting means is detected, a warning sound generating means for generating an alarm sound by the warning sound generator, to any one of claims 1 to 6 with a The fume hood described.

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