JPH0824673A - Elevating and lowering mechanism for observation door of fume hood - Google Patents

Abstract

PURPOSE:To conduct experiments safely and smoothly by installing a drive means for driving the rotation of a detection means for detecting the presence of a person, a switch means with a timer, and a sprocket and a lower limit switch means for stopping the drive means. CONSTITUTION:The elevating and lowering mechanism for an observation door 17 of a fume hood is equipped with a detection means 22 for detecting the presence of a person, a switch means with a timer which is turned on after a specified time when the detection means 22 detects the absence of a person and turned off immediately when the presence of a person is detected, and a drive means 25 for driving a sprocket 26 through a clutch means 27 which is directly connected with the sprocket 26 when the switch means is turned or and released from the sprocket 26 when the switch means is turned off. A chain is set at the positions of wires 18, 19 which correspond at least to the length of the vertical stroke of the observation door 17, and the drive of the drive means 25 is stopped by a lower limit switch means 30 in relation to the position of the chain 28 when the observation door 17 is brought down automatically to a specified position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fume hood capable of maintaining a constant surface speed at the work opening regardless of the opening of the observation door, and the work opening formed at the front thereof. The present invention relates to an elevating mechanism for an observation door of a fume hood that can be automatically closed only when there is no operator in the observation door provided in the section.

[0002]

2. Description of the Related Art A fume hood (including a draft chamber) is a device installed based on a standard set in advance in a chemical laboratory in order to ensure the safety and health of workers. It is intended to be used to efficiently discharge offensive odors and harmful gases generated by various chemical experiments conducted indoors to the outside of the laboratory without leaking and diffusing into the laboratory through the work openings provided on the front surface. There is.

With regard to the fume hood used for such a purpose, it is necessary to keep the inside of the processing chamber at a negative pressure state in order to prevent leakage of a foul odor or harmful gas into the laboratory. While taking air into the processing chamber, it can be discharged to the outside together with foul odors and harmful gases.

On the side of the work opening provided on the front surface of the processing chamber, an observation door is provided so that it can be raised and lowered so that its opening can be freely changed. The opening area of the working opening can be adjusted by the lifting position of the.

By the way, in the fume hood and the like, the surface speed of the working opening should be maintained at a predetermined value according to the type and amount of the chemicals defined by the Industrial Safety and Health Act. In order to meet such a requirement, the observation door can always be stopped at a fixed position (half-open state with an opening of 1/2) and the opening area of the working opening is fixed. It is now possible to satisfy a legal requirement by always ensuring a constant surface wind speed in relation to the fixed opening area.

In addition to the above-mentioned prior art, as disclosed in, for example, Japanese Utility Model Publication No. 3-9792, the working opening is controlled by controlling the rotation speed of the exhaust fan according to the opening of the observation door. There has already been proposed a technique for keeping the surface speed of the above-mentioned constant, so as to satisfy the legal requirement stipulated by the Industrial Safety and Health Law.

On the other hand, from the viewpoint completely different from the above-mentioned prior art, the applicant of the present invention changes the exhaust amount, that is, if the opening of the observation door is large, the exhaust amount is large, and if the opening is small, the exhaust amount is small. By reducing the displacement, the surface speed of the work opening is always constant (for example, 0.5 m / irrespective of the opening of the observation door).
s) to ensure a safe exhaust and reduce the total amount of conditioned air taken in through the work openings to achieve an excellent energy saving effect. We are developing a variable fume hood.

FIG. 4 shows an example of the overall construction of the variable air volume type fume hood. The work surface 2 in the main body 1 is shown in FIG.
The processing chamber 3 partitioned and formed above has a working opening 4 formed in the front surface thereof, and the working opening 4 depends on the degree of opening of the observation door 5 that can be moved up and down. The opening area can be freely adjusted.

The surface speed control system mounted on the fume hood comprises a wind speed measuring sensor 7, a volume damper 9 and a safety exhaust warning device 10 which are interconnected via a control box 6. Has been done.

In this case, the wind velocity measuring sensor 7 is arranged through the through hole 8 which communicates the processing chamber 3 with the laboratory, and the slow air velocity passing through the through hole 8 is measured. That is, assuming that the exhaust volume is constant, when the opening degree of the observation door 5 is small, the negative pressure state in the processing chamber 3 is increased and the surface speed of the working opening 4 is increased. By measuring the air velocity under the correspondence relationship that the air velocity passing through the hole 8 also becomes faster, the wind velocity equivalent to the surface velocity of the working opening 4 can always be detected.

Further, the wind speed data detected by the wind speed measuring sensor 7 is processed through the control box 6, and the exhaust amount of the volume damper 9 is adjusted to a predetermined value which is preset based on the wind speed data. Therefore, the surface speed of the working opening 4 can be kept constant.

On the other hand, for example, the volume damper 9 cannot adjust the displacement according to the set value for some reason, and the surface speed of the working opening 4 is a safe wind speed (0.5 m / s).
When it is significantly lower or higher than, the wind speed measurement sensor 7 detects this, activates the safety exhaust warning device 10 via the control box 6, and informs the researcher etc. of the occurrence of an abnormal situation with an alarm sound or a blinking lamp. I can inform you.

[0013]

By the way, according to the variable air volume type fume hood developed by the present applicant, if the opening of the observation door 5 is large, the exhaust amount is large and the opening is small. For example, by reducing the exhaust volume, the surface speed of the working opening 4 is always kept constant regardless of the opening of the observation door 5, and the air conditioning is taken in from the working opening 4 during the experimental work. Since the total amount of air can be reduced as a result,
It is possible to secure a safe exhaust and also obtain an excellent energy saving effect.

However, in the case of the variable air volume type fume hood, the surface speed of the working opening 4 can always be kept constant according to the size of the opening of the observation door 5, but in the laboratory. It is unavoidable that the conditioned air of is taken in and discharged to the outside of the room.

In particular, a researcher or the like who is performing an experimental work usually does not open the observation door 5 when it is necessary to leave the fume hood for a while, without opening the observation door 5 completely. There are many examples of leaving the seat in the open state.

Therefore, in the case of using the fume hood, while the researcher or the like is abandoned after interrupting the experiment work,
The conditioned air in the laboratory is taken in through the work opening 4,
Since it is always discharged to the outside of the room, the air conditioning effect in the laboratory is reduced as a result, and the costly air-conditioned air is wasted, so there is still a demand for energy saving. There was a problem that could not be completely answered.

[0017]

The present invention has been made in view of the above problems found in the prior art. Among them, the structural feature of the invention of claim 1 is that the work surface in the main body is Observation in which the work opening provided on the front side of the defined processing chamber is supported by a balance weight having the same weight via a wire and the work opening can be freely opened and closed. A fume hood, which includes at least a door and is configured to always maintain a constant surface speed in the work opening regardless of the opening of the observation door, and detects the presence / absence of a person near the work opening. And a timer-equipped switch means for turning on the switch after a lapse of a predetermined time when the unattended state is detected by the detection means, and for immediately turning off the switch when the unmanned state is detected, and the timer-equipped switch. hand Is connected directly to the sprocket when turned on, and is released when turned off.Provided with driving means for rotating the sprocket through the clutch means, which corresponds to at least the lifting stroke of the observation door in the wire. A chain having a meshing relationship with the sprocket is interposed at a portion of the length to be driven, and the drive means is driven in relation to the chain position when the observation door is automatically lowered to a predetermined position. The lower limit switch means for stopping is provided.

Further, according to the second aspect of the present invention, the drive of the drive means is controlled in the vicinity of the contact portion with the observation door when the main body is fully closed, along the length direction thereof. There is a tape switch attached.

[0019]

Therefore, according to the first aspect of the invention, the manned state is always detected by the detecting means while the researcher or the like continues to perform the experimental work in the vicinity of the working opening of the fume hood. Therefore, the switch means with timer does not maintain the off state to drive the drive means, and at that time, the clutch means releases the direct connection state between the sprocket and the drive means. Since it operates like this, researchers can continue the experiment work while keeping the observation door in the original opening state, and can freely move the observation door up and down as desired. It is possible to carry out experiment work safely and smoothly.

On the other hand, during experiment work, when a researcher or the like separates from the fume hood side under the condition that the observation door is raised to open the work opening, the detection means detects the unmanned state. Then, based on this detection signal, the timer-equipped switch means starts clocking, the switch is turned on after a preset predetermined time has elapsed, and the drive means starts driving.

When the drive means starts to drive, the clutch means simultaneously operates in the direction to directly connect the sprocket and the drive means, so that the sprocket is also driven to rotate, and thus includes the chain in mesh with the sprocket. The wire also moves in the direction to forcibly pull up the balance weight, and as a result, the observation door side starts to descend due to its own weight.

Moreover, since the lower limit switch means is provided which operates in relation to the chain position when the observation door is automatically lowered to a predetermined position, the drive means is released from the drive by the operation of the lower limit switch means. As a result, the observation door stops descending under the condition that the working opening is automatically closed, and the conditioned air in the laboratory is effectively taken in and exhausted from the working opening. Can be stopped.

Further, even if the detecting means detects an unmanned state and the timer starts counting the elapse of a predetermined time set in advance, the researcher or the like returns to the vicinity of the working opening before the elapse of the predetermined time and detects it. When it is detected again that the means is in the manned state, the timer-equipped switch means is immediately turned off, so that the drive means does not start driving, and at that time, the clutch means becomes a sprocket. Since it operates so as to release the direct connection with the driving means, the researchers can restart the experiment work while keeping the observation door at the original opening state, or manually if desired. Since the observation door can be freely moved up and down, the experiment work can be performed safely and smoothly.

According to the second aspect of the invention, since the tape switch is attached near the contact portion with the observation door when the main body is fully closed, some object is placed on the tape switch. In that case, the tape switch is turned off due to its weight, and it is possible to control so that the driving means is turned off to stop the lowering of the observation door.
It is possible to carry out the experiment work more safely.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is an overall perspective view illustrating the outline of the external configuration of a fume hood to which the present invention is applied.
The processing chamber 13 defined on the work surface 12 in 1 has a working opening 14 formed on the front surface thereof. The working opening 14 is a pair of standing members arranged on the left and right sides of the main body 11. The opening area of the observation door 17, which is arranged so as to be able to move up and down along the side plate portions 15, 15, can be freely expanded and contracted. In addition, reference numeral 1 in the drawing
0 indicates the safety exhaust warning device 10 as in FIG.

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. In the main body 11, one wire 18 and one wire 19 are erected on both left and right sides of the main body 11 via pulleys 20. One ends 18a and 19a of the wires 18 and 19 are the main body 11
At the observation door 17 located on the front side of the
b and 19b have the same weight as the observation door 17 and are directly connected to the balance weights 21 located on the rear surface side of the main body 11.

For this reason, the observation door 17 is arranged to be movable up and down on the side of the main body 11 in a state where it can be stopped not only at the opening and closing of the working opening 14 but also at an arbitrary position. .

Further, as shown in FIG. 3, in the front side plate portion 16 of the main body 11 located above the working opening portion 14,
A detection means 22 for detecting the presence or absence of a person such as a researcher near the work opening 14 is provided. In this case, as the detecting means 22, an infrared sensor type of detecting the heat generated by the human body can be preferably used.
Various types such as a visible light sensor type such as a photo sensor and a magnetic sensor can be properly used according to need. The observation door 1 when the main body 11 is fully closed
It is desirable that a tape switch 36 be additionally provided along the length direction on the air foil 35 located near the contacting portion with 7, so that the drive control of the drive means 25 can be performed.

Further, in the electric box (not shown) installed in the lower stand 24 of the main body 11, the detecting means 22 is provided.
Is equipped with a timer-equipped switch means (not shown) that turns on the switch when a predetermined time elapses after detecting the unmanned state and turns off immediately when the manned state is detected. It is set up.

The timer-equipped switch means sets the timer to an appropriate time so that the elapsed time until the switch is turned on after the detection means 22 detects the unmanned state is arbitrarily long. It can be set to any one.

On the other hand, on the back surface of the main body 11, as a drive source for moving the other end 19b of the wire 19 directly connected to the balance weight 21 in the direction of forcibly pulling, for example, an induction motor or the like. Is provided with the driving means 25.

In this case, the drive means 25 is provided with a sprocket 26 which is connected so as to be driven by the rotation shaft thereof. The sprocket 26 and the drive means 25 are connected to each other.
The clutch means 2 having an appropriate structure, such as an electromagnetic clutch, is directly connected when the timer-equipped switch means is turned on, and is released from the direct-connection state when turned off.
By interposing 7, the contact and separation of both 26, 25 are freely controlled and connected to each other.

Moreover, on the wire 19 side, the chain 28 is interposed at a position where a meshing relationship is maintained between the wire 19 and the sprocket 26 at least under the length corresponding to the lifting stroke of the observation door 17. The whole is formed.

In the vicinity of the chain 28 interposed by the wire 19, lower limit switch means for stopping the drive of the drive means 25 in relation to the position of the chain 28 when the observation door 17 is automatically lowered to a predetermined position. 30 are provided.

Lower limit switch means 30 in this case
As shown in FIG. 2, for example, the main limit switch 31 is arranged along the moving direction of the chain 28 forcibly pulling the side of the other end 19b directly connected to the balance weight 21,
The auxiliary limit switch 32 and the auxiliary limit switch 32 are vertically arranged at a predetermined interval on a column portion 34 erected on the base portion 33, and a protruding piece 29 fixedly arranged at a predetermined position of the chain 28 is attached to the operating piece 31a or 32a. It can be formed so as to be turned off when it comes into contact, or can be formed by a photoelectric switch, a proximity switch, or the like.

Since the present invention is configured in this way, according to the invention of claim 1, while a researcher or the like continues to carry out experimental work in the vicinity of the working opening 14 in the fume hood. , The detection means 22 always detects the manned state, and therefore the switch means with a timer can keep the off state, so that the driving means 25 is not driven.

Moreover, when the detecting means 22 detects a manned state, the clutch means 27 including an electromagnetic clutch is used.
Can freely rotate the sprocket 26 by releasing the direct connection between the sprocket 26 and the driving means 25. In addition to continuing the work, the observation door 25 can be freely moved up and down manually as desired, so that the experiment work can be performed safely and smoothly.

On the other hand, during the experimental work, when a researcher or the like separates from the fume hood side under the condition that the observation door 17 is raised and the working opening 14 is opened, for example, the detection means 22 is If it is formed by an infrared sensor, infrared rays will not be detected and an unmanned state will be detected unless there is a reflecting object including a human being.

When the unmanned state is detected by the detecting means 22 in this way, the timer-equipped switch means starts timing based on the detection signal at that time.

In this case, the timer-equipped switch means is set so that the switch is turned on and the driving means 25 is driven after a preset predetermined time has elapsed, so that the predetermined time at that time elapses. Drive means 2
5 will start driving.

When the driving means 25 starts driving in this way, the clutch means 27 operates simultaneously in the direction in which the sprocket 26 and the driving means 25 are directly connected, so that the driving force from the driving means 25 is applied. Will be forcibly driven to rotate.

Therefore, as a result of the chain 28 in meshing relation with the sprocket 26 moving in the direction to forcibly pull up the balance weight 21, as a result, the balance weight is passed through the wire 19 including this chain 28 and the other wire 18. The side of the observation door 17 connected to 21 starts to descend due to its own weight.

Moreover, when the observation door 17 is automatically lowered to a predetermined position, the projection piece 29 provided on the chain 28 comes into contact with the operating piece 31a of the main limit switch 31a constituting the lower limit switch means 30. Switch off,
The drive means 2 is operated by the operation of the lower limit switch means 30 side.
The drive of No. 5 is released, and the sprocket 26 is also stopped from rotating.

As a result, the observation door 17 has the work opening 1
4 is automatically closed and the descent is stopped. Therefore, when a researcher or the like leaves the work opening 14 for a predetermined time or longer, the conditioned air in the laboratory is wasted from the work opening 14. The uneconomical situation of being taken in and discharged to the outside of the room can be effectively prevented.

Further, even if the detecting means 22 detects the unmanned state and the timer starts to count the elapse of a predetermined time set in advance, the researcher or the like returns to the vicinity of the working opening 14 before the elapse of the predetermined time. When the detecting means 22 detects again that the manned state is present, the timer-equipped switch means is immediately turned off, so that the driving means 25 does not start driving.

Moreover, at this time, since the clutch means 27 operates so as to release the direct connection state between the sprocket 26 and the drive means 25, the researcher or the like has set the observation door 17 in the initial opening state. The experiment work can be resumed without changing the state, and the observation door 17 can be freely moved up and down as desired, so that the experiment work can be safely and smoothly performed.

According to the second aspect of the invention, since the tape switch 36 is attached on the air wheel 35 located near the contact portion with the observation door 17 when the main body 11 is fully closed, The tape switch 36 is turned off by sensing the weight when an object is placed on the tape switch 36, and as a result, the driving means 25 is turned off and the observation door 17 is automatically lowered. Therefore, even when the detecting means 22 detects that the observer is unmanned, the automatic lowering of the observation door 17 can be prevented and the experiment work can be performed more safely.

[0048]

As described above, according to the first aspect of the present invention, while a researcher or the like continues to perform an experimental work in the vicinity of the working opening in the fume hood, Since the detection means always detects the manned state, the timer-equipped switch means is not kept in the off state and the driving means is not driven, and at that time, the clutch means is the sprocket and the driving means. Since it operates so as to release the direct connection between the observation door and the researcher, the researcher etc. can continue the experiment work while keeping the observation door in the original opening state, and manually open the observation door if desired. Since it can be raised and lowered freely, it is possible to carry out the experiment work safely and smoothly.

On the other hand, during the experiment work, when the researcher or the like separates from the fume hood side under the condition that the observation door is raised to open the work opening, the detecting means detects the unmanned state. Then, based on this detection signal, the timer-equipped switch means starts clocking, the switch is turned on after a preset predetermined time has elapsed, and the drive means starts driving.

When the driving means starts driving, the clutch means actuates simultaneously in the direction to directly connect the sprocket and the driving means, so that the sprocket is also rotationally driven and therefore includes the chain in mesh with the sprocket. The wire also moves in the direction to forcibly pull up the balance weight, and as a result, the observation door side starts to descend due to its own weight.

Moreover, since the lower limit switch means is provided which operates in relation to the chain position when the observation door is automatically lowered to the predetermined position, the drive means is released from the drive by the operation of the lower limit switch means. As a result, the observation door stops descending under the condition that the working opening is automatically closed, and the conditioned air in the laboratory is effectively taken in and exhausted from the working opening. Can be stopped.

Further, even if the detecting means detects an unmanned state and the timer starts to measure the elapse of a predetermined time set in advance, the researcher or the like returns to the vicinity of the working opening before the elapse of the predetermined time, and the detection is performed. When it is detected again that the means is in the manned state, the timer-equipped switch means is immediately turned off, so that the drive means does not start driving, and at that time, the clutch means becomes a sprocket. Since it operates so as to release the direct connection with the driving means, the researchers can restart the experiment work while keeping the observation door at the original opening state, or manually if desired. Since the observation door can be freely moved up and down, the experiment work can be performed safely and smoothly.

According to the invention of claim 2, the effect of the invention of claim 1 can be obtained, and at the same time, a tape switch is provided near the contact portion with the observation door when the main body is fully closed. Therefore, if any object is placed on the tape switch, the weight of the tape switch causes the tape switch to turn off, and the drive means can be turned off to stop the observation door from descending. Because you can
It is also possible to carry out the experiment work more safely.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory view of a principal part showing an enlarged part of a driving unit in FIG.

FIG. 3 is an overall perspective view illustrating the appearance of a fume hood to which the present invention is applied.

FIG. 4 is an explanatory diagram showing an example of the overall configuration of a variable air volume type fume hood in which the lifting mechanism according to the present invention can be suitably mounted.

[Explanation of symbols]

 11 Main Body 12 Working Surface 13 Processing Chamber 14 Working Opening 15 Side Plate 16 Front Plate 17 Observation Doors 18, 19 Wires 18a, 19a One Ends 18b, 19b Other Ends 20 Pulley 21 Balance Weight 22 Detection Means 24 Lower Stand 25 Drive Means 26 Sprockets 27 Clutch Means 28 Chains 29 Projection Pieces 30 Lower Limit Switch Means 31 Main Limit Switches 31a Actuating Pieces 32 Auxiliary Limit Switches 32a Actuating Pieces 33 Bases 34 Struts 35 Air Wheels 36 Tape Switches

Claims (2)

[Claims] 1. A balance weight having a weight equivalent to that of a work opening provided on the front side of a processing chamber defined on the work surface in the main body and supported by a wire through a wire. A fume hood, which is provided with at least an observation door in which the opening and closing of the opening can be freely opened and closed, and in which the surface speed in the work opening is always kept constant regardless of the opening of the observation door. Detecting means for detecting the presence / absence of a person in the vicinity of the work opening, and when the detecting means detects an unmanned state, the switch is turned on after a predetermined time has passed,
A timer-equipped switch means that is immediately turned off when a manned state is detected, and a clutch means that is directly connected to the sprocket when the timer-equipped switch means is turned on and that is released when turned off. A drive means for rotating the sprocket interveningly, and at least a portion of the wire having a length corresponding to a lifting stroke of the observing door has a chain intervening between the chain and the sprocket. An elevating mechanism for an observation door of a fume hood, which is provided with a lower limit switch means for stopping the driving of the drive means in relation to the chain position when the observation door is automatically lowered to a predetermined position. 2. A tape switch for controlling the drive of the drive means is attached along the length of the main body in the vicinity of the contact portion with the observation door when the main body is fully closed. Item 1. A lifting mechanism for an observation door of a fume hood according to item 1.