JPH01182481A - Intermediate stop device for door and draft chamber - Google Patents

Abstract

PURPOSE: To eliminate the possibility of leaving a door unlocked, simplify the structure of the door and door attaching work and improve safety by positioning the stopping section of a stopping piece at a locking position by its self weight in an normal state and positioning it at an opening position by external force. CONSTITUTION: The intermediate stopping device 22 of a door 16 comprises an engaging section 23 projected frontward from the door 16 provided at one side end of a sash 18 and a stopping piece 24, which is pivotally attached to a position which is nearly the center of an opening in the inside face of the left side plate 19 of a body which is a support body guiding the vertical movement of the door 16 and a position adjacent to a guiding groove 20 through a shaft 25 which faces the right and left side and comprises a set screw 25a and a sleeve 25b. This stopping pieces 24 is positioned at a stopping position where a locking section 32 is projected into the vertical movement locus of the projection 23 of the door 16 due to its self weight in a normal state. In addition, the operation section 33 of the stopping piece 24, when pushed up rearward, turns to a position where the rear section of a through hole 27 abuts on the rear section of the nut 31 of a guide means 28.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention enables a door that moves up and down along the side edge of an opening to be stopped at a required intermediate position or to be allowed to pass through. This invention relates to an intermediate stop device for a sliding door and a draft chamber equipped with this device.

[Conventional technology]

Conventional fume hoods used in chemical laboratories, etc. have openings on the front for work and air intake, and these openings can be opened and closed using a balanced lift door that can be stopped at any height. It has become.

In this type of draft chamber, harmful gases and foul-smelling gases generated inside the draft chamber are passed through the opening to the outside (indoors).
There is a risk of radiation. For this reason, exhaust capacity, duct dimensions, and other conditions are determined so as not to harm the health and safety of experimenters.

In particular, in the case where the door is biased toward the opening, the draft chamber should be set so that the side wind speed at the opening when fully opened is 0.25 m/see, and the controlled wind speed at the opening when half open is 0.5 m/see. It is considered desirable to design

Incidentally, the Industrial Safety and Health Act requires that the controlled wind speed of this opening be set to a predetermined value depending on the content of the work.

In order to satisfy such practical and legal requirements, it is preferable to provide a stop device that allows the door to open to a predetermined degree, for example, 1/2 (half open). .

As a conventional intermediate stop device for this type of door, a chain or cable is stretched between the door and the side plate of the draft chamber, and when the door opens to a predetermined opening degree, the chain or cable, etc. If you are nervous and want to prevent the door from opening any further, or if you want to fully open the door to bring equipment into or out of the chamber, tie one end of the chain or strip, etc. Some are designed to be removed from the door or side panel.

In addition, a stop lever is provided on the side plate of the chamber so as to be slidable in the front-rear direction, and the tip of the stop lever is made to protrude into the movement trajectory of the door, so that a part of the door comes into contact with the tip of the stop lever. Some are designed to prevent the door from opening further.

[Problem to be solved by the invention]

When the above-mentioned chain is used, there is a risk of forgetting to attach the chain, and when the door is fully opened, the chain hangs down in front, which is unsightly.

Furthermore, not only when the chain is hanging down, but also when it is under tension, there is a risk that the worker's arm or clothes may get caught in the chain. In addition, chains and ropes
There is also a risk of breakage due to aging or overload.

In the case where a stop lever is used, there is a risk of forgetting to push the stop lever into the movement trajectory of the door when necessary, and the structure is complicated and installation is troublesome.

The present invention has been made in view of the problems of the prior art, and its purpose is to reduce the risk of forgetting to hang it, and to provide an extremely simple structure and installation work. The object of the present invention is to provide an intermediate stop device for a door that is easy to implement and has high safety. , and a door that moves up and down along the side edge of the opening of the housing.

An engaging part provided on the door that protrudes laterally is pivotally attached to the side edge of the opening of the casing with a substantially horizontal axis, and the engaging part protrudes into the vertical locus of the engaging part. It has a locking part that prevents either one of the upward and downward movements of the engaging part and allows the other movement, and when no external force is applied, the locking part moves due to its own weight. A locking position in which the engaging part enters the vertical locus of the engaging part is taken, and the locking part is rotated about the axis by an external force to an open position laterally away from the vertical locus of the engaging part. It is equipped with a stop piece adapted to be able to be rotated.

The stop piece can be a simple plate.

For example, the stop piece is made of a trapezoidal plate whose upper and lower end surfaces are approximately horizontal, the front end surface is approximately vertical, and the rear end surface is inclined rearward downward. It can be pivotally connected to the housing with the.

In addition, the stop piece is made of a plate material consisting of a fan-shaped upper half that expands upward around the pivot part, and a lower half that has a weight attached to the lower end of the hanging part that hangs down from the pivot part, In addition, one corner of the fan shape in the upper half can be used as a locking part.

The stop piece is preferably provided with an operating part for rotating the stop piece to the open position.

The engaging portion that protrudes laterally from the door may be a door sash.

Further, in the present invention, in addition to the above-mentioned door-side engaging portion and stop piece, the stop piece is provided with a through hole parallel to the axis, and the through hole is provided with a hole protruding from the housing. The guide means, which has a head larger than the through hole at its tip, is passed through the guide means with enough play to allow the stop piece to rotate between the locking position and the release position, thereby allowing the stop piece to rotate. It is best to guide the movement smoothly.

Furthermore, an engaging portion similar to that described above is provided on the housing side.

Further, even if a stop piece similar to that described above is provided on the door side, similar actions and effects can be produced.

[For production]

According to the intermediate stop device for a door of the present invention, the stop piece is always located at the locking position due to its own weight, and the locking portion projects into the relative vertical movement locus of the protrusion.

Therefore, in this state, the door cannot be raised or lowered.
When moving in one direction, the engaging part contacts the locking part of the stop piece during the movement, and the stop piece is interposed between the engaging part and the shaft of the stop piece in a stretched state. This prevents the door from moving in one direction.

In addition, when moving the door in the other direction opposite to the above-mentioned state in this state, the engaging part contacts the locking part of the stop piece during the movement, and the stop piece moves to the open position around the axis. By being rotated in this direction, the engaging part can freely pass through the stop piece, and the movement of the door in this direction is not hindered by the abutment between the engaging part and the stop piece.

After the engaging portion passes through the stop piece, the stop piece automatically returns to the locking position again due to its own weight, and then prepares for an intermediate stop when the door moves in the one direction.

When moving the door in one direction as described above, if you want to move the door to its maximum limit without stopping it at an intermediate position, by rotating the stop piece to the open position,
Move the locking part to a position where it does not interfere with the engaging part,
The door may be moved in one direction while maintaining this state. Then, the door can be moved to its maximum limit without the engaging portion and the stop piece coming into contact with each other.

After the engaging portion passes the side of the stop piece, when the user releases the stop piece, the stop piece returns to the locking position due to its own weight.

〔Example〕

FIG. 5 shows an example of a draft chamber for biasing the intermediate stop device of the door according to the first embodiment of the present invention.

The configuration of the draft chamber itself is not directly related to the present invention and may be any known configuration, so only the parts related to the present invention will be explained with emphasis, and the other parts will be briefly explained. .

The draft chamber (1) has a storage compartment (
2) and a rear space (3) as a space for connecting various pipes; a base (4) that is placed on this base (4) and has an opening (5) in the front. The main body, which is the casing (
6) It consists of.

The rear lower part of the opening (5) is a workbench (7).
On the workbench (7) are a gas pipe connection port (8) and a water supply pipe (
9), a discharge port (10), etc. are provided.

There is an operation panel (11) on the lower front side of the workbench (7) (8).
), and the operation panel (11) is provided with a gas operation handle (12), a water supply operation handle (13), an electric control panel (4), etc.

An upward duct (15) having an intake port (15a) at the bottom is provided at the rear of the main body (6).
) is connected to an upwardly facing exhaust port (isb).

A blower (not shown) is connected to the duct (15), and air flows into the main body (6) through the opening (5).

Air mixed with harmful gases etc. generated from various experimental equipment (not shown) on the workbench (7) is sucked upward as shown by the arrow by the exhaust fan and exhausted from the exhaust port (j5b). Ru.

The flow rate of air flowing into the main body (6) from the opening (5) is
An elevating door (16) that can open and close the opening (5) is provided to maintain a predetermined optimum value and to transport various experimental equipment, etc., in and out as necessary. ing.

The door (16) has a sash (18) fixed to the lower end of a transparent glass plate (17), which also serves as a handle.

Both side ends of the glass plate (17) are connected to both side plates (
19) A guide groove (
20).

The door (16) is balanced with a balance weight or a lifting coil spring (not shown), and when the door is released from the door at an arbitrary position, it will stop at that position.

(21) is provided above the glass plate (17), and the door (
As the door (16) approaches the fully open position, the ventilation control plate is designed to open gradually as the door (16) approaches the fully open position. (6) is for bypassing. Since the interlocking mechanism between the ventilation adjustment plate (21) and the door (16) is well known, illustration and description thereof will be omitted.

(22) shows an intermediate stop device according to the present invention.

Ji (16) is stopped in the middle at the optimum opening degree of the door (16) during the experiment, for example, 1/2 opening degree.

As clearly shown in FIGS. 1 to 4, the intermediate stop device (22) is a 7B (
an engaging portion (23) protruding forward from i(1
6), which is a support body for guiding the vertical movement of , a stop piece (24) pivotally mounted with a shaft (25) facing in the left-right direction and consisting of a set screw (25a) and a sleeve (25b).
It consists of

The stop piece (24) has an upper end surface (24a) and a lower end surface (24
b) is substantially horizontal, the front end surface (24c) is substantially vertical, and the rear end surface (24d) is inclined rearward and downward, so that the side surface is trapezoidal and is made of a hard synthetic resin or metal plate.

At the rear upper part of the stop piece (24) is a shaft hole (26) through which the shaft (25) passes, and also at the center is a through hole (27) parallel to and larger in diameter than the shaft hole (26). ) are drilled in each case.

(28) is a guide means for guiding the stop piece (24) so that it can smoothly rotate over a desired range, which will be described later, about the shaft (25), and is configured to freely pass through the first through hole (27). Set screws (2) protruding from key points on the inner surface of the side plate (19).
9) and has a larger outer diameter than the through hole (27) to form a large diameter head, and is externally fitted onto the set screw (29) so as to be able to come into sliding contact with the inner surface of the stop piece (24). The through hole (27) has a washer (30) that has a thickness that is approximately half the thickness of the stop piece (24) and has an outer diameter smaller than the inner diameter of the first through hole (27). It consists of two nuts (31) that are screwed into the setscrew (27) inside.

Thus, when no external force is applied to the stop piece (24), the stop piece (24) closes in the through hole (2) as shown in FIGS.
7) is almost concentric with the set screw (29), and the locking part (32) formed by the rear lower part is pushed into the locking position where the protrusion (23) of the door (16) enters the vertical trajectory. It comes to a standstill.

Further, as shown in FIG. 3, when the operating part (33) formed by the front upper part is pushed up rearward and upward, the locking part (32) moves away from the upward and downward locus of the engaging part (23), and
The rear part of the through hole (27) is connected to the nut (3) of the guide means (28).
It can be rotated to the open position where it abuts the rear part of 1).

Since the fan intermediate stop device (22) of the first embodiment has the above-described configuration, when the door (16) is raised from the fully open position to the intermediate position, the engaging portion (23) moves to the stop position. The stop piece (24) comes into contact with the locking part (32) of the stop piece (24) which is stationary, and the stop piece (24) is interposed between the engaging part (23) and the shaft (25) in a stretched state. . Therefore, the door (16) is prevented from rising any further, and the door (16) is stopped at that position (see FIG. 2).

When it is desired to fully open i (16) to carry experimental equipment into or out of the chamber (6), the engaging portion (23) does not interfere with the rotation of the stop piece (24). Lower the door (16) until the door (16) reaches the desired position. Then, as shown in FIG. ) to the open position. In this way, the locking part (32
) is moved forward from the vertical locus of the engaging part (23), and then the door (16) is raised.

Then, the engaging part (23) engages the engaging part (24) of the stop piece (24).
32) and rises behind it without contacting it,
The door (16) can be opened freely to the fully open position.

After the engaging part (23) passes upward behind the locking part (32), when you release your hand from the operating part (33), the stop piece (2
4) automatically returns to the locked position due to its own weight.

When the door (16) is lowered from the fully open position to the fully open position, the engaging portion (23) comes into contact with the intermediate position of the rear end surface of the stop piece (24) that slopes downward, and the stop piece (24) is lowered. 2
4) toward the open position, press the engaging portion (23)
is descending.

When the engaging part (23) passes downward through the locking part (32) of the stop piece (24), the stop piece (24) returns to the locking position due to its own weight, and when the door (16) subsequently rises. Prepare for stopping at an intermediate position.

In this way, 1 (16) can freely lower to the fully open position without being hindered by the stop piece (24).

FIG. 6 shows a second embodiment of the invention.

In addition, in each of the embodiments shown in FIG. 6 and after, the above-mentioned first
Members that correspond to those of this embodiment and other embodiments described below are shown with common reference numerals, and detailed explanations will be omitted.

In the second embodiment, a protrusion (24e) extending upward is provided on the front upper part of the stop piece (24), and this is used as an operation part (33).By pressing with a finger or the like, the stop piece (24) is designed to be easily rotated from the locking position (solid line in Figure 6) to the release position (imaginary line in Figure 6).

The other configurations are the same as those of the first embodiment.

FIG. 7 shows a third embodiment of the present invention.

In the third embodiment, the stop piece (41) is attached to the shaft (25).
A fan-shaped upper half (41a) that expands upward around a pivot joint that is pivotally connected to the side plate (19) (see Figures 1 and 5), and a drooping part that hangs down from the pivot joint. (41b
) with a weight (41c) at the lower end (41d).
), and the fan-shaped rear corner of the upper half (41a) is connected to the locking part (32) and the weight (4
1c) is the operating section (33).

By adopting the configuration of the third embodiment, contrary to the case of the first embodiment, when lowering 1 (16) from the fully open position, the engaging portion (23) is moved as shown by the solid line in FIG. The door can be prevented from further lowering by coming into contact with the locking portion (32) of the stop piece (41) that is stationary at the locking position shown by .

Also, push the weight (41c) which is the operation part (33) with your finger as shown in Fig. 7, rotate the stop piece (41) to the open position shown by the imaginary line in Fig. 7, and then Stop part (32
) can be moved forward from the upward and downward trajectory of the engaging portion (23) to freely lower the door (16) to the fully open position.

When raising the door from the fully open position, the engaging part (23) comes into contact with the locking part (32) of the stop piece (41), and the stop piece (4
1(16) by rotating the engaging part (23) to the rear of the stop piece (41) while rotating the part 1(1) to the open position.
can be freely raised to the fully open position without being hindered by the stop piece (41).

After the engaging part (23) passes behind the stop piece (41), the stop piece (41) automatically rotates back to the locking position due to its own weight, and prevents the door (16) from descending thereafter. Be prepared.

Therefore, in the third embodiment, the direction of the action of stopping the door (16) at the intermediate position is just reversed from that of the first embodiment, and the principle and action of stopping the door (16) are the same as those of the first embodiment. It is the same as that of the example.

FIG. 8 shows a fourth embodiment of the invention.

In the fourth embodiment, a side plate (19) that is a part of the housing
An engaging part (42) is provided on the side, and a stop piece (24) identical to that in the first embodiment is provided on the front surface of the satush (18) of the door (16). By pivoting the door (16) at the intermediate position, the lowering of the door (16) is stopped at an intermediate position, similar to the operation of the third embodiment shown in FIG.
16) should be allowed to rise.

As in the case of the first embodiment, the stop piece (24) is operated as shown by the solid line in FIG. 8 when no external force is applied.

The locking part (32) rests due to its own weight in a locking position where it can come into contact with the engaging part (42), and by pushing up the operating part (33), the locking is performed as shown by the imaginary line in FIG. Part (3
2) is in the open position laterally away from the engaging portion (42).

It can rotate around the axis (25).

In the fifth embodiment shown in FIG. 9, an engaging portion (43) is provided on the side plate (19) side that is a part of the housing, and
) on the front of the satsui (18) of the third embodiment (Fig. 7).
By pivoting the same stop piece (41) with the shaft (25) facing in the front-rear direction, the lifting of the door (16) can be stopped at an intermediate position in the same manner as in the first embodiment. , the lowering of the door (16) may be permitted.

As in the case of the third embodiment, the stop piece (41) is operated as shown by the solid line in FIG. 9 when no external force is applied.

The locking portion (32) rests under its own weight at a locking position where it can come into contact with the engaging portion (43).

In addition, by pushing the operation part (33) clockwise in Fig. 9, the locking part (3
2) can be rotated about the shaft (25) to an open position laterally away from the engaging portion (43).

In each of the embodiments described above, the present invention is applied to a draft chamber, but the present invention can be applied to any device other than a draft chamber as long as it is equipped with a liftable door.

Further, the present invention is not limited to the above-mentioned embodiments, and can be modified in many ways.

〔Effect of the invention〕

According to the present invention, the stop piece normally remains stationary at the locked position due to its own weight, and when a finger or the like is released from the stop piece after being rotated to the open position, it automatically returns to the locked position due to its own weight. .

Therefore, it is possible to eliminate the conventional problems of forgetting to hook the tie or forgetting to move the locking rod to the locking position, thereby improving safety.

Further, the engaging portion and the stop piece can be easily manufactured from a simple plate material, the overall structure is extremely simple, and the installation is easy.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of the essential parts of a draft chamber equipped with a first embodiment of the door intermediate stop device of the present invention, and FIG. 2 similarly shows the state when the door is stopped at an intermediate position. Figure 3 is a vertical side view of the main part, and Figure 3 is a vertical side view similar to Figure 2, showing the state when the stop piece is rotated to the open position. FIG. 5 is a partially vertical perspective view showing the appearance of the draft chamber, and FIG. 6 is a vertical sectional side view similar to FIG. FIG. 7 is a vertical sectional side view similar to FIG. 2, showing the second embodiment, and FIG.
FIG. 2 is a vertical sectional side view similar to FIG. 2, showing the embodiment. FIG. 8 is a front view of the main parts of the fourth embodiment, and FIG. 9 is a front view of the main parts of the fifth embodiment. (1) Draft chamber (2) Storage area (3) Space
(4) Base (5) Opening
(6) Main unit (7) Workbench (8) Gas pipe connection port (9) Water supply pipe (10) Discharge port (1
1) Control panel (12) Gas operation handle (
13) Water supply operation handle (14) Electric control panel (15)
) Rear duct (15a) Intake port (15b) Exhaust port (16) Door (17) Glass plate
(18) Satsushi (19) Side plate (
20) Guide groove (21) Ventilation adjustment plate (22) Door stop device (23) Engagement part (24) Stop piece (24a) Upper end surface (24b) Lower end surface (2
4c) Front end surface (24d) Rear end surface (24e)
Projection (25) Shaft (25a) Set screw
(25b) Sleeve (26) Shaft hole
(27) Through hole (28) Guide means (29
) Set screw (30) Washer (31) Nut (32) Locking part (33) Operation part (41
) Stop piece (41a) Upper half (41b) Hanging part (41c) Weight (41d) Lower half
(42) (43) Protrusion Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Procedure Neho Authorized Letter (Volunteer) March 1986 ll Japanese Patent Office Commissioner Kunio Ogawa 1, of the case Display Patent Application No. 007102 of 1988 2, Name of the invention Intermediate stop device for door and draft chamber 3, Relationship with the case of the person making the amendment Patent applicant name Title Hamilton Industries 4, representative
2 5. Date of amendment order 6. Number of claims increased by amendment 07. Claims column and Detailed description of invention column of the specification to be amended (Contents of amendment ) (1) Page 1, line 5 to page 5, line 9 (Claims) of the specification are corrected as shown in the attached sheet. (2) Delete "It can be done" in line 14 of page 5. (3) ``Electrical control panel (4)'' on page 13, line 2. r Electrical control panel (14) Correct as J. (4) On the bottom line of page 13, "Main body (5)" is corrected to "Main body (6)." (5) On page 14, line 10, "Opening (7)" is corrected to "Opening (5)." (6) On page 15, line 2, "Opening (7)" is corrected to "Opening (5)." (7) "Set screw (27) J" on page 16, line 6 is corrected to "Set screw (29) J." (Summary) (Claims) (1) Side edge of opening of housing a door that moves up and down along a horizontal axis; an engaging part provided on the door that protrudes laterally; The engaging part has a locking part that prevents either the upward or downward movement of the engaging part and allows the other movement by entering the vertical movement trajectory of the engaging part, so that no external force is applied. When, due to its own weight, the locking part assumes a locking position in which it enters the vertical locus of the engaging part, and due to an external force, the locking part moves away from the vertical locus of the engaging part laterally. An intermediate stop device for a door, characterized in that it is provided with a stop piece that can be rotated about the shaft in an open position.(2) Claim (1) wherein the stop piece is made of a hard plate material. ) Intermediate stop device for the door described in (3) The stop piece has a trapezoidal side surface shape in which the upper end surface and the lower end surface are approximately horizontal, the front end surface is approximately vertical, and the rear end surface is inclined rearward downward. The intermediate stop device for a door according to claim 1 or 2, wherein the intermediate stop device for a door is pivotally connected to the support body with a shaft at the upper center, and the lower rear portion serves as a locking portion. (4) Stop piece. The intermediate stop device for a door according to any one of claims (1) to (3), further comprising an operating portion for rotating the locking piece to the open position. The intermediate stop device for a door according to claim (3), wherein the door intermediate stop device is an operating portion for rotating the stop piece to the open position.(6) Claim: wherein the operating portion is a projection extending upward from the front upper part of the stop piece. (4) Intermediate stop device 6 (7) for the door described
The stop piece is made of a plate material having a fan-shaped upper half that expands upward around the pivot part, and a lower half that has a weight attached to the lower end of the hanging part that hangs down from the pivot part. Claim (1) in which one fan-shaped corner of the section is a locking section (
The intermediate stop device for the door described in 1) or (2). (8) The intermediate stop device for a door according to claim (7), wherein the weight serves as an operating part for rotating the stop piece to the open position. (9) The intermediate stop device for a door according to any one of claims (1) to (8), wherein the protrusion projecting laterally from the door is formed by a part of the sash of the door. (10) A door that moves up and down along the side edge of the opening of the housing. and an engaging portion protruding laterally provided on the door. It is pivotally mounted on the side edge of the opening of the housing with a substantially horizontal axis, and enters into the vertical locus of the engaging section, thereby causing either the upward or downward movement of the engaging section. It has a locking part that prevents one movement and allows the other to move, and when no external force is applied, the locking part maintains a locking position where the locking part enters the vertical locus of the engaging part due to its own weight. and by an external force, the locking part can be rotated about the axis to an open position laterally away from the vertical locus of the engagement part, and the locking part can be rotated about the axis parallel to the axis. a stop piece having a hole; and a stop piece protruding from a side edge of the opening of the housing, the stop piece having an amount of play that allows the stop piece to rotate to both a locking position and an open position. An intermediate stop device for a door, characterized in that it is provided with a guide means that extends behind the through hole and has a head larger than the through hole at a tip portion that projects from the through hole. (11) an engaging part provided on a side edge of the opening of the housing so as to protrude laterally; and a door that moves up and down along the side edge of the opening of the housing; A lock that is pivotally attached to the door with a substantially horizontal axis, and that prevents the door from moving in one direction, either upward or downward, while allowing movement in the other, by coming into contact with the engaging portion. When the outside part is not engaged, the locking part assumes a locking position where it can come into contact with the engaging part due to its own weight, and the locking part is in contact with the engaging part due to its own weight. An intermediate stop device for a door, characterized in that it is provided with a stop piece which is arranged to be rotated about the axis in an open position that is further away from the side. (12) A draft chamber comprising the door intermediate stop device according to any one of claims (1) to (11).

Claims (12)

[Claims] (1) A door that moves up and down along the side edge of the opening of the housing, an engaging portion provided on the door that protrudes to the side, and a door that extends approximately horizontally along the side edge of the opening of the housing. A lock that is pivotally mounted with a shaft and that enters into the vertical locus of the engaging portion to prevent one of the upward and downward movements of the engaging portion while allowing the other to move. When no external force is applied, the locking part assumes a locking position where it enters the vertical locus of the engagement part due to its own weight, and the locking part moves into the engagement position due to external force. An intermediate stop device for a door, characterized in that it is provided with a stop piece that can be rotated about the shaft and is located at an open position laterally away from the vertical path of the door. (2) The intermediate stop device for a door according to claim (1), wherein the stop piece is made of a hard plate material. (3) The stop piece has a trapezoidal side surface with an upper end surface and a lower end surface that are almost horizontal, a front end surface that is almost vertical, and a rear end surface that slopes backward and downward, and is attached to the support body with a shaft at the upper center of the stop piece. The intermediate stop device for a door according to claim 1 or 2, wherein the intermediate stop device for a door is pivotally mounted and has a rear lower portion serving as a locking portion. (4) The intermediate stop device for a door according to any one of claims (1) to (3), wherein the stop piece is provided with an operating part for rotating the stop piece to the open position. (5) The intermediate stop device for a door according to claim (3), wherein the front upper corner of the locking piece serves as an operating portion for rotating the locking piece to the open position. (6) The intermediate stop device for a door according to claim (4), wherein the operating portion is a projection extending upward from the front upper part of the stop piece. (7) The stop piece is made of a plate material having a fan-shaped upper half that expands upward around the pivot joint, and a lower half that has a weight attached to the lower end of the drooping part that hangs down from the pivot joint. The intermediate stop device for a door according to claim 1 or 2, wherein one fan-shaped corner in the upper half serves as a locking portion. (8) The intermediate stop device for a door according to claim (7), wherein the weight serves as an operating part for rotating the stop piece to the open position. (9) The intermediate stop device for a door according to any one of claims (1) to (8), wherein the protrusion projecting laterally from the door is formed by a part of the sash of the door. (10) A door that moves up and down along the side edge of the opening of the casing, an engaging portion provided on the door that protrudes laterally, and a door that extends substantially horizontally along the side edge of the opening of the casing. An engagement that is pivotally mounted with a fixed shaft, and that enters into the vertical locus of the engagement section to prevent one of the upward and downward movement of the engagement section while allowing the other movement. When no external force is applied, the locking part assumes a locking position in which it enters the vertical locus of the engaging part due to its own weight, and the locking part moves to the locking position due to external force. a stop piece that can be rotated about the axis to an open position laterally away from the vertical locus of the joint and has a through hole parallel to the axis; and a stop piece that protrudes from the support. and the stop piece passes freely through the through hole of the stop piece with enough play to be able to rotate to both the locking position and the open position, and the stop piece is attached to the distal end protruding from the through hole. An intermediate stop device for a door, comprising: a guide means having a head larger than the through hole. (11) an engaging part provided on a side edge of the opening of the housing so as to protrude laterally; and a door that moves up and down along the side edge of the opening of the housing; A locking part is pivotally attached to the door with a substantially horizontal axis and comes into contact with the engaging part to prevent the door from moving in either one of the upward and downward directions while allowing the other to move. and when no external force is applied, the locking part assumes a locking position where it can come into contact with the engaging part due to its own weight, and the locking part moves laterally from the engaging part due to the external force. An intermediate stop device for a door, characterized in that the stop piece is provided in a separate open position and is adapted to be rotated about the axis. (12) A draft chamber comprising the door intermediate stop device according to any one of claims (1) to (11).