JP4499807B2 - Closing speed adjusting device and door closer - Google Patents

Description

  The present invention relates to a door closer, and more particularly, to a speed adjusting device capable of separately adjusting a closing speed from a maximum opening and a speed immediately before completion of closing when the closer closes the door.

  A door closer is a device that automatically closes an open door.For example, immediately before the closing of the door, the door closer is slower than the closing speed so far, so that the finger is not pinched between the door and the door frame. Door closers with speed regulators have been developed.

  The speed adjusting device for a door closer usually has a cylinder and a piston that reciprocates in the longitudinal axis direction of the cylinder as the door is opened and closed. When the door is opened, the piston moves without resistance and closes the door. Sometimes, the fluid pushed out from the fluid chamber on the side of the piston in the cylinder in the cylinder flows through the flow passage having a predetermined flow passage resistance to the fluid chamber on the opposite side of the piston to provide a certain resistance to the movement of the door. In addition, immediately before the closing of the door is completed, the flow rate resistance is increased to make the door closing speed slower.

  However, in the conventional speed adjusting device, since the flow path having the fluid resistance is formed in the side wall of the cylinder, the side wall becomes thicker and the diameter of the cylinder becomes larger. The door closer with the door could not be set inside the door and had to be installed outside the door.

  From the point of view of beauty, it is desirable that the door closer can be set inside the door.

In view of these points, the present invention
A cylinder (denoted by reference numbers 22; 22A, 22B; 122A, 122B; 222 in the description of the embodiment described below);
A piston (32; 132; 232) provided in the cylinder and reciprocating between a first position and a second position in an axial direction;
A first chamber (36; 136; 234) and a second chamber (34; 134; 236) respectively located in the cylinder on the first position side and the second position side of the piston;
A check valve (40; 140; 240) provided in a communication passage (38; 138; 238) formed through the piston so as to communicate with the first chamber and the second chamber;
An inner pipe (42; 142; 242) extending axially in the cylinder from the first chamber side through the piston to the second chamber;
Outside the inner tube, it extends in the axial direction from the first chamber (36; 136; 234) side to the second chamber (34; 134; 236) side, and has one end at the second chamber (34; 134; 236). ) And an outer tube (46; 46A, 46B; 146A, 146B; 246) attached to form an axial flow path (44; 144; 244) with the inner tube, The axial flow path (44; 144; 244) is hermetically cut off from the second chamber (34; 134; 236) on the one end side of the outer tube, and is provided through the side wall of the outer tube. (50, 52; 150, 152; 250, 252), and the piston (32; 132; 232) is adapted to slide along the outer tube, the piston being in the first position. At some point the openings (50, 52; 150, 152; 2 0,252) communicates the second chamber (34; 134; 236) and the axial flow path (44; 144; 244), and the piston (32; 132; 232) moves from the first position to the When moved a predetermined distance toward the second position, the opening (50, 52; 150, 152; 250, 252) is blocked from the second chamber (34; 134; 236), and the opening is the first position. An outer tube (46; 46A, 46B; 146A, 146B; 246) adapted to communicate the chamber (36; 136; 234) and the axial flow path (44; 144; 244);
A first restriction channel (56; 156; 256) having a first channel resistance communicating with the other end of the inner tube (42; 142; 242) and the axial passage (44; 144; 244); ,
A second restricting flow path (68; 168; 268) having a second fluid resistance in communication with the first chamber (36; 136; 234) and the axial flow path (44; 144; 244);
A closing speed adjusting device is provided.

  When this door closing speed adjusting device is attached to the door, the piston is displaced in the axial direction in the cylinder as the door is opened and closed, and when the door is opened, fluid flow through the communication passage is allowed through the check valve. When the door is closed, the check valve prevents the flow of fluid through the communication path, and allows the fluid to pass through the first and second restriction flow paths, thereby enabling the second speed adjustment. In this door closing speed adjusting device, since the flow path for adjusting the speed is provided inside the cylinder, there is no need to increase the diameter of the cylinder, and therefore the diameter can be reduced. Even if set inside, the door closer can be set inside the door.

In particular,
The check valve (40; 140; 240) is moved through the communication passage (38; 138; 238) when the piston (32; 132; 232) moves from the first position to the second position. Fluid flow from the chamber (34; 134; 236) to the first chamber (36; 136; 234) and when the piston moves from the second position to the first position, 38; 138; 238) to allow fluid to flow from the first chamber (36; 136; 234) to the second chamber (34; 134; 236).

  This is a case where the piston is set to go from the first position to the second position when the door is closed.

On the contrary, when the piston is set so as to go from the second position to the first position when the door is closed, the check valve (40; 140; 240) is moved to the piston (32; 132; 232). Fluid flows from the second chamber (34; 134; 236) to the first chamber (36; 136; 234) through the communication passage (38; 138; 238) when the fluid moves from the first position to the second position. Flow from the first chamber (36; 136; 234) through the communication passage (38; 138; 238) when the piston moves from the second position to the first position. Block fluid from flowing into the chamber (34; 134; 236).

More specifically,
A first opening (50; 150; 250) having an opening in a side wall of the outer tube spaced apart in the axial direction, and a second opening provided on the one end side of the outer tube from the first opening (52; 152; 252) and when the piston is moved a certain distance from the first position toward the second position, the second opening is closed and the first opening (50; 150; 250). ) In communication with the first chamber (36; 136; 234) so that the piston can be moved.

  When the piston is set so as to go from the first position to the second position when the door is closed, the second chamber becomes a high-pressure chamber, and the fluid in the second chamber of the high-pressure chamber is in the middle of the door closing. The first opening is communicated with the first chamber, which is a low-pressure chamber, shielded from the opening. That is, in the first stage of the door closing, the second chamber, which is a high pressure chamber, has the first and second openings (50; 150; 250; 52; 152; 252), the axial flow path (44; 144; 244), the first It flows to the 1st chamber which is a low-pressure chamber via one restriction channel (56; 156; 256). At this time, one end of the second restriction channel (68; 168; 268) is communicated with the second chamber, which is a high-pressure fluid, via the inner pipe (42; 142; 242), and the other end is the axial channel ( 44; 144; 244), the fluid does not flow. When the piston moves a certain distance, the axial flow path is shut off from the high pressure chamber, and the high pressure fluid is low pressure through the inner tube (42; 142; 242), the second restriction flow path (68; 168; 268). It flows to the first chamber, which is a chamber. In this way, the resistance to the door when the door is closed is changed in two stages, and the second speed adjustment is performed.

  On the other hand, when the piston is set so as to go from the second position to the first position when the door is closed, the first chamber becomes a high pressure chamber, and the fluid flow from the high pressure chamber flows in the middle of the door closing. The flow through the first restriction channel is changed to the flow through the second restriction channel, and the second speed adjustment is performed in the same manner.

  Further, the channel resistances of the first and second restricted channels can be adjusted.

The present invention also provides
A door closer (20) set along the pivot axis (A) of the door (12) and for closing the door;
Provided with an opening / closing speed adjusting device as described above,
The cylinder (22; 22A, 22B) of the opening / closing speed adjusting device is fixed to the door frame (10; 10A, 10B) and extends along the pivot axis, and the outside of the inner cylinder portion And an outer cylinder part (22A) that is coaxial with the inner cylinder and is fixed inside the door,
The outer cylinder portion (22A) has a closing member (48) defining the first chamber (36, 36A) with the piston (32);
The outer tube (46) extends coaxially from the first outer tube portion (46A) extending from the closing member toward the piston, passes through the piston, and the piston A second outer tube portion (46B) that is slidable,
The piston (32) has a cylindrical portion (32A) extending toward the closing member (48), and the cylindrical portion (32A) is splined with the first outer pipe portion (46A). Thus, the piston (32) can be displaced only in the axial direction with respect to the first outer tube portion (46A), and the female screw (22C) formed on the inner peripheral surface of the inner cylinder portion. ) And an outer peripheral surface having a male screw (46C) to be engaged, and when the door (12) is opened and closed, the outer cylinder portion (22A) rotates with respect to the inner cylinder portion (22B). Thus, the door closer in which the piston (32) including the cylindrical portion (32A) is moved in the axial direction is provided.

  In this door closer, as described above, the speed adjusting device can be made to have a small diameter, and the door closer can be set inside the door.

  Embodiments of a door closer equipped with a speed adjusting device according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a door 12 attached to a door frame 10 (only the upper frame portion 10A and the lower frame portion 10B of the door frame are shown in the figure) so as to be pivotable. Specifically, the door 12 is pivotally opened and closed by a top hinge device 14 and a bottom hinge device 16 about a vertical axis A defined by the hinge devices.

  The upper hinge device 14 includes a base portion 14A that is fixed to the upper frame portion 10A and a movable portion 14B that is set to the inside of the door 12 so as to be rotatable around the vertical axis with respect to the base portion.

  The lower hinge device 16 includes a base portion 16A fixed to the lower frame portion 10B, and a door closer 20 according to the present invention which is attached to the base portion and set inside the door 12.

  As shown in FIG. 2, the door closer 20 is fitted into a recess formed in the cylinder 22 and the base portion 16 </ b> A, enters from the lower end of the cylinder 22, and extends to a substantially central position in the vertical direction of the cylinder 22. have. The cylinder 22 has an outer cylinder portion 22A and an inner cylinder portion 22B that is set to be rotatable inside the outer cylinder portion 22A. The outer cylinder portion 22A is attached in the vicinity of the lower end thereof and extends laterally to be fixed to the door 12. A fixing member 26 is provided.

  The upper end 24A of the shaft 24 has a large diameter and is fixed to the inner cylinder part 22B, thereby preventing the inner cylinder part 22B from rotating.

  A coil spring 28 is set in a cylindrical space between the shaft 24 and the outer cylinder portion 22A, and an upper end thereof is locked to a spring locking member 29 fixed to the outer cylinder portion 22A, and a lower end is locked to the shaft 24. When the door 12 is opened and the outer cylinder portion 22A is rotated relative to the shaft 24, the coil spring 28 is wound and the urging force for closing the door is stored.

  A substantially upper half portion of the shaft is a speed adjusting device 30 according to the present invention.

  That is, the speed adjusting device 30 is provided in the inner cylinder portion 22, and the first position corresponding to the door opening position as the door 12 opens and closes between the door opening position and the door closing position (FIG. And a piston 32 that reciprocates between a second position (upper position shown in FIG. 4) corresponding to the door closing position. A high pressure chamber (second chamber) 34 is formed below the piston 32 and a low pressure chamber (first chamber) 36 is formed above the piston 32 in the internal cylinder portion 22B. The piston 32 is formed with a communication passage 38 through the piston 32 so as to communicate with the high pressure chamber 34 and the low pressure chamber 36. The communication passage 38 is provided with a check valve 40, and the door is closed. When the piston 32 is moved from the first position (FIG. 6) to the second position (FIG. 4), the flow of fluid from the high pressure chamber 34 to the low pressure chamber 36 is prevented and the door is opened. When the door is moved, that is, when the piston is moved from the second position (FIG. 4) toward the first position (FIG. 6), fluid flow from the low pressure chamber 36 to the high pressure chamber 34 is allowed. Yes.

  In the inner cylinder portion 22B, an inner tube 42 extending in the axial direction and having one end communicating with the high pressure chamber 34, and extending in the axial direction and provided in the high pressure chamber 34 outside the inner tube, the one end is in the high pressure chamber 34, and An outer pipe 46 hermetically sealed from the high-pressure chamber 34 is provided, and specifically, the outer pipe 46 is an upper outer pipe portion (a first outer pipe portion) that extends downward from a closing member 48 that closes the upper end of the cylinder 22. 46A and a lower outer tube portion (second outer tube portion) 46B that is concentrically attached to the lower end of the upper outer tube portion and extends to the high pressure chamber 34. As clearly shown in FIGS. 4 to 6, an axial flow path 44 is formed between the outer tube 46 and the inner tube 42.

  The piston 32 slides in the axial direction on the outer tube 46. Specifically, the piston 32 slides on the lower outer pipe portion 46B, and has a piston upper portion (cylindrical portion) 32A that is fixed to the piston 32 and extends upward. The upper portion 32A is splined to the upper outer tube portion 46A, and is slidable only in the axial direction with respect to the upper outer tube portion 46A. As clearly shown in FIGS. 4 to 6, the upper outer pipe portion 46 </ b> A has its upper outer peripheral surface sealed and engaged with the inner cylinder portion 22 </ b> B by an O-ring 47, and a male screw 46 </ b> C is formed on the lower outer peripheral surface thereof. And is engaged with a female screw 22C formed on the inner peripheral surface of the inner cylinder part 22B, the door 12 is opened and closed, and the outer cylinder part 22A is rotated relative to the inner cylinder part 22B. Then, the piston 32 moves up and down. An upper low pressure chamber 36A is formed between the piston upper portion 32A and the closing member 48, and is formed between the outer peripheral surface of the upper outer pipe portion 46A and the inner peripheral surface of the piston upper portion 32A that are splined together. It communicates through a gap.

  Further, a first opening 50 and a second opening 52 are provided on the side wall of the lower outer pipe portion 46B at intervals in the axial direction, and the piston 32 is illustrated in the first and second openings. 6 (ie, when the door is open), the high pressure chamber 34 and the axial flow path 44 are communicated, and the piston 32 is moved from the first position to the second position (the door is opened). 4, the communication between the high pressure chamber 34 and the axial flow path 44 is cut off, and the low pressure chamber 36 is communicated. Specifically, the downwardly moving piston first closes the first opening 50 (at that time, the high pressure chamber 34 and the axial flow path 44 are in communication with each other through the second opening 52), as shown in FIG. When the piston moves further downward, both the first and second openings 50 and 52 are closed, and when the piston 32 moves slightly downward from that position, the first opening 50 is opened and the low pressure is passed through the first opening 50. The chamber 36 and the axial flow path 44 are communicated with each other.

  The upper end portion of the inner tube 42 is fixed to the closing member 48. The closing member 48 has a first restriction channel 56 that communicates the internal passage 42 </ b> A of the inner pipe 42 and the axial passage 44, and a second restriction channel 68 that communicates the low pressure chamber 36 and the axial passage 44. And are formed.

  Specifically, the first restriction flow channel 56 includes a flow channel 56A extending obliquely upward in the radial direction from the upper end of the internal passage 42A of the inner tube 42 and a rightward direction in the radial direction from the axial flow channel 44. And a flow path 56C that communicates with the flow paths 56A and 56B. A flow path resistance adjusting member 60 set coaxially with the flow path is threadedly engaged with the flow path 56C, and the first restricted flow path is formed by screwing the flow path resistance adjusting member. The flow path resistance of 56 can be adjusted.

  The second restricted flow path 68 includes a flow path 68A extending from the axial flow path 44 to the left in the radial direction as viewed in FIG. 3, and a flow path 68B extending upward from the intermediate position of the flow path 56A as viewed in FIG. The flow path 68C communicates with the flow path 68B and extends inward in the radial direction, and communicates with the radially inner end of the flow path 68C and extends downward in the closing member 48 as viewed in FIG. 2, into the upper low pressure chamber 36A. It is comprised from the flow path 68D (FIG. 2) connected. A flow path resistance adjusting member 62 set coaxially with the flow path is threadedly engaged with the flow path 68B, and the second restricted flow path is formed by screwing the flow path resistance adjusting member. The flow path resistance of 68 is adjusted.

  When the door 12 provided with the door closer is pivoted from the closed position toward the open position, the outer cylinder portion with respect to the shaft 24 fixed to the lower door frame 10B and the inner cylinder portion 22B fixed to the shaft. 22A relatively rotates, and the closing member 48 fixed to the outer cylinder portion 22A and the upper outer pipe portion 46A extending downward from the closing member rotate to rotate the piston 32. Since the inner cylinder portion 22B that is screw-engaged with the piston 32 is fixed to the shaft 24 and does not rotate, the piston 32 rises from the position of FIG. 4 toward the position of FIG. At this time, the check valve 40 provided in the piston 32 does not resist the flow from the low pressure chamber 32 to the high pressure chamber 34 via the communication passage 38 formed in the piston 32, and therefore, the door Can be opened without any special resistance.

  On the other hand, when the door 12 is pivoted from the opening position toward the closing position, the piston 32 descends from the position shown in FIG. 6 to the position shown in FIG. At this time, the check valve blocks the flow of the communication passage 38. For this reason, the fluid in the high pressure chamber 34 is first directed to the inner tube 42 and the axial flow path 44 (via the first and second openings 50, 52). As described above, the first restriction channel 56 communicates the upper end of the inner tube 42 and the axial direction channel, and therefore, the same pressure is applied to both ends of the first restriction channel 56. There is no flow in the direction.

  On the other hand, the second restriction flow path 68 communicates the axial flow path 44 with the upper low pressure chamber 36A, and the upper low pressure chamber 36A communicates with the low pressure chamber, so that fluid flows from the high pressure chamber 34 to the second low pressure chamber 36A. It flows to the upper low pressure chamber 34A and the low pressure chamber 34 through the restriction flow path 68, and therefore the door 12 is closed while receiving a predetermined flow resistance applied by the second restriction flow path 56.

  For example, when the door 12 is closed to a position close to completion of closing, the high pressure chamber 34 is shut off from the axial flow path 44, and the low pressure chamber 36 is communicated with the axial flow path 44 through the first opening 50. Therefore, the fluid in the high pressure chamber 34 is passed from the flow path in the inner pipe 42 to the axial flow path and the upper low pressure chamber 34 </ b> A via the first restriction flow path 56. At this time, both ends of the second restricted flow path 68 are subjected to the fluid pressure of the low pressure chamber, so that no flow occurs through the second restricted flow path, and the fluid from the high pressure chamber does not flow. Only through 56 flows into the low pressure chamber. Therefore, if the flow resistance of the first restriction flow path 56 is made larger than the flow resistance of the second restriction flow path 68, the door is decelerated by receiving resistance higher than the resistance received so far. It becomes possible to avoid pinching the finger between the door and the door frame. On the contrary, the flow resistance of the first restriction flow path 56 can be made smaller than that of the second restriction flow path 68. In this case, the door closes slowly in the first closing range, and then closes quickly. It becomes the effect that.

FIG. 7 shows a case where the door closing speed adjusting device according to the present invention is applied to the hinge 130.
In this case, the hinge 130 does not include the outer cylinder portion and the inner cylinder portion as in the first embodiment described above, but includes the upper and lower cylinder portions 122A and 122B, and the upper cylinder portion 122A. Is fixed to the door frame, and the lower cylinder portion 122B is fixed to the door. The relationship of the other components to the upper and lower cylinder parts is substantially the same as that for the outer and inner cylinder parts in the first embodiment, and therefore corresponds to the elements of the first embodiment. The same reference numerals in the 100s are attached and detailed description is omitted.

  FIG. 8 shows a case where the door opening speed adjusting device 230 according to the present invention is applied to an external door closer.

  The door closer includes a cylinder 222 that is fixed to the door, and is attached to the cylinder so that a rotating shaft 202 that rotates when the door is opened and closed passes therethrough. The rotating shaft 202 has a gear 206 engaged with a rack 204 formed inside the piston 232, and reciprocates the piston 232 as the door is opened and closed. A coil spring 228 is set in the cylinder 222 to urge the piston 232 to a position corresponding to the closed state of the door. The door is opened and the piston 232 is displaced leftward in the drawing. And the urging force for returning the door to the closed position is stored. In the first closing range in the closing operation, the fluid in the high pressure chamber 234 is pushed out to the axial flow path 244 through the opening 250, but the second restriction flow path 268 has one end communicating with the axial flow path 244 and the other end. Since the fluid is communicated with the flow path 268D and both ends thereof are communicated with the high pressure chamber, the fluid flows through the first restriction flow path 256 from the inner pipe 242 to the low pressure chamber without passing through the second restriction flow path. At the time of closing, the opening 250 is closed, so that the fluid in the high pressure chamber flows to the low pressure chamber via the second restriction channel 268. Regarding the other points, the positional relationship between the high pressure chamber and the low pressure chamber with respect to the piston is opposite to that of the first embodiment described above, and therefore the action of the check valve is also opposite to the movement of the piston. The constituent elements are substantially the same as those in the first embodiment, and are denoted by the same reference numerals in the 200s, and detailed description thereof is omitted.

It is a figure which shows the outline | summary of the door which attached the door closer which concerns on this invention. It is sectional drawing which shows the inside of the door closer. It is a figure for showing the relation of the channel of the speed regulation device in the door closer at the time of seeing the door closer in the direction of an axis. It is a figure which shows the inside of the speed adjustment apparatus at the time of a closed door state. It is a figure which shows the inside of the speed adjustment apparatus when it exists between an open door state and an open door state. It is a figure which shows the inside of the speed adjustment apparatus at the time of a closed door state. It is a figure which shows the inside of the hinge which attached the speed regulator which concerns on this invention. It is a figure which shows the inside of the external door closer which attached the speed regulator which concerns on this invention.

Explanation of symbols

Vertical pivot axis A; door frame 10; upper frame portion 10A; lower frame portion 10B; door 12; upper hinge device 14; movable portion 14B; lower hinge device 16; Inner cylinder portion 22B; shaft 24; upper end 24A; fixing member 26; coil spring 28; spring locking member 29; speed adjusting device 30, 130, 230; piston 32, 132, 232; Chamber (second chamber) 34, 134; low pressure chamber (first chamber) 36; communication passage 38; check valves 40, 140, 240; inner pipes 42, 142, 242; internal passage 42A; 144, 244; outer tube 46, 146, 246; upper outer tube portion 46A; lower outer tube portion 46B; male screw 46C; O-ring 47; 148, 248; first openings 50, 150, 250; second openings 52, 152, 252; axial passages 44, 144, 244; first restricted flow paths 56, 156, 256; flow paths 56A; Flow path 56C; Second restriction flow path 68, 168, 268; Flow path 68A; Flow path 68B; Flow path 68C; Flow path 68D; Flow path resistance adjusting member 60; Rotating shaft 202; rack 204; gear 206; coil spring 228; piston 232; high pressure chamber (first chamber) 234; low pressure chamber (second chamber) 236

Claims (6)

A cylinder,
A piston provided in the cylinder and reciprocating between a first position and a second position in an axial direction;
A first chamber and a second chamber located in the cylinder on the first position side and the second position side of the piston, respectively;
A check valve provided in a communication passage formed through the piston so as to communicate with the first chamber and the second chamber;
An inner tube extending axially in the cylinder from the first chamber side through the piston to the second chamber;
Attached so as to extend in the axial direction from the first chamber side to the second chamber side outside the inner tube and to have one end in the second chamber and to form an axial flow path between the inner tube and the inner tube. An outer pipe, wherein the axial flow path is sealed off from the second chamber at the one end of the outer pipe, and has an opening provided through a side wall of the outer pipe, and the piston Slid along the outer tube, and when the piston is in the first position, the opening communicates the second chamber and the axial flow path, and the piston is in the first position. When moved from the first position toward the second position by a predetermined distance, the opening is cut off from the second chamber, and the opening communicates with the first chamber and the axial flow path. Tube,
A first restricted flow path having a first flow path resistance communicating the other end of the inner tube and the axial passage;
A second restricting flow path communicating with the first chamber and the axial flow path and having a second fluid resistance;
A closing speed adjusting device. The check valve prevents fluid from flowing from the second chamber to the first chamber through the communication passage when the piston moves from the first position to the second position, and the piston is moved to the second position. The door closing speed adjusting device according to claim 1, wherein a fluid is allowed to flow from the first chamber to the second chamber through the communication path when moving from the position to the first position. The check valve allows fluid to flow from the second chamber to the first chamber through the communication passage when the piston is moved from the first position to the second position, and the piston is in the second position. The door closing speed adjusting device according to claim 1, wherein a fluid is prevented from flowing from the first chamber to the second chamber through the communication path when moving from the position to the first position. The opening on the side wall of the outer pipe has a first opening provided at an interval in the axial direction and a second opening provided on the one end side of the outer pipe with respect to the first opening. When moved from the first position to the second position by a predetermined distance, the second opening is closed and the first opening is in communication with the first chamber so that the piston is moved. The closing speed adjusting device according to claim 2 or 3.   The door closing speed adjusting device according to any one of claims 1 to 4, wherein channel resistances of the first and second restricted channels are adjustable. A door closer that is set along the pivot axis of the door inside the door and performs a closing action of the door,
An opening / closing speed adjusting device according to any one of claims 1 to 5,
The cylinder of the opening / closing speed adjusting device is fixed to the door frame and extends along the pivot axis, and the outside is fixed to the inside of the door coaxially with the inner cylinder outside the inner cylinder. A cylinder portion,
The outer cylinder portion has a closure member defining the first chamber with the piston;
The outer tube extends from the closing member toward the piston, and extends outward from the first outer tube so as to be coaxial with the piston. The piston is slidable. A second outer tube portion,
The piston has a cylindrical portion extending toward the closing member, the cylindrical portion is splined to the first outer tube portion, and the piston is connected to the first outer tube portion. And an inner peripheral surface that can be displaced only in the axial direction, and an outer peripheral surface having a male screw that engages with a female screw formed on the inner peripheral surface of the inner cylinder part, and the door is opened and closed to A door closer in which the outer cylinder portion rotates with respect to the inner cylinder portion so that the piston including the cylindrical portion moves in the axial direction.

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