EP2131001A2 - Door closing damper - Google Patents

Abstract

Closing damper (20) comprises a piston rod (220) extending from a first end surface of a moving piston (210) along a longitudinal axis of a hydraulic cylinder (200) through a first cylinder chamber (200-1) and protruding from the cylinder. An independent claim is also included for a fire protection door with the closing damper. Preferred Features: A flow limiting device connects the first cylinder chamber with a second cylinder chamber (200-2). A pre-tensioning device presses the moving piston in a predetermined direction so that a door closes itself.

Description

Field of the invention

The present invention relates to a door closing damper and more particularly to a door closing damper for use with rotary wing fire doors.

More specifically, the present invention relates to a door closing damper comprising a hydraulic cylinder in which a movable piston is arranged, which divides the cylinder into a first cylinder space and a second cylinder space, and a flow restriction device, which comprises a flow of a hydraulic medium from the limited first cylinder space.

State of the art

Modern building regulations stipulate that building structures are to be arranged in such a way that the formation of a fire and the spread of fire and smoke are prevented, and in the event of a fire the rescue of humans and animals as well as effective extinguishing work are possible. This requires that a building be partitioned off into segments between which the spread of fire is difficult. On the other hand, escape routes must be kept open so that unhindered access between the foreclosed segments of the building is possible. Typically, the building segments are shielded by fire doors, which are normally open and which close automatically in case of fire. However, self-closing doors must be easy to open, even in the event of fire, so that it is possible for people to rescue themselves within a partitioned segment of the building. Thus, there is a conflict between the requirement for hermetically sealing individual building segments and the requirement that people should have the least possible access between the sealed building segments.

To meet these requirements for fire protection in buildings, fire doors are used, which have a freewheeling or locking device which is coupled to a fire alarm device. In everyday life, the door is kept open by the locking device. In case of fire, a mechanical door closer with a high closing force is usually activated so that the door closes automatically.

Fig. 1 shows an example of such an arrangement. A door 3 is connected to a lock mechanism 2. A locking device 4 keeps the door open in everyday use. A locking mechanism can, for. B. be realized by an electromagnet. A fire alarm device 1, z. As a smoke detector is functionally connected to the locking device 4. If the fire alarm device reports fire, the locking device is released, z. B. by the power supply to the electromagnet is interrupted. A door closing device 2 can then close the door 3. A closing force is z. B. generated by a spring.

Such door closing devices are well known in the art. For example, shows the US patent US 3,648,326 an electromechanical door holder / closer of this type. The door closer principle of US 3,648,326 will be in the FIGS. 2a and 2b clarified. Fig. 2a shows a schematic of the door closing mechanism 2 for an open door and Fig. 2b shows the closing mechanism 2 for a door 3 in the closed state. The door closing mechanism of US 3,648,326 includes an arm 7, one end of which engages in a guide rail 8 which is fixed to a door 3, movable. The other end of the arm 7 is fixed to a rotatable cylinder 9 perpendicular to a cylinder axis of rotation 91. The cylinder 9 is formed as a hollow cylinder. The hollow cylinder is rotatably supported to the cylinder axis of rotation 91 and mounted on the cylinder axis of rotation 91 in a housing. A clearance 92 between the cylinder cavity and the cylinder rotation axis 91 is filled with a damping material. The damping material is a viscoelastic plastic material, for. B. unvulcanized silicon rubber. One end of a chain 6 is fixed to the cylinder 9 so that a torque on the cylinder 9 can be transmitted by a train on the chain 6. A spring 5a, 5b is connected to the other end of the chain 6 to transmit a spring tension on the chain 6 on the cylinder 9 in the form of a torque.

When the door 3 is opened, one end of the arm 7 slides along the guide rail 8 and the cylinder 9 rotates in the in Fig. 2a shown scheme in the counterclockwise direction. About the chain 6, the spring is tensioned. To hold the door in the open position, the cylinder 9 is locked by a locking device (not shown). The lock can z. B. be provided by an electromagnet. If the lock is released, z. B. by a signal from a fire alarm, transmits the chain 6, the tensile force of the tensioned spring 5 a on the cylinder 9 as torque and the arm 7 rotates in the in Fig. 2a shown in the clockwise direction, so that the door 3 closes automatically. When closed ( Fig. 2b ), the spring 5b is relaxed. By the damping material in the intermediate space 92 between the cylinder axis of rotation 91 and the cylinder internal volume of the cylinder 9 acts as a damping element, so that the door 3 is not accelerated uncontrollably during the closing process and injured persons or material destroyed.

However, the previously described door closing device has a number of disadvantages. On the one hand, the door closing device consists of a variety of movable and wear-prone parts, such. As the chain, the spring, the rotatable cylinder and the damping material together. On the other hand, the damping mechanism of the cylinder is fixed to a certain spring force and a certain door weight and is difficult to adjust and adjust to other doors and door systems. The natural abrasion of moving parts can cause malfunction. Furthermore, the closing speed of the door can not be controlled effectively. Abrasion in the cylinder cavity 92 may even lead to jamming of the door.

In order to improve the control over the closing speed of the door closing device and the reliability of the closing operation, hydraulic systems are used in the prior art in which a piston moves in a cylinder according to the movement of the door. In this case, a hydraulic fluid is forced from one side of the piston to the other side within the hydraulic cylinder. Due to the limited flow rate of the hydraulic fluid, the movement of the door is slowed down.

An example of such a system is disclosed in the European patent application EP-A 1 895 086 disclosed. In a cylinder, a two-piece movable cylinder is arranged, so that the cylinder volume is divided into two parts. A tension spring pushes the piston in a certain direction. The two parts of the piston are connected by a cam, which convert a linear movement of the two-part piston into a rotary movement for a shaft assembly. During the linear movement of the piston, hydraulic fluid is moved from one side of the piston to another side of the piston. The speed of the piston movement and thus the closing speed The door is determined by the flow rate of the hydraulic fluid from one side of the cylinder volume to the other side. In the EP-A 1 895 086 A control valve controls the flow rate of the hydraulic oil flowing from one side to the other side of the cylinder volume.

The EP-A 1 895 086 However, has the disadvantage that the linear movement of the piston must be converted into a rotational movement of the shaft assembly, whereby the production is complicated and more wear parts complicate trouble-free operation. Furthermore, the hydraulic damping device requires the EP-A 1 895 086 a complicated channel structure in the cylinder walls of the hydraulic cylinder which is costly and susceptible to wear. The required valves are also incorporated in the complicated channel structure in the walls of the hydraulic cylinder, which increases the manufacturing and the susceptibility to errors. Furthermore, the transmission mechanism consisting of the cam and the shaft assembly for implementing the linear movement of the piston in a rotational movement unsuitable for receiving large forces, such as. B. occur in heavily loaded large doors in large public buildings.

For example, in stadiums such. As the Allianz Arena in Munich, strong air currents occur, which greatly accelerate the rotary doors of the fire doors. Conventional closing / damping mechanisms, such. As described above, are not sufficient to absorb the acceleration forces and slow down the doors so that no damage to the doors occur. The result is that a large part of the doors are constantly damaged and must be replaced, which also leads to conflicts with the fire protection authorities.

In view of the above-described disadvantages, it is an object of the present invention to provide a reliable door closing damper that can accommodate high acceleration forces.

Summary of the invention

The object is achieved by a door closing damper with the features of claim 1.

In particular, the door closing damper of the present invention is characterized by a piston rod extending from a first end surface of a movable piston dividing a hydraulic cylinder into first and second cylinder chambers along a longitudinal axis of the hydraulic cylinder through the first cylinder space and that of the hydraulic cylinder Cylinder protrudes.

By this measure, the door closing damper can be arranged between door and wall so that only forces occur along the hydraulic cylinder. Rotary movements in the door closing damper are avoided. As a result, much larger forces can be absorbed. Furthermore, less wear due to abrasion and fatigue, since the material is not burdened by additional torsional and shear forces. Also, the number of moving parts is reduced, so that the production is cheaper.

In a preferred embodiment, the flow restriction device is a flow control valve. As a result, the closing dynamics of a door can be adapted individually to the boundary conditions, such as door weight, closing force, opening force, etc.

In another embodiment, the flow control valve is designed to control the flow as a load dependent on a closing force. As a result, the door closes always the same speed regardless of the wind speeds that can occur on the escape routes.

In another embodiment, the flow restriction device connects the first and second cylinder chambers. In this case, the hydraulic medium is only pushed back and forth between the first and the second cylinder space and no external reservoirs for hydraulic media and no external pressure feeds are necessary.

In yet another embodiment, the flow restricting device may assume a first state with a flow control and a second state with a flow resistance that is smaller than the flow resistance in the first state. Since a fire door has two dynamic states, namely the opening operation and the closing operation, this embodiment allows each dynamic state to be assigned its own dynamic characteristic. For example, the door must not close uncontrollably, but must be easy to open by hand. This creates a conflict between the Requirements for the dynamic states of opening and closing. With the present embodiment, the two dynamic conditions of the fire door can be assigned different dynamic characteristics.

In a particular embodiment thereof, the flow restriction device automatically switches to the second state with a low flow resistance when an opening force acts on the door, wherein the opening force must be above a predetermined value. This makes it easy to open the door by hand when a certain threshold, eg. B. 25 Newton (equivalent to a weight of about 2.5 kg) is exceeded.

In a particular embodiment thereof, the flow-limiting device is realized by a two-way flow control valve having a first position corresponding to the first state and a second position corresponding to the second state. Two-way flow control valves are available configured and can be installed virtually modularly with a hydraulic cylinder.

In a particular embodiment thereof, the flow-limiting device is realized by a lowering brake, which connects the first cylinder chamber with the second cylinder chamber. A lowering brake is a special two-way flow control valve, the z. B. is used in forklifts. Such lowering brake valves are preferably used for flow control tasks single-acting cylinder. The lowering speed is kept largely constant regardless of the size of the load. An integrated thrust diaphragm releases the full passage cross-section in the opposite direction so that the lowest possible flow resistance is applied in the opposite direction. Counterbalance valves are available in various types and designed for heavy loads. For example, there are types with a slight vibration-avoiding load dependency and a largely load-independent flow control characteristic. This makes door closers for particularly heavily loaded doors efficient and economical to realize, because the door can not accelerate faster when closing, as it corresponds to the flow rate regulated by the lowering brake, regardless of accidental or deliberately applied to the door higher closing forces.

In a further embodiment, the flow-limiting device is integrated in the movable piston. This avoids all external fluid management devices and channels in the cylinder wall. Line lengths and pressure drops are thereby minimized. Furthermore, the installation is space-saving and inexpensive.

In one embodiment, the door closing damper comprises a locking device that fixes the movable piston at a predetermined position so that a door can be held in an open position, wherein the locking device can be controlled by a fire alarm device so that the lock releases when the Fire alarm device reports fire. The locking device allows a constant hold open the door, so that in the normal state of everyday operation a barrier-free passage is possible.

In a further embodiment, the door closing damper comprises a biasing device which presses the movable piston in a predetermined direction so that a door can close itself. As a result, the door closer receives a door self-closing functionality, which is necessary for fire doors, as fire doors must close themselves in case of fire.

In another embodiment, the piston rod is a double-sided piston rod extending from opposite end surfaces of the movable piston along a longitudinal axis of the hydraulic cylinder through the first cylinder space and the second cylinder space. As a result, the sum of the volume of the first cylinder space and the second cylinder space remains constant even when the piston moves. That is, no compensation volume for the hydraulic medium is necessary when the piston moves in the cylinder.

In a particular embodiment thereof, one end of a first portion of the double-sided piston rod projects out of the hydraulic cylinder and is provided with a fastener, and one end of a second portion of the double-sided piston rod projects into a pressure chamber, thereby pushing the movable piston in a predetermined direction , The fastening device provides a means for attaching the door closing damper to a wall or the door. Through the pressure chamber into which protrudes an end of a second portion of the piston rod on both sides, a low-maintenance and efficient biasing device is provided, which ensures that a door can close automatically.

Another aspect of the present invention relates to a fire door having a door closing damper according to any one of the aforementioned embodiments, wherein one end of the door closing damper is connected to a wall and another end of the door closing damper is connected to the fire door, and wherein a locking device is a door open holding device having a fire alarm device is connectable, so that the fire door closes when the fire alarm device reports fire.

Brief description of the figures

Fig. 1

ein Schema für eine Feuerschutztür gemäß des Standes der Technik zeigt;

Fig. 2a und 2b

einen Türschließmechanismus gemäß des Standes der Technik für eine Tür in geöffneten Zustand bzw. für eine Tür in geschlossenen Zustand zeigen;

Fig. 3

eine Feuerschutztür gemäß der vorliegenden Erfindung zeigt;

Fig. 4

ein Schema des Türschließdämpfers gemäß der vorliegenden Erfindung zeigt; und

Fig. 5

ein Schema eines Flussregelventils aus dem Türschließdämpfer gemäß der Fig. 4 im Detail zeigt.

Further embodiments of the present invention are defined in the appended claims and will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1

shows a scheme for a fire door according to the prior art;

Fig. 2a and 2b

show a door closing mechanism according to the prior art for a door in the open state and for a door in the closed state;

Fig. 3

shows a fire door according to the present invention;

Fig. 4

Fig. 12 shows a schematic of the door closing damper according to the present invention; and

Fig. 5

a schematic of a flow control valve from the door closer according to the Fig. 4 in detail shows.

Detailed description of preferred embodiments

Although the present invention is described with reference to embodiments as illustrated in the following detailed description, the detailed description is not intended to limit the present invention to the particular embodiments described therein, but rather to those described Embodiments are intended to exemplify only the various aspects of the present invention, the scope of which is defined by the appended claims.

Fig. 3 shows a fire door assembly according to the present invention. Fig. 3 shows a fire door 30, a door seal damper 20, a door opener 40 and a fire alarm device 10. The fire door is designed as a swing door. In the FIG. 3 For example, the door closer 20 is shown as a hydraulic cylinder from one end of which protrudes a piston rod connected to the door. The other end of the hydraulic cylinder is connected to the wall. The door closer 20 may be provided with biasing means so that the door closes itself. The door opener 40 may, for. B. may be attached to the wall and z. B. be realized by an electromagnet. Although in the Fig. 3 As the door opener is shown as an external member, the door opener 40 can also be realized in the form of a locking device of the piston or piston rod, which can be integrated with the hydraulic cylinder. A fire alarm 10 is operatively connected to the door opener 40.

Hereinafter, the function of the band protection door assembly according to Fig. 3 explained.

If the door z. B. is opened by hand, the piston rod, which protrudes from the cylinder, pushes into the cylinder. The cylinder moves in the representation of Fig. 3 toward the door opener 40. When the solenoid of the door open fixture 40 is activated, as is the case in the normal state, the door open fixture 40 holds the cylinder tight, e.g. B. if the cylinder itself consists of its magnetizable material, or if a magnetizable element is attached to the cylinder. If z. B. the fire alarm 10 registered fire, z. B. by heat or smoke, it can interrupt the circuit to the electromagnet of the door opener 40 and the door opener unlocks the lock, so that the door can close. When the door closer damper 20 is provided with biasing means, the door is actively closed by the force of the bias. However, a closing process can also be done by the weight with appropriate storage of the door, especially in swing doors.

The function of the fire door was for an arrangement according to the Fig. 3 explained, in which the door closer damper is arranged in the same room to which the door opens. Ie. The door moves towards the door closer when opening. However, as those skilled in the art will readily appreciate, it is also possible for the door closer of the present invention to be located outside of the room to which the door will open. In this case, the door moves away from the door closer during opening. Ie. the pretensioner must be provided so that the hydraulic cylinder contracts when the door closes.

Hereinafter, the door closing damper 20 will be described with reference to FIG Fig. 4 explained in more detail. It is important to note that Fig. 4 refers to a door closer, which is suitable for a fire door assembly according to the Fig. 3 is provided. Ie. The door moves towards the door closer when opening. In the event that the door closing damper is arranged so that the door moves away from the door closer during opening, functionalities of components must be correspondingly kinematically inverted, such. B. has been exemplified above with the biasing device. That is, the piston rod would have to move into the cylinder when the door closes, and the biasing means must be designed to draw the piston rod into the cylinder. However, the following description is by way of example limited to the arrangement of Fig. 3 and the corresponding details 4 and 5 ,

Fig. 4 shows a hydraulic cylinder 200 in which a movable piston 210 is arranged, which divides the cylinder 200 into a first cylinder chamber 200-1 and a second cylinder chamber 200-2. It should be noted that the cylinder may have any cross-section, in particular a circular, oval or polygonal.

A double-sided piston rod 220 extends from opposite end faces of the movable piston 210 along a longitudinal axis of the hydraulic cylinder 200 through the first cylinder space 200-1 and the second cylinder space 200-2, respectively, one end of a first portion 200-1 and a second one Section 200-2 of the double-sided piston rod 220 protrudes into the adjacent room. The end of the first section 220-1 of the double-sided piston rod 220 is provided with a fastening device 21 with which the door closing damper 20 can be fastened to a door (or a wall). The first and second cylinder chambers 200-1 and 200-2 are equipped with a hydraulic medium, z. As oil filled. In the piston 210, a two-way flow control valve 400 and a check valve 300 is incorporated. The 2-way flow control valve can z. B. be a lowering brake of the company HAWE type SB or SQ. For example, the type SB designates a two-way flow control valve with a slightly vibration-avoiding pressure-volume flow characteristic. Type SQ has a largely load-independent characteristic. One end of a second portion 220-2 of the two-sided Kolbenstrange 220 protrudes from the second cylinder chamber 200-2 and protrudes into a pressure chamber 200-3. The pressure chamber 200-3 is z. B. formed by separating a portion of the second cylinder chamber 200-2 with a pressure, gas and liquid-tight partition 230. Alternatively, the pressure chamber 200-3 may be provided by an attachment 200a attached to the hydraulic lift cylinder. The pressure chamber 200-3 is filled with a gas so that a constant pressure is maintained, e.g. B. 3 bar. At one end of the pressure chamber 200-3, which is opposite to the second cylinder chamber 200-2, on the outside of the pressure chamber 200-3, a second fastening device 22 is formed with which the door closing mechanism 20 on the wall (or Door) can be attached.

The two-way flow control valve will now be referred to Fig. 5 explained in more detail. The two-way flow control valve 400 has two connection lines 400-1 and 400-2. The connection line 400-1 is connected to the second cylinder space 200-2, and the connection line 400-2 is connected to the first cylinder space 200-1. The two-way flow control valve 400 has two switching states 400A and 400B. A control line 401 is connected to the port 400-1. A control line 402 is connected to the port 400-2. The control line 401 causes the two-way flow control valve to switch to the state 400A when there is a pressure on the connection line 400-1 that is large enough to overcome the spring force of the spring 410. In the normal state, the two-way flow control valve is in switch position 400B. The control line 402 causes the flow to be controlled depending on the pressure on the connection line 400-2.
For example, the line cross section at the switch position 400B may be regulated depending on the pressure applied to the lead 400-2. D. h., Depending on the control characteristic, the line cross-section, for example, in the simplest case, reduce in proportion to the applied pressure. That is, in this case, the flow rate would be constant and independent of pressure. But there are also other control characteristics possible in which, for example, the flow rate of the hydraulic medium and thus the Closing speed of the door decreases with increasing pressure. Thus, any dynamic door closing processes can be realized.

The operation of the door closing damper according to the Fig. 4 in a fire door assembly according to the Fig. 3 is installed described. In the normal state, the door 30 is in the Fig. 3 is opened and held by the door opener 40 in this state. When the fire alarm 10 signals a fire, the door opener 40 is unlocked and the pressure in the pressure chamber 200-3 exerts a force on the piston 210 via the end face of the second portion 220-2 of the double-sided piston rod 220. If z. B. a pressure of 3 bar in the pressure chamber 200-3 prevails, and when the diameter of the end surface of the second portion 220-2 of the reciprocal piston rod 220, for example, about 5 cm, a force of about 600 Newton acts on the piston 210th By this force, the piston 210 shifts within the hydraulic cylinder 200, and the first portion 220-1 of the reciprocal piston rod 220 slides out of the cylinder 200. The door 30 is actively closed. As the piston 210 shifts, the hydraulic medium, e.g. As oil, move from the first cylinder chamber 200-1 in the second cylinder chamber 200-2. This is done via the two-way flow control valve 400, which is in the idle state in the position 400b. The pressure in the pressure chamber 200-3 is transmitted via the second portion 220-2 of the double-sided piston rod 220 to the piston 210 and thus to the connecting line 402. About the control line 402 is in accordance with the pressure on the connecting line 400-2, the passage cross-section for a set specific flow. Occur additional closing forces, z. B. by a wind in the escape route, the pressure increases on the input line 400-2, which is reduced via the control line 402 of the passage cross-section so that a constant flow of the hydraulic medium from the first cylinder chamber 200-1 in the second cylinder chamber 200th -2 takes place. Due to the double-sided piston rod, the sum of the volumes of the first and second cylinder chambers 200-1 and 200-2 remains constant, so that no compensation reservoirs for the hydraulic medium are necessary.

When the closed door 30 is opened by hand, the first portion 220-1 of the double-sided piston rod 220 is pushed into the cylinder 200. In this case, the pressure in the second cylinder chamber 200-2, which transfers to the input line 400-1, increases. Via the control line 401, the pressure on the connecting line 401 to switch of the two-way flow control valve is used in the state 400A, when the pressure on the control line 401 exceeds a switching force, which is predetermined by a spring 410. In the position 400A, hydraulic fluid can flow from the second cylinder space 200-2 into the first cylinder space 200-A almost unhindered, and the door 30 can thus be opened without much effort. The closing force applied by the biasing means (the pressure chamber in this embodiment) is reduced by the lever action of the door 30 upon opening.

In order to further reduce the flow resistance of the hydraulic medium from the second cylinder space 200-2 to the first cylinder space 200-1, a check valve 300 may be employed, as in FIG FIG. 3 is shown. Since the flow resistance during movement of the piston and opening the check valve 300 is additionally reduced because of the larger flow area, so z. As children or people who are to be confronted with the least possible opening force in panic, open the door very easily and quickly. Furthermore, the check valve 300 serves as a backup for the case of unintentional large and / or rapid-acting opening forces when z. B. a vehicle accidentally hits the door. For safety then opens the check valve 300 and thus prevents destruction of the two-way flow control valve 400 or the door 30 due to the pressure relief via the check valve 300, which shuts off in the flow direction from the first cylinder chamber 200-1 in the second cylinder chamber 200-2 , and in the opposite direction of flow, for example, against the force of a closing spring opens. Because the check valve may optionally respond faster with an opening movement than the valve 400, for example, if the door was just about to close partially or almost completely with a large closing force.

The present invention has been made to provide a door closer for fire doors that can accommodate large forces that can occur when opening and closing the door, so that the fire door is not damaged and still easy to open by hand. The embodiment associated with the Fig. 3 . 4 and 5 has been described, represents a particularly preferred embodiment, which achieves the desired effect particularly efficient and cost-saving. In particular, the linear structure no forces must be redirected and converted into rotational movements, which increases the cost of the system, the wear and the maintenance vulnerability would. In the door closer according to the present invention, all forces are taken along the cylinder axis.

As one skilled in the art realizes, this objective can also be achieved by modifications of the Fig. 3 . 4 and 5 be achieved embodiment shown. For example, it is not absolutely necessary that the hydraulic medium between the first and second cylinder chamber is pushed back and forth. It would also be conceivable to use only a one-sided piston rod and to fill only one cylinder chamber with hydraulic medium. In this case, however, an external reservoir for the hydraulic medium must be provided and a means for transporting the hydraulic medium. Furthermore, the bias can also be achieved by a spring. The two-way flow control valve or alternatively the lowering brake can also be replaced by a combination of individual valves that can perform the same functions.

Furthermore, it is not necessary to cause the closing of the door by extending the piston rod from the hydraulic cylinder. Although the desired effect of the door closing damper by the described arrangement according to the Figures 3 . 4 and 5 Particularly simple and efficient to implement, the door closer can be designed and arranged between the door and wall, that closes the door when the piston rod pushes into the hydraulic cylinder. As previously explained, functionalities of components must be correspondingly kinematically inverted. That is, for example, that the biasing means must be designed so that the piston rod is drawn into the cylinder.

Furthermore, it is possible to store the door so that it closes itself by gravity. However, a biasing device for closing the door, as described in this invention, increases the reliability.

Therefore, the description should be considered as illustrative only and serves the skilled person only to teach the general principle of carrying out the present invention. The scope of the invention is therefore defined only by the appended claims.

Claims (15)

A door closure damper (20) comprising: a hydraulic cylinder (200) in which a movable piston (210) is arranged which divides the cylinder (200) into a first cylinder space (200-1) and a second cylinder space (200-2); and a flow restriction device (400) that limits a flow of a hydraulic medium from the first cylinder space (200-1) or the second cylinder space (200-2);
marked by a piston rod extending from a first end surface of the movable piston along a longitudinal axis of the hydraulic cylinder through the first cylinder space and protruding from the hydraulic cylinder. The door closer (20) of claim 1, wherein the flow restricting device (400) is a flow control valve. The door closer (20) according to claim 2, wherein the flow control valve is arranged to control the flow as a load depending on a closing force. The door closer (20) of claim 3, wherein the flow control valve is adapted to keep the flow constant independent of the load. The door closer (20) according to any one of claims 1 to 4, wherein the flow restriction device (400) connects the first and second cylinder chambers (200-1, 200-2). The door closer (20) according to any one of claims 1 to 5, wherein the flow restricting device (400) has a first state (400B) with a flow control and a second state State (400A) with a flow resistance smaller than the flow resistance in the first state. The door closer (20) of claim 6, wherein the flow restricting device (400) is adapted to automatically switch to the second low-flow resistance state (400A) when an opening force is applied to the door above a predetermined value. The door closer (20) of any of claims 6 and 7, wherein the flow restricting device (400) is a 2-way flow control valve having a first position (400B) corresponding to the first state and a second position (400A) corresponding to the second state. The door closer (20) according to any one of claims 1 to 8, wherein the flow restricting device (400) is at least one counterbalance brake connecting the first and second cylinder chambers (200-1, 200-2). The door closer (20) according to any one of claims 1 to 9, wherein the flow restriction device (400) is integrated in the movable piston (210), preferably combined with at least one check valve (300) connected in parallel, which blocks in the flow direction in which the flow restriction device (400) 400) assumes the first state. The door closer (20) according to any one of claims 1 to 10, further comprising a locking device that fixes the movable piston at a predetermined position so that a door (30) can be held in an open position, the locking device being controlled by a fire alarm device ( 10) can be controlled so that a lock triggers when the fire alarm device (10) reports fire. The door closer (20) according to any one of claims 1 to 11, further comprising a biasing device that urges the movable piston (210) in a predetermined direction so that a door (30) can close itself. The door closer (20) according to any one of claims 1 to 12, wherein the piston rod (220) is a double-sided piston rod (220, 220-1, 220-2) extending from opposite end surfaces of the movable piston (210) along a longitudinal axis of the hydraulic piston Cylinder (200) through the first cylinder chamber (200-1) and the second cylinder chamber (200-2) extend. The door closer (20) of claim 13, wherein one end of a first portion (220-1) of the double-sided piston rod (220) protrudes from the hydraulic cylinder (200) and is provided with a fastener (21), and wherein one end of a second portion (220-2) of the double-sided piston rod (220) into a pressure chamber (200-3), whereby the movable piston (210) is pressed in a predetermined direction. A fire door (30) having a door closer (20) according to any one of claims 1 to 14, wherein one end of the door seal damper (20) is connected to a wall and another end of the door seal damper (20) is connected to the fire door (30); and wherein a detent as a door open fixture (40) is connectable to a fire alarm (10) such that the fire door (30) closes when the fire alarm (10) reports fire.

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