Door drive

Abstract

Door drive (1), in particular a door closer, with hydraulic damping, in particular for a fire door, wherein the door drive (1) comprises: a housing (3) with a housing interior in which a hydraulic fluid is provided, a functional element (7, 9) which is inserted into an opening (5) of the housing (3), and a sealing element (11) which seals the housing (3) to the outside in the area of ​​the opening (5), wherein the sealing element (11) consists at least partially of a material which has a defined melting temperature, characterized in that that the sealing element (11) is a sealing ring, that the functional element (7) comprises a circumferential outer groove (13) which receives the sealing element (11), and that the outer groove (13) of the functional element (7) has an outwardly directed support surface (15) with at least one recess (17) which acts as a flow contour for the hydraulic fluid.

Description

[0001] The present invention relates to a door drive, in particular a door closer, with hydraulic damping, especially for a fire door, according to the preamble of claim 1.

[0002] Such a door drive is known from DE 41 34 509 A1.

[0003] Conventional door drives comprise a housing, at least one functional element, and at least one sealing element. The housing includes an interior containing a hydraulic fluid. The at least one functional element is inserted into an opening in the housing. The sealing element is designed to seal the housing to the outside in the area of ​​the opening when the functional element is inserted. Thus, the door drive essentially forms a closed system containing the hydraulic fluid. Conventionally, industrially used rubber, such as acrylonitrile butadiene rubber, is used as the material for the sealing element.

[0004] In the event of a fire, however, there is a risk with such door drives that the hydraulic fluid inside the drive housing generates such high pressures as the temperature rises that the hydraulic fluid causes the drive to explode uncontrollably. This poses, among other things, the danger of flying debris, especially sharp-edged pieces, and of hot, especially burning, hydraulic fluid being sprayed. The conventionally used sealing elements coke up with increasing temperatures, becoming brittle and hard, but do not allow for a controlled reduction of the high hydraulic fluid pressures.

[0005] To solve this problem, it is known to provide separate outlet valves in the door actuator housing, sealed with a plug of soft solder that melts at a certain temperature, thus allowing the hydraulic fluid to escape from the inside of the door actuator housing. This prevents an uncontrolled explosion of the door actuator. However, such a design is comparatively complex.

[0006] A comparable device is the door drive known from document DE 41 34 509 A1. This known door drive has an outlet channel at the base of the hydraulic cylinder that opens to the outside and is secured with a spherical locking element. The locking element is designed as a fused body made of polyoxymethylene (POM).

[0007] Against this background, it is an object of the present invention to provide a door drive in which the problem of overpressure in the door drive in the event of fire described above is solved in a simpler and more cost-effective way than is the case in the prior art described above.

[0008] This problem is solved by a door drive with the features of main claim 1. Advantageous further developments can be found in the dependent claims.

[0009] According to the invention, the intended sealing element consists at least partially of a material which has a defined melting temperature.

[0010] By selecting a material with a defined melting point, the sealing element, at a precisely defined temperature, at least partially releases the opening to be sealed, allowing the hydraulic fluid to flow through or escape and relieve the overpressure. This reliably prevents the overpressure in the hydraulic fluid from reaching critical levels and potentially damaging the door drive. Previously used sealing elements made of industrial rubber do not have a true melting point; instead, they simply coke or char at high temperatures. The behavior of such conventional sealing elements under increasing pressure in the hydraulic fluid is difficult to control and reproduce. This was also the reason for the previously required separate outlet valve.However, according to the present invention, such an exhaust valve is not necessary, since the sealing element already provided is modified in such a way that it also fulfills the function of the exhaust valve. This is achieved according to the invention by adapting the material of the sealing element, at least in part.

[0011] Preferably, the defined melting temperature is at most 600°C, in particular at most 500°C, in particular at most 300°C, in particular at most 260°C.

[0012] By selecting the defined melting temperature in this way, an uncontrolled pressure drop, for example through an explosion of the door drive, can be reliably avoided.

[0013] Preferably the defined melting temperature is at least 100°C, in particular at least 120°C, in particular at least 140°C.

[0014] By selecting the defined melting temperature in this way, premature melting of the sealing element can be reliably avoided.

[0015] Preferably, the material in question is a thermoplastic polymer, in particular polyurethane.

[0016] Such materials were found to be particularly suitable for implementing the solution according to the invention.

[0017] The sealing element is a sealing ring, in particular an O-ring.

[0018] Adapting such a sealing element to implement the present invention is particularly simple and leads to a particularly reliable overall design.

[0019] Preferably, the functional element is a closure cover, in particular provided laterally, a valve, in particular for controlling a hydraulic fluid flow between two chambers separated by a piston inside the housing, or a bearing for a drive shaft of the door drive.

[0020] These functional elements have been recognized as being particularly suitable for combination with the sealing element designed according to the invention.

[0021] The functional element includes a circumferential outer groove which accommodates the sealing element.

[0022] Such an external groove allows for improved fixing or holding of the sealing element in the opening to be sealed.

[0023] The outer groove of the functional element has an outwardly directed support surface with at least one recess, which serves as a flow contour for the hydraulic fluid.

[0024] The aforementioned recess defines a specific area through which the hydraulic fluid should pass in the event of a fire. This facilitates or enables better control of the flow of hydraulic fluid exiting the door drive.

[0025] Preferably, at least two, and in particular four, of the aforementioned recesses are formed along the outer groove. In particular, the recesses formed are evenly distributed along the outer groove.

[0026] Such a design enables a safe reduction of the overpressure of the hydraulic fluid, even at particularly rapidly rising temperatures.

[0027] Preferably, the sealing element is made entirely of the aforementioned material.

[0028] Such a design is particularly easy and therefore inexpensive to manufacture.

[0029] Preferably, the hydraulic fluid is non-flammable or at least flame-retardant.

[0030] This can reduce the dangers posed by the leaked hydraulic fluid.

[0031] Preferably, the door drive has only one sealing element designed according to the invention and at least one further sealing element, which in particular consists of a rubber, preferably of acrylonitrile butadiene rubber.

[0032] This design allows for even better control of the pressure reduction process through the release of hydraulic fluid. In particular, it makes it possible to clearly define which opening the hydraulic fluid exits from, while the other openings remain largely closed.

[0033] The invention is described below by way of example with reference to the accompanying drawings. The accompanying figures show: Fig. 1 a partial cross-section of an end section of an exemplary door drive according to the present invention; and Fig. 2 a spatial view of the in Fig. 1 of the illustrated end section.

[0034] As in the Fig. 1 and Fig. As shown in Figure 2, a door drive 1 according to the invention comprises a housing 3 which surrounds an interior. Various components, such as a closing piston and a closing spring (not shown), are housed within the interior of the housing to enable the functionality of the door drive 1. The specific components depend on the particular design of the door drive 1 and are well known to those skilled in the art, and are therefore not discussed separately here.

[0035] Furthermore, a hydraulic fluid is provided inside the housing to dampen the movement of the closing piston and thus of a door leaf actuated by the door drive. The housing 3 comprises at least one opening 5 through which at least one functional element is inserted into the housing 3. Examples of such a functional element are a cover 7, particularly one provided laterally, a valve 9 for controlling a hydraulic fluid flow between two chambers inside the housing 3 separated by the closing piston, or a bearing (not shown) for a drive shaft (not shown) of the door drive 1. In the example shown, a cover 7 provided laterally serves as the corresponding functional element.

[0036] To seal the housing 3 in the area of ​​the opening 5, into which the closure cover 7 is inserted as a functional element, the door drive 1 further comprises a sealing element 11. According to the invention, this is formed at least partially, and in particular completely, from a material which has a defined melting temperature.

[0037] In this regard, it should be noted that industrially used rubber, such as acrylonitrile butadiene rubber, does not have a defined melting point. Instead of melting at a specific temperature, it cokes or chars.

[0038] Due to the defined melting temperature, rising temperatures, particularly in the event of a fire, cause at least partial melting of the sealing element 11. This allows the hydraulic fluid, under increasing pressure, to find its way through the opening 5, which is no longer sealed by the sealing element 11. This enables the overpressure in the door drive 1, especially inside the housing, to be relieved. With the design according to the invention, this is possible without having to provide a separate "temperature-controlled" outlet valve.

[0039] In order for the sealing element 11 to not only fulfill its sealing function but also to act as a "temperature-controlled" outlet valve, the defined melting temperature for the material is preferably at least 100°C, in particular at least 120°C or 140°C. The defined melting temperature should be at most 600°C, in particular at most 500°C, at most 300°C or at most 260°C.

[0040] Materials from the group of thermoplastic polymers, such as polyurethane in particular, have proven to be especially suitable for the formation of the sealing element 11.

[0041] In the present case, the sealing element 11 is a sealing ring in the form of an O-ring, although other designs are conceivable if required.

[0042] As particularly in Fig. As can be seen in Figure 1, the closure cover 7 has a circumferential outer groove 13 which at least partially receives the sealing element 11. This outer groove 13 is bounded on the outside by a support surface 15.

[0043] As in Fig. As shown in Figure 2, this circumferential support surface 15 has four recesses 17, which are evenly distributed along the outer groove 13. These recesses 17 act as outflow contours for hydraulic fluid, which, according to the invention, is drained from the door drive 1 in the event of a fire at a defined temperature. The recesses 17 make it possible to better control and regulate the outflow of the hydraulic fluid. At the same time, they allow larger quantities of hydraulic fluid to flow out. Depending on the requirements, it is also possible to provide more or fewer recesses 17 and / or to arrange them differently around the outer groove 13.

[0044] In order to control the flow of hydraulic fluid as effectively as possible, the door drive 1 preferably has only one sealing element 11 formed according to the invention. Further sealing elements, for example for the valve 9, are preferably formed in a conventional manner from rubber, in particular from acrylonitrile butadiene rubber.

[0045] Given that the hydraulic fluid is drained from the door drive 1 according to the invention, it is preferred to provide a hydraulic fluid in the door drive 1 that is non-flammable or at least flame-retardant. This reduces the hazard posed by the escaping hydraulic fluid.

[0046] Finally, it should be noted that, in light of the above description of the exemplary embodiments, a person skilled in the art would readily think of a multitude of combinations and modifications thereof, which are not explicitly described here, but are covered by the scope of protection of the accompanying claims. Reference symbol list 1 door drive 3 cases 5 Opening 7 Closure lids (functional element) 9 Valve (functional element) 11 Sealing element 13 Outer groove 15 outward-facing support surfaces 17 recess

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