EP2031156B1 - Reset mechanism for a door handle - Google Patents

Description

The present invention relates to a return mechanism for a pusher for actuating a door lock according to the preamble of claim 1, as known from DE 39 04 997 A1 or the DE 295 16 846 U1 has become known.

Usually, a return spring is provided in the lock case of a door lock, which serves to return the pusher after it has been pressed down from its horizontal position for actuating the door lock in its horizontally aligned initial position. However, the return spring located in the lock case often fatigues over time, resulting in the handle being unable to fully retract to the horizontal position.

To support the return movement of the pusher therefore additional spring systems are used, which are arranged in the rosette of the handle set. In this handle sets, in which an additional spring system to support the return movement of the pusher is arranged in the rosette, the pusher is firmly connected to the rosette, which means that not only different pusher held for different sizes of protruding from a lock box square pins Need to become. Rather, it is necessary to provide for each special square pin its own handle set available and vorzuhalten, but this proves to be particularly disadvantageous in economic terms.

Furthermore, pushers and rosette are either not separable from each other in known handle sets or it is only a release the pusher of the rosette only possible with a special tool, the purchase of which is not profitable for the average consumer. For these reasons, it is often necessary disadvantageously, instead of the pusher renew the complete handle set.

The invention is therefore based on the object to provide a located in the rosette of a handle set return mechanism for a door handle, is specially designed to counteract any over claims its springs.

This object is achieved with a return mechanism for a door handle, which has the features of claim 1.

Although it is sufficient for the complete operation of many door locks, their square pin to turn by about 40 °, but also door locks are available to complete the operation of the pusher by more than 45 ° must be pressed down. However, since upon actuation of the return mechanism according to the invention with increasing rotation of the driver ring, the springs of the slider are increasingly stressed, there is a fundamental risk that the springs are overstressed, which can lead to permanent spring breakage or an at least partially plastic behavior of the springs. In order to counteract such overstressing of the springs, the sliding ramps of mutually adjacent indentations can be connected to each other in accordance with a further embodiment by means of sliding surfaces formed on the circumference of the driving ring. These sliding surfaces have a constant distance from the center of the driver ring, so that the springs of the slider in the region of the sliding surfaces learn no further stress. Although an overuse of the springs could also be prevented by providing a fixed stop at the end of the sliding surfaces, which prevents rotation of the sliding ring of, for example, more than 40 °, however, the return mechanism according to the invention would then no longer be suitable for door locks whose square pin is intended for complete operation of the lock must be rotated by more than 40 °. In addition, there would be the danger of canceling the fixed stop in case of overuse.

The sliding ramps of adjacent indentations to be connected to one another via said sliding surfaces is also advantageous because, as a rule, when the sliding bodies slide on the sliding surfaces, it is no longer necessary to apply an additional restoring force to the driving ring via the return mechanism according to the invention. Namely, if the drive ring has been rotated so far that the sliding slide on the sliding surfaces, namely the return spring located in the lock case will be effective even if they should already show signs of fatigue. In the area of the sliding surfaces thus only the return spring located in the lock case is effective, whereby an undesirable stiffness of the pusher can be counteracted, which could be adjusted by a simultaneous effect of the springs of the slider. In other words, therefore, the return mechanism according to the invention tends to be effective in that area in which there is a risk that any signs of fatigue of the return spring located in the lock case that the pusher no longer returns completely back to its horizontal starting position.

Therefore, the ring in question is a "dog" ring, as it is specially designed to be coupled to a pusher - not a square pin - so that a pusher coupled to the dog ring, after having he has caused the rotation of the driver ring due to its operation, due to the interaction of the spring-loaded slider and the driving ring of this is moved back into its horizontal starting position. The ring in question is therefore due to its interaction with the slider and the possible coupling with a pusher suitable to move such a pusher from its operating position back to its horizontal starting position. In other words, therefore, the driving ring, when it is rotated back as a result of the force exerted by the slider on the sliding ramp force, with a ring-coupled pusher with what the chosen terminology "driver" ring justified.

The driving ring thus effectively serves as a coupling between the return mechanism and a suitable for actuating a door lock pusher, said coupling can be made detachable. This solvability ensures that, for example, in a defective handle not the entire handle set of rosette and door handle but only the pusher must be replaced.

It is made exclusively through the pusher - and not about the return mechanism - the connection to the square pin of the door lock, so that the return mechanism of the dimensions of the square pin of the door lock is completely independent. In other words, one and the same, the reset mechanism according to the invention comprehensive rosette can be used with different square pins, so that no different, matched to different square pins rosettes must be kept.

The function of the return mechanism itself is based on the interaction between the spring-loaded sliding body and the trained on the circumference of the driving ring slide ramp. The sliding ramp can be a jacket section on the outer circumference of the driver ring, which extends over the longitudinal extent of the slide ramp Viewed circumferential direction of the driver ring has a depending on the viewing direction steadily decreasing or increasing distance to the center of the driver ring. In other words, the sliding ramp is a circumferential section of the driving ring, which continuously approaches the center of the driving ring in the circumferential direction or which steadily moves away from the center of the driving ring in the circumferential direction.

In the initial position of the driver ring, which generally corresponds to the horizontally oriented starting position of the door handle, while the slider is located at the point of the sliding ramp, which has the smallest distance to the center of the driver ring. However, when the drive ring is rotated by operation of the pusher, the slide slides along the slide ramp, continuously moving away from the center of the drive ring, thereby biasing the return spring applied thereto.

This biasing force is in turn transmitted via the slider on the sliding ramp, whereby to a certain extent an output force is exerted on the slip ramp, which counteracts the previous rotation due to the operation of the pusher. As a result, the driving ring is transferred including a coupled with the driving ring pusher back to the starting position, in which the slider again assumes the position in which it has the smallest distance to the center of the driving ring in the sliding ramp.

Advantageous embodiments of the invention will become apparent from the dependent claims, the description and the drawings.

Thus, a simple and easy-to-assemble coupling of the driving ring can be made possible with a door handle by a trained on the driving ring plug engagement means, via which the driving ring is coupled torsionally rigid with a door handle. For this purpose, the door handle can have on its handle neck a plug engagement means which is complementary to the plug engagement means in order to be able to produce a positive and rotational connection with the plug engagement means of the drive ring.

According to a preferred embodiment, the plug-in engagement means of the driving ring can be arranged on the inner circumference, whereas the complementary plug engagement means of the presser neck are located on the outer circumference thereof. To couple the driving ring with the pusher while the pusher neck is inserted into the driving ring until the respective male engagement means engage positively with each other. Due to the arrangement of the respective plug engagement means on the inner circumference drive ring or on the outer circumference of the pusher neck thus the height of the return mechanism and thus the height of the rosette body can be kept low.

According to another embodiment, the male engagement means of the driver ring and the complementary thereto formed on the pusher neck of the pusher plug engagement means may be formed such that the pusher can be selectively coupled in two offset by 180 ° positions with the driver ring. This embodiment proves to be advantageous in that one and the same pusher can be used on both right- and left-handed doors, so that regardless of the size of the square pin and regardless of which side of the door is hinged, only a single pusher type must be kept.

Particularly advantageous, this embodiment proves to be when the driving ring has at its periphery a plurality of steadily widening, symmetrical indentations whose contour surfaces are formed by two oppositely aligned slide ramps on the circumference of the driving ring, wherein the individual indentations at regular angular intervals, preferably are arranged at angular intervals of 180 °, 120 ° or 90 ° to each other.

Due to the symmetrically widening shape of the indentations can be achieved in a sense a kind of self-centering of the driving ring with respect to the or the slider, since the slider due to the previously described acting on them biasing force then only so far on one of the slide ramps in the Indentation can penetrate until they come into contact with the other sliding ramp of the respective indentation. As a result of the mirror-symmetrical arrangement of the slide ramps defining the indentations, the driver ring and thus a pusher which can be coupled to the driver ring can be reliably returned to its starting position even if the sliding bodies should be slightly worn out.

The indentations at regular angular intervals such as below 180 ° at two indentations, below 120 ° at three indentations or below 90 ° at four indentations to each other, proves to be advantageous in that thereby any eccentricities or unbalanced power distributions are avoided, which could otherwise lead to an undesirable misalignment of the driving ring. Due to the uniform arrangement of the indentations on the driving ring this is rather uniformly applied by the associated sliding body with the desired restoring forces, which are due to the uniform arrangement of the indentations on the circumference of the driving ring in balance with each other, so that an offset of the driving ring can be largely excluded.

In addition, it can be characterized by the fact that a plurality of indentations are provided on the driving ring, reduce wear both on the sliding ramps of the indentations and on the associated sliding bodies, as to produce the required restoring forces instead of a biased with a strong spring slider several sliding body with correspondingly weaker springs for Can use, so act on each of the sliding ramps lower output or sliding friction forces, which consequently also lead to less wear.

According to another preferred embodiment, the slide ramps of a recess concave with a radius of curvature of 1 mm may merge into each other, the slide ramps themselves being generally convex with a radius of curvature of 6 mm. When viewed in the circumferential direction, a convex curvature of a sliding ramp of a recess is followed by a concavely curved transition region followed by a turn convex curvature of the other sliding ramp of the indentation.

Although the Gleitrampen could also have a flat surface, but can be achieved by the convex shape that during the initial handle operation, the force increase of the sliding bodies or their springs outgoing restoring force is relatively large, whereas this increase in force on further actuation of the pusher fails , In the event that the return spring located in the lock case should show signs of fatigue, the reset mechanism according to the invention is thus primarily active upon initial actuation of the pusher, whereas its influence becomes less with increasing actuation of the pusher as a result of the then increasing influence of the then restoring force of the return spring located in the lock case ,

The restoring forces of the return mechanism according to the invention are thus not simply superimposed on the restoring forces of the spring located in the lock case; Rather, the action of the resetting mechanism according to the invention at least partially replaces the action the return spring located in the lock case, if it should no longer be effective due to signs of fatigue in certain areas.

As can already be seen from the above explanations, the sliding body slides on a rotation of the driving ring along the sliding ramps formed on the circumference thereof. However, since a handle set is operated several hundred thousand times in the course of its life, appropriate precautions must be taken to minimize unwanted wear caused by the friction between the slide ramp and the slider.

To meet this requirement, the slider has a sliding surface which has a shape complementary to the indentations. The sliding body thus has a convex tip corresponding to the concave transition of the two sliding ramps of a recess, to which two concave sliding surface sections adjoin on both sides.
Due to the convex design of the slide ramps and the likewise convex design of the tip of Gleitkörpergleitfläche can thus be achieved that the slider only occurs along a line or along a line with the sliding ramp in contact, whereby unwanted friction phenomena can be kept low. The complementary to the booking form of the slider also proves to be advantageous in that a rich and planar engagement of the slider can be achieved in the booking when the slider are in its rest position, which corresponds to the horizontal starting position of the door handle.

In order to further reduce any signs of wear between the sliding bodies and the sliding ramps, the driving ring can be made a metal, preferably of chromium-plated die-cast zinc, and the sliding body made of a plastic material such as polyoxymethylene (POM), which is preferably enriched with Teflon or chalk. By selecting these materials, it is possible to reduce the friction between the sliding bodies and the slide ramps to a minimum so that there is no or only little undesired wear and tear. The reduction of friction is also of utmost importance, since in case of too large (adhesive) frictional forces between the sliding bodies and the sliding ramps, the restoring effect of the return mechanism according to the invention could not be used.

To secure the pusher on the rosette body, the return mechanism further comprises on the door leaf side facing the driving ring a spring ring, which engages in a formed on the front end of the pusher neck annular groove. To improve the ease of assembly, the pusher neck can taper conically in the direction of its front end, so that the conically tapered end of the pusher neck must be inserted only in the spring ring for mounting the pusher, causing it to spread and ultimately formed in the front end of the pusher neck Ring groove snaps.

For the sake of fire protection, the rosette body may be covered on the side facing away from the door leaf by a cap made of metal, which in turn may be covered for artistic reasons with a plastic cover.

Fig. 1

eine Explosionsdarstellung des erfindungsgemäßen Rückstellmechanismus zeigt;

Fig. 2

eine perspektivische Rückansicht einer den erfindungsgemäßen Rückstellmechanismus aufnehmenden Rosette zeigt; und

Fig. 3

das Zusammenwirken des Mitnehmerrings mit zwei federbeaufschlagten Gleitkörpern veranschaulicht.

In the following, the invention will now be described purely by way of example with reference to an exemplary embodiment with reference to the accompanying drawings, in which:

Fig. 1

an exploded view of the return mechanism according to the invention;

Fig. 2

shows a rear perspective view of a rosette according to the invention receiving rosette; and

Fig. 3

illustrates the interaction of the driving ring with two spring-loaded sliding bodies.

First, with reference to the Fig. 1 the individual components of the return mechanism 10 and the rosette 12 according to the invention described in which the individual components of the return mechanism 10 are arranged. The Fig. 1 shows an exploded view of a handle set, in which case only the pusher neck 16 of a pusher is recognizable. The handle set further comprises an oval rosette body 14, which may be a substantially solid component of polyoxymethylene (POM). On the side facing the pusher neck 16, the rosette body 14 is covered by a cap 18 made of metal for purposes of fire protection, which only has an opening 36 for the pusher neck 16 and two openings 44 for fastening screws 30. For design reasons, the cap 18 is again covered by a Kunststoffabdeckkappe 18, which also has an opening 38 for the pusher neck 16, which is aligned with the opening formed in the cap 18 opening 36.

The rosette body 14 has a with the openings 36, 38 of the cap 18 and the cover 20 aligned opening 34 into which on the side facing the pusher neck 16 two opposing crescent-shaped flanges 32 project, which are integrally formed with the rosette body 14.

In addition to the rosette body 14, the return mechanism 10 according to the invention further comprises two force-loaded by return springs 26 sliding body 24, which are preferably made of polyoxymethylene (POM), which is enriched with Teflon or chalk. In addition, the return mechanism includes in the Fig. 1 characterized by the reference numeral 22 driver ring made of metal, preferably made of chromium-plated die-cast zinc, which is rotatably received on the back of the rosette body 14 in the aperture 34 adjacent to the sickle-like flanges 32.

To secure the pusher neck 16 and the driver ring 22 on the rosette body 14, a clamping or spring ring 28 is further arranged on the side facing the door leaf of the driver ring 22, which engages in the assembled state of the handle set in a formed on the front end of the pusher neck 16 annular groove 50. To facilitate the assembly while the pusher neck 16 has a conically tapered front end, so that during assembly of the pusher neck 16 only through the openings 38, 36 and through the opening 34 and the driver ring 22 and the spring ring 28 must be inserted through, so that the Spring ring 16 aufläuft on the conical front end of the pusher neck 16 and is spread apart until it finally engages in the annular groove 50 of the pusher neck 16.

As already the representation of the Fig. 1 can be removed, the driver ring 22 on its inner circumference two inwardly projecting, diametrically opposed engagement lugs 48 (of which only one is recognizable due to the perspective view), which is formed with complementary thereto formed slot 46 at the front end of the pusher neck 16 due to can be engaged described plug movement. In this way, the pusher neck 16 or the pusher integrally formed on the pusher neck 16 is rotationally rigidly coupled to the driver ring 22. The clamping ring 22 thus serves as a coupling between the return mechanism 10 and the pusher neck 16 and the associated with the pusher neck 16 pushers.

As the perspective rear view of the in the Fig. 2 shown handle set are next to the opening 34 in the rosette body 14 also two diametrically opposed guide channels 52 are formed, in which the sliding body 24 are arranged against the likewise arranged therein return springs 26 slidably. The return springs 26 are based on the one hand on the sliding bodies 24 and on the other hand on the rear boundary of the guide channels 52, whereby the sliding body 24 are urged in the direction of the rotatably mounted in the aperture 34 driver ring 22. Due to the limited space available in the area of the rosette body 14 while the guide channels 52 are arranged inclined relative to the vertical at an angle.

To the pusher neck 16 and the entire pusher from the in the Fig. 2 shown secured by the spring ring 28 assembly to be able to remove again from the rosette 12 are in the rosette body 14 and in the in the Fig. 2 only partially visible cap 18 aligned with each other inspection openings 54, 56 are provided, through which For example, an ordinary screwdriver can be inserted through it, in order to be able to spread apart the spring ring tongues 58 located directly behind the inspection opening 56 and thus the entire spring ring 28, so that the presser neck 16 can be pulled out of the rosette 12.

The following will now be with reference to the Fig. 3 on the return mechanism 10 according to the invention, whose restoring effect is due essentially to the interaction of the spring-loaded sliding body 24 with the recorded in the rosette body 14 driver ring 22, which is why the sake of clarity in the Fig. 3 only the spring-loaded sliding body 24 and the driving ring 22 are shown.

Again Fig. 3 can be removed, two steadily widening symmetrical indentations 66 are formed on the circumference of the driver ring 22 at two opposite points, the contour surfaces are formed by two oppositely aligned slide ramps 62 on the circumference of the driver ring 22. The slide ramps 62 of each of the recesses 66 are concave with each other with a radius of curvature of about 1 mm into each other, wherein the slide ramps 62 in turn are not concave but convexly formed with a radius of curvature of preferably 6 mm. Further, two sliding surfaces 64 are formed on the outer circumference of the driving ring 22, which connect the mutually adjacent slide ramps 62 of the two recesses 66 with each other.

Like in the Fig. 3 is shown schematically, the return springs 26 are based on the rear boundary of the guide channels 52, whereby the sliding body 24 in the direction of the center of the driving ring 22 to be biased. The sliding bodies 24 each have a sliding surface which has a shape complementary to the indentations 66. In order to prevent slipping back of the sliding body 24, the driving ring 22 also on the side facing the door leaf on an annular flange 40 which projects in the radial direction over the slide ramps 62 and the sliding surfaces.

The following will now discuss the operation of the resetting mechanism 10 according to the invention. In the starting position of the pusher, in which this is usually in a horizontal position, the sliding body 24 fully engage with their sliding surfaces in the formed on the circumference of the driving ring 22 indentations 66 by by the return springs 26 toward the center of the Mitnehmerrings 22 are biased. Since the return springs 26 are already biased in the initial position, they help to compensate for the weight exerted by the pusher.

Now, when it is started to actuate the pusher, the rotational movement of the pusher neck 16 caused thereby is transmitted via the engagement lugs 48 of the driver ring 22 on the same, so that it begins to rotate in accordance with the rotational movement of the pusher neck 16. If, for example, in the Fig. 3 the driving ring 22 is rotated clockwise, this leads to the anti-clockwise sliding shoe 62 sliding ramps 62 slide under the sliders 24, resulting in that the sliding body 24 is displaced in the guide channels 52 against the action of the return springs 26 become. The return springs 26 thereby act on the sliding bodies 24 with steadily increasing restoring forces, which are transmitted by the sliding bodies 24 to the sliding ramps 62, so that the driving ring 22 counteracts counterclockwise forces is charged. These restoring forces exerted by the sliding bodies 24 on the slide ramps 62 thus lead to the fact that, after the operation of the pusher, the same is again moved completely back into its horizontally aligned initial position against the weight of the driver via the driver ring 22.

Due to the symmetrical design of the recesses 66 and by the indentations 66 complementary shape of the sliding surfaces of the slider 24 can be achieved in a certain way a self-centering of the return mechanism 10, since the slider 24 due to the restoring forces exerted by the return springs 26 by itself in her in the Fig. 3 return shown starting positions in which they are in engagement with the recesses 66 and are "full" and flat with the slide ramps 62 of the recesses 66 in abutment.

Due to the steadily widening symmetrical shape of the indentations 66, a reliable self-centering of the sliding bodies 24 can be ensured even if their convex tips should be slightly worn due to friction. In this case, the sliding body 24 are always so far pushed into the indentations 66 of the return springs 26 due to the symmetrical shape of the recesses 66 until the slider 24 abut at corresponding points of the indentations 66 defining slip ramps 62.

Due to the convex shape of the slide ramps 62, starting from the lowest point of the indentations 66, they continuously merge into the sliding surfaces 64 formed on the circumference of the driver ring 22 at a location offset by an angle of approximately 35 °. Thus, can be in the Angle range between 0 and 35 ° with the help of the return mechanism 10 according to the invention achieve a particularly good return effect.

However, if it is necessary, for example, to operate a door lock to turn a pusher by more than 35 °, so the inventive reset mechanism 10 also allows, in which case the sliding body 24 then slide on the sliding surfaces 64. Although it can be when the slider 24 slide on the sliding surfaces 64, with the return mechanism 10 according to the invention no longer achieve restoring effect, but this will usually not be necessary because in this case the return springs located in the lock case are effective in this area even if they show some signs of fatigue.

In this respect, it is even desirable that the restoring action decreases with increasing rotation of the driver ring 22, since otherwise only a superposition of the action of the return spring located in the lock case and the return mechanism 10 according to the invention would occur, which would cause the handle to operate only with difficulty leaves.

Finally, it should be mentioned again that the driving ring 22 is made of a metal material, preferably made of chromed die-cast zinc, whereas the sliding body 24 are made of a plastic material and preferably made of enriched with Teflon or chalk polyoxymethylene. The combination of these two materials, the friction between the sliders 24 and the driver ring 22 can be kept low, which also contributes to the fact that the slider 24 are not or only slightly worn over hundreds of thousands of operating cycles.

LIST OF REFERENCE NUMBERS

10

Reset mechanism

12

rosette

14

rosette body

16

pusher neck

18

cap

20

cover

22

driver ring

24

sliding

26

Return spring

28

spring washer

30

fixing screw

32

flange

34

perforation

36

opening

38

opening

40

annular flange

42

guide eye

44

screw opening

46

insertion slot

48

engaging nose

50

ring groove

52

guide channel

54

inspection opening

56

inspection opening

58

Spring ring tongue

62

slide ramp

64

sliding surface

66

indentation

Claims (11)

1. A restoring mechanism (10) for a door handle, having a rosette body (14) which can be attached to a door leaf and which rotatably accepts a follower ring (22) which can be releasably coupled to a door handle and which has at its circumference at least two constantly widening symmetrical indentations (66) whose contour surfaces are formed by two slide ramps (62) at the circumference of the follower ring (22), which are oriented oppositely to one another and which cooperate with a spring-loaded slide body (24) such that it is preloaded on a rotation of the follower ring (22) from a position of rest into a deflected work position in which the slide body (24) exerts a force on the follower ring (22) acting counter to the rotation,
   characterised in that
   the slide ramps (62) of mutually adjacent indentations (66) are connected to one another via slide surfaces (64) formed at the circumference of the follower ring (22); and in that the slide ramps (62) of an indentation (66) concavely mutually merge into one another and the slide ramps (62) are generally formed convex.
2. A restoring mechanism in accordance with claim 1,
   characterised in that
   the follower ring (22) has a plug engagement means (48) via which the follower ring (22) is rotationally rigidly coupled to a door handle which has at its handle neck (16) a plug engagement means (46) configured complementary to the plug engagement means (48).
3. A restoring mechanism in accordance with claim 2,
   characterised in that
   the plug engagement means (48) of the follower ring (22) is provided at its inner circumference and the plug engagement means (46) of the handle neck (16) complementary thereto is provided at its outer circumference.
4. A restoring mechanism in accordance with claim 2 or claim 3,
   characterised in that
   the plug engagement means (48) of the follower ring (22) and the plug engagement means (46) at the handle neck (16) configured complementary thereto are configured such that the door handle is selectively couplable to the follower ring (22) in two positions offset by 180°.
5. A restoring mechanism in accordance with at least one of the preceding claims,
   characterised in that
   the follower ring (22) has at its circumference a plurality of constantly widening symmetrical indentations (66) whose contour surfaces are formed at the circumference of the follower ring (22) by two slide ramps (62) oriented opposite to one another, wherein the individual indentations (66) are arranged at regular angular intervals to one another, preferably at angular intervals of 180°, 120° or 90°.
6. A restoring mechanism in accordance with claim 1,
   characterised in that
   the slide ramps (62) of an indentation (66) mutually merge into one another with a radius of curvature of 1 mm and the slide ramps (62) are formed with a radius of curvature of 6 mm.
7. A restoring mechanism in accordance with at least one of the claims 5 or 6,
   characterised in that
   the slide bodies (24) each have a slide surface having a design complementary to the indentations (66).
8. A restoring mechanism in accordance with at least one of the preceding claims,
   characterised in that
   the follower ring (22) is produced from a metal, preferably from a chrome-plated zinc die-cast, and the slide bodies (24) are produced from a plastic material which is preferably enriched with Teflon or chalk.
9. A restoring mechanism in accordance with at least one of the preceding claims,
   characterised in that
   a spring ring (28), which engages into a ring groove (50) formed at the end face of the handle neck (16), is provided at the side of the follower ring (22) facing the door leaf.
10. A restoring mechanism in accordance with claim 9,
    characterised in that
    the handle neck (16) tapers conically in the direction of its end face.
11. A restoring mechanism in accordance with at least one of the preceding claims,
    characterised in that
    the rosette body (14) is covered on the side remote from the door leaf by a cover cap (18) produced from metal.

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