GB2576069A

GB2576069A - Drive for a door or window sash

Info

Publication number: GB2576069A
Application number: GB1907549.8A
Authority: GB
Inventors: Woerner Benjamin
Original assignee: Geze GmbH
Current assignee: Geze GmbH
Priority date: 2018-05-30
Filing date: 2019-05-29
Publication date: 2020-02-05
Anticipated expiration: 2039-05-29
Also published as: GB201907549D0; FR3081905B1; DE102018208576A1; FR3081905A1; GB2576069B; GB2576069A8

Abstract

The drive 10 comprises a piston 16 slidably guided in a housing 12, a spring 14, an output shaft 20 and a rack-and-pinion gear 18 with an out-of-round pinion 22 with teeth 24 and counter-teeth 26 on the piston side, wherein a tooth pair is designed such that when opening the sash a rising line of action results, which runs horizontally in the direction of displacement of the piston, and wherein the effective lever arm length of the pinion teeth decreases upon opening of the sash up to a first opening angle, then after a second angle the length increases with an increasing opening angle. The line of action may be produced by a profile shift varying when rolling over the curve. The pinion and piston each have an asymmetrical tooth and the output shaft is provided with an undercut. The piston may be hollow with internal toothing.

Description

DRIVE FOR A DOOR OR WINDOW SASH

The invention relates to a drive for a sash of a door, a window or the like, having a housing, a piston that is slidably guided in the housing and acted on by a spring unit and an output shaft that is rotatably mounted in the housing and connected with the piston by a rack and pinion gear.

More specifically, such a drive can be a door closer.

In a drive of the type mentioned above, when opening and closing the sash, the output shaft and thus the pinion is rotated, whereby the piston is axially displaced in the housing by means of the out-of-round rack and pinion gear when opening the sash against the force of the spring unit, usually comprising a compression spring. The spring unit thus generates the opening and closing moment of the drive or door closer.

In order to meet the increasingly stringent requirements for accessibility when walking through doors, an opening moment of the door and thus of the drive is required that drops steeply when opening the door.

Door closers with a rack and pinion gear only achieve very weakly dropping opening moments, with which the aforementioned accessibility requirements cannot be achieved. In some cases, the opening moments even increase when the door is opened. In order to generate a corresponding drop in moment, additional components are thus required.

By using a cam disk gear in the door closer, the required drop in moment can indeed be realized relatively easily. However, these door closers are more complex in construction and therefore more expensive than door closers with a rack and pinion gear. In addition, the efficiency and the damping performance are often poorer than door closers with a rack and pinion gear.

Door closers with a scissor linkage as a power transmission device between the output shaft and the door sash or frame have in principle, by the high gear ratio drop of the linkage when opening the door, a steep dropping opening moment, wherein the gearbox in the door closer can be embodied arbitrarily. With a power transmission device with a lever or a sliding arm guided in a slide rail, the gear ratio does not drop so steeply that the gearbox in the door closer must have a higher gear ratio drop for a dropping opening moment. In order to meet the increasing demands for comfort and accessibility, door closers having, between the output shaft and the sash, a power transmission device comprising a sliding arm guided in a slide rail are designed nowadays almost exclusively with a cam disk gear, which allows a steeply decreasing gear ratio or steeply dropping opening moments on the door, making the door easy to access. The respective drop of the gear ratio or the opening moments is strongly pronounced by design and occurs especially in door closers with door opening angles up to 180°, which however now involves a lower closing moment, whereby secure closing of the door is no longer guaranteed, especially for doors in outdoor areas, which are exposed to wind loads and the like. Therefore, a mean drop in the door moments would be preferable.

In addition, door closers with cam disk gears have significantly lower piston strokes compared to door closers with a rack and pinion gear and require higher spring forces since the effective lever arm in the gearbox is smaller. As a result, door closers with a cam disk gear have poorer hydraulic damping properties and higher component loads. In addition, due to the design, cam disk gears have higher lateral forces or friction forces in the area of the power-transmitting piston than a rack and pinion gear, resulting in higher wear, poorer service life of the components, and a poorer efficiency of the door closer. In addition, door closers with cam disk gears are usually more complex in construction and thus more expensive than door closers with rack and pinion gears.

The hitherto conventional door closers with rack and pinion gears generate a barely dropping opening moment despite the out-of-round rack and pinion gear. In DE 36 38 353 and DE 93 19 547, door closers with a rack and pinion gear with out-of-round toothing are described, in which the effective lever arm of the gearbox shortens up to a predetermined door opening angle to produce a dropping opening moment. However, the gear ratio of the gearbox of these known rack and pinion gears drops too little in an initial opening range to allow a drop of opening moment comparable to that of cam disk gears. In an initial sash opening angle range, the effective lever arm only shortens to about 65% of the initial value with a 0° sash opening angle. Upon further opening of the door, the effective lever arm remains virtually constant for large door opening angles or shortens even further.

In addition, a very small spring rate of the compression spring would be required for a sharp drop in the opening moment, whereby the closing moments would however be too small for large door opening angles due to the small effective lever arm length of the gear at these large door opening angles and the low spring force. In order to produce a sufficient closing moment for large door opening angles, a high spring rate must be selected here. Thus, the opening moment on the door results from the gear ratio of the power transmission device between the output shaft and the sash or frame and the output moment of the door closer on the door closer pinion, which results from the product of the effective lever arm length of the gearbox and the spring force. The spring rate of the compression spring must be chosen to be so high here that the increase in the spring force is sufficient to compensate for the drop in the gear ratio of the power transmission device and thus to produce a sufficient closing moment to close the door safely even for large door opening angles. As a result, when the door is opened, the force of the compression spring now increases more quickly than it can compensate for the shortening effective lever arm of the out-of-round toothing. The decrease in the gear ratio is too low over the rotation angle of the pinion, whereby only a small drop in the opening moment is achieved. However, the gear ratio drop in the gearbox would have to be higher for adequate accessibility.

In DE 44 44 131, a door closer with a rack and pinion gear having an out-of-round toothing is described, which is intended to produce a steeply dropping opening moment. For this purpose, the pinion has a specially shaped first tooth, which engages with the surface which is located between the tooth tip and the push-side tooth flank, in the tooth foot area of the counter-toothing on the piston.

Since the main reduction of the effective lever arm length of the gearbox takes place by rolling the first pair of teeth that engage with the second when the door is opened, the height difference between the first and second teeth on the piston must be designed to be very large to facilitate a dropping opening moment similar to that of cam disk gears. However, with the known design, this is not feasible because the pressure angles of the pinion in the piston teeth at the transfer point from the first to the next tooth are too large due to the large difference in height of the first two teeth on the piston, consequently when closing the door a selfinhibition effect I jamming of the system, in the worst case, or at least a drop in efficiency and signs of wear would occur. With the known design, the effective lever arm shortens in an initial sash opening angle range only to about 64% of the initial value at 0° sash opening angle. In addition, the longer tooth is exposed to very high bending loads due to its elongated shape and the contact region at the tooth tip, which impairs the robustness of the system.

The contact region in the tooth tip on the pinion is represented by a rounding, which is very small as a result of geometry, causing extreme surface pressures that can quickly lead to damage of the toothing. The system is thus only suitable for door closers with low closing force (lower spring forces) for which a dropping opening moment is now again no longer relevant since the opening moments are already very low. In addition, the wear of the toothing is increased by the predominantly sliding teeth.

In addition, by design, such a system has relatively large pressure-side tooth flank angles (> 35° with a door opening angle of 0°) on the first tooth of the toothing of the piston, which generate very high transverse forces that impair the efficiency of the door closer, which in turn results in greatly increased opening moments of the door closer and also increased wear.

The object of the invention is to propose a drive or door closer of the type mentioned above in which the previously mentioned disadvantages have been eliminated. In this case, the drive that is provided with a rack and pinion gear should have in particular a steeply dropping opening moment comparable to a cam disk drive and thus ensure the highest possible accessibility, with the simplest possible and correspondingly cost-effective structure. In addition, the drive should also particularly have a sufficient closing moment against wind loads and the like, highest possible efficiency even without special sliding rings on the piston and a high resistance to wear.

The object is achieved according to the invention by a drive having the features of claim 1. Preferred embodiments of the drive according to the invention result from the dependent claims, the present description and the drawing.

The drive according to the invention for a sash of a door, a window or the like comprises a housing, a piston that is slidably guided in the housing and acted on by a spring unit, and an output shaft that is rotatably mounted in the housing and connected with the piston by a rack and pinion gear. Thus, the rack and pinion gear comprises an out-of-round pinion connected to the output shaft, the toothing of which meshes with a counter-toothing on the piston side, wherein a tooth pair of the pinion-side and piston-side toothings, which respectively engage with each other in an initial sash opening angle range of 0° up to a predefined sash opening angle are designed so that, when opening the sash, a line of action running horizontally, i.e. parallel to the direction of displacement of the piston or rising relative to the horizontal, i.e. the direction of displacement of the piston or the direction of displacement of the piston is produced, and the effective lever arm length of the pinion-side toothing in the initial sash opening angle range decreases with an increasing sash opening angle to the first predefined sash opening angle starting from a maximum effective lever arm length with the sash opening angle of 0°, and from a second predefined sash opening angle, which is greater than or equal to the first predefined sash opening angle and smaller than the maximum sash opening angle, further increases with an increasing sash opening angle.

Due to this design, the drive provided with a rack and pinion gear has a sharply declining opening moment comparable to that of a cam disk drive with a simple and correspondingly cost-effective structure, thus ensuring a correspondingly high level of accessibility, characterized by convenient, child-friendly and accessible access through the door. In addition, the drive according to the invention has a sufficient closing moment against wind loads and the like and a highest possible efficiency and high degree of robustness against wear, even without any special sliding rings on the piston.

The first pressure-side tooth flank of the piston-side counter-toothing, which engages with the pinion-side toothing when opening the sash, preferably has a tooth flank angle which is less than 25°, preferably less than 20°.

Due to the special configuration of the toothing, the tooth flank angle of the first pressure-side tooth flank engaging with the pinion-side toothing when opening the sash on the piston is very small (less than 25°, preferably less than 20°). Thus, only small transverse forces are transmitted from the piston to the housing, whereby the friction is reduced. Due to the reduced friction, a high efficiency of the drive is achieved while reducing wear, which increases the service life of the drive. Due to the high efficiency, a considerably lower initial opening moment of the sash can be achieved than for door closers with a cam disk gear with the same closing moment of the drive, whereby the access comfort is increased accordingly.

The horizontal or rising course of the line of action of a pair of teeth of the pinionside and piston-side toothings, which respectively engage with each other in the initial sash opening angle range, is produced at least partially by a profile shift varying accordingly when rolling over the rolling curve and/or a module varying accordingly when rolling over the rolling curve and/or flank angles varying accordingly when rolling over the rolling curve and/or radii of curvature of the tooth flanks of the pinion-side toothing varying accordingly when rolling over the rolling curve.

Profile shift is a term from the field of gearings and mechanisms. In the design and manufacture of gearwheels with a profile shift, the shape of the teeth is changed, but without changing the underlying base curve. In the case of a gearwheel with a profile shift, a different part of the same curve (usually involute or cycloid) is used as the tooth flank compared to a gear without a profile shift. The module is a gauge for the size of the teeth of gearwheels. It is defined as the quotient of the gearwheel partition or the distance between two adjacent teeth and pi, which is a mathematical constant defined which is defined as the ratio of the circumference of a circle to its diameter.

By the teeth meshing with one another in the initial sash opening angle range, and in particular the first tooth pair of the pinion-side and piston-side toothings, when opening the sash, having a horizontal or rising line of action due to a varying profile shift and/or a varying module and/or varying flank angles and/or varying radii of curvature of the tooth flanks during opening of the sash, a shorter contact length of the relevant tooth pairs is achieved in certain regions, which allows a rapid shortening of the effective lever arm length of the rack and pinion gear such that the sash moment drops steeply upon a further opening of the sash, whereby a more comfortable access is facilitated. In addition, an advantageous engagement of the first pair of teeth at particularly small flank angles is made possible by a rising line of action in combination with the special shape of the first pair of teeth with flank angles varying on the pinion-side and piston-side tooth and/or varying radii of curvature of the tooth flanks, in order to reduce the transverse forces and to increase the efficiency. Due to the curve shape of the line of action, also referred to as the so-called engagement line, this could also be referred to as an engagement curve. The point of contact of the flanks of the intermeshing teeth runs on the line of action.

The line of action initially drops in the event of a tooth engagement behind the centre line of the pinion. With an appropriate assembly, however, it can be ensured that an effective tooth engagement takes place only from the centre line of the pinion where the line of action accordingly rises or extends horizontally.

Due to the shape according to the invention of the toothing, the effective lever arm length of the rack and pinion gear and thus the gear ratio of the gearbox when opening the sash (rolling curve increases massively) drops steeply, whereby the opening moment drops very steeply comparable to that of a cam disk gear, thus allowing comfortable, child-friendly and accessible access through the door.

The initial sash opening angle range advantageously extends from 0° to a predefined sash opening angle in the range of 40°, preferably up to a predetermined opening angle in the range of 30°.

According to a preferred practical embodiment of the drive according to the invention, the toothings of the rack and pinion gear are designed such that the effective lever arm length of the pinion-side toothing when opening the sash, starting from an initial value with the sash closed, drops not later than a sash opening angle of 40°, preferably a sash opening angle of 30°, to at least 60%, preferably to at least 55% of the initial value. This results in a correspondingly steeply dropping opening moment of the sash and accordingly a high accessibility. For example, a sash opening angle of 30° corresponds to an axle angle of approximately 48°.

It is also particularly advantageous if the rack and pinion gear is designed so that the drop in the gear ratio in a sash opening angle range of 0° to 30° is passed on via at least two tooth flanks and preferably by three tooth flanks.

With such an embodiment of the rack and pinion gear, an error-free shifting of the tooth flanks of the pinion-side and the piston-side toothing to one another is guaranteed.

Advantageously, the rack and pinion gear can be designed so that the effective lever arm length of the pinion-side toothing drops further when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range, in order to facilitate even easier access, or at least substantially remains constant (trapezoidal rolling curve) to keep the door moment low and still allow a sufficient closing moment against wind loads or the like.

According to a further advantageous embodiment of the drive according to the invention, the rack and pinion gear can however also be designed so that the effective lever arm length of the pinion-side toothing increases again when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range.

In order to further increase the drop in opening moment, the spring unit preferably comprises a compression spring with a spring rate R <80 N/mm.

In this case, the lower increase of the spring force and in particular with larger sash opening angles the low gear ratio of the power transmission device between the output shaft and the sash or the frame can be compensated to produce a sufficient closing moment even with larger sash opening angles. For this purpose, the gear ratio of the gearbox or the effective lever arm length can be further increased with a corresponding design of the toothing when opening the sash from a sash opening angle in the range of 60°, which is associated with a corresponding dropping rolling curve. The effective lever arm length of the pinionside toothing thus increases again with an increasing sash opening angle, whereby, despite the lower gear ratio of the power transmission device between the output shaft and the sash or the frame and the lower spring force, a sufficient closing moment is generated at larger sash opening angles.

In certain cases, it is also advantageous if the rack and pinion gear is designed so that its gear ratio when opening the sash increases from the sash opening angle in the range of 60° to the maximum sash opening angle of 180° back to at least 60° of the initial value with a sash opening angle of 0°.

It is particularly advantageous if the pinion-side toothing is designed so that, with the further opening of the sash from the sash opening angle in the range of 60°, the output shaft moment increases so that a decreasing gear ratio of a power transmission device provided between the output shaft and the sash or frame and particularly comprising a lever or a rod is at least substantially compensated.

According to an expedient practical embodiment of the drive according to the invention, the rack and pinion gear is designed so that the increase of the gear ratio in the sash opening angle range of about 60° to the maximum sash opening angle of particularly 180° is passed on over at least two tooth flanks and preferably over at least three tooth flanks.

In order to guarantee a low wear and thus a high level of efficiency even with larger sash opening angles with larger spring forces, the pressure-side tooth flanks of the teeth of the piston-side counter-toothing, which engage with the pinion-side toothing at sash opening angles in a sash opening angle range of about 60° to a maximum sash opening angle of particularly 180° and particularly in the range of the maximum sash opening angle, each preferably have a tooth flank angle which is smaller than 20°, preferably smaller than 15°.

A further advantageous practical embodiment of the drive according to the invention is characterized in that the effective lever arm length of the pinion-side toothing initially decreases when opening the sash to a reversal point and then increases again and the section of the pinion-side toothing with the initially decreasing effective lever arm length when opening the sash and the section of the pinion-side toothing with the re-increasing effective lever arm length when opening the sash each have at least one asymmetrical tooth, wherein each asymmetrical tooth of the section of the pinion-side toothing with the decreasing lever arm length when opening the sash has a push-side tooth flank, the tooth flank angle of which is smaller than the tooth flank angle of the tooth flank facing away from the pressure, and each asymmetrical tooth of the section of the pinionside toothing with the increasing lever arm length when opening the sash has a push-side tooth flank, the tooth flank angle of which is greater than the tooth flank angle of the tooth flank facing away from the pressure. In this case, in particular, a triangular rolling curve may arise.

With the relevant embodiment of the pinion-side teeth and their tooth flank angle, a clean engagement of the toothings is guaranteed both in the pull and push direction.

Preferably, at least one respective section of the pinion-side toothing, with decreasing effective sash lever length when opening the sash, and a respective section of the pinion-side toothing, with re-increasing effective lever arm length during opening of the sash, are produced at least partially by a profile shift varying accordingly when rolling over the rolling curve and/or a module varying accordingly when rolling over the rolling curve and/or flank angles varying accordingly when rolling over the rolling curve and/or radii of curvature of the tooth flanks of the pinion-side toothing varying accordingly when rolling over the rolling curve.

The piston is preferably designed as a hollow piston with an internal toothing. The piston-side toothing is thus provided within the piston in this case.

The invention is explained in more detail below on the basis of exemplary embodiments and with reference to the drawings, in which:

Fig. 1 shows a schematic representation of the basic structure of an exemplary embodiment of a drive according to the invention,

Fig. 2 shows a schematic partial view of an out-of-round rack and pinion gear, having a trapezoidal rolling curve, of an exemplary embodiment of the drive according to the invention at a sash opening angle of 0°,

Fig. 3	shows two schematic representations of the out-of-round rack and pinion gear, having a trapezoidal rolling curve, according to Fig. 2 at a sash opening angle of 30°,
Fig.4	shows a schematic representation of the out-of-round rack and pinion gear, having a trapezoidal rolling curve, according to Fig. 2 at a sash opening angle of 60°,
Fig. 5	shows a schematic representation of the out-of-round rack and pinion gear, having a trapezoidal rolling curve, according to Fig. 2 at the maximum sash opening angle,
Fig. 6	shows two schematic representations of the out-of-round rack and pinion gear, having a triangular-shaped rolling curve, of a further exemplary embodiment of the drive according to the invention at a sash opening angle of 0° and a sash opening angle of 30° respectively,
Fig. 7	shows a schematic representation of the out-of-round rack and pinion gear, having a triangular-shaped rolling curve, according to Fig. 6 at a sash opening angle of 60°,
Fig. 8	shows a schematic representation of the out-of-round rack and pinion gear, having a triangular-shaped rolling curve, according to Fig. 6 at the maximum sash opening angle,
Fig. 9	shows a schematic representation of the out-of-round rack and pinion gear, having a triangular-shaped rolling curve, of a further exemplary embodiment of the drive according to the

	invention, in which a toothing section with an effective lever arm length decreasing when opening the sash and a toothing section with a lever arm length increasing again when opening the sash each have at least one asymmetrical tooth,
Fig. 10	shows a schematic representation of the exemplary output shaft, provided with a pinion, of the drive according to the invention,
Fig. 11	shows an enlarged schematic representation of the output shaft, provided with the pinion, according to Fig. 10,
Fig. 12	shows a schematic plan view of the output shaft, provided with the pinion, according to Fig. 10 and 11, and
Fig. 13	shows a diagram in which the course, that is dependent on the sash opening angle, of the opening moment of an exemplary embodiment of the drive according to the invention with a steeply dropping opening moment is compared with that of a drive having a conventional rack and pinion gear and that of a conventional drive with a cam disk gear.

Fig. 1 shows the basic structure of an exemplary embodiment of a drive 10 according to the invention for a sash of a door, which is designed in the present case, for example, as a door closer.

Then, the drive 10 comprises a housing 12, a piston 16 that is slidably guided in the housing 12 and acted on by a spring unit 14, and an output shaft 20 that is rotatably mounted in the housing 12 and connected with the piston 16 by a rack and pinion gear 18. The spring unit 14 comprises in the present case, for example, a compression spring.

The rack and pinion gear 18 comprises an out-of-round pinion 22 connected to the output shaft 20, the toothing 24 of which meshes with a counter-toothing 26 on the piston side.

When opening and closing the sash, the output shaft 20 is rotated with the pinion 22 and displaced over the out-of-round rack and pinion gear 18 of the piston 16 in the housing 12, whereby the spring unit 14 is tensioned with the opening of the sash and relaxed again with the closing of the sash. The spring unit 14 thus serves as a mechanical energy store of the drive 10.

The first push-side tooth flank 36 of the piston-side counter-toothing 26 (see in particular Fig. 2), which engages with the pinion-side toothing 24 when opening the sash, has a tooth flank anglea which is less than 25°, preferably less than 20°. In the embodiment shown in Fig. 2, this tooth flank angle a is for example 18.5°.

A tooth pair, each engaging with one another in an initial sash opening angle range of 0° to a predefined sash opening angle, of the pinion-side and piston-side toothings 24 and 26 is designed such that, when opening the sash, a rising line of action 48 results, which runs horizontally, i.e. parallel to the displacement direction of the piston 16 or runs opposite to the horizontal, i.e. the direction of displacement of the piston 16. In the exemplary embodiment shown in Fig. 2, a rising line of action 48 results for each of the first two tooth pairs of the pinion-side and pistonside toothings 24 and 26 when opening the sash. In the case of a tooth engagement, the line of action 48 only increases from the centre line 50 (see in Fig. 2) of the pinion 22 extending through the centre point of the output shaft 20 and the longest pinion-side tooth 34, while it drops behind the centre line 50.

Through appropriate mounting, however, a tooth engagement behind the centre line 50 can be excluded.

As can be seen in particular from Fig. 2 to 9, the effective lever arm length R of the pinion-side toothing 24 in the initial sash opening angle range, starting from a maximum effective lever arm length Ro, decreases with a sash opening angle of 0° with an increasing sash opening angle.

The horizontal or rising course of the line of action 48 of a pair of teeth of the pinion-side and piston-side toothings 24 or 26, which each engage mutually in the initial sash opening angle range, can at least partially be produced by a profile shift varying accordingly when passing over the rolling curve and/or a module varying accordingly when passing over the rolling curve and/or flank angles varying accordingly when passing over the rolling curve and/or radii of curvature of the tooth flanks of the pinion-side toothing 24 varying accordingly when passing over the rolling curve. The rolling curve describes the power transmission points between the pinion-side and piston-side toothings 24 and 26 over the actuation cycle of the drive 10.

The initial sash opening angle range may for example extend from 0° to a predefined sash opening angle in the range of 40°, and in particular up to a predetermined opening angle in the range of 30°.

It is particularly advantageous if the toothings 24, 26 of the rack and pinion gear 18 are designed so that the effective lever arm length of the pinion-side toothing when opening the sash starting from an initial value when the sash is closed, i.e. a sash opening angle of 0°, drops not later than a sash opening angle of 40°, preferably by not later than a sash opening angle of 30°, to at least 60%, preferably to at least 55% of the initial value.

In addition, the rack and pinion gear 18 is in particular designed so that the drop in the gear ratio in a sash opening angle range of 0° to 30° is passed on via at least two tooth flanks and preferably by three tooth flanks.

As can be seen particularly in Fig. 3 and 4 and Fig. 6 and 7, the rack and pinion gear 18 can also be designed so that the effective lever arm length R of the pinionside toothing 24 decreases further when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range.

However, such embodiments of the rack and pinion gear 18 are also conceivable where the effective lever arm length R of the pinion-side toothing 24 at least substantially remains constant or increases again when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range.

The spring unit 14 may comprise a compression spring with a spring rate R <80 N I mm. With a compression spring with the lowest possible spring rate, for example, of R < 80 N/mm, the drop in opening moment is amplified. The lower increase of the spring force, and in particular with larger sash opening angles, the low gear ratio of the power transmission device between the output shaft 20 and the sash or the frame, comprising for example a lever or a rod, can be compensated to produce a sufficient closing moment even with large sash opening angles. With a corresponding shape of the toothing, the gear ratio of the gearbox or the effective lever arm R rises sharply again after reaching the minimum, for example, from a sash opening angle of 60°, i.e. the rolling curve drops again accordingly. The effective lever arm length L thereby increases with an increasing sash opening angle, whereby despite the lower gear ratio of the power transmission device between the output shaft 20 and the sash or the frame and the lower spring force a sufficient closing moment is generated at larger sash opening angles.

The rack and pinion gear 18 can in particular be designed so that its gear ratio or the effective lever arm length R when opening the sash increases from the sash opening angle in the range of 60° to the maximum sash opening angle of 180° back to at least 60% of the initial value with a sash opening angle of 0°.

The pinion-side toothing 24 can for example also be designed so that, with the further opening of the sash from the sash opening angle in the range of 60°, the output shaft moment increases so that a decreasing gear ratio of a power transmission device provided between the output shaft 20 and the sash or frame and particularly comprising a lever or a rod is at least substantially compensated.

In order to guarantee an error-free passing over of the tooth flanks, the increase of the gear ratio of the rack and pinion gear 18 in the sash opening angle range of about 60° to the maximum sash opening angle of particularly 180° can be passed on over at least two tooth flanks and preferably over at least three tooth flanks.

In order to guarantee the lowest possible wear and a high level of efficiency even with large door angles and greater spring forces, the push-side tooth flanks 36 of the teeth 42 of the piston-side counter-toothing 26, which engage with the pinionside toothing 24 at sash opening angles in a sash opening angle range of about 60° to a maximum sash opening angle of particularly 180°, and particularly in the range of the maximum sash opening angle, each have a tooth flank angle a which is smaller than 20°, and in particular smaller than 15°.

With the exemplary out-of-round rack and pinion gears 18 shown in Fig. 6 to 8, a triangular-shaped rolling curve is produced. In this case, the rack and pinion gear 18 in Fig. 6 is shown with a sash opening angle (SOA) of 0° or 30°, in Fig. 7 with a sash opening angle of 60°, and in Fig. 8 with the maximum sash opening angle. While the maximum effective lever arm length Ro of 100% results at the sash opening angle of 0° (see the left part of Fig. 6), the sash opening angle of 30° (see the right part of Fig. 6) results in an effective lever arm length R corresponding for example to 59% of the maximum effective lever arm length Ro, the sash angle of 60° (see Fig. 7) in an effective lever arm length R corresponding for example to 41% of the maximum lever arm length Ro, and the maximum sash opening angle (see Fig. 8) results in an effective lever arm length R corresponding for example to 68% of the maximum effective lever arm length Ro. As can be seen from Fig. 6, in the present exemplary embodiment, a twist angle for example of the output shaft 20 of 48° is produced with a sash opening angle of 80°.

As can be seen in particular from Fig. 9, the effective lever arm length R of the pinion-side toothing 24 can initially decrease when opening the sash to a reversal point 52 and then increase again and the section of the pinion-side toothing 24 with the initially decreasing effective lever arm length when opening the sash and the section of the pinion-side toothing 24 with the re-increasing effective lever arm length when opening the sash each have at least one asymmetrical tooth 34’. In this case, a respective asymmetrical tooth 34 Of the section of the pinion-side toothing 24 with decreasing effective lever arm length R when opening the sash has a push-side tooth flank 36, the tooth flank angle αι of which is smaller than the tooth flank angle a_rof the tooth flank facing away from the pressure, while a respective asymmetrical tooth 34 Of the section of the pinion-side toothing 24 with increasing effective lever arm length R when opening the sash has a push-side tooth flank 38, the tooth flank angle αι of which is greater than the tooth flank angle a_r of the tooth flank facing away from the pressure.

In the various exemplary embodiments represented in the figures, at least one respective section of the pinion-side toothing 24, with decreasing effective sash lever length R when opening the sash, and a respective section of the pinion-side toothing 24. with re-increasing effective lever arm length R during opening of the sash, are produced at least partially by a profile shift varying accordingly when rolling over the rolling curve and/or a module varying accordingly when rolling over the rolling curve and/or flank angles varying accordingly when rolling over the rolling curve and/or radii of curvature of the tooth flanks of the pinion-side toothing 24 varying accordingly when rolling over the rolling curve.

In the exemplary embodiments of an out-of-round rack and pinion gear 18 shown in Fig. 2 to 5, a trapezoidal rolling curve 40 is produced. In this case, the rack and pinion gear 18 in Fig. 2 is shown with a sash opening angle (SOA) of 0°, in Fig. 3 with a sash opening angle of 0° or 30°, in Fig. 4 with a sash opening angle of 60° and in Fig. 5 with the maximum sash opening angle. A sash opening angle of 0° results in the maximum effective lever arm length Ro of 100% (see the left of Fig. 3), while a sash opening angle of 30° (see the right of Fig. 3) results in an effective lever arm length R corresponding for example to 52% of the maximum effective lever arm length Ro, the sash angle of 60° (see Fig. 4) in an effective lever arm length R corresponding for example to 50% of the maximum lever arm length Ro, and the maximum sash opening angle (see Fig. 5) in an effective lever arm length R corresponding for example to 78% of the maximum effective lever arm length Ro.

As can be seen from Fig. 3, in the present exemplary embodiment, a twist angle for example of 48° is produced for the output shaft 20 with a sash opening angle of 30°.

As already stated, the effective lever arm length R of the rack and pinion gear 18 decreases steeply in an initial sash angle range. As can be seen from Fig. 3 to 5, the output shaft 20 can be provided with an undercut 28 to its adjacent bearing surfaces 30 in the area of the pinion-side toothing section having the minimum effective lever arm length R_min (see in particular Fig. 11 and 12). In this case, the pinion-side toothing section having the minimum effective lever arm length Rmin has a minimum root radius Rrmin which is smaller than the bearing surface radius Rl of the adjacent bearing surfaces 30 of the output shaft 20. The rapid drop in the pinion-side effective lever arm length is thus realized, for example, by the special construction of the output shaft 20. This special construction of the output shaft 20 provided with the pinion 22 and having the undercut 28 can be seen in particular from Fig. 11 and 12. The bearing surfaces 30 of the output shaft 20 may be provided, for example, for rotatably mounting the output shaft 20 by means of needle bearings.

Fig. 13 shows a diagram, in which the course, that is dependent on the sash opening angle (SOA), of the opening moment of a drive according to the invention 10 with an abruptly dropping opening moment (curve a)) is contrasted with that of a drive with a conventional rack and pinion gear (curve b)) and that of a conventional drive with a cam disk gear (curve c)). As the diagram shows, the drive 10 or door closer according to the invention (see curve a)) has a drop in the opening moment similar to that of cam disk drives, wherein at the same time a sufficient closing moment against wind loads or the like, a high efficiency and high robustness against wear can also be achieved.

Reference list

10 12 14 16 18 20 22 24 26 28 30 34 34' 36 38 40 48 50 52	Drive Housing Spring unit Piston Rack and pinion gear Output shaft Pinion Pinion-side toothing Piston-side counter-toothing Undercut Bearing surface Pinion-side tooth Asymmetrical tooth First pressure-side tooth flank Pressure-side tooth flank Rolling curve Line of action Centre line Reversal point
R Ro Rmin Rl Rpmin a ai a_r	Effective lever arm length Maximum effective lever arm length Minimum effective lever arm length Bearing surface radius Minimum root circle radius Tooth flank angle Pressure-side flank angle Pull-side flank angle

Claims

1. A drive (10) for a sash of a door, a window or the like, having a housing (12), a piston (16) that is slidably guided in the housing (12) and acted on by a spring unit (14), and an output shaft (20) that is rotatably mounted in the housing (12) and connected with the piston (16) by a rack and pinion gear (18), wherein the rack and pinion gear (18) comprises an out-of-round pinion (22) connected to the output shaft (20), the toothing (24) of which meshes with a piston-side counter-toothing (26), and wherein a tooth pair, each engaging with one another in an initial sash opening angle range of 0° to a predefined sash opening angle, of the pinion-side and piston-side toothings (24 and 26) is designed such that when opening the sash a rising line of action (48) results, which runs horizontally, i.e. parallel to the displacement direction of the piston (16) or runs opposite to the horizontal, i.e. the direction of displacement of the piston (16), and the effective lever arm length (R) of the pinion-side toothing (24) in the initial sash opening angle range starting from a maximum effective lever arm length (Ro) decreases with the sash opening angle of 0° with an increasing sash opening angle to a first predefined sash opening angle, and from a second predefined sash opening angle, which is greater than or equal to the first predefined sash opening angle and smaller than the maximum sash opening angle, further increases with an increasing sash opening angle.

2. The drive (10) according to claim 1, characterized in that the first pressure-side tooth flank (36) of the pistonside counter-toothing (26), which engages with the pinion-side toothing (24) when opening the sash, has a tooth flank angle (a) which is less than 25°, preferably less than 20°.

3. The drive (10) according to claim 1 or 2, characterized in that the horizontal or rising course of the line of action (48) of a pair of teeth of the pinion-side and piston-side toothings (24 or 26), which each engage mutually in the initial sash opening angle range, is at least partially produced by a profile shift varying accordingly when passing over the rolling curve and/or a module varying accordingly when passing over the rolling curve and/or flank angles varying accordingly when passing over the rolling curve and/or radii of curvature of the tooth flanks of the pinion-side toothing (24) varying accordingly when passing over the rolling curve.

4. The drive (10) according to at least one of the preceding claims, characterized in that the initial sash opening angle range extends from 0° to a predetermined sash opening angle in the range of 40°, preferably up to a predetermined sash opening angle in the range of 30°.

5. The drive (10) according to at least one of the preceding claims, characterized in that the toothings (24, 26) of the rack and pinion gear (18) are designed such that the effective lever arm length (R) of the pinion-side toothing (24) drops when opening the sash, starting from an initial value with the wing closed at no more than a sash opening angle of 40°, preferably at no more than a sash opening angle of 30°, to at least 60%, preferably to at least 55% of the initial value.

6. The drive (10) according to at least one of the preceding claims, characterized in that the rack and pinion gear (18) is designed so that the drop in the gear ratio in a sash opening angle range of 0° to 30° is passed on via at least two tooth flanks and preferably by three tooth flanks.

7. The drive (10) according to at least one of the preceding claims, characterized in that the rack and pinion gear (18) is designed so that the effective lever arm length (R) of the pinion-side toothing (24) further decreases when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range.

8. The drive (10) according to one of claims 1 to 6, characterized in that the rack and pinion gear (18) is designed so that the effective lever arm length (R) of the pinion-side toothing (24) remains at least substantially constant when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range.

9. The drive (10) according to one of claims 1 to 6, characterized in that the rack and pinion gear (18) is designed so that the effective lever arm length of the pinion-side toothing increases again when opening the sash up to a sash opening angle in the range of 60° following the initial sash opening angle range.

10. The drive (10) according to at least one of the preceding claims, characterized in that the spring unit (14) comprises a compression spring with a spring rate R <80 N/mm.

11. The drive (10) according to at least one of the preceding claims, characterized in that the rack and pinion gear (18) is designed so that its gear ratio when opening the sash from a sash opening angle in the range of 60° increases again.

12. The drive (10) according to at least one of the preceding claims, characterized in that the rack and pinion gear (18) is designed so that its gear ratio when opening the sash from the sash opening angle in the range of 60° to the maximum sash opening angle of in particular 180° increases back to at least 60% of the initial value with a sash opening angle of 0°.

13. The drive (10) according to at least one of the preceding claims, characterized in that the pinion-side toothing (24) is designed so that with the further opening of the sash from the sash opening angle in the range of 60°, the output shaft moment increases so that a decreasing gear ratio of a power transmission device provided between the output shaft (20) and the sash or frame and particularly comprising a lever or a rod is at least substantially compensated.

14. The drive (10) according to at least one of the preceding claims, characterized in that the rack and pinion gear (18) is designed so that the increase of the gear ratio in the sash opening angle range of about 60° to the maximum sash opening angle of particularly 180° is passed on over at least two tooth flanks and preferably over at least three tooth flanks.

15. The drive (10) according to at least one of the preceding claims, characterized in that the pressure-side tooth flanks (36) of the teeth (42) of the piston-side counter-toothing (26), which engage with the pinion-side toothing (24) at sash opening angles in a sash opening angle range of about 60° to a maximum sash opening angle of particularly 180°, and particularly in the range of the maximum sash opening angle, each have a tooth flank angle (a) which is smaller than 20°, preferably smaller than 15°.

16. The drive (10) according to at least one of the preceding claims, characterized in that the effective lever arm length (R) of the pinion-side toothing (24) initially decreases when opening the sash to a reversal point (52) and then increases again and the section of the pinion-side toothing (24) with the initially decreasing effective lever arm length (R) when opening the sash and the section of the pinion-side toothing (24) with the reincreasing effective lever arm length (R) when opening the sash each have at least one asymmetrical tooth (34’), wherein a respective asymmetrical tooth (34’) of the section of the pinion-side toothing (24) with decreasing effective lever arm length (R) when opening the sash has a push-side tooth flank (36), the tooth flank angle (cq) of which is smaller than the tooth flank angle (ar) of the tooth flank (38) facing away from the pressure and a respective asymmetrical tooth (34’) of the section of the pinion-side toothing (24) with increasing effective lever arm length (R) when opening the sash has a push-side tooth flank (36), the tooth flank angle (αι) of which is greater than the tooth flank angle (ar) of the tooth flank facing away from the pressure.

17. The drive (10) according to at least one of the preceding claims, characterized in that at least one respective section of the pinion-side toothing (24), with decreasing effective wing lever length (R) when opening the sash, and a respective section of the pinion-side toothing (24), with reincreasing effective lever arm length (R) during opening of the sash, are produced at least partially by a profile shift varying accordingly when rolling over the rolling curve and/or a module varying accordingly when rolling over the rolling curve and/or flank angles varying accordingly when rolling over the rolling curve and/or radii of curvature of the tooth flanks of the pinionside toothing (24) varying accordingly when rolling over the rolling curve.

18. The drive (10) according to at least one of the preceding claims, characterized in that the output shaft (20) is provided with an undercut (28) to its adjacent bearing surfaces (30) in the area of the pinion-side toothing section having the minimum effective lever arm length (Ro) and the pinionside toothing section, having the minimum effective lever arm length (Ro), has a minimum root radius (Rpmin) which is smaller than the radius (Rl) of the adjacent bearing surfaces (30) of the output shaft (20).

19. The drive (10) according to at least one of the preceding claims, characterized in that the piston (16) is designed as a hollow piston with an internal toothing.