Safety device for the drive element of a bicycle and bicycle therewith

Abstract

Safety device for the drive element (2) rotating around a front sprocket (14) and a rear sprocket (18), in particular for the toothed belt rotating around a front pulley and a rear pulley, in the drive train of a bicycle, which has a frame (17) with a right rear dropout (22) and with a left rear dropout and which has a rear wheel (15) drivable via the drive train and having a rear wheel axle (21) held in receiving openings (23) on the dropouts (22), characterized in that the safety device (1) has a holding element (3) with an interface for fastening the holding element (3) to the right rear dropout (22) and has a safety element (4) held at a predetermined distance from the interface on the holding element (3) to prevent the drive element (2) from jumping off the rear sprocket (18).

Description

The invention relates to a safety device according to claim 1 for the drive element in the drive train of a bicycle rotating around a front sprocket and a rear sprocket. The invention relates in particular to such a safety device for a bicycle with belt drive and is intended to prevent the toothed belt from running off the rear pulley in such a bicycle if the toothed belt does not run under sufficient tension toward the rear pulley. However, the invention can also be used in bicycles with a chain drive, in which running of the chain is to be prevented. The bicycles in question, in which the invention is to be used, have only a single rear pulley or a single rear sprocket wheel, i.e. as a rule no derailleur. Unless such bicycles do not dispense with a gearshift, they are usually equipped with a hub gearshift accommodated in the rear wheel axle. The invention also relates to a bicycle according to claim 12 with a safety device for a revolving drive element.In particular in bicycles with a hub transmission, in most cases it must be ensured manually that the drive element is sufficiently tensioned by fastening the rear wheel together with the rear sprocket at a suitable distance from the front sprocket in the region of the rear dropouts on the frame of the bicycle. For this purpose, the dropouts generally have recesses formed as elongated holes. Recently, and in particular in bicycles with belt drive, it is also common to use bicycle frames having dropouts with round holes for the fastening of the rear wheel axle, i.e. the same bicycle frames as are otherwise used for bicycles with derailleur. In these cases, the tension of the revolving drive element, i.e. the chain or the toothed belt, is ensured by a tensioning element which presses the lower section of the drive element, which runs back between the toothed rings to the rear toothed ring, upward with a certain prestress in the direction of the upper section of the drive element which is under tension and thus likewise keeps it under tension. Such a clamping element can in many cases already prevent the drive element from running off the toothed rings, in particular from the rear belt pulley. However, it has been shown that there may be situations in which the revolving drive element can run off the rear sprocket, in particular the rear pulley, despite a clamping element.The invention has therefore set itself the object, in particular for bicycles with belt drive, to provide a safety device for the drive element in the drive train of a bicycle, which rotates around a front sprocket and a rear sprocket, with which the risk that the drive element runs off the rear sprocket, in particular that in bicycles with belt drive the toothed belt runs off the rear pulley, is further reduced. Furthermore, a bicycle, in particular a belt-driven bicycle, is to be provided with such a safety device.The invention achieves this object with a safety device according to claim 1 and with a bicycle according to claim 12.In a safety device for the drive element revolving around a front sprocket and a rear sprocket, in particular for the toothed belt revolving around a front pulley and a rear pulley, in the drive train of a bicycle, which has a frame with a right rear dropout and with a left rear dropout and which has a rear wheel drivable via the drive train with a rear wheel axle held in receiving openings on the dropouts, it is provided according to the invention that the safety device has a holding element with an interface for fastening the holding element to the right rear dropout and a safety element held at a fixed distance from the interface on the holding element for preventing the drive element from jumping off the rear sprocket.In a bicycle with a frame having a right rear dropout and a left rear dropout, and with a drive train having a front sprocket and a rear sprocket and a drive element revolving around the front sprocket and the rear sprocket, and with a rear wheel drivable via the drive train and having a rear wheel axle held in receiving openings on the dropouts, and with a safety device for the drive element, it is provided according to the invention that the safety device has a holding element which is fastened to the right rear dropout via an interface provided for this purpose, and a safety element held at a fixed distance from the interface on the holding element for preventing the drive element from jumping off the rear sprocket.When the drive element underneath the rear sprocket runs as a result of hanging down onto the rear sprocket, it is supported by the securing element before it could run off the rear sprocket. The position of the securing element, in particular its distance from the rear sprocket, is preferably selected such that a distance of less than 5 mm, preferably less than 2 mm, particularly preferably less than 1 mm remains between the drive element and the securing element when the drive element is tensioned. Alternatively, the distance is selected such that the drive element abuts the securing element, wherein the drive element rolls along the securing element, in particular. In normal driving operation, the securing element thus preferably has no contact with the encircling drive element or has contact, but is not deflected in its direction at the securing element.For positioning the securing element, the holding element is preferably configured to hold the safety element at a distance from the drive train at a fixed position under the rear sprocket. In this region, where the drive element meshes with the rear toothed ring, otherwise a running off of the drive element could be initiated. The safety element can be rotatably held while maintaining its distance from the rear sprocket. The position of the rear sprocket is again determined by the position of the rear wheel. In particular, the geometric axis of rotation of the rear wheel is arranged coaxially with the axis of rotation of the rear sprocket.The holding element of the safety device according to the invention is particularly preferably designed to be mounted on the right rear dropout instead of a shifting eye which is provided for the connection of the rear derailleur of a derailleur to the frame. For this purpose, the interface is particularly preferably configured to be able to mount the mounting element universally on each arbitrarily selected frame from a group of frames or from all frames which are each configured for mounting the switching eye. In particular, the interface preferably uses specifications of the so-called Universal Derailur Hanger (UDH) interface established by the company SRAM and described in DE 10 2018 222 834 A1, in order to be able to mount the mounting element on a frame configured for the use of the UDH interface. Reference is made to the content of DE 10 2018 222 834 A1.The mounting instead of a switching eye, in particular the universal switching eye of the company SRAM, has the advantage that the numerous frames which are configured to be equipped with the known switching eye can now also be used in conjunction with the safety device according to the invention. Due to the use of the known interface, no additional attachment points need to be provided on the frame for the mounting of the safety device.Particularly preferably, the interface has an insertion sleeve, in particular in the form of a fastening screw or an axle bolt, which is configured to receive the rear wheel axle of the bicycle and to be arranged in the receiving opening on the right rear dropout in order to fix both the rear wheel axle and the holding element on the right rear dropout. The safety device is mounted here in particular instead of a safety eye for derailleur between the rear wheel axle and the frame. The mounting of the safety device together with the rear wheel axle on the dropout also has the advantage that the safety element always remains positioned at a sufficient distance from the rear sprocket and cannot block the rear sprocket even if the angle of the safety device relative to the frame should unintentionally change.In advantageous embodiments of the safety device, the plug-in sleeve is configured to hold a defined rotational angular position relative to this right rear dropout by means of a form-fitting contact or a frictional contact, in particular by means of knurling, on the inner side of the receiving opening of the right rear dropout. The insertion sleeve is preferably made of metal. In particular, the plug-in sleeve is an integral component of a base element which extends as far as the safety element and holds the safety element.To further secure against rotation of the safety device relative to the frame and to facilitate assembly in the intended position, it is preferably provided that the interface has a stop edge running in a straight line for bearing against a counterstop formation or against a projection on the right rear dropout. In this case, the stop edge is advantageously oriented at an angle in the range between 30 degrees and 60 degrees, preferably in the range between 35 degrees and 55 degrees, particularly preferably in the range between 40 degrees and 50 degrees, with respect to the direction in which the safety element is arranged relative to the rear wheel axle to be accommodated. Mounted on the bicycle, the safety element is then arranged behind the rear wheel axle with respect to the direction of travel, while the stop edge is arranged in front of the rear wheel axle.In advantageous embodiments of the safety device, the safety device has a base element, in particular made of metal, with an axle opening formed therein for the rear wheel axle and with an assembly opening formed therein for fastening the safety element. The safety element is preferably indirectly fixed to the mounting opening via a screw connection.Particularly preferably, the mounting opening is formed as an elongated hole for the radially longitudinally adjustable fastening of the safety element at a selected distance from the axle opening. This allows individual adaptation, for example to the diameter of the rear toothed ring or the thickness of the drive element.The safety element is particularly preferably a rotatably mounted roller. As a result, the drive element can roll over this roller when it makes contact with the roller, so that the drive element does not unintentionally block. The axis of rotation of the roller is preferably fixed in the mounting opening and is preferably designed as a screw connection. The axis of rotation of the roller is arranged parallel to the geometric axis of the rear wheel axle when this rear wheel axle is received in the axle opening.In particularly preferred embodiments of the safety device according to the invention, the safety device is designed for use in a bicycle with a drive train which is a belt drive and in which the toothed rings are belt pulleys and the drive element is a toothed belt. The safety element is designed, in particular positioned, to prevent the toothed belt from springing off the rear pulley.The safety element used to secure a toothed belt is adapted to the width of the toothed belt. The surface of the safety element facing the drive element, i.e. here the toothed belt, is preferably unstructured.In a corresponding embodiment of the bicycle according to the invention, the drive train is a belt drive, wherein the toothed rings are belt pulleys and the drive element is a toothed belt.In a conceivable alternative embodiment of the safety device and of the bicycle, the revolving drive element is a chain, in particular a bicycle chain. The drive train in which this chain is arranged is referred to herein as a chain drive. In the chain drive, the front sprocket is a chainring and the rear sprocket is a sprocket.In this embodiment of the safety element for securing a safety element designed as a chain, the width of the safety element is in turn adapted to the width of the chain and optionally has a structuring or a sprocket, wherein the structuring or the sprocket can engage in the chain and thereby also provide a guide. Alternatively, the surface of the security element is again unstructured.Further embodiments of the safety device according to the invention can be seen from the claims, from the drawings and from the following description of a particularly preferred exemplary embodiment of the invention illustrated in the drawings. The safety device of the bicycle according to the invention preferably has individual, several or all specifications according to the possible embodiments of the safety device according to the invention. In the drawings, there are shown: FIG. 1 : shows the securing device according to the invention for arrangement on the right dropout of a bicycle according to an exemplary embodiment of the invention together with the drive element of the bicycle shown in sections in the form of a toothed belt in a perspective view from a viewing direction from the right rear with respect to the bicycle not otherwise shown; FIG. 2 : shows the securing device of the exemplary embodiment of FIG. 1 in a side view, which is achieved when viewed from behind on a bicycle, when the securing device is mounted on this bicycle. FIG. 3 : the securing device of the exemplary embodiment of FIGS. 1 and 2 together with the drive element of FIG. 1 shown in sections in a side view from the direction of the right side of the bicycle not otherwise shown; FIG. 4 : parts of the securing device of the exemplary embodiment from FIGS. 1 to 3 in an exploded perspective view; FIG. 5 : the securing device of the exemplary embodiment of FIGS. 1 to 4 together with the drive element of FIGS. 1 and 3 shown in sections in a side view from the direction of the left side of the bicycle, which is otherwise not shown; FIG. 6 : the securing device of the exemplary embodiment of FIGS. 1 to 5 on a bicycle shown in parts in a side view; FIG. 7 shows a detail of a bicycle equipped with the securing device of the exemplary embodiment of FIGS. 1 to 6 in the region of its rear axle with the right rear dropout of its frame in a side view; FIG. 8 : shows an isolated detail of the right rear dropout from FIG. 7 in a first perspective view; and FIG. 9 : shows the detail of the right rear dropout from FIG. 8 shown in isolation in a second perspective view.FIG. 1 shows a safety device 1 according to the invention, which is intended to prevent, in bicycles with belt drive, a drive element 2, which is designed here as a toothed belt, from running off a rear sprocket, which is not shown here and is a pulley here, in the drive train of the bicycle. The drive element 2 and the safety device 1 are shown in FIG. 1 in exactly the position relative to one another they assume mounted on a bicycle. In particular, the drive element is shown in the region of the safety device 1 as if it were laid around the rear sprocket and, outside the region shown, also around a front sprocket, which in the case of belt drive is a front pulley, and were held in a tensioned manner between the sprockets in order to drive the drive element 2 via the front sprocket and to drive a rear wheel axle via the drive element 2 and via this a rear wheel of the bicycle.The drive element 2 has, in its embodiment as a toothed belt, an inner side with an endless row of teeth arranged equidistantly with respect to one another for the toothing with the toothed rings and a corrugated outer side.The safety device 1 comprises a holding element 3 and a safety element 4 designed as a roller, as well as a plurality of elements with which the safety element 4 is rotatably held and fastened on the holding element 3. The safety element 4 is positioned such that only a very small distance of at most 2 mm from the drive element 1 remains. For the exact positioning of the safety element 4, the holding element 3 has a mounting opening 5 designed as an elongated hole, in which a pin 6 is displaceably mounted by means of a guide section 7 and fixed by means of a first fastening screw 8 at the end. The fastening screw 8 is arranged countersunk in a groove in the holding element 3. The guide section 7 has a hexagonal outer surface and is either part of the pin 6 or connected to the pin 6, for example screwed onto the pin 6 as a nut.The mounting opening 5 is arranged in a base element 9 of the mounting element 3 which is formed from metal and in which an axle opening 10 for the rear wheel axle of the bicycle is also formed. The base element 9 is here formed in one piece with a plug-in sleeve 11 which likewise consists of metal and radially directly surrounds the rear wheel axle when the safety device 1 and the rear wheel axle are mounted on the bicycle. The plug-in sleeve abuts radially on the outside at a right receiving opening formed in the right rear dropout of the bicycle when the safety device is installed on the bicycle.FIG. 2 shows the safety device 1 from FIG. 1 isolated, i.e. without the drive element 2 from a viewing direction in which the longitudinal axes of the insert sleeve 11 and of the pin 6 are perpendicular to the image plane. Like reference numerals designate like parts throughout the figures.FIG. 3 again shows the arrangement of FIG. 1 from a different viewing direction than FIG. 1, namely the safety device 1 with the drive element 2 of the bicycle with viewing direction from the right side in the direction of travel to the bicycle not otherwise shown in more detail. It can be clearly seen that the base element 9 extends rearward in the range from 10 degrees to 25 degrees, in particular from about 15 degrees to 20 degrees, with respect to the direction of travel, at an angle of attack of the base element 9 defined by the position of the mounting opening 5 with respect to the axle opening 10 with respect to the vertical. The drive element 2 passes the safety element 4 in a region in which it normally, i.e. with sufficient tension of the drive element 2, already rests completely on the rear sprocket and is deflected by the latter. As a result, the drive element 2 does not come into contact with the safety element 4 until it runs at an angle of approach relative to the horizontal from obliquely below onto the rear toothed rim, which angle is greater than the angle of attack of the base element 9, so that in the normal case no friction losses occur through the safety element 4.The holding element 3, in particular the base element 9, is formed in the region of the axle opening 10 with a stop edge 13 which is oriented rotated by approximately 30 degrees with respect to the vertical and in the process points obliquely downwards and obliquely forwards with respect to the position of the holding element 3 mounted on the bicycle. The stop edge can abut against frames of suitable bicycles and thus help during assembly mount the safety device 1 in the intended angular position.FIG. 4 shows an exploded view of the safety device 1. the safety device 1 consists of five parts detachably connected to one another, namely the holding element 3, the pin 6, the fastening screw 8 predominantly covered by the holding element 3 here, the safety element 4 and a holding screw 12 which holds the safety element 4 rotatably on the pin 6.FIG. 5 again shows the arrangement of FIGS. 1 and 3, but viewed from the left on the bicycle not otherwise shown and thus from the opposite side with respect to FIG. 3.FIG. 6 shows the arrangement of FIG. 5 in a larger detail with further parts of the bicycle and in particular the drive train of the bicycle. In particular, sections of a crankset are shown with the already mentioned front toothed ring 14, which is designated here for the first time and is designed as a front pulley. Also shown is a portion of the rear wheel 15 of the bicycle. The individual components and sections of the safety device 1 are not all again provided with reference numerals here for reasons of clarity.In the region of the front sprocket 14, the bicycle has a clamping element 16 for clamping the drive element 2. The clamping element 16 is designed as a roller with lateral radially protruding projections for the lateral guidance of the drive element 2 and is held on the frame, likewise not shown, by means of a lever, not shown, with a prestress which presses the clamping element 16 upward against the outer side of the returning drive element 2.FIG. 7 shows the arrangement of FIG. 3 from the same viewing direction and together with further parts of the bicycle, which are shown in sections and are designated here for the first time, namely the frame 17, the rear sprocket 18 designed as a rear pulley and the rear wheel 19. Outwardly adjoining the hub 20 are spokes, not designated.The rear wheel axle 21, which is likewise designated here for the first time and which holds the rear wheel 19 rotatably mounted with the hub 20 and with the rear sprocket 18, is mounted in receiving openings in a right rear dropout 22 visible in FIG. 7 and in a left rear dropout arranged there such that it is hidden in the background. The insertion sleeve 11 of the holding element 3 is interposed on the right rear dropout 22, i.e. it protrudes through the right receiving opening and itself encloses the rear wheel axle 21, as already described. The base element 9 of the holding element 3, on the other hand, abuts the frame 17 on the side facing away from the observer in the region of the right rear dropout 22.FIG. 8 shows a section of the frame 17 with the right rear dropout 22 and the right rear receiving opening 23 arranged therein and designated for the first time here. The frame 17 is made completely or substantially of metal, i.e. has at least one metallic base. In the region of the receiving opening 23, the frame is shaped in the manner of a sleeve 24 surrounding the receiving opening 23. The frame 17 is thereby suitable for accommodating a so-called universal switch eye which has an interface adapted thereto. The shifting eye is understood to be a holder which is provided to hold the rear derailleur on the frame of a bicycle during a derailleur. In particular, the frame 17 is designed to receive contact pins which use the so-called Universal Derailur Hanger (UDH) interface of the company SRAM. The safety device according to the invention uses the same interface and is therefore suitable for being installed on the frame 17 instead of the universal shifting eye in bicycles without derailleurs, in which a holder for fastening a rear derailleur is unnecessary, in particular in combination with the hub 20.FIG. 9 shows the part of the frame 17 illustrated in FIG. 8 with a view to the left side of the right rear dropout 22, i.e. the side against which the base element 8 bears when the safety device 1 is mounted on the frame 17. The protrusion extends up to a protruding edge on the frame 17, which forms a counterstop formation 25 for the stop edge 13 of the safety device 1 formed with the holding element 3 when the safety device 1 is mounted on the bicycle with the frame 17.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2018 222 834 A1

[0009]

Claims

Safety device for the drive element (2) revolving around a front sprocket (14) and a rear sprocket (18), in particular for the toothed belt revolving around a front pulley and a rear pulley, in the drive train of a bicycle, which has a frame (17) with a right rear dropout (22) and with a left rear dropout and which has a rear wheel (15) drivable via the drive train with a rear wheel axle (21) held in receiving openings (23) on the dropouts (22), characterized in that the safety device (1) has a holding element (3) with an interface for fastening the holding element (3) to the right rear dropout (22) and has a safety element (4) held at a fixed distance from the interface on the holding element (3) for preventing the drive element (2) from jumping off the rear sprocket (18).Safety device according to claim 1, characterized in that the support element (3) is arranged to support the safety element (4) at a fixed position below the rear sprocket (18), spaced from the drive train.Safety device according to claim 1 or claim 2, characterised in that the holding element (3) is designed to be mounted on the right rear dropout (22) instead of a switching eye which is provided for the connection of the rear derailleur of a derailleur to the frame (17), wherein the interface is designed to be able to mount the holding element (3) universally on any arbitrarily selected frame (17) from a group of frames (17) or from all frames (17) which are each designed for the mounting of the switching eye.Safety device according to one of the preceding claims, characterized in that the interface uses specifications of the so-called Universal Derailur Hanger (UDH) interface established by the company SRAM in order to be able to mount the mounting element (3) on a frame (17) set up for the use of the UDH interface.Safety device according to one of the preceding claims, characterized in that the interface has an insertion sleeve (11), in particular in the form of a fastening screw or an axle bolt, which is configured to receive the rear wheel axle (21) of the bicycle and to be arranged in the receiving opening (23) on the right rear dropout (22) in order to fix both the rear wheel axle (21) and the holding element (3) on the right rear dropout (22).Safety device according to one of the preceding claims, characterized in that the insertion sleeve (11) is configured to hold a defined rotational angular position relative to this right rear dropout (22) by means of positive contact or frictional contact, in particular by means of knurling, on the inner side of the receiving opening (23) of the right rear dropout (22).Safety device according to one of the preceding claims, characterized in that the interface has a stop edge (13) running in a straight line for bearing against a counterstop formation (25) or against a projection on the right rear dropout (22), wherein the stop edge (13) is oriented at an angle in the range between 30 degrees and 60 degrees, preferably in the range between 35 degrees and 55 degrees, particularly preferably in the range between 40 degrees and 50 degrees, in relation to the direction in which the safety element (4) is arranged relative to the rear wheel axle (21) to be accommodated.Safety device according to one of the preceding claims, characterized in that the safety device (1) has a base element (9), in particular made of metal, with an axle opening (10) formed therein for the rear wheel axle (21) and with an assembly opening (5) formed therein for fastening the safety element (4).Safety device according to claim 8, characterised in that the mounting opening (5) is formed as an elongated hole for the radially longitudinally adjustable fastening of the safety element (4) at a selected distance from the axle opening (10).Safety device according to one of the preceding claims, characterized in that the safety element (4) is a rotatably mounted roller.Safety device according to any one of the preceding claims, characterized in that the safety device (1) is designed for use in a bicycle with a drive train which is a belt drive and in which the toothed rings (14, 18) are belt pulleys and the drive element (2) is a toothed belt, wherein the safety element (4) is designed to prevent the toothed belt from jumping off the rear belt pulley.A bicycle comprising a frame (17) having a right rear dropout (22) and a left rear dropout, and comprising a drive train having a front sprocket (14) and a rear sprocket (18) and a drive element (2) rotating around the front sprocket (14) and the rear sprocket (18), and comprising a rear wheel (15) drivable via the drive train and having a rear wheel axle (21) held in receiving openings (23) on the dropouts (22), and comprising a safety device (1) for the drive element, characterized in that the safety device (1) comprises a holding element (3) which is fastened to the right rear dropout (22) via an interface provided for this purpose, a safety element (4) held at a fixed distance from the interface on the holding element (3) for preventing the drive element (2) from jumping off the rear sprocket (18).Bicycle according to claim 12, characterized in that the drive train is a belt drive, wherein the sprockets (14, 18) are pulleys and the drive element (2) is a toothed belt.A bicycle according to claim 12 or claim 13, characterized in that the safety device is configured according to any one of claims 1 to 11.

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