Toothed belt pulley

Abstract

The invention relates to a toothed belt pulley (1, 1') for a toothed belt drive, in particular for a bicycle. The toothed belt pulley (1, 1') has a plurality of radially outwardly directed teeth (3, 3') distributed over the circumference of the toothed belt pulley (1, 1') for engaging with corresponding teeth (4) of a toothed belt (2), and at least one guide element (5, 5') for preventing the toothed belt (2) from running off the toothed belt pulley (1, 1') in the axial direction. According to the invention, the at least one guide element (5, 5') is in contact with precisely one tooth (3, 3'). The associated reduction in the expansion of the guide element (5, 5') facilitates the removal of dirt and foreign bodies from the spaces (6, 6') between the teeth of the toothed belt pulley (1, 1').

Description

[0001] Timing belt pulley

[0002] Description

[0003] The entire content of priority application DE 10 2024 121 603.4 is hereby incorporated by reference into the present application.

[0004] The present invention relates to a toothed belt pulley for a toothed belt drive. The invention is described in connection with a toothed belt drive for a bicycle. It is noted that the invention can also be used in other toothed belt drives, for example, for other vehicles such as motorcycles or for stationary machines of all kinds.

[0005] Toothed belt drives for bicycles have been known in the state of the art for a long time and serve in particular as an alternative to a conventional chain drive.

[0006] A toothed belt drive of the type considered here for a bicycle comprises a driving and a driven toothed belt pulley and a toothed belt, wherein the driving toothed belt pulley is non-rotatably connected to the bottom bracket axle or to the output shaft of a bottom bracket gearbox, and the driven toothed belt pulley is non-rotatably connected in at least one direction of rotation to the rear wheel hub or to the input shaft of a gearbox arranged in the rear wheel hub. The two toothed belt pulleys are arranged in the same plane and have axes of rotation parallel to each other.

[0007] The toothed belt pulley according to the invention can be used in the toothed belt drive both as a driving and as a driven toothed belt pulley.

[0008] Each toothed belt pulley has a plurality of radially outward-facing teeth distributed around its circumference for meshing with corresponding teeth on a toothed belt. The toothed belt has correspondingly shaped, radially inward-facing teeth for meshing with the teeth of the toothed belt pulley and is formed into an endless loop that wraps around both toothed belt pulleys.

[0009] Since a timing belt does not engage the teeth of the timing belt pulley in an axial direction – unlike, for example, a chain with its links engages the teeth of a sprocket – there is always a risk that the timing belt will run off the teeth of the timing belt pulley in an axial direction with a timing belt drive.

[0010] A worn timing belt can have serious consequences. These can include a sudden loss of pedal control, a resulting loss of control for the rider, and in the worst case, a fall. It can also lead to damage to, and especially the breaking of, the timing belt itself.

[0011] To avoid this, toothed belt pulleys generally have at least one guide element that guides the toothed belt axially on the pulley and thus prevents it from slipping off.

[0012] The most common type of guide element is a flange. This is mounted on one axial side of the toothed belt pulley in the form of a circumferential ring, is in contact with or attached to the axial end faces of the teeth, and its axial side surface covers the spaces between the teeth of the toothed belt pulley. During operation of the toothed belt drive, the flange limits the freedom of movement of the toothed belt on the relevant axial side of the toothed belt pulley. When the toothed belt moves in the axial direction, the teeth of the toothed belt, or even the belt itself, abut the flange, preventing the toothed belt from slipping off the toothed belt pulley on this axial side. Preferably, a flange is mounted on each axial side of the toothed belt pulley, thus guiding the toothed belt in both axial directions and preventing it from slipping off the toothed belt pulley.

[0013] Particularly when using a toothed belt drive on a bicycle, the problem persists that dirt and foreign objects, especially soil, pebbles, twigs, leaves, or mud, can accumulate in the toothed belt pulley. These materials either strike the pulley directly from the surrounding environment during riding or are carried into the pulley by the toothed belt. The dirt and foreign objects collect especially in the spaces between the teeth of the toothed belt pulley and are further compacted there by the pressure exerted by the teeth of the toothed belt. By clogging the spaces between the teeth of the toothed belt pulley with dirt and foreign objects, the radial height difference between the teeth and the spaces between them on the toothed belt pulley is reduced.This can cause the teeth of the timing belt to engage less effectively with the pulley, and in the worst case, the timing belt can slip. This problem is particularly relevant when using a timing belt drive for driving in the woods or off-road, especially when dirt and foreign objects adhere more readily to the pulley due to moisture.

[0014] Furthermore, this problem is exacerbated by the presence of the flanges described above - especially when these are attached to both axial sides of the timing belt pulley - as the spaces between the teeth on the timing belt pulley then form closed recesses in all directions, from which dirt and foreign matter are difficult to remove on their own.

[0015] Therefore, various designs have been proposed to facilitate the removal of dirt and foreign matter from the spaces between the teeth on a timing belt pulley:

[0016] For example, US patent 8,057,337 B2 provides for recesses in the tooth spaces on the timing belt pulley, which are inclined in the axial direction.

[0017] In the TW M645963 U, the flanges have the form of arc-shaped, radially outward-facing webs, each connecting the same axial ends of two adjacent teeth, with the webs being arranged alternately on both axial sides of the toothed belt pulley.

[0018] In EP 2 289 792 B1, the teeth of the toothed belt pulley are designed as bars projecting from a narrow central web in both axial directions. A circumferential flange also extends radially outwards from the central web, penetrating the teeth and engaging in a corresponding groove in the toothed belt teeth, located centrally in the axial direction, during operation of the toothed belt drive. This guides the toothed belt axially and prevents it from slipping off the toothed belt pulley, thus eliminating the need for additional flange washers.

[0019] However, it has been shown that the latter design, with a circumferential flange on the central web of the toothed belt pulley (so-called "center track") and a corresponding groove in the teeth of the toothed belt, is insufficient to prevent the toothed belt from slipping off the toothed belt pulley at high torques, especially when the rider's pedaling power is assisted by an electric auxiliary motor.

[0020] The object of the present invention is to prevent the toothed belt from slipping off the teeth of the toothed belt pulley in the axial direction and at the same time to facilitate the removal of dirt and foreign bodies from the spaces between the teeth on the toothed belt pulley.

[0021] This problem is solved by the teaching of independent claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

[0022] The invention provides a toothed belt pulley for a toothed belt drive, in particular for a bicycle, with a plurality of radially outwardly directed teeth distributed around the circumference of the toothed belt pulley for engagement with corresponding teeth of a toothed belt and with at least one guide element to prevent the toothed belt from running off the toothed belt pulley in an axial direction, wherein the at least one guide element is in contact with exactly one tooth.

[0023] Since the at least one guide element is intended to prevent the timing belt from slipping off the timing belt pulley, the invention assumes that the at least one guide element is arranged directly on one of the teeth and is thus in contact with it.

[0024] In the context of the present invention, "contact" between two components is understood to mean mechanical contact between the two components. This contact can enable force transmission, for example, through a friction-fit, form-fit, or material-fit connection, or even through the two components being formed as a single piece. However, this is not strictly necessary for the two components to be in contact. In particular, mere contact between the two components, preferably a surface contact, and more preferably, a pressing of the two components against each other, should suffice for contact to occur.

[0025] The invention is based on the understanding that the removal of dirt and foreign matter from the spaces between the teeth is easier the more the dimension of at least one guide element is reduced, because this also reduces the surface area that can prevent dirt and foreign matter from escaping the spaces between the teeth. If the at least one guide element is in contact with at least two teeth of the toothed belt pulley, the minimum dimension of the guide element in the circumferential direction of the toothed belt pulley corresponds to the distance between two adjacent teeth. By providing that the at least one guide element is in contact with only exactly one tooth, the dimension of the guide element can be further reduced.At the same time, it has been shown that a correspondingly small extension of the guide element is sufficient to prevent the timing belt from unintentionally slipping off the timing belt pulley.

[0026] The inventive feature that the at least one guide element is in contact with only exactly one tooth opens up new design possibilities, since the guide element can be designed independently of any connection to one or more adjacent teeth. The manufacture of a toothed belt pulley according to the invention is also simplified, as the spaces between the teeth at both axial ends can be completely open without the need to create an opening enclosed by the teeth and the guide element, which is associated with increased manufacturing effort. Finally, the reduction in the dimensions of the guide element results in corresponding savings in weight, material, and costs. In a preferred embodiment of the invention, the at least one guide element is attached to the tooth with which it is in contact.

[0027] The term "fastening" two components to one another refers to a contact in which the relative position of the two components is fixed and force transmission between them is possible, preferably through a positive-locking or material-locking connection, or even a one-piece construction of the two components. The fact that a first component is fastened to a second component can also mean, in particular, that the first component is fixed and supported in its relative position to the second component.

[0028] By attaching the guide element to the tooth with which it is in contact, further fastening elements for the guide element are unnecessary, thus keeping the number of elements that make up the timing belt pulley low.

[0029] In a further preferred embodiment of the invention, the at least one guide element is in contact with an axial end face of the tooth with which it is in contact and is in particular attached to this end face.

[0030] The position of the guide element on an axial end face of the tooth thus corresponds to that of a conventional flange and therefore prevents the toothed belt from slipping off the teeth in the axial direction in the same way.

[0031] In a preferred embodiment, the at least one guide element has the form of a disc which extends essentially in a plane perpendicular to an axis of rotation of the toothed belt pulley.

[0032] This shape and orientation of the guide element also corresponds to the shape and orientation of a conventional flange pulley and again prevents the toothed belt from slipping off the teeth in the axial direction. However, the size of the pulley can be significantly reduced compared to a conventional flange pulley thanks to the guide element according to the invention.

[0033] In a preferred embodiment of this embodiment, the at least one guide element has a chamfer on its radially outer edge on its side axially facing the tooth with which it is in contact, extending radially outwards away from the tooth with which it is in contact.

[0034] Preferably, the chamfer extends radially inwards to the tooth head of the tooth with which the guide element is in contact.

[0035] The chamfer creates a wedge-shaped recess on the side of the guide element facing the tooth, at least in the area of ​​the chamfer. If guide elements with such a chamfer are attached to both axial sides of the tooth, a complete wedge-shaped recess results, at least in this area.

[0036] The chamfer facilitates threading the toothed belt into the toothed belt pulley and prevents the belt from rubbing against the inside of the guide element. Furthermore, the chamfer serves to prevent the toothed belt from slipping axially, particularly when it cannot run exactly in the plane of the toothed belt pulley, for example, because the axes of the driving and driven toothed belt pulleys are no longer perfectly parallel to each other due to deformation of the bicycle frame under high load. Conversely, the chamfer can also compensate for a certain degree of misalignment of the toothed belt and guide it back to a central position on the teeth of the toothed belt pulley. In a further preferred embodiment of the invention, the at least one guide element has an asymmetrical shape in a cross-section perpendicular to an axis of rotation of the toothed belt pulley.

[0037] Since torque in a bicycle is only transmitted in one direction of rotation, the tooth flanks of the toothed belt only need to be guided in an asymmetrical shape with a limited area as they enter the toothed belt pulley during rotation. This advantageously provides a larger gap axially outwards and radially inwards for dirt displacement.

[0038] In a further preferred embodiment of the invention, the at least one guide element extends in the circumferential direction of the toothed belt pulley further away from the tooth with which it is in contact in one of the two directions than in the other direction.

[0039] This property also leads to improved dirt displacement.

[0040] In a preferred embodiment of this invention, the at least one guide element extends less far away from the tooth with which it is in contact in the intended drive direction of rotation of the toothed belt pulley than in the opposite direction of rotation.

[0041] In addition to the advantageous property of improved dirt displacement, this design also leads to reduced noise when the belt enters the toothed belt pulley at an angle.

[0042] In a preferred embodiment of this design, the at least one guide element does not extend substantially beyond the tooth with which it is in contact in the intended direction of rotation of the toothed belt pulley. Besides the advantageous property of improved dirt displacement, this design also results in reduced noise when the belt enters the toothed belt pulley at an angle.

[0043] In a further preferred embodiment of the invention, the at least one guide element extends in the radial direction of the toothed belt pulley beyond the tooth with which it is in contact.

[0044] This allows the timing belt to be guided by the guide element even radially outside the teeth of the timing belt pulley, and thus in the continuous section of the timing belt that connects the individual teeth and in which the tensile cords made of steel wire or carbon fibers are embedded. This corresponds to the arrangement of a conventional flange, which generally also extends radially beyond the teeth of the timing belt pulley, but again with the advantage of the reduced extension of the guide element.

[0045] In a further preferred embodiment of the invention, the extent of the at least one guide element in the circumferential direction of the toothed belt pulley is at most three quarters, preferably at most half, and more preferably at most one quarter of the distance measured in the circumferential direction of the toothed belt pulley between two adjacent teeth of the toothed belt pulley.

[0046] By appropriately selecting the ratio between the circumference of the guide element and the tooth spacing, a secure and stable guidance of the timing belt can be achieved, depending on the application, particularly the expected load on the timing belt pulley. This also ensures good removal of dirt and foreign matter from the tooth spaces on the pulley. A larger value of this ratio results in a correspondingly larger guide element, which covers a correspondingly larger portion of the space between the tooth it contacts and one of the adjacent teeth.

[0047] In a further preferred embodiment of the invention, the extension of the at least one guide element in the radial direction radially outside the tooth head of the toothed belt pulley is at most half, preferably at most one quarter, further preferably at most one fifth of the distance measured in the circumferential direction of the toothed belt pulley between two adjacent teeth of the toothed belt pulley.

[0048] The effects of choosing this ratio, which relates to the extension of the at least one guide element in the radial direction, are similar to those of the previous preferred embodiment of the invention, which related to the extension of the guide element in the circumferential direction.

[0049] In a further preferred embodiment of the invention, the toothed belt pulley has a plurality of guide elements which are alternately in contact with an axial end of one tooth and with the opposite axial end of another tooth in the circumferential direction of the toothed belt pulley and are preferably attached to the respective axial end of the respective tooth.

[0050] Regarding the arrangement and distribution of the guide elements on the individual teeth of the toothed belt pulley, the fact that each guide element is in contact with exactly one tooth opens up a large number of possibilities for the designer. An alternating arrangement of guide elements at the two axial ends of the teeth ensures uniform guidance of the toothed belt on the pulley in both axial directions, while requiring only a relatively small number of guide elements. Alternatively, it is of course possible to arrange one guide element at each axial end of one or all teeth. In a preferred embodiment of this invention, a guide element is in contact with each tooth and is preferably attached to that tooth.

[0051] This means that a guide element is arranged on every second tooth on each axial side of the toothed belt pulley, with the arrangements of the guide elements on both axial sides offset by one tooth in the circumferential direction. The number of teeth on the toothed belt pulley is expediently chosen to be an even number. A guide for the toothed belt that is only provided on every second tooth on one axial side is generally perfectly adequate for reliable belt guidance.

[0052] In an alternative to this variant, a guide element is in contact with every second, every third or every nth tooth in the circumferential direction of the toothed belt pulley, where n is a natural number greater than three, and is preferably attached to this tooth.

[0053] The previously described arrangement of guide elements can be further reduced in this way. A guide element is arranged on each axial side of the toothed belt pulley at every fourth, sixth, or 2nth tooth, with the arrangements of the guide elements on both axial sides being offset by a maximum of three, five, or 2n-1 teeth, respectively, in the circumferential direction. The number of teeth on the toothed belt pulley is expediently chosen to be divisible by four, six, or 2n. Depending on the application, even such a smaller number of guide elements may be sufficient for reliable guidance of the toothed belt.

[0054] In a further preferred embodiment of the invention, the toothed belt pulley has a plurality of guide elements, all of which are in contact with an axial end of a tooth on the same axial side of the toothed belt pulley and are preferably attached to the respective axial end of the respective tooth.

[0055] This embodiment is based on the understanding that in a toothed belt drive, each toothed belt pulley has a "preferred" axial direction in which the toothed belt is at risk of slipping. For example, in a toothed belt drive for a conventional bicycle, this is the right side for the front toothed belt pulley, which is mounted at the bottom bracket and thus drives the belt, and the left side for the rear toothed belt pulley, which is mounted at the rear wheel and thus drives the belt. It may therefore be sufficient to install at least one guide element only on each of these "preferred" axial sides.

[0056] Further advantages, features and applications of the present invention will become apparent from the following description in conjunction with the figures.

[0057] They show:

[0058] Fig. 1 shows a toothed belt drive with two toothed belt pulleys according to the invention and a toothed belt;

[0059] Fig. 2 shows the driving toothed belt pulley from Fig. 1 with the toothed belt in an enlarged view;

[0060] Fig. 3 shows the driven toothed belt pulley from Fig. 1 with the toothed belt in an enlarged view;

[0061] Fig. 4 shows the toothed belt pulley from Fig. 3 with the toothed belt in a perspective view;

[0062] Fig. 5 shows the toothed belt pulley from Fig. 3 without the toothed belt in a perspective view;

[0063] Fig. 6 shows an enlarged section of Fig. 5;

[0064] Fig. 7 shows an enlarged section of Fig. 3; Fig. 8 shows a further enlarged section of Fig. 7 without the toothed belt;

[0065] Fig. 9 is a top view of Fig. 3.

[0066] Fig. 1 shows a toothed belt drive for a bicycle with two toothed belt pulleys 1, T and a toothed belt 2 according to the invention. The toothed belt pulley 1' can be attached, for example, to a crank spider of a pedal crank and thus to the bottom bracket axle of the bicycle by means of the mounting holes 8, and thus forms the driving toothed belt pulley in the toothed belt drive. The toothed belt pulley 1 can be attached by means of the mounting grooves 9 to corresponding radially outwardly directed projections ("splines") of a rear wheel hub and thus forms the driven toothed belt pulley in the toothed belt drive. The two toothed belt pulleys 1, T are mounted on the bicycle in the same plane and with axes of rotation parallel to each other – corresponding to the axes of the bottom bracket and the rear wheel hub.

[0067] The direction of rotation of the toothed belt drive, and thus also of the two toothed belt pulleys 1, T, is in the usual manner, such that the upper part of the toothed belt 2 is pulled by the driving toothed belt pulley T, and thus in all figures in a clockwise direction of the toothed belt pulleys 1, T.

[0068] An endless timing belt 2 is wound around both timing belt pulleys 1 and T, transmitting the torque from the driving timing belt pulley T to the driven timing belt pulley 1. The timing belt pulley T has a larger diameter than the timing belt pulley 1, resulting in a gear ratio greater than 1.

[0069] Both toothed belt pulleys 1, T have a plurality of radially outwardly directed teeth 3, 3' on their outer circumference, each tooth being equidistant from the others. The teeth 3, 3' engage with corresponding teeth 4 of the toothed belt 2, the shape of the tooth gaps 6, 6' on the toothed belt pulley 1, 1' corresponding to the shape of the teeth 4 on the toothed belt 2 and vice versa.

[0070] Figure 2 shows an enlarged view of the driving toothed belt pulley 1'. Figures 3 to 9 show the driven toothed belt pulley 1 with and without the toothed belt 2 in various views and perspectives. An embodiment of the invention is explained below using the driven toothed belt pulley 1 as an example. However, the invention is implemented equally well in the driving toothed belt pulley T.

[0071] The toothed belt pulley 1 has an annular, radially inner part 10, on the radially inner edge of which the mounting grooves 9 are arranged. The teeth 3 are attached centrally to the inner part 10 of the toothed belt pulley 1 in the form of axially oriented, approximately wedge-shaped rods. In particular, the inner part 10 and the teeth 3 can also be manufactured in one piece, for example, milled together from a solid block or as a one-piece casting. The term "attached" is therefore always intended to include such one-piece manufacturing here and in the following. The axial width of the teeth 3 is slightly larger than the width of the toothed belt 2.

[0072] The axial width of the inner part 10 is significantly smaller than the axial width of the teeth 3. The resulting “open” formation of the interdental spaces 6 between the teeth 3 has, as explained at the beginning, the advantage that dirt and foreign matter that accumulate on the toothed belt pulley 1 during cycling can be more easily removed from there.

[0073] Guide elements 5 are alternately attached to the axial end faces of the teeth 3, preventing the toothed belt 2 from slipping in the axial direction. Each guide element 5 has the form of a thin disc arranged in a plane parallel to the inner part 10 of the toothed belt pulley 1. The shape of the guide element 5 is asymmetrical, and its attachment to the tooth 3 is also off-center. The guide element 5's shape resembles an "ear" attached to the end face of the tooth 3.

[0074] The guide element 5 has a rectangular shape when viewed axially. The radially outer corners of the rectangle are strongly rounded. On its radially inner side, the rectangle has a bulge at the front (viewed in the direction of drive rotation), which corresponds approximately to the shape of the front flank of the tooth 3 to which the guide element 5 is attached, and a recess at the rear (viewed in the direction of drive rotation). At the front (viewed in the direction of drive rotation), the guide element 5 is essentially flush with the shape of the tooth 3 to which it is attached. At the rear (viewed in the direction of drive rotation) and radially upwards, the guide element 5 projects beyond the tooth 3 to which it is attached. The guide element 5 thus also covers part of the gap 6 between the tooth 3 to which it is attached and the adjacent tooth 3 located behind it (viewed in the direction of drive rotation).The aforementioned indentation further reduces the coverage of the interdental space 6 at the radially inner end of the guide element 5, thereby further improving the removal of dirt and foreign matter from the interdental space 6. In the exemplary embodiment, the portion of the interdental space 6 covered by the guide element 5 is approximately half the width of the interdental space 6 when viewed circumferentially.

[0075] Since torque in a bicycle is transmitted in only one direction of rotation, the tooth flanks of the toothed belt 2 only need to be guided in an asymmetrical shape with a limited surface area as they engage the toothed belt pulley 1 during rotation. This advantageously provides a larger gap axially outwards and radially inwards for dirt displacement. The asymmetrical shape of the guide element 5 and its off-center attachment to the tooth 3 are therefore advantageous.

[0076] However, it would also be possible to design the guide element 5 symmetrically and / or to attach the guide element 5 centrally to the face of the tooth 3. In this case, the tooth gap 6 could be covered circumferentially from both sides by a guide element 5, each of which projects beyond the tooth 3 to which it is attached. Such a symmetrical design and / or central attachment of the guide element 5 might be preferred, for example, for aesthetic reasons, to give the toothed belt pulley 1 a more uniform appearance.

[0077] On its radially outer inner surface, the guide element 5 has a chamfer 7, which slightly "opens" the space in which the toothed belt 2 is accommodated radially outwards. This facilitates threading the toothed belt 2 into the toothed belt pulley 1. The chamfer 7 also serves to "guide" the toothed belt 2 back into alignment if it runs slightly askew onto the toothed belt pulley 1 – for example, due to slight deformation of the bicycle frame as a result of high load from high torque. In this case, the space outside the teeth 3 of the toothed belt pulley 1, which opens radially outwards in a slightly wedge shape, causes the toothed belt 2 to slide along the chamfer 7 from radially outwards towards the teeth 3 and run straight again on the toothed belt pulley 1, so that the teeth 4 of the toothed belt 2 can once again engage precisely with the teeth 3 of the toothed belt pulley 1. (Reference numeral list)

[0078] 1, 1' Timing belt pulley 2 Timing belt

[0079] 3, 3' tooth of the timing belt pulley

[0080] 4th tooth of the timing belt

[0081] 5.5' guide element

[0082] 6, 6' Interdental space 7, 7' Bevel

[0083] 8 mounting holes

[0084] 9 Mounting groove

[0085] 10, 10' Inner part of the timing belt pulley

Claims

Patent claims 1. Toothed belt pulley (1 , 1 ') for a toothed belt drive, in particular for a bicycle, with a plurality of radially outward directed teeth (3, 3') distributed over the circumference of the toothed belt pulley (1 , 1') for engagement with corresponding teeth (4) of a toothed belt (2) and with at least one guide element (5, 5') to prevent the toothed belt (2) from slipping off the toothed belt pulley (1 , 1 *) in the axial direction, characterized in that the at least one guide element (5, 5') is in contact with exactly one tooth (3, 3').

2. Toothed belt pulley (1 , 1') according to claim 1 , characterized in that the at least one guide element (5, 5') is attached to the tooth (3, 3') with which it is in contact.

3. Toothed belt pulley (1 , 1') according to at least one of the preceding claims, characterized in that the at least one guide element (5, 5') is in contact with an axial end face of the tooth (3, 3') with which it is in contact and is in particular attached to this end face.

4. Toothed belt pulley (1 , 1') according to claim 3, characterized in that the at least one guide element (5, 5') has the form of a disc which extends substantially in a plane perpendicular to an axis of rotation of the toothed belt pulley (1 , 1').

5. Toothed belt pulley (1, 1') according to claim 4, characterized in that the at least one guide element (5, 5') has on its radially outer edge, on its side axially facing the tooth (3, 3') with which it is in contact, a radially outwardly extending has a chamfer (7, 7') extending away from the tooth (3, 3') with which it is in contact.

6. Toothed belt pulley (1 , 1') according to at least one of the preceding claims, characterized in that the at least one guide element (5, 5') has an asymmetrical shape in a cross-section perpendicular to an axis of rotation of the toothed belt pulley (1 , 1').

7. Toothed belt pulley (1 , 1') according to at least one of the preceding claims, characterized in that the at least one guide element (5, 5') extends further away from the tooth (3, 3') with which it is in contact in one of the two directions in the circumferential direction of the toothed belt pulley (1 , 1') than in the other direction.

8. Toothed belt pulley (1 , 1') according to claim 7, characterized in that the at least one guide element (5, 5') extends less far away from the tooth (3, 3') with which it is in contact in the intended drive direction of rotation of the toothed belt pulley (1 , 1') than against the intended drive direction of rotation.

9. Toothed belt pulley (1 , 1') according to claim 8, characterized in that the at least one guide element (5, 5') does not extend substantially beyond the tooth (3, 3') with which it is in contact in the intended drive direction of rotation of the toothed belt pulley (1 , 1').

10. Toothed belt pulley (1, 1') according to at least one of the preceding claims, characterized in that the at least one guide element (5, 5') extends in the radial direction of the The timing belt pulley (1 , 1') extends beyond the tooth (3, 3') with which it is in contact.

11. Toothed belt pulley (1 , 1 ') according to at least one of the preceding claims, characterized in that the extent of the at least one guide element (5, 5') in the circumferential direction of the toothed belt pulley (1 , 1') is at most three quarters, preferably at most half, further preferably at most one quarter of the distance between two adjacent teeth (3, 3') of the toothed belt pulley (1 , 1') measured in the circumferential direction of the toothed belt pulley (1 , 1').

12. Toothed belt pulley (1 , 1') according to at least one of the preceding claims, characterized in that the extension of the at least one guide element (5, 5') in the radial direction radially outside the tooth head of the toothed belt pulley (1 , 1') is at most half, preferably at most one quarter, further preferably at most one fifth of the distance between two adjacent teeth (3, 3') of the toothed belt pulley (1 , 1') measured in the circumferential direction of the toothed belt pulley (1 , 1').

13. Toothed belt pulley (1 , 1') according to at least one of the preceding claims, characterized by a plurality of guide elements (5, 5') which in the circumferential direction of the toothed belt pulley (1 , 1') alternately contact an axial end of one tooth (3, 3') and the opposite axial end of another tooth (3, 3') and are preferably attached to the respective axial end of the respective tooth (3, 3').

14. Toothed belt pulley (1 , 1 ') according to claim 13, characterized in that a guide element (5, 5') is in contact with each tooth (3, 3') and is preferably attached to this tooth (3, 3').

15. Toothed belt pulley (1 , 1') according to claim 13, characterized in that in the circumferential direction of the toothed belt pulley (1 , 1') a guide element (5, 5') is in contact with every second, every third or every nth tooth (3, 3'), where n is a natural number greater than three, and is preferably attached to this tooth (3, 3').

16. Toothed belt pulley (1, 1') according to at least one of claims 1 to 12, characterized by a plurality of guide elements (5, 5') which are all in contact with an axial end of a tooth (3, 3') on the same axial side of the toothed belt pulley (1, 1') and preferably at the respective axial end of the respective tooth (3, 3'). 3') are attached.

Images