Hub, especially for bicycles, with freewheel mechanism

Abstract

Hub comprising an axis (1) on which a hub body (2) and a freewheel body (6) are each rotatably arranged, wherein the hub body (2) and the freewheel body (6) are coupled to each other by a freewheel mechanism which is based on a pairing of mutually meshing sawtooth teeth of axially adjacent toothed discs and thereby forms a rotationally fixed connection between the freewheel body (6) and the hub body (2) for one direction of rotation, characterized in that at least two pairings (4-3, 5-3) of cooperating sawtooth teeth are provided, wherein at least two sawtooth tooth pairings (4-3, 5-3) are phase-shifted relative to each other.

Description

[0001] The invention relates to a hub, particularly for bicycles, with a freewheel mechanism. In addition to bicycles, the hub can also be used for other purposes, e.g., all types of trailers, especially bicycle trailers, wheelchairs, and the like.

[0002] Hubs of the type in question serve to connect the stationary wheel axle to a rim rotating around this axis, which carries a pneumatic tire. The connection between the hub and the rim is usually realized by spokes made of steel, aluminum, carbon, or other textiles, arranged according to a predetermined pattern and held at each of their two ends in a designated hole in the hub and rim.

[0003] Particularly for bikes used in sports, and especially for bikes used in competitions, the hub must meet stringent requirements. On the one hand, the hub should rotate with as little friction as possible, on the other, it should provide largely play-free support, be subject to minimal dirt and wear, and be easy to assemble and disassemble.

[0004] Typically, the rear wheel of a bicycle is driven. For this purpose, a freewheel body is arranged next to the actual hub shell on the axle of the rear wheel hub. A single sprocket or a cassette comprising several sprockets is firmly attached to the freewheel body. This cassette transmits the drive torque generated by the rider at the cranks to the rear wheel via a roller chain, belt, or cardan shaft.

[0005] To prevent the pedal cranks from constantly rotating, for example when riding downhill or taking a break from pedaling, the rear hub of most bicycles has a freewheel mechanism which transfers the drive force of the driver or freewheel body from the freewheel body to the hub shell and thus to the rear wheel, while when pedaling backwards the freewheel causes the hub shell and the freewheel body to rotate against each other.

[0006] According to the current state of the art, torque is transmitted in freewheel hubs with toothed pulley freewheels via two annular toothed pulleys and a clutch interface. The toothed pulleys each have a sawtooth toothing on their facing end surfaces. These toothed pulleys interlock during relative rotation in one direction of rotation, thus enabling torque transmission through positive engagement. In the opposite direction of rotation, they slide against each other, preventing torque from being transmitted. However, the axial distance between the two toothed pulleys increases.

[0007] Alternative designs use a pairing of a toothed pulley with sawtooth teeth and a perforated pulley with holes into which the sawtooths engage positively in one direction of rotation.

[0008] A sawtooth toothing can be flat or uneven, it can be conical, spiral, straight or helical or a mixture of these.

[0009] The German utility model DE 94 19 357 U1 describes a freewheel hub for a two-wheeler with a wheel axle on which a hub body and a freewheel body are rotatably arranged axially thereto, wherein the hub body and the freewheel body are coupled via a freewheel mechanism which forms a rotationally fixed connection between the freewheel body and the hub body for only one direction of rotation, and wherein the freewheel body is connected to the wheel axle via two ball bearings, wherein a releasable securing means is provided with which the freewheel body can be pressed against the hub body, and wherein when the securing means is released the freewheel body can be pulled away from the hub body in the axial direction without the application of force.

[0010] From DE 198 47 673 A1, a hub is known, in particular for bicycles and the like, comprising a hub axle, a hub shell arranged concentrically to this hub axle, at least one bearing device containing at least two bearings, which is arranged between this hub axle and this hub shell, so that this hub shell is rotatably mounted with respect to this hub axle, a freewheel body rotatably mounted with respect to this hub axle, which is designed such that at least one gear is to be arranged on this freewheel body, a freewheel device which is arranged between this freewheel body and this hub shell, and which has two toothed disks, the tooth surfaces of which are pressed against one another by a pretensioning device,wherein these two toothed discs are arranged concentrically to this hub axle and, in the intended assembly of this hub, are arranged at least in the rest state in a plane perpendicular to an axis line of this hub axle, and wherein these toothed discs are held in a floating manner so that tilting with respect to this plane perpendicular to this axis line of this hub axle is possible.

[0011] DE 10 2019 000 511 A1 discloses a bicycle hub with a release effect achieved on the pawl surfaces during idle operation, in which the freewheel function is also realized by a pairing of two asymmetric sawtooth toothings that enable torque transmission in one direction of relative rotation and slide against each other in the other direction of relative rotation. One of these sawtooth toothings is arranged on the end face of a first toothed disk that is connected in a rotationally fixed manner to the hub shell, and the other is arranged on an end face of an axially displaceable second toothed disk that is connected in a rotationally fixed manner to the freewheel body. A symmetrical serration is arranged on the other end face of the second toothed disk.This spline, in turn, interacts with another symmetrical spline located on the face of an axially movable, non-rotatable thrust washer; the tooth flanks of the two splines slide against each other in both directions of relative rotation. Two spring elements acting in opposite axial directions, in conjunction with the two symmetrical splines, which convert relative rotation into axial displacement, ensure that the sawtooth teeth of the first spline and the second spline are only engaged when the pedal cranks move forward, in order to move the wheel forward, and are disengaged when the pedal cranks are stationary or when the pedal cranks move backward, thus preventing friction and wear of the sawtooth teeth.

[0012] There is a need for an improved, highly resilient and low-wear freewheel mechanism for bicycle hubs, which serves the positive transmission of the drive torque and enables independence of input and output as soon as the output speed is higher than the input speed.

[0013] The number of saw teeth determines the idle angle through which one toothed pulley must rotate relative to the other before the two saw teeth mesh and torque transmission is possible. It is obvious that this idle angle should be as small as possible. To achieve this, the saw teeth must have as many saw teeth as possible. The conflicting objectives here lie in the fact that the meshing surface of each tooth pair decreases the more saw teeth are distributed around the circumference of a toothed pulley, which leads to lower transmittable torque and reduced durability due to increased wear.

[0014] An object of the present invention is therefore to provide an improved hub, in particular for bicycles, which has a freewheel mechanism which provides the largest possible engagement surface for torque transmission at the smallest possible idle angle, which is low-maintenance and durable.

[0015] This object is achieved by a hub having the features of independent claim 1. Advantageous embodiments and further developments are described and explained in the dependent claims.

[0016] When reference is made below to a pairing of meshing sawtooth teeth of axially adjacent toothed pulleys, this also includes a pairing of a toothed pulley with sawtooth teeth and a perforated pulley with holes into which the sawteeth engage positively and torque-transmittingly in only one direction of rotation. In this variant, the sawteeth slide along the edges of the holes in the opposite direction of rotation. The holes thus fulfill the same function as a second sawtooth toothing. This variant, which is expressly intended to be covered by the protection, has the additional advantage of saving material and thus weight, and requiring less installation space.

[0017] In a hub, in particular for bicycles, which has an axle on which a hub body and a freewheel body are each rotatably arranged, wherein the hub body and the freewheel body are coupled to one another by a freewheel mechanism which is based on a pair of meshing sawtooth toothings of axially adjacent toothed disks and thereby forms a rotationally fixed connection between the freewheel body and the hub body for one direction of rotation, at least two pairs of interacting sawtooth toothings are provided according to the invention.

[0018] By using two or more pairs of interacting sawtooth gears, the engagement surface can be doubled immediately without any additional measures compared to the conventional use of a single pair of interacting sawtooth gears, whereby the transmittable torque is also doubled and wear is extremely minimized.

[0019] In a simple embodiment, several pairs of sawtooth teeth can be created by using twice as many toothed disks as there are to be pairs. For example, it would be possible to create two pairs by using four toothed disks, three pairs by using six toothed disks, and so on. It could also be provided that the interacting toothed disks of one sawtooth toothing are rotated relative to the interacting toothed disks of another sawtooth toothing in such a way that the sawtooth teeth are out of phase with each other, i.e. that the teeth of one pairing are each arranged between two teeth of another pairing. In this way, the number of detent points at which a pair of interacting sawtooth teeth engage over a full revolution can be doubled, tripled, etc. in a very simple way.

[0020] According to an advantageous embodiment, to simplify the structural design of the proposed hub, an arrangement of three toothed disks can be provided, comprising two outer toothed disks and a central toothed disk arranged between the outer toothed disks. The central toothed disk has a sawtooth toothing on each of its two end faces, and each of these two sawtooth toothings interacts with a corresponding sawtooth toothing on one of the two outer toothed disks. In other words, the same effect as described above can be achieved with fewer toothed disks: two pairs with three toothed disks, three pairs with four toothed disks, etc.

[0021] In the above configuration with three toothed disks, for example, the middle toothed disk can be connected to the hub body in a rotationally fixed manner, and the two outer toothed disks can be connected to the freewheel body in a rotationally fixed manner. Alternatively, the middle toothed disk can be connected to the freewheel body in a rotationally fixed manner, and the two outer toothed disks can be connected to the hub body in a rotationally fixed manner.

[0022] Furthermore, in the above design with three toothed pulleys, it can be provided, for example, that the two sawtooth teeth of the middle toothed pulley are phase-shifted relative to one another. This still achieves the effect described above, namely that the idle angle is reduced while the engagement surface remains the same, even when the number of toothed pulleys used is reduced. Depending on the total number of toothed pulleys used and thus the pairings of interacting sawtooth teeth created, the engagement surface can even be increased by reducing the number of teeth per sawtooth tooth, so that a higher load capacity can be achieved. By cleverly applying the phase shift, a very high number of detent points can still be created, so that the idle angle is very small.

[0023] In a special embodiment of the proposed hub, at least two pairs of interacting sawtooth gears in opposite directions of action can form a rotationally fixed connection between the freewheel body and the hub body. This makes it possible to achieve torque transmission in both directions of relative rotation, either simultaneously or as needed.

[0024] For this purpose, a preferred embodiment of the proposed hub can provide at least one toothed disk that can be axially displaced back and forth between two positions to establish or interrupt the engagement of a pair of interacting sawtooth gears. In other words, the proposed hub makes it possible to switch back and forth between a "forward gear" and a "reverse gear," while still maintaining a freewheel function in the other direction of rotation, or to completely disable the freewheel, so that the impeller is driven in either direction of rotation.

[0025] Furthermore, it may be useful to provide at least one return spring acting axially on at least one toothed pulley. This ensures that the interacting sawtooth gears of a pair are always brought back into engagement with each other when a drive torque is applied.

[0026] It has proven particularly advantageous to provide the freewheel body with a section located outside the hub body, which is rotatably mounted on the axle, and a section located inside the hub body, on which the hub body is rotatably mounted. Furthermore, the toothed discs can be arranged in the area of ​​the section of the freewheel body located inside the hub body. In this way, the most sensitive components of the freewheel mechanism are housed inside the hub body, saving space and protecting them from dirt and damage.

[0027] For the improved freewheel hub proposed here, this invention provides at least three toothed disks. These are arranged concentrically in series on the rotational axis of the bicycle hub, with at least one disk attached to the hub body for slip-free power transmission and at least one disk attached to the freewheel body for tangential power transmission. To achieve the independence of input and output, teeth with a sawtooth profile are provided on the parallel surfaces of the disks. Similar to a ratchet mechanism, these enable positive torque transmission in one direction of rotation while permitting free movement in the opposite direction of rotation. For this purpose, the toothed disks can be attached so that they can be axially displaceable relative to one another and clamped via a spring mechanism or other tensioning mechanism. The teeth create a defined number of locking points.

[0028] The arrangement of at least three toothed pulleys creates at least two pairs of interacting sawtooth gears, which can contribute to torque transmission. This provides several options for influencing the power transmission between the input and output shafts. Firstly, each additional toothed pulley can increase the engagement surface and thus the potential power transmission while maintaining the same radial space. Furthermore, a phase-shifted arrangement of the tooth engagements can increase the number of engagement points, thereby reducing the idle angle before the first tooth engagement.

[0029] Particularly advantageous is the design of the discs, which allows for a choice between continuous power transmission in both directions of rotation (fixed gear) and freewheeling in one direction of rotation. The teeth are arranged in the direction of force on one side and opposite to the direction of force on the other.

[0030] The invention will be explained in more detail below using an exemplary embodiment and the accompanying drawings. Fig. 1 an overall view of the hub according to the embodiment, Fig. 2 an axial section through the embodiment, Fig. 3 an exploded view of the hub according to the embodiment, Fig. 4 a detailed representation of the components of the freewheel mechanism of the embodiment.

[0031] Fig. Figure 1 shows the hub according to the invention in an overall view. It can be seen how the hub body 2 and the freewheel body 6 are arranged relative to each other on the axle 1, which is closed off on the drive side by the cover cap 11 and on the non-drive side by the cover cap 10.

[0032] With reference to the Fig. 2, Fig. 3 and Fig. 4 it can be seen that the hub has an axle 1 on which a hub body 2 and a freewheel body 6 are each rotatably arranged.

[0033] The freewheel body 6 has a section located outside the hub body 2, which is rotatably mounted on the axle 1 by means of two freewheel bearings 7, and a section located inside the hub body 2, on which the hub body 2 is rotatably mounted by means of a hub bearing 9. On the non-drive side, the hub body 2 is rotatably mounted directly on the axle 1 by means of another hub bearing 8.

[0034] The hub body 2 and the freewheel body 6 are coupled to each other by a freewheel mechanism based on a pair of meshing sawtooth teeth of axially adjacent toothed disks, thereby forming a rotationally fixed connection between the freewheel body 6 and the hub body 2 for one direction of rotation. In the exemplary embodiment, two pairs of interacting sawtooth teeth 4-3, 5-3 are formed by three toothed disks 3, 4, 5.

[0035] The toothed disks 3, 4, 5 are arranged in the area of ​​the section of the freewheel body 6 located inside the hub body 2. The drive-side outer toothed disk 4 and the non-drive-side toothed disk 5 are arranged on the section of the freewheel body 6 located inside the hub body 2 and are connected to the freewheel body 6 in a rotationally fixed manner. At the same time, they are axially displaceable against the force of a return spring 15 in order to engage or disengage their front-side sawtooth teeth with the two sawtooth teeth on the two front sides of the middle toothed disk 3 as needed. The middle toothed disk 3 is arranged axially between the drive-side outer toothed disk 4 and the non-drive-side toothed disk 5 and is connected to the hub body 2 in a rotationally fixed manner with its outer circumference.

[0036] The two sawtooth teeth of the central toothed disk 3 are phase-shifted relative to one another, i.e., each tooth of one sawtooth tooth is arranged between two teeth of the other sawtooth tooth. This halves the idle angle that must be overcome until idle engages and torque is transmitted from the freewheel body 6 to the hub body 2. In other words, despite a very small idle angle of the proposed freewheel mechanism, each sawtooth tooth can have a relatively large angle between the individual teeth, thus a relatively small number of teeth and a relatively large engagement surface for the other sawtooth tooth, whereby a relatively high torque can be transmitted and relatively little wear occurs. List of reference symbols 1 axis 2 hub bodies 3 Middle two-sided toothed disc 4 Outer toothed pulley drive side 5 Outer toothed pulley non-drive side 6 Freewheel body and shaft 7 freewheel bearings 8 Non-drive side hub bearings 9 Hub bearing drive side 10 End cap non-drive side 11 End cap drive side 12 Non-drive side seal 13 Drive side seal 14 spacer sleeve 15 Return spring 16 Sealing and cover cap

Claims

[1] Hub, comprising an axle (1) on which a hub body (2) and a freewheel body (6) are each rotatably arranged, wherein the hub body (2) and the freewheel body (6) are coupled to one another by a freewheel mechanism which is based on a pair of meshing sawtooth teeth of axially adjacent toothed discs and thereby forms a rotationally fixed connection between the freewheel body (6) and the hub body (2) for one direction of rotation, characterized by that at least two pairs (4-3, 5-3) of interacting sawtooth teeth are provided, wherein at least two sawtooth tooth pairs (4-3, 5-3) are phase-shifted relative to one another. [2] Hub according to claim 1, in which an arrangement of three toothed discs (3, 4, 5) comprises two outer toothed discs (4, 5) and a central toothed disc (3) arranged between the outer toothed discs (4, 5), wherein the central toothed disc (3) has a sawtooth toothing on each of its two end faces and each of these two sawtooth toothings interacts with a corresponding sawtooth toothing of one of the two outer toothed discs (4, 5). [3] Hub according to claim 2, wherein the central toothed disc (3) is connected in a rotationally fixed manner to the hub body (2) and the two outer toothed discs (4, 5) are connected in a rotationally fixed manner to the freewheel body (6). [4] Hub according to claim 2, wherein the central toothed disc (3) is connected in a rotationally fixed manner to the freewheel body (6) and the two outer toothed discs (4, 5) are connected in a rotationally fixed manner to the hub body (2). [5] Hub according to one of claims 2 to 4, wherein the two sawtooth teeth of the central toothed disc (3) are phase-shifted relative to one another. [6] Hub according to one of claims 1 to 5, in which at least two pairs (4-3, 5-3) of cooperating sawtooth teeth in opposite directions of action form a rotationally fixed connection between the freewheel body (6) and the hub body (2). [7] Hub according to one of claims 1 to 6, in which at least one toothed disc (3, 4, 5) is axially displaceable back and forth between two positions in order to establish or interrupt the engagement of a pair (4-3, 5-3) of cooperating sawtooth toothings. [8] Hub according to claim 7, wherein at least one return spring (15) acts in the axial direction on at least one toothed disc (3,4,5). [9] Hub according to one of claims 1 to 8, wherein the freewheel body (6) has a portion located outside the hub body (2) which is rotatably mounted on the axle (1), and a portion located inside the hub body (2) on which the hub body (2) is rotatably mounted. [10] Hub according to claim 9, wherein the toothed discs (3, 4, 5) are arranged in the region of the section of the freewheel body (6) lying within the hub body (2).

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