Unidirectional torque coupling and method of use

Abstract

A torque coupling comprising a drive body, an output side body which is coaxially arranged, a pressure disk which is coaxially arranged, movable in rotation coaxial direction, and having a first torque transmission surface on its face side, and a torque transmission device. The torque transmission device (5) comprises rigid pressure transfer elements (6) loadable by compressive forces only upon a gripping of the non driven by the driven torque transmission surface which points in drive direction (A), thereby moving in rotation coaxial direction contrary to the pressure disk (3), and pressing the same in direction of the second torque transmission surface (4B).

Claims

1. A unidirectional torque coupling for a wheel hub (9) of a bicycle as a freewheel for transmitting a drive torque which is provided in a drive direction (A), the torque coupling comprising: a drive body (1) rotatable about an axis of rotation (R) to provide a drive torque, wherein the drive body (1) is immobile axially along the axis of rotation (R) during rotation; an output side body (2) rotatable about the axis of rotation (R) and onto which the drive torque is transmissible, wherein the output side body (2) is immobile axially along the axis of rotation (R) during rotation; a single piece pressure disk (3) able to rotate and move axially along the axis of rotation (R) during rotation, the pressure disk (3) comprising a first torque transmission surface (4A) on a face side being arranged for transmission of the drive torque; a torque transmission device (5) which is arranged between the pressure disk (3) and the output side body (2), and by means of which the drive torque can be transferred; wherein the drive body (1), which is opposite to the first torque transmission surface (4A), has a second torque transmission surface (4B) that remains in mechanical contact with the first torque transmission surface (4A), further wherein the first and second torque transmission surfaces (4A, 4B) are configured to grip one another by way of form-closed and/or frictional resistance, further wherein the torque transmission device (5) comprises rigid pressure transfer elements (6) that rest against a side of the pressure disk (3), which is opposite to the first torque transmission surface (4A), as well as against the output side body (2) in such a manner that the transfer elements (6) are loaded by compressive forces in a direction of the axis of rotation (R) upon gripping the first torque transmission surface (4A) by the second torque transmission surface (4B), thereby moving the transfer elements (6) contrary to the pressure disk and pressing the pressure disk (3) toward the second-torque transmission surface (4B).

2. The torque coupling according to claim 1, wherein the pressure transfer elements (6) are push rods (7) which rest with a drive side end (7A) against the pressure disk (3) and with an output side end (7B) against the output side body (2), wherein the push rods (7) are inclined at least upon compressive stress in an erecting angle () contrary to the drive direction (A), such that the erecting angle () of the push rods (7) increases upon compressive stress, pushing the pressure disk (3) in direction of the second-torque transmission surface (4B).

3. The torque coupling according to claim 2, wherein the push rods have a ball head at their drive side end (7A) and/or at their output side end (7B), and wherein the support area provided for the resting of the respective end (7A, 7B) has a suitable pocket (8A, 8B) for housing this ball head, such that the push rods (7) can be joined or are joinable in a ball joint manner with the first torque transmission surface (4A).

4. The torque coupling according to claim 1, wherein the output side body (2) is fixedly joinable with a hub body (9B) of a wheel hub (9), and/or wherein the drive body (1) is fixedly joinable with a freewheel body (9A) of a wheel hub (9).

5. The torque coupling according to claim 1, wherein the output side body (2) is a hub body (9B) of a wheel hub (9), and/or wherein the drive body (1) is a freewheel body (9A) of a wheel hub (9).

6. The torque coupling according to claim 1, wherein the first and second torque transmission surfaces (4A, 4B) are selected from the group consisting of a spur gearing with and without undercut, a symmetric and asymmetric wave profile, and a friction surface.

7. The torque coupling according to claim 1, wherein the mechanical contact of the first and second torque transmission surfaces (4A, 4B) is effected by gravity, by means of centrifugal force, by means of fluidic force, or by an approaching means (10) which uses spring force or magnetic force.

8. A method for the operation of a unidirectional torque coupling for a wheel hub (9) of a bicycle as a freewheel, the method comprising: providing a unidirectional torque coupling having a rotatable drive body (1), a rotatable output side body (2), wherein each is immobile axially along an axis of rotation (R), a single-piece pressure disk (3) which able to move axially during rotation, and a torque transmission device (5) which is arranged between the pressure disk (3) and the output side body (2) and which comprises rigid pressure transfer elements (6), wherein in a drive case which is firstly characterized in a relative rotation between the drive body (1) and the output side body (2) in drive direction (A), the pressure transfer elements (6) are loaded by compressive forces, so that their center of gravity (M) moves contrary to a back side of the pressure disk (3), onto which they then exert pressure, resulting in a rotation and axial motion of the pressure disk (3) in direction of the drive body (1) leading to a frictional and/or form-closed connection between a first-torque transmission surface (4A) arranged at the pressure disk (3) and a second-torque transmission surface (4B) which is arranged at the drive body (1) such that the relative rotation becomes zero, and, while maintaining the compressive load, the drive torque is transmitted from the drive body (1) to the pressure disk (3), and from there, to the output side body (2), and in a freewheeling case which is characterized in a permanent relative rotation between the drive body (1) and the output side body (2) contrary to the drive direction (A), the pressure transfer elements (6) are pressure relieved, so that their center of gravity (M) moves away from the back side of the pressure disk (3), such that they do not exert pressure onto the pressure disk (3), resulting in a rotation and motion of the pressure disk (3) away from the drive body (1), resulting in a release of the connection between the first and second torque transmission surfaces (4A, 4B), so that no drive torque is transmitted from the drive body (1) to the output side body (2), but drive and output side body (1, 2) rotate freely with respect to each other; and driving the drive body (1).

9. The method according to claim 8, wherein the motion of the centers of gravity (M) of the pressure transfer elements (6) is effected in that the pressure transfer elements (6) have a longitudinal shape and are, in drive direction (A), fixed and inclined in such a manner at the back side of the pressure disk (3) as well as at the output side body (2) which is arranged opposite to this back side, so that they erect upon compressive load and require more space in rotation axial direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, exemplary embodiments of the invention are described by aid of the figures.

(2) FIG. 1 shows a perspective sectional view of a torque coupling which is provided as freewheel for a wheel hub.

(3) FIG. 2 shows details of the torque coupling.

(4) FIG. 3 shows a view of the output side body with push rods.

(5) FIG. 4 shows a view of the back side of the pressure disk.

(6) FIG. 5 shows the view of a drive body with a variant of a second torque transmission surface.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) In FIG. 1, a perspective sectional view of a torque coupling which is provided as freewheel for a wheel hub 9 is shown. The drive body 1 which can be rotated around the rotation axis R and which is presently designed as freewheel body 9A is envisaged to receive a sprocket cluster (not shown). The latter is drivable with a chain (not shown) in drive direction A. The wheel hub 9 is depicted without bearings, spacers and the same. The output side body 2 which is arranged rotation coaxially with the drive body 1 is presently designed as screw-in ring which is firmly attached to the hub body 9B of the wheel hub 9. A pressure disk 3 is positioned rotation coaxially between drive body 1 and output side body 2, being rotation coaxially moveable in contrast to the drive and output side body 1, 2.

(8) A first torque transmission surface 4A is arranged on that side of the pressure disc 3 which points in direction of the drive body 1. A second torque transmission surface 4B is arranged at that end of the drive body 1 which is facing the pressure disk 3. Presently, both torque transmission surfaces 4A, 4B have a spur gearing.

(9) For the sake of better visibility, the drive body 1 is shown apart from the pressure disk 3. In the operational state, the first torque transmission surface 4A and the second torque transmission surface 4B touch each other at any time at least slipping by frictional resistance (in the freewheel case) or catching by form-closing (in the drive state), respectively.

(10) In FIG. 2, details of the torque coupling from FIG. 1 are shown. Here, the perspective is diagonally as seen from the hub body 9B (not depicted). For improved visibility, the drive body 1 is shown forshortened, so that basically its second torque transmission surface 4B is recognizable.

(11) Opposite to the latter, the first torque transmission surface 4A with the pressure disk 3 is arranged. The pressure disk 3 is not fixed in rotational axial direction. In contrast, the drive body 1 is immobile in this direction, since it is fixed by means of not depicted bearings; the same is true for the output side body 2 which is presently designed as screw-in ring in order to provide the possibility of being fixed in the hub body 9B (not shown) which is also fixed in rotational coaxial direction.

(12) Pressure transfer elements 6 are evenly distributed between the back side of the pressure disk 3 and that side of the output side body 2 which faces the pressure disk 3. They are presently designed as push rods 7. They are designed in shape of a spherical segment at their drive side end 7A and their output side end 7B. These ends 7A, 7B rest in pockets 8A, 8B (not visible in FIG. 2), which are arranged in the back side of the pressure disk 3, or in that side of the output side body 2 which faces this back side, respectively. The push rods 7 are secured on the drive side in the pressure disk 3 by means of a snap ring against falling out.

(13) The push rods 7 form, together with the pockets 8A, 8B, the torque transmission device 5. Since they are loaded upon rotation of the drive body 1 in drive direction A with compressive force, and since they are fixed in drive direction A, the drive torque is transferred from the back side of the pressure disk 3 via the pockets 8A, the pressure transfer elements 6 (push rods 7) and the pockets 8B onto the output side body 2, as long as the drive torque is transmitted by means of frictional resistance and/or form-closing via both torque transmission surfaces 4A, 4B. It is clear that the pressure transfer elements 6 must be designed rigid, since otherwise, the transmission of the typically high drive torque which is transferred through the pressure transfer elements 6 in form of compressive forces would not be possible.

(14) In FIG. 3, a sectional view of the assembly of the output side body 2 from FIG. 1, equipped with two push rods 7 (only one with reference numeral), is shown. The drive side end 7A which is spherically shaped is well visible. Accordingly shaped pockets 8B (only one with reference numeral) are arranged for the supporting reception of the output side end 7B.

(15) Also well visible is the fact that each push rod 7 has an erecting angle . Presently, the same is measured between the plane of the screw-in ring and the pitch line W. The pitch line W is the imaginary line to which the push rod could be reduced if having an indefinitely small thickness. Also other, not depicted, differently shaped bodies, with the exception of spheres, have such a pitch line. According to the depicted embodiment, viewed in axial direction, the pitch line runs tangentially.

(16) When the push rods 7 are compressively loaded, i.e. pushed into the pockets 8A, 8B (the latter not shown), they will try to further erect themselves due to the upwards (in direction of the non depicted pressure disk) pointing pitch line W. Thus, their center of gravity M is moved in direction of the back side of the pressure disk 3. Due to the tangential orientation (see above), an erecting of the push rod 7 will presently result not only in an axial, but also in a tangential motion of its center of gravity M. Since the push rod 7 is a rigid structure, its drive side end 7A moves accordingly further in this, but in particular, in the axial direction, while the output side end 7B remains in its joint socket in which it rotates. As a result, the push rods have in rotation axial direction, measured from the output side bodies' 2 rotation plane which is perpendicular to the rotation axis (not drawn), at any time a smaller drive side distance to this plane than an output side distance. Synonymously, the push rods have in rotational axial direction, measured from the non depicted pressure disk, at any time a smaller drive side distance than an output side distance.

(17) As well, FIG. 3 shows several approaching means 10 designed as springs, by means of which the permanent mechanical contact of the pressure disk 3 with the drive body 1 (each not depicted) is ensured. The springs rest against the output side ends 7B of the push rods 7, so that these are pressed into the pockets 8B. In the assembled state of the torque coupling, the ends of the springs which are depicted as free ends and which point rotation coaxially upwards in the picture rest against the back side of the pressure disk 3 which permanently co-rotates with the output side body 2, the springs exerting pressure onto the pressure disk 3.

(18) In FIG. 4, a view of the back side of the pressure disk 3 and that side of the drive body 1 which faces the pressure disk 3 with second torque transmission surface 4B is shown. Other components have been omitted for the sake of clarity; well visible are the pockets 8A which are present in the back side of the pressure disk 3 and which are adapted to the geometry of the drive side ends 7A of the push rods 7 (each not depicted). Visible are also seats 10B for the springs which are not shown in this figure (only one seat with reference numeral).

(19) Since the pressure disk 3 does only insignificantly rotate relative to the output side body 2 upon erecting of the push rods 7, this rotation can be tolerated by the springs with no problems, without them being pulled or pushed out of the seats 10B.

(20) Eventually, FIG. 5 depicts a variant of a drive body, in particular with a variant of a second torque transmission surface 4B; it is clear that the same should interact with a not depicted, analogous designed first torque transmission surface 4A. The shown embodiment has a wave profile without undercuts, wherein the same is equipped with a frictionally acting surface (dotted area). Thus, the shown component is suitable for a simultaneous form-closed and/or frictional resistance torque transmission.

LIST OF REFERENCES

(21) 1 drive body 2 output side body 3 pressure disk 4A first torque transmission surface 4B second torque transmission surface 5 torque transmission device 6 pressure transfer element 7 push rod 7A drive side end 7B output side end 8A,8B pocket 9 wheel hub 9A freewheel body 9B hub body 10 approaching means 10B seat 11 recesses A drive direction R rotation axis erecting angle W pitch line M center of gravity