Torque transmission device

Abstract

A torque transmission device includes a shaft which has shaft teeth around its outer circumference, a hub which has hub teeth on an inner circumference, wherein the hub is arranged on the shaft in such a way that the shaft teeth and the hub teeth mesh with one another in order to transmit torque. The torque transmission device furthermore includes at least one spring element which passes entirely through the hub and is supported on the shaft and the hub and exerts a spring force on the hub and the shaft, wherein at least a component of the spring force is directed in such a way that around the entire circumference of the shaft and hub adjacent flanks of the shaft teeth and the hub teeth are pushed together.

Claims

1. A torque transmission device, comprising: a shaft having an outer circumference provided with a shaft toothing adjacent a distal end surface of the shaft; a hub comprising a bore extending between opposing end faces of the hub, said bore having an inner circumference provided with a hub toothing, said hub being arranged on the shaft so that the shaft toothing and the hub toothing engage one another to transmit a torque, wherein one of the hub toothing and the shaft toothing comprises a pair of opposing gaps defined between respective adjacent teeth thereof, adjacent teeth of the other of the hub toothing and shaft toothing being arranged within each said gap; and a spring element having two legs formed as one-piece with a base of the spring element and forming bent abutment portions therebetween disposed at opposing ends of the base, said legs being arranged at opposing positions between the shaft and the hub, each said leg being arranged within one of said gaps and disposed between said adjacent teeth of the other of the hub toothing and shaft toothing, each said leg having at least one support site on tooth flanks of the other of the shaft toothing and the hub toothing, said spring element completely traversing the hub between said opposing end faces of the hub and being supported on the shaft and the hub, wherein the base extends across said distal end surface of the shaft and said abutment portions abut one of said end faces of the hub, and outwardly bent free ends of said legs abut the other said opposing end face of the hub to exert a spring force on the hub, and wherein a bending angle of each said leg is defined by an inwardly extending bent portion of said leg abutting the shaft to exert a spring force on the shaft, and at least one component of the spring force is oriented so that adjacent flanks of the shaft toothing and the hub toothing are pushed against each other over an entire circumference of the shaft and hub.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following, the invention is explained in more detail by way of exemplary embodiments with reference to the included figures. In the Figures

(2) FIGS. 1A and 2A are schematic representations of two embodiments of a torque transmission device;

(3) FIGS. 1B and 2B are schematic representations of two embodiments of the spring element of the torque transmission device;

(4) FIGS. 1C and 2C are schematic cross sectional view of the torque transmission devices;

(5) FIGS. 3A and 4A are schematic representations of two further embodiments of a torque transmission device;

(6) FIGS. 3B and 4B are representations of two further embodiment of the spring element of the torque transmission device;

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) FIGS. 1A and 2A schematically show two exemplary embodiments of a torque transmission device 1. the torque transmission devices 1 have respectively a shaft 2 with the rotation axis Z, a hub 3 and a sprig element 4.

(8) The exemplary embodiments of the FIGS. 1A, 1B and 1C differ from the exemplary embodiments of the FIGS. 2A, 2B and 2C only regarding the configuration of the respective spring element 4.

(9) FIG. 1C or 2C are schematic cross sectional view of the torque transmission devices of FIG. 1A or 2A taken along the sectional lines B-B or C-C.

(10) FIGS. 3A, 3B, 4A and 4B show two further exemplary embodiments of a torque transmission device. These differ only with regard to the type and shape of the used spring element.

(11) As can be seen in FIGS. 1A, 2A and 1C, 2C, the hub 3 is arranged on the shaft 2. For this the hub 3 has a correspondingly dimensioned bore 5, with the shaft 2 being inserted with one end into the bore 5. In the exemplary embodiment the bore is a through bore. At least in the region of the mutual overlap of the shaft 2 and the hub 3, the shaft 3 has at its outer circumference a shaft toothing 6 and the hub 2 has at its inner circumference of the through bore 5 a hub toothing 7 (see FIGS. 1C and 2C). The shaft toothing 6 and the hub toothing 7 engage with each other for form fittingly transmitting a torque between each other (see FIGS. 1C and 2C).

(12) FIGS. 1B and 2B show schematic embodiments of the spring element 4 in the free un-mounted state.

(13) Both embodiments of the spring element 4 are configured one-piece and are advantageously made of spring-elastic material, for example spring steel. The spring elements 4 are cost-effectively producible with regard to the material as wells as manufacture. Any extrinsically effected change of shape, in particular a compression, extension or stretching of the spring element 4 causes a restoring force in the material of the spring element 4.

(14) The embodiment of the spring element according to FIG. 1B has the shape of a multiply bent spring rod, wherein an additional increased bent or shaping is imposed on the respective opposing free ends. As will become apparent from FIG. 1A the special shaping serves for fastening of the spring element 4 on the hub.

(15) The embodiment of the spring element 4 according to FIG. 2B has two legs 4-1, 4-2 with a common base 4-3. The main directions of extent of the legs 4-1, 4-2 are the same and point in the same direction (in FIG. 2B towards the left hand side).

(16) The mounting, arrangement and function of the spring elements 4 are now explained by way of FIGS. 1A, 2A and 1C, 2C:

(17) The spring elements 4 are mounted on the hub 3 prior to joining the shaft 2 and the hub 3.

(18) In the embodiment of the spring element 4 according to FIG. 1B the spring element 4 is guided with a free end through the through bore 5 of the hub (see FIG. 1A). In the mounted state the spring element fully traverses the hub, wherein the spring element 4 is shaped so that it engages behind opposing front sides 8, 9 of the hub 3 (i.e., the free ends abut a front side 8, 9 of the hub 3). A free end of the spring element can in addition be fastened on an outer side of the hub 3 which faces away from the through bore 5. In the exemplary embodiment of FIG. 1A the bore 10 is arranged on the outside of the hub 3 into which the free end of the spring element 4 is inserted. However, other shapes are also conceivable in order to bring the free end in form fitting engagement with the hub.

(19) Advantageously in the free state, i.e. in the relaxed state, the spring element 4 is shorter than the through bore, so that the spring element 4 has to be slightly stretched for the mounting. As a result of the stretching a spring tension is built up in the spring element 4 which in combination with the ends which engage behind, ensures a secure fit of the spring element 4 in the hub.

(20) In the embodiment of the spring element 4 according to FIG. 2B, the spring element is guided with both free legs 4-1, 4-2 through the through bore 5 of the hub 3 so that the spring element 4 completely traverses the hub 4 (see FIG. 2A). The spring element 4 is configured so that in the mounted state the base 4-3 of the spring element 4 covers or engages behind the hub 3 on the front side 9 or the spring element rests against a front side 9 of the hub. The two free ends of the legs 4-1, 4-2 protrude out of the through bore 5 on the opposite side of the hub 3 and engage behind the hub 3 on the opposing front side 8 (i.e., they abut the front side of the hub 3).

(21) Advantageously the spring element 4 according to the embodiment according to FIG. 2B is configured so that for the purpose of mounting in the hub 3 the two legs 4-1, 4-2 have to be pushed together. In particular the distance of the free ends of the legs 4-1, 4-2 is greater than the diameter of the through bore 5 of the hub 3. As a result the spring element 4 or the legs 4-1, 4-2 are radially outwardly pre-tensioned in the mounted state so that a radially outwardly acting force acts on the spring element 4. This results in a better fit of the spring element 4 in the hub 3.

(22) After mounting the respective spring element 4 on the hub 3, the shaft 2 is pushed through the through bore 5 of the hub 3 so that the shaft toothing 6 and the hub toothing 7 come into engagement with each other. The spring element 4 is configured and dimensioned so that when introducing the shaft 2 in to the bore 5 of the hub the spring element 4more precisely the section inside the spring element situated in the through bore 5, is pushed radially outwardly. In the completely mounted state of the torque transmission device 1 the spring element 4 is arranged between the shaft 2 and the hub 3 and is supported on the support sites A on the shaft 2 and on the hub 3. As a result of the deformation of the spring element 4 during insertion of the shaft 2 into the hub 3 a restoring material tension and spring force is established.

(23) As can be recognized in FIGS. 1C and 2C, the spring element 4 is supported on the flanks of adjacent teeth of the shaft toothing. As mentioned above the compression of the spring element 4 during the insertion of the shaft 2 into the through opening of the hub 3 causes a restoring material tension and spring force F. As a result of this arrangement at least one component of the spring force F is oriented in a circumferential direction or rotation direction of the shaft 2, i.e., tangentially to the shaft 2 or the hub 3, and causes the flanks of the shaft toothing 6 and hub toothing 7 to be pushed together over the entire circumference. The force F or the corresponding component, acts over the entire circumference of the shaft 2 and hub 3 and is oriented tangentially to the shaft and hub over the entire circumference. The spring force F thus acts over the entire circumference of shaft 2 and hub 3 against a possible relative rotation movement M of the shaft 2 and the hub 3. As a result the position of the shaft 2 and hub 3 relative to each other is fixed or stabilized and a striking of the flanks of the shaft toothing 6 and hub toothing against each other is at least significantly reduced.

(24) Even though only one spring element 4 is used in the embodiment according to FIG. 1B multiple spring elements 4 can also be arranged at different angular positions in circumferential direction of the shaft 2 and hub 3. This makes it possible that the relative position between shaft and 2 and hub 3 can be further stabilized and a manufacture-related tolerance in the toothing can be compensated.

(25) For a simple mounting of the spring element 4 at least one gap 11 can be formed in the hub toothing 7 and/or the shaft toothing 6. For this purpose for example a tooth may be omitted in the hub toothing 7 and/or the shaft toothing 6.

(26) A further advantage of the present invention is that even though the radial tolerance in the toothing 6, 7 of shaft 2 and hub 3 is reduced or eliminated (relative to the rotation axis Z of the shaft) an axial compensation still remains possible. Further, for the mounting of the torque transmission device, a relative alignment of shaft 2 and hub 3 in rotation direction is not required, i.e., the shaft 2 and hub 3 can be inserted into each other in any desired angular position (relative to the rotation axis).

(27) FIGS. 3A, 3B, 4A and 4B show alternative embodiments of the torque transmission device 1. The differences reside in the shape and fastening of the spring element 4 and in the mounting of the torque transmission device 1. The principle functioning and the resulting advantages are identical to the ones of the exemplary embodiments of FIGS. 1A, 1B and 2A, 2B, 2C or are appreciated by a person with skill in the art analogously. In the following only the differences are explained. Same elements are provided with the same reference numerals.

(28) For mounting of the exemplary embodiments of the torque transmission device 1 according to FIGS. 3A and 4A, the corresponding spring elements 4 (see FIGS. 3b and 4B) are first arranged on the respective shaft 2.

(29) When using the spring element according to FIG. 3B its free ends are inserted into correspondingly configured indentations 10 of the shaft 2, so that a form fitting connection of the shaft 2 results and the spring element 4 is securely fastened on the shaft 2. Advantageously the spring element 4 is dimensioned so that it has to be slightly stretched for the mounting on the shaft, thus resulting in a pre-tension that additionally supports the fastening. In the fastened state at least one free end of the spring element 4 engages behind the shaft 2 on a front side 10. However, it is also possible that both free ends of the spring element 4 engage behind the shaft 2 on opposing front sides.

(30) When using a spring element according to FIG. 4B the spring element is inserted with the free ends into correspondingly configured indentations 10 on opposing outer sides of the shaft 2 so that a form fitting connection with the shaft 2 results and the spring element 4 is securely fastened on the shaft 2. Advantageously the spring element 4 is dimensioned so that the two legs 4-1, 4-2 have to be slightly pushed apart for the mounting so that additionally a pre-tension results which supports the fastening. In the fastened state the spring element 4 engages around the shaft 2 with the legs 4-1, 4-2 and the base 4-3 on a front side 10 and the outer sides.

(31) Subsequently in both exemplary embodiments, the hub 3 is pushed over the shaft 2 with the spring element 4 mounted thereon. The spring elements 4 are dimensioned and configured so as to be slightly compressed along their longitudinal extent and are supported on the shaft 2 and the hub 3 on the support sites A. This results in a pre-tension in the spring element 4, which securely fixes the spring element between the shaft 2 and the hub 3. At the same time this material tension generates a spring force F (analogous to FIGS. 1C and 2C), which counteracts a rotation of the shaft and the hub relative to each other. In contrast to the exemplary embodiments of FIGS. 1A, 1B, 1C and 2A, 2B, 2C the spring element is supported on the flanks of adjacent teeth of the hub toothing 7.