Coaxial Transmission Device

Abstract

The coaxial transmission (1) comprises: a crankshaft (3) rotatable about a rotation axis (2) with at least one crank pin (4); at least one crank set with a number of pistons (5a-i) each having a toothing (11) with at least one tooth on their end face (10) facing away from the rotation axis; a hollow shaft (7) with internal teeth (8), the pistons being arranged inside the hollow shaft as viewed in a plane normal to the rotation axis; and guide units (9), in which the pistons are linearly guided and can reciprocate parallel to a radial direction (12) normal to the rotation axis, so that the toothing on a first end face of the pistons can be sequentially engaged with and released from the internal teeth. According to the invention, it is intended that a common star-configured connecting rod (6) is provided for connecting the pistons of each piston set with the at least one crank pin, the connecting rod being connected to the pistons of each piston set.

Description

[Technical field]

[0001] The present invention relates to a coaxial transmission, comprising a crankshaft rotatable about a rotation axis having at least one crank pin, the coaxial transmission further comprising at least one piston set having a plurality of, preferably at least three, pistons each having a meshing portion with at least one tooth on a first end surface facing away from the rotation axis, the coaxial transmission further comprising a hollow shaft having internal teeth, the pistons being arranged inside the hollow shaft as viewed in a plane normal to the rotation axis, the coaxial transmission further comprising a guide unit, the pistons each being linearly guided in the guide unit and capable of reciprocating parallel to a radial direction normal to the rotation axis, whereby the meshing portion on the first end surface of the piston can be sequentially engaged with the internal teeth and released from the internal teeth, so that during each engagement, preferably under surface contact between the respective meshing portion and the internal teeth, the hollow shaft or the guide unit is further rotated about the rotation axis. [Background technology]

[0002] From AU Patent Specification No. 521617, a crankshaft transmission or coaxial transmission is known which comprises a crankshaft rotatable about an axis of rotation with at least one connecting rod bearing or crank pin, and further comprises a plurality of, for example three, pistons, each connected to at least one crank pin by a connecting rod and each having a toothing with at least one tooth on their first end face facing away from the axis of rotation, the coaxial transmission further comprises a hollow shaft with internal toothing, the pistons being arranged inside the hollow shaft as viewed in a plane normal to the axis of rotation, the coaxial transmission further comprises guide units, the pistons each being linearly guided in the guide units and reciprocating parallel to a radial direction normal to the axis of rotation, so that the toothing on the first end face of the piston can be successively brought into engagement with the internal toothing and released from the internal toothing, so that during each engagement the hollow shaft or the guide unit is further rotated about the axis of rotation under surface contact between the respective toothing and the internal toothing. Such coaxial transmissions allow high torques to be transmitted with small design dimensions, and high transmission ratios as well as high precision and zero backlash can be achieved. In order to make the force introduction as uniform as possible, a larger number of pistons would be provided, but this would entail a corresponding increase in the design length of the coaxial transmission, measured parallel to the axis of rotation, which may prove to be disadvantageous in some application cases. In addition, the increased number of components leads to a corresponding increase in the complexity of the system, which is also considered to be disadvantageous in terms of errors due to manufacturing tolerances. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Austrian Patent Specification No. 521617 Summary of the Invention

[0004] SUMMARY OF THE PRESENT EMBODIMENTS The object of the present invention is to provide an improved coaxial or crankshaft transmission which overcomes the above-mentioned disadvantages.

[0005] In order to achieve the above object, a coaxial transmission includes a crankshaft having at least one crank pin and rotatable about a rotation axis, the coaxial transmission further includes at least one piston set having a plurality of, preferably at least three, pistons each having a meshing portion having at least one tooth on a first end face facing away from the rotation axis, the coaxial transmission further includes a hollow shaft having internal teeth, the pistons being arranged inside the hollow shaft as viewed in a plane normal to the rotation axis, the coaxial transmission further includes guide units, the pistons being linearly guided in the guide units and reciprocatable parallel to a radial direction normal to the rotation axis. It is intended that the hollow shaft or guiding unit can be further rotated about the axis of rotation during each engagement, preferably under surface contact between the respective engagement portions and the internal teeth, and that according to the present invention a common star-configured connecting rod is respectively provided for connecting the pistons of each piston set with at least one crank pin, said connecting rod and said pistons of each piston set being connected, in such a way that offset of the pistons of each piston set relative to one another along the axis of rotation can be avoided.

[0006] That is, for each piston set, a star-configured connecting rod is used, which is also called "star connecting rod" in the following. A further possible designation for a star-configured connecting rod would be a "star coupler". A "piston set" accordingly includes pistons that are connected with a common or identical star-configured connecting rod.

[0007] Furthermore, each star-shaped connecting rod may have its own crank pin; or, in theory, several star-shaped connecting rods per crank pin are also possible, which allows for more pistons overall with a compact dimensioning of the coaxial transmission in order to further improve uniformity, torque capacity and force transmission. Each crank pin can also be called a crankshaft journal.

[0008] The crank pin is an eccentric. Therefore, within the scope of the present invention, the crank pin or the eccentric of an eccentric shaft can also be meant. Therefore, within the scope of the present invention, the term "crankshaft" is also understood in principle to mean "eccentric shaft" and vice versa. The fact that an eccentric shaft is usually supported in a cantilevered manner, whereas a crankshaft is usually supported on both sides, is not relevant here.

[0009] By arranging several star-shaped connecting rods on different crank pins one after the other as viewed along the axis of rotation, further or even lower transmission ratios can be realized in a simple manner.

[0010] A star connecting rod, like a normal connecting rod, often also called a "thrust rod", serves to convert the rotation of the crankshaft into a linear movement of the piston, and unlike the crank pin which constitutes an eccentric, the star connecting rod does not rotate relative to the guide unit (around the axis of rotation) as such in a plane normal to the axis of rotation, but performs an orbital movement in said plane. The above-mentioned orbital movement normal to the axis of rotation is due to the eccentricity and can be considered as a parallel slide relative to the guide unit, which is to a certain extent superimposed by a kind of rocking movement.

[0011] The star connecting rod then not only transmits the "prestroke", i.e. the movement of the piston in the direction of the internal teeth of the hollow shaft, but also the so-called "return stroke", i.e. the movement of the piston away from the internal teeth of the hollow shaft. The fact that the piston is pulled back again by the star connecting rod (return stroke) can be considered a major advantage when compared to solutions without connecting rods. This allows, in particular, virtually any mounting position of the coaxial transmission, since there is no risk that the piston, which is not in engagement with the internal teeth, will fall back due to gravity and thus unintentionally engage the internal teeth again.

[0012] The solution with a cam disc also prevents the drop back, but in order to do so, multiple eccentricities of the cam disc must be implemented, which results in a cross section of the cam disc that differs from a circle (polygonality of the cam disc). The disadvantage is that the possible transmission ratios are reduced (transmission ratio i = number of teeth / polygonality; correspondingly, for a polygonality of 2 the transmission ratio is halved, for a polygonality of 3 it is reduced to one third, etc.). The star connecting rod thus also eliminates the disadvantage of a reduced transmission ratio.

[0013] In addition, in the coaxial transmission according to the invention, the cam disc does not slide on the sliding surface of the respective piston facing the cam disc, which is also preferred, since for optimisation of the sliding it is usually necessary to largely round the sliding surfaces of the pistons, which is regarded as an unnecessary constraint in the coaxial transmission according to the invention.

[0014] By providing a single star-shaped connecting rod for all pistons of a piston set, the design length of the coaxial or crankshaft transmission, measured parallel to the axis of rotation, can be drastically reduced, since the pistons can be arranged with virtually no offset relative to one another in the direction along the axis of rotation. In theory, of course, it cannot be excluded that some offset occurs, for example due to manufacturing tolerances. In addition, a slight offset, also for manufacturing reasons, can be intentionally intended.

[0015] In either case, the number of components is correspondingly reduced since each piston does not need its own connecting rod, which reduces the complexity of the system and thus acts favorably in terms of manufacturing tolerances.

[0016] The problem-free use of a large number of pistons thus makes it possible, on the one hand, to achieve a particularly uniform force input and, on the other hand, to transmit extremely high torques.

[0017] Furthermore, the following also applies to the coaxial or crankshaft transmission according to the invention: The crankshaft is, or may be referred to as, the driving member.

[0018] As viewed in a plane normal to the axis of rotation, the crankshaft is preferably arranged at least locally inside the hollow shaft.

[0019] The hollow shaft is preferably rotatably supported about an axis of rotation and is capable of functioning as a driven member.

[0020] Alternatively, the guide unit can function as the driven member below the fixed hollow shaft, for which purpose it must be rotatably mounted.

[0021] In order to be able to rotate the hollow shaft or, if appropriate, the guide unit further in a certain direction, preferably at least three pistons are provided. For example, an integer multiple of N times 3 can be selected, for example 9 (i.e. for N=3), although the exact number is in principle not subject to any restrictions and accordingly does not have to be an integer multiple of 3. The exact number can be adapted to the respective application, in particular with regard to the desired efficiency as well as with regard to the system preload, which is important for the starting torque of the coaxial transmission.

[0022] Further rotation is caused by the meshing portion of the first end face of at least one piston being pressed, in a particularly planar manner, against the internal teeth of the hollow shaft, whereas the other pistons exert little or no pressing force against the internal teeth.

[0023] The behavior of the pistons in terms of how many pistons engage with the internal teeth, when and how strongly can be designed very variably. For example, in the case of 3N pistons, N pistons may be intended to engage with and press against the internal teeth. The remaining 2N pistons exert no or only a small pressing force on the internal teeth in the meantime. At least 1N of the remaining 2N pistons then preferably engage partially with the internal teeth in order to generate zero backlash. At least one of the remaining pistons then preferably does not come into contact with the internal teeth at all.

[0024] It should be noted that by appropriately designing the coaxial transmission according to the invention, the exact number of pistons which engage or partially engage with the internal teeth can be varied virtually anywhere in order to ensure zero backlash.

[0025] Generally, under multiple pistons, zero backlash can be ensured by at least two pistons simultaneously at least partially engaging with the internal teeth, preferably one of the two pistons being a pre-stroke and the other being a return stroke.

[0026] Very high transmission ratios are achieved with this mode of operation.

[0027] As mentioned above, a surface contact between the meshing of the respective first end face and the internal toothing of the hollow shaft is possible. A prerequisite for this is a linear movement of the piston. In addition to this, the meshing and the internal toothing can be geometrically designed or optimized accordingly in order to further improve the pressing or surface contact and thus the transmission of high torques. In contrast to the solutions known from the prior art, in which a linear contact or engagement is achieved, the surface pressing or surface contact of the meshing of the respective first end face and the internal toothing of the hollow shaft allows a much higher torque to be transmitted from the crankshaft to the hollow shaft or, if appropriate, to the guide unit. Furthermore, the surface pressing or surface contact reduces Hertzian contact stresses, which leads to a longer service life.

[0028] It should be noted that the geometry of the meshing portions or internal teeth can also be designed in the present coaxial transmission device so that linear contact occurs despite the linear movement of the piston, which may be preferable when reduced friction (and therefore increased efficiency) is desired.

[0029] The fact that it is easily possible to increase the number of pistons also offers further expansion possibilities in such cases, which are related to the amount of torque that can be transmitted.

[0030] With at least three pistons, it can be ensured that the next piston, which presses the internal toothing in a particularly surface-like manner with the engagement of its first end face, does not rotate the hollow shaft or, as the case may be, the guide unit back in the opposite direction, but only produces a reciprocating movement of the hollow shaft or, as the case may be, the guide unit about its axis of rotation, whereas in the case of two pistons, this is in principle excluded, although in the case of two pistons, additional elements, for example of the type of locks or freewheeling, can nevertheless be provided, which allow the hollow shaft or, as the case may be, the guide unit to rotate only in a certain direction, so that even with only two pistons, a further rotation of the hollow shaft or, as the case may be, the guide unit is possible.

[0031] The teeth on the first end surface may be referred to as teeth cut into the first end surface, and each piston may be referred to accordingly as a "toothed member."

[0032] The guide unit may be constructed integrally or by combining a plurality of members.

[0033] Due to the linear guidance of the pistons in the guide units, the pistons accordingly only move parallel to the respective radial direction, the radial direction assigned to each piston being defined by the guide units.

[0034] The linear guides may in particular be constituted by hollow cylinders in the guide unit, in which the pistons are arranged. In this case, the radial directions assigned to the respective pistons are defined by the respective cylinder axes. Typically, the pistons then have a substantially circular cross section (normal to the respective radial directions). However, in principle, other cross-sectional shapes of the pistons, for example rectangular or slot-shaped cross sections, are also possible, in particular in order to increase the "depth" of the engagement (i.e. its dimensioning parallel to the axis of rotation) and thus the forces that can be transmitted. It should be noted again that it is also conceivable for the guide unit to be not stationary but to be able to rotate. In that case, the radial directions assigned to the pistons also change accordingly with the rotation of the guide unit, or, mathematically speaking, there are then infinitely many radial directions over the time period during which the guide unit rotates.

[0035] In addition, due to the high transmission ratio and the friction of the tooth contact, the coaxial transmission is in principle also self-locking in the event of a drive failure. In particular, the coaxial transmission can be locked by one of the pistons remaining at top dead center, i.e. when it has slid a maximum distance away from the axis of rotation in the respective radial direction, thereby implementing a braking function. Solutions without connecting rods do not normally allow such a locking.

[0036] A further advantage of the coaxial transmission is that it allows high dynamics, since at least one crank pin of the crankshaft describes a circular motion about the axis of rotation and preferably has a circular cross section perpendicular to the axis of rotation itself, so that mass compensation can be very easily implemented, for example by compensation weights in a manner known per se or by the bore of the crankshaft.

[0037] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that several piston sets are provided, each of which is provided with a common star-configured connecting rod, which connects the pistons of the respective piston set, thereby further increasing the uniformity of the force input as well as the magnitude of the transmittable torque, without the need to excessively increase the design length.

[0038] In order to preclude in a particularly simple manner in terms of design a rotation (pivoting) of the star-shaped connecting rod relative to the guide unit beyond the above-described orbital movement, in a preferred embodiment of the coaxial transmission according to the invention it is provided that in order to preserve the orbital movement and prevent a rotation of each star-shaped connecting rod relative to the guide unit beyond this, at least two guide bolts are provided which are fixedly connected to each star-shaped connecting rod and which engage in at least one corresponding recess of at least one guiding section which is arranged stationary with respect to the guide unit.

[0039] Preferably, each guide bolt is assigned a corresponding notch.

[0040] The at least one guiding section may be a fundamentally separate part of the guiding unit, or alternatively, the at least one guiding section may be part of the guiding unit and / or may be configured integrally with the guiding unit.

[0041] In this case, the at least two guide bolts can be arranged inside the guide unit, as viewed in a plane normal to the axis of rotation, which results in a particularly compact arrangement.

[0042] The dimensioning of the at least one corresponding recess can of course be adapted to the eccentricity of the crank pin or the crank. For example, if one corresponding recess is provided for each guide bolt, each corresponding recess can be produced as a bore with a correspondingly adapted diameter, in particular by selecting the bore diameter to be equal to twice the eccentricity plus the diameter of the guide bolt. In that case, each guide bolt will always come into tangential contact with the assigned recess or guide area.

[0043] In order to minimize friction losses between the guide bolts and the notches, a particularly preferred embodiment of the coaxial transmission according to the invention provides for the guide bolts to be provided with rollers in order to facilitate rolling along at least one guiding area as the guide bolt moves in at least one corresponding notch, i.e. each guide bolt does not slide along the guiding area but rolls on at least one guiding area by means of one or more rollers.

[0044] The connection between the pistons and the star-shaped connecting rods can in principle be made in a wide variety of ways: in order to realise a particularly simple connection in design, a preferred embodiment of the coaxial transmission according to the invention provides that the pistons of the respective piston sets are provided with oblong holes extending transversely to the respective radial direction for connecting the pistons with the associated star-shaped connecting rods, the star-shaped connecting rods being fitted with connecting bolts which engage in the oblong holes.

[0045] Such a connection method has proven to be particularly space-saving, as a result of which the crankshaft can have a correspondingly large diameter, which is not only favorable from the standpoint of mechanical stability, but also allows, in the case of the hollow embodiment of the crankshaft, particularly large space for the particularly twist-free insertion of cables, etc.

[0046] The slots preferably extend normal to the radial direction of the respective piston, or it is conceivable that the extension of each slot has a curvature rather than being linear.

[0047] The connecting bolt or its longitudinal axis preferably extends parallel to the axis of rotation.

[0048] The connecting bolt is arranged in a slot in the piston, whereby the engagement is realised, so that the movement of the piston is based on the slider crank principle.

[0049] In a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that at least one of the connecting bolts is also configured as at least one guide bolt. This further reduces the number of parts, which saves space, weight and costs. It is preferred that at least two of the connecting bolts form at least two guide bolts. It is particularly preferred that all guide bolts are configured by connecting bolts.

[0050] In order to realise an alternative way of connection between the pistons and the star-configured connecting rods, which is simple in design, a preferred embodiment of the coaxial transmission according to the invention provides for a substantially stationary intermediate piece to be provided for connecting the pistons of each piston set with the associated star-configured connecting rods, each intermediate piece being pivotally connected on the one hand with the associated piston and on the other hand with the star-configured connecting rod, whereby the movement of the star-configured connecting rods can be realised with particularly low friction, whereby power losses are minimised.

[0051] The pivotal connection between the respective intermediate piece and the associated piston can, for example, be embodied by a rotary or solid joint in a manner known per se. For the pivotal connection between the respective intermediate piece and the associated star-configured connecting rod, for example, a rotary or solid joint can also be provided in each case.

[0052] In a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that for the pivot connection between the respective intermediate piece and the associated connecting rod configured in star shape, a connecting bolt is provided, at least one of which also constitutes a guide bolt, thereby reducing the number of parts, which saves space, weight and costs. It is preferred that at least two of the connecting bolts constitute at least two guide bolts. It is particularly preferred that all the guide bolts are constituted by connecting bolts.

[0053] In order to further increase the magnitude of the transferable torque, in a preferred embodiment of the coaxial transmission according to the invention, it is provided that the engagement of the first end face has a number of teeth, preferably three. With the number of teeth of the engagement of the first end face, the area over which the respective piston can press against the internal teeth increases, which allows the transfer of particularly large torques between the crankshaft and the hollow shaft or, if appropriate, the guide unit.

[0054] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that the crankshaft is made hollow in order to allow the cable to be passed through it, preferably along the axis of rotation, without twisting.

[0055] In a preferred embodiment of the coaxial transmission according to the invention, it is intended that the pistons each have a meshing portion with at least one tooth on a second end face opposite the first end face and are provided with an inner ring with external teeth, rotatably supported about the axis of rotation, and a guide unit is arranged at least locally between the inner ring and the hollow shaft, and the meshing portion on the second end face of the piston can be sequentially engaged with the external teeth and released from the external teeth, so that during each engagement, preferably under surface contact between the respective meshing portion and the external teeth, the inner ring or the guide unit is further rotated about the axis of rotation.

[0056] The meshing portion on the second end surface may also be referred to as a meshing portion engraved on the second end surface.

[0057] The inner ring is preferably mounted rotatably about the axis of rotation and, insofar as it is locked, has in principle the function of a shaft and can therefore also be called the inner shaft. Its external teeth face towards the internal teeth of the hollow shaft.

[0058] In principle, what has been said about the engagement of the meshing of the first end face with the internal toothing of the hollow shaft also applies mutatis mutandis to the engagement of the meshing of the second end face with the external toothing of the inner ring, and therefore essentially what has been said above applies. In particular, surface contact or surface pressing between the meshing of the second end face of the respective piston and the external toothing of the inner ring allows the transmission of particularly high torques between the crankshaft and the inner ring or, if appropriate, the guide unit, in contrast to solutions in which linear contact is achieved.

[0059] Furthermore, in order to transmit particularly high torques between the crankshaft and the inner ring or, if appropriate, the guide unit, several, in particular three, teeth can in each case be provided in the meshing portion of the second end face.

[0060] One or each piston alternately drives the hollow shaft and the inner ring under a braked or fixed guiding unit. Both the inner ring and the hollow shaft can act as the drive. Only the hollow shaft or only the inner ring can act as the drive, in which case the other part is braked or locked, respectively.

[0061] Since the inner ring has a smaller diameter than the hollow shaft, a lower tangential speed can be achieved or obtained at the inner ring at the same angular speed, i.e., the inner ring and the hollow shaft can simultaneously provide two outputs for different speeds, so that, depending on the application, a second gear can possibly be dispensed with.

[0062] The inner ring may, but does not have to, be connected to the hollow shaft so that it cannot rotate relative to it; if this is the case, on the one hand a higher resolution of the coaxial transmission can be achieved, and on the other hand a greater torque transmission can be achieved.

[0063] Furthermore, in theory, embodiments with only two pistons are also conceivable, in which case the inner ring ensures that the hollow shaft or, as the case may be, the guide unit can only move further in one particular direction based on a total of four (piston) engagements.

[0064] Finally, the inner ring may also rotate in the opposite direction compared to the direction of rotation of the hollow shaft.

[0065] In a preferred embodiment of the coaxial transmission according to the invention, it is intended that the guide unit is arranged stationary relative to the axis of rotation. In this case, the hollow shaft moves further and acts as a driven member. Optionally, in such an embodiment, the inner ring (if present) can also move further and can also be braked or can act as a driven member.

[0066] As already mentioned above, by arranging several star-shaped connecting rods one after the other on different crank pins when viewed along the rotation axis, other or very high transmission ratios can be realized in a simple manner.Accordingly, a preferred embodiment of the coaxial transmission according to the invention comprises a hollow shaft, which is locked or braked with respect to rotational movement about the rotation axis, a further crank pin, a further piston set is provided with several pistons, each of which has a toothed portion with at least one tooth on its first end face facing away from the rotation axis, a further star-shaped connecting rod is provided for connecting the pistons of the further piston set with the further crank pin, which is connected to the pistons of the further piston set, a further hollow shaft with internal toothing is provided, and the internal toothing of at least the further hollow shaft is preferably at least 100 mm in a plane normal to the rotation axis. The entirety of the other hollow shaft is arranged inside the cross section of the hollow shaft, and the pistons of the other piston set are each linearly guided in the guide unit and are capable of reciprocating parallel to the radial direction, so that when the guide unit rotates around the rotation axis, the meshing portions of the first end faces of the pistons of the other piston set can be sequentially engaged with the internal teeth of the other hollow shaft and released from the internal teeth of the other hollow shaft, and thus, during each engagement, preferably under surface contact between the respective meshing portions and the internal teeth of the other hollow shaft, the other hollow shaft is intended to be further rotated around the rotation axis.

[0067] In this embodiment, the hollow shaft, rather than the guide unit, is arranged immovably relative to the axis of rotation or is locked or braked.

[0068] The output is via another hollow shaft.

[0069] The guide unit then guides not only the pistons of at least one piston set, but also the pistons of another piston set.

[0070] The at least one crank pin and the further crank pin or the further eccentric are arranged one after the other when viewed along the rotation axis, and the at least one crank pin and the further crank pin do not necessarily have to be directly adjacent to each other or directly follow each other, i.e. a distance between them may be intended.

[0071] Of course, it is possible to provide a number of separate crank pins, a number of separate piston sets, a number of separate connecting rods arranged in a star shape, and a number of separate hollow shafts, which are typically arranged one behind the other when viewed along the axis of rotation.

[0072] In the resulting two-stage or multi-stage embodiment of the coaxial transmission, on the one hand a relatively large number of teeth are involved in the power transmission, which makes it possible to transmit higher torques, and on the other hand relatively high transmission ratios, particularly to low speeds, can be realized.

[0073] At this time, the overall gear ratio i is calculated by the number of teeth zf of the fixed or braked stage, i.e., the number of teeth of the internal teeth of the hollow shaft, and the number of teeth of the driven stage, i.e., the number of teeth of the internal teeth of another hollow shaft, as follows: i = za * It is calculated according to (zf-1) / (za-zf). For example, if the internal toothing of the hollow shaft has 42 teeth and the internal toothing of the other hollow shaft has 41 teeth, then an overall transmission ratio i=-1681 is obtained, i.e. a very high transmission ratio to low speed (also called reduction in everyday language), since |i|>>1. The minus sign indicates that the guiding unit and the other hollow shaft rotate in opposite directions.

[0074] Accordingly, in order to realize a wide bandwidth of the transmission ratio and in particular high transmission ratios, in a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that the internal teeth of the hollow shaft and the internal teeth of the further hollow shaft each have a different number of teeth.

[0075] In principle, the eccentricity of the at least one crank pin and the eccentricity of the further crank pin may be of different magnitudes. In a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that the at least one crank pin and the further crank pin have equal eccentricities. This has proven to be favorable from the standpoint of good mass compensation.

[0076] Likewise, a certain crankpin offset not equal to zero has also proven to be advantageous from the standpoint of good mass compensation. Therefore, in a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that at least one crankpin and the further crankpin are arranged rotated relative to one another about the axis of rotation, preferably by 360° / h, where h is the total number of all crankpins.

[0077] It has been found that a crank pin offset of 360° / h is best in terms of mass compensation, where h is the sum of the number of at least one crank pin and the number of further crank pins, i.e. in the above embodiment of the coaxial transmission, if for example exactly one crank pin and exactly one further crank pin are provided, then h=2, so a crank pin offset of 360° / 2=180° results between the crank pin and the further clamp pin.

[0078] The present invention will now be described in more detail with reference to examples. The drawings are exemplary and illustrative of the invention, but are not limiting in any way and are by no means exhaustive. [Brief description of the drawings]

[0079] [Figure 1] 1 is a schematic cross-sectional view showing a first embodiment of a coaxial transmission according to the present invention; [Diagram 2] FIG. 4 is a schematic cross-sectional view showing a second embodiment of a coaxial transmission device according to the present invention. [Diagram 3]FIG. 2 is a schematic cross-sectional view of a second embodiment of a coaxial transmission according to the invention, in which the guide sections are visible. [Figure 4] 5A and 5B are schematic cross-sectional and front views showing a third embodiment of a coaxial transmission device according to the present invention. [Diagram 5] 5 is a schematic cross-sectional view showing the third embodiment taken along the line VV in FIG. 4, with the arrow indicating the line of sight. [Figure 6] 6 is a schematic cross-sectional view showing the third embodiment taken along line VI-VI in FIG. 5, with the arrow indicating the line of sight. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0080] In the cross-sectional view of Figure 1, a first embodiment of a coaxial transmission 1 according to the invention is shown. This coaxial transmission 1 comprises a crankshaft 3 which is rotatable about an axis of rotation 2 and which comprises a crankpin 4, which can be seen in Figure 1 and which constitutes an eccentric which rotates about the axis of rotation 2 when the crankshaft 3 rotates.

[0081] The coaxial transmission 1 of the first embodiment comprises a piston set with nine pistons 5a-i, each of which has a first end face 10 facing away from the rotation axis 2, a meshing portion 11 with inscribed teeth.

[0082] Furthermore, in this coaxial transmission 1, a hollow shaft 7 with internal teeth 8 is provided. In the drawing plane of FIG. 1, which is perpendicular to the axis of rotation 2, the pistons 5a-i and, at least in part, the crankshaft 3 are arranged inside the hollow shaft 7. The same also applies to the guide units 9, in which the pistons 5a-i are each linearly guided and can each reciprocate parallel to a radial direction 12 normal to the axis of rotation 2. For this purpose, the guide units 9 have hollow cylinders which serve as linear guides for the pistons 5a-i in the illustrated embodiment. The pistons 5a-i have a circular cross section in the area arranged in the hollow cylinder of the guide unit 9, the respective cross sections being normal to the respective radial direction 12.

[0083] As the pistons 5a-i reciprocate, the teeth 11 of the first end faces 10 of the pistons 5a-i are successively engaged with the internal teeth 8 and released from the internal teeth 8, and due to the linear movement of the pistons 5a-i, a surface contact can be ensured between the respective teeth 11 and the internal teeth 8 during engagement, and the respective teeth 11 are pressed surface-wise against the internal teeth 8. As a result, if the guide unit 9 is arranged immovably relative to the rotation axis 2, or if the guide unit 9 is arranged rotatably about the rotation axis 2 but is braked, the hollow shaft 7 rotates further by one section about the central axis 2. In contrast, if the hollow shaft 7 is fixed or immovable relative to the rotation axis 2 or is braked, the guide unit 9 (supported rotatably about the rotation axis 2) rotates further by one section. Due to the surface engagement or pressing, very high torques can be transmitted from the crankshaft 3 to the hollow shaft 7 or, if applicable, to the guide unit 9.

[0084] In the embodiment shown in figures 1 to 3, the guide unit is preferably arranged stationary relative to the axis of rotation 2, so that when the crankshaft 3 rotates the hollow shaft 7 moves.

[0085] To connect the pistons 5a-i of a piston set with the crank pin 4, a common connecting rod 6 configured in a star shape is provided according to the invention, to which the pistons 5a-i are connected. In the illustrated embodiment, this results in an arrangement of the pistons 5a-i with virtually no mutual offset in relation to the axis of rotation 2, which results in an extremely small overall length of the coaxial transmission 1, measured parallel to the axis of rotation 2, despite the relatively large number of pistons 5a-i. At the same time, a very uniform force input is achieved due to the relatively large number of pistons 5a-i, and furthermore extremely high torques can be transmitted.

[0086] In order to ensure the orbital movement and, beyond this, to accommodate the rotation of the star-configured connecting rod 6 relative to the guide unit 9, in the exemplary embodiment shown in Figures 1 to 3, two guide bolts 16 are respectively provided, which are fixedly connected to the star-configured connecting rod 6 and project therefrom in a manner that runs parallel to the axis of rotation 2. The guide bolts 16, in particular in the region with their free ends, engage in or are arranged locally in corresponding recesses 17 of a guide section 19, see Figure 3, which guide section 19 is arranged stationary relative to the guide unit 9 or is connected thereto. In the exemplary embodiment shown, the corresponding recesses 17 are made as bores and the dimensioning of the recesses 17 is adapted to the eccentricity of the crank pin 4.

[0087] The connection between the pistons 5a-i and the star-configured connecting rods 6 can be made in many different ways. In a first exemplary embodiment shown in FIG. 1, for connecting the pistons 5a-i of a piston set with the associated star-configured connecting rods 6, the pistons 5a-i are provided with elongated holes 13 extending transversely to the respective radial direction 12, and the star-configured connecting rods 6 are fitted with connecting bolts 14 which engage with the elongated holes 13 or are arranged locally in the elongated holes 13. In this way, the movement of the pistons 5a-i is performed according to the slider crank principle. In the illustrated exemplary embodiment, the elongated holes 13 extend essentially in a straight line and essentially normal to the respective radial direction 12 as well as essentially normal to the axis of rotation 2. The connecting bolts 14 extend essentially parallel to the axis of rotation 2 or project from the star-configured connecting rods 6 parallel to the axis of rotation 2.

[0088] In the first exemplary embodiment shown in Fig. 1, two of the connecting bolts 14 form guide bolts 16, since they are slightly longer than the remaining connecting bolts 14 and pass through their respective slots 13 into respective recesses 17 in the guide sections 19. This further reduces the number of parts.

[0089] 2 differs from the first embodiment only by the connection of the pistons 5a-i to the star-configured connecting rods 6, so that what has been said above applies with regard to the basic mode of operation of the coaxial transmission 1. In particular, in the second embodiment, it is provided that for connecting the pistons 5a-i of a piston set with the star-configured connecting rods 6, an intermediate piece 15 which is made substantially stationary is provided, each intermediate piece 15 being pivotally connected on the one hand to the associated piston 5a-i and on the other hand to the star-configured connecting rod 6.

[0090] In the illustrated exemplary embodiment, for the pivot connection between the respective intermediate piece 15 and the star-configured connecting rod 6, connecting bolts 18 are provided which define a rotary joint or its axis of rotation, which is parallel to the axis of rotation 2. The connecting bolts 18 then project from the star-configured connecting rod 6 parallel to the axis of rotation 2. In order to save parts, two of the connecting bolts 18 simultaneously form the guide bolts 16, since they are slightly longer than the remaining connecting bolts 18 and project into the respective recesses 17 of the guide sections 19, see FIG. 3.

[0091] The pivot connection between each intermediate member 15 and the associated piston 5a-i may in the illustrated second embodiment be embodied in each case by a rotary joint 20, the rotation axis of which extends parallel to the rotation axis 2.

[0092] In both the illustrated embodiments of FIGS. 1 and 2, the crankshafts 3 are each configured hollow along the axis of rotation 2, which allows for example twist-free passage of cables (not shown).

[0093] Unless otherwise stated, what has been said above also applies to the third embodiment, so that a corresponding repetition will be omitted. In the third embodiment shown in Figures 4, 5 and 6, the guide unit 9 is not arranged immobile or is not locked or braked with respect to the rotational movement about the rotation axis 2, but the hollow shaft 7 is locked or braked.

[0094] The coaxial transmission 1 includes in this case another crank pin 21, as well as another piston set having a number of pistons 5a-t, each having a meshing portion 11 with at least one tooth on a first end face 10 facing away from the rotation axis 2.

[0095] In this embodiment, the eccentric shaft or crankshaft 3 is made in one piece with the eccentric or crankpin 4 and the further eccentric or crankpin 21, the crankpins 4, 21 being arranged directly one behind the other when viewed along the axis of rotation 2, see FIG.

[0096] To connect the pistons 23a-t of the further piston set with the further crank pins 21, further star-configured connecting rods 22 are provided, to which the pistons 23a-t of the further piston set are connected.

[0097] For connecting the pistons 23a-t with the star-configured further connecting rods 22, an intermediate piece 15 is likewise provided, in this case not with the star-configured connecting rods 6 but with the star-configured further connecting rods 22. The intermediate piece 15 is rotatably mounted on the side of the star-configured further connecting rods 22 by a connecting bolt 18 and on the side of the pistons 23a-t by a rotary joint 20, the associated axis of rotation of which runs parallel to the axis of rotation 2.

[0098] The star-shaped further connecting rod 22 is supported on the further crankpin 21 by means of a bearing formed by a needle bearing 26 in the illustrated embodiment, analogously to the bearing of the star-shaped connecting rod 6 on the crankpin 4 .

[0099] In the illustrated third embodiment, the coaxial transmission 1 further comprises a further hollow shaft 245 with internal teeth 25, the further hollow shaft 24 being entirely arranged inside the cross section of the hollow shaft 7, as viewed in a plane normal to the axis of rotation 2. See in particular figures 4 and 5.

[0100] In the third exemplary embodiment shown, the hollow shaft 7 and the further hollow shaft 24 are arranged one behind the other when viewed along the axis of rotation 2, with the further hollow shaft 24 being located outside the hollow shaft 7 and directly following it. Naturally, however, it would also be possible for the hollow shaft 7 to project parallel to the axis of rotation 2 from the further hollow shaft 24, in particular with a section 27 of the hollow shaft 7 which does not have internal teeth. Alternatively, this section 27 of the hollow shaft 7 without internal teeth 8 can also constitute a bearing, in particular a plain bearing, for the further hollow shaft 24. A possible geometry or design of such a hollow shaft 7 with a section 27 without internal teeth is indicated by dotted lines in FIG. 5.

[0101] The pistons 23a-t of the other piston set, like the pistons 5a-t of the piston set, are each linearly guided in the guide unit 9 and are capable of reciprocating movement parallel to the radial direction 12. As a result, when the guide unit 9 rotates about the rotation axis 2, the meshing portions 11 of the first end faces 10 of the pistons 23a-t of the other piston set sequentially engage with the internal teeth 25 of the other hollow shaft 24 and are released from the internal teeth 25 of the other hollow shaft 24, thereby causing the other hollow shaft to further rotate about the rotation axis 2 during each engagement, preferably under surface contact between the respective meshing portions 11 and the internal teeth 25 of the other hollow shaft 24.

[0102] In this way, a two-stage coaxial transmission 1 is realized, with the further hollow shaft 24 acting as the driven part, making it possible to realize particularly high transmission ratios. In this connection, in the third exemplary embodiment shown, the internal teeth 8 of the hollow shaft 7 and the internal teeth 25 of the further hollow shaft 24 each have a different number of teeth.

[0103] Specifically, in the illustrated third embodiment, the number of teeth za of the internal teeth 25 of the other hollow shaft 24 is za=41, and the number of teeth zf of the internal teeth 8 of the hollow shaft 7 is zf=42. Thus, the overall gear ratio i=za *We obtain (zf-1) / (za-zf)=-1681, i.e. a very high reduction ratio, so that the guide unit 9 and the further hollow shaft 24 rotate in opposite directions.

[0104] In the third embodiment shown, the crank pin 4 and the further crank pin 21 have equal eccentricities, see figure 5. This has a positive effect from the point of view of mass compensation.

[0105] Additionally, in the third embodiment, a crank pin offset of 180° is provided for optimizing mass compensation, i.e. the crank pin 4 and the further crank pin 21 are arranged rotated by 180° relative to each other with respect to the axis of rotation 2, see FIG. The invention as originally claimed in the present application is set forth below. [1] A coaxial transmission (1), comprising a crankshaft (3) rotatable about a rotation axis (2) having at least one crank pin (4), the coaxial transmission (1) further comprising at least one piston set having a plurality of, preferably at least three, pistons (5a-i) each having a meshing portion (11) having at least one tooth on a first end face (10) facing away from the rotation axis (2), the coaxial transmission (1) further comprising a hollow shaft (7) having internal teeth (8), the pistons (5a-i) being arranged inside the hollow shaft (7) as viewed in a plane normal to the rotation axis (2), The coaxial transmission (1) further comprises a guide unit (9), in which the pistons (5a-i) are each linearly guided and reciprocable parallel to a radial direction (12) normal to the rotation axis (2), so that the meshing portions (11) of the first end faces (10) of the pistons (5a-i) can be sequentially engaged with and released from the internal teeth (8), such that during each engagement, the meshing portions (11) of the first end faces (10) of the pistons (5a-i) are preferably in a position parallel to the radial direction (12) normal to the rotation axis (2), and each of ... a coaxial transmission (1) for further rotating the hollow shaft (7) or the guide unit (9) about the rotation axis (2) under surface contact between the internal teeth (8) and the hollow shaft (7) or the guide unit (9); characterized in that a common connecting rod (6) configured in a star shape is provided for connecting the pistons (5a-i) of each of the piston sets to at least one of the crank pins (4), and the connecting rod is connected to the pistons (5a-i) of each of the piston sets. [2] The coaxial transmission device (1) described in [1], characterized in that a plurality of piston sets are provided, and a common connecting rod (6) configured in a star shape is provided for each of the piston sets, and the connecting rod is connected to the pistons (5a-i) of each of the piston sets. [3] A coaxial transmission (1) according to [1] or [2], characterized in that in order to ensure the orbital movement and beyond this, in order to accommodate the relative rotation of each of the star-configured connecting rods (6) with respect to the guiding unit (9), at least two guide bolts (16) are provided, which are fixedly connected to each of the star-configured connecting rods (6) and engage with at least one corresponding notch (17) of at least one guiding section (19) arranged immovably with respect to the guiding unit (9). [4] A coaxial transmission device (1) as described in [3], characterized in that the guide bolt (16) is provided with a roller to facilitate rolling along at least one of the guide sections (19) when the guide bolt (16) moves in at least one corresponding notch (17). [5] A coaxial transmission (1) according to any one of claims [1] to [4], characterized in that the pistons (5a-i) of each piston set are provided with elongated holes (13) extending transversely to the respective radial directions (12) for connecting the pistons (5a-i) of each piston set with the associated connecting rods (6) arranged in a star shape, and connecting bolts (14) engaging with the elongated holes (13) are attached to the connecting rods (6) arranged in a star shape. [6] A coaxial transmission device (1) as described in [5] referring to [3] or [4], characterized in that at least one of the connecting bolts (14) also constitutes at least one of the guide bolts (16). [7] A coaxial transmission (1) according to any one of claims [1] to [4], characterized in that for connecting the pistons (5a-i) of each of the piston sets with the associated connecting rods (6) arranged in a star shape, a substantially fixedly manufactured intermediate piece (15) is provided, each of the intermediate pieces (15) being pivotally connected on the one hand to the associated pistons (5a-i) and on the other hand to the connecting rods (6) arranged in a star shape. [8] A coaxial transmission device (1) according to [7], referring to [3] or [4], characterized in that connecting bolts (18) are provided for the pivotal connection between each of the intermediate members (15) and the associated connecting rods (6) arranged in a star shape, at least one of the connecting bolts (18) also constituting the guide bolt (16). [9] A coaxial transmission device (1) described in any one of [1] to [8], characterized in that the meshing portion (11) of the first end face (10) each has a plurality of teeth, preferably three.

[10] The coaxial transmission device (1) described in any one of [1] to [9], characterized in that the crankshaft (3) is made hollow.

[11] A coaxial transmission (1) according to any one of claims [1] to

[10] , characterized in that the pistons (5a-i) each have a meshing portion having at least one tooth on a second end face facing the first end face (10) and are provided with an inner ring having external teeth rotatably supported about the rotation axis (2), and the guide unit (9) is at least locally arranged between the inner ring and the hollow shaft (7), and the meshing portion on the second end face of the pistons (5a-i) can be sequentially engaged with the external teeth and released from the external teeth, so that during each engagement, the inner ring or the guide unit (9) is further rotated about the rotation axis (2), preferably under surface contact between the respective meshing portion and the external teeth.

[12] A coaxial transmission device (1) described in any one of [1] to

[11] , characterized in that the guide unit (9) is arranged immovably relative to the rotating shaft (2).

[13] The hollow shaft (7) is locked or braked with respect to rotational movement about the rotation axis (2); Another crank pin (21) is provided, a second piston set is provided having a plurality of pistons (23a-t) each having a meshing portion (11) having at least one tooth on a first end face (10) facing away from the rotation axis (2); a connecting rod (22) arranged in a star shape is provided for connecting the pistons (23a-t) of the other piston set to the other crank pins (21), the connecting rod and the pistons (23a-t) of the other piston set being connected; a further hollow shaft (24) having internal teeth (25) is provided, at least the internal teeth of said further hollow shaft (24) being arranged inside the cross section of said hollow shaft (7) when viewed in a plane normal to said axis of rotation (2), preferably the entirety of said further hollow shaft being arranged inside the cross section of said hollow shaft (7); The coaxial transmission (1) according to any one of claims [1] to

[11] , characterized in that the pistons (23a-t) of the other piston set are each linearly guided in the guide unit (9) and are capable of reciprocating motion parallel to the radial direction (12), so that, when the guide unit (9) rotates around the rotation axis (2), the meshing portions (11) of the first end faces (10) of the pistons (23a-t) of the other piston set can be sequentially engaged with the internal teeth (25) of the other hollow shaft (24) and released from the internal teeth (25) of the other hollow shaft (24), thereby causing the other hollow shaft (24) to further rotate around the rotation axis (2) during each engagement, preferably under surface contact between each of the meshing portions (11) and the internal teeth (25) of the other hollow shaft (24).

[14] The coaxial transmission device (1) described in

[13] , characterized in that the internal teeth (8) of the hollow shaft (7) and the internal teeth (25) of the other hollow shaft (24) each have a different number of teeth.

[15] The coaxial transmission device (1) according to

[13] or

[14] , characterized in that at least one of the crank pins (4) and the other crank pin (21) have equal eccentricity.

[16] A coaxial transmission (1) according to any one of

[13] to

[15] , characterized in that at least one of the crank pins (4) and the further crank pin (21) are arranged rotated relative to one another about the rotation axis (2), preferably by 360° / h, where h is the total number of all crank pins. [Explanation of symbols]

[0106] 1 Coaxial transmission 2 Rotation Axis 3. Crankshaft 4 Crank pin 5a-i,jt Piston 6 Star-shaped connecting rods 7 Hollow Shaft 8 Internal teeth of hollow shaft 9 Guide Unit 10 first end face of piston 11 First end face engagement portion 12 Radial 13 long hole 14 Connecting bolt 15 Intermediate parts 16 Guide bolt 17 Notch 18 Connecting bolt 19 Guide Area 20 Rotary joint 21 Different crank pin 22 Another connecting rod configured in a star shape 23a-t Pistons from another piston set 24 Another hollow shaft 25 Internal teeth of another hollow shaft 26 Needle bearing 27 Hollow shaft area without internal teeth

Claims

1. A coaxial transmission (1) comprising a crankshaft (3) rotatable about a rotation axis (2) having at least one crank pin (4), said coaxial transmission (1) further comprising at least one piston set having a plurality of pistons (5a-i) each having a meshing portion (11) having at least one tooth on a first end face (10) facing away from said rotation axis (2), said coaxial transmission (1) further comprising a hollow shaft (7) having internal teeth (8), said pistons (5a-i) being arranged inside said hollow shaft (7) as viewed in a plane normal to said rotation axis (2), The coaxial transmission (1) further comprises a guide unit (9), in which the pistons (5a-i) are linearly guided in the guide unit (9) and are reciprocatable parallel to a radial direction (12) normal to the rotation axis (2), so that the meshing portions (11) of the first end faces (10) of the pistons (5a-i) can be sequentially engaged with and released from the internal teeth (8), during each engagement, further rotating the hollow shaft (7) or the guide unit (9) about the rotation axis (2). The coaxial transmission (1) is characterized in that a common connecting rod (6) configured in a star shape is provided to connect the pistons (5a-i) of each piston set with at least one crank pin (4), and the connecting rod is connected to the pistons (5a-i) of each piston set.

2. 2. The coaxial transmission (1) according to claim 1, characterized in that a plurality of piston sets are provided, each of which is provided with a common star-configured connecting rod (6) for connecting the pistons (5a-i) of each of the piston sets.

3. A coaxial transmission device (1) as described in claim 1 or 2, characterized in that at least two guide bolts (16) are provided for the guide units (9) of each of the star-shaped connecting rods (6) to ensure orbital movement and prevent further rotation, and these guide bolts are fixedly connected to each of the star-shaped connecting rods (6) and engage with at least one corresponding notch (17) of at least one guiding section (19) arranged immovably with respect to the guide units (9).

4. 4. The coaxial transmission (1) according to claim 3, characterized in that the guide bolt (16) is provided with rollers to facilitate rolling along at least one of the guide sections (19) when the guide bolt (16) moves in the at least one corresponding recess (17).

5. 4. A coaxial transmission (1) according to claim 3, characterized in that the pistons (5a-i) of each piston set are provided with oblong holes (13) extending transversely to the respective radial direction (12) for connecting the pistons (5a-i) of each piston set with the associated connecting rods (6) arranged in a star shape, the connecting rods (6) being fitted with connecting bolts (14) engaging with the oblong holes (13).

6. 6. Coaxial transmission (1) according to claim 5, characterized in that at least one said connecting bolt (14) also constitutes at least one said guide bolt (16).

7. 4. A coaxial transmission (1) according to claim 3, characterized in that for connecting the pistons (5a-i) of each piston set with the associated connecting rods (6) arranged in a star shape, a substantially fixedly manufactured intermediate piece (15) is provided, each intermediate piece (15) being pivotally connected on the one hand to the associated piston (5a-i) and on the other hand to the star-configured connecting rods (6).

8. 8. A coaxial transmission (1) according to claim 7, characterized in that for the pivotal connection between each intermediate piece (15) and the associated connecting rod (6) configured in a star shape, connecting bolts (18) are provided, at least one of the connecting bolts (18) also constituting the guide bolt (16).

9. 3. A coaxial transmission (1) according to claim 1 or 2, characterized in that the meshing portions (11) of the first end face (10) each have a plurality of teeth.

10. Coaxial transmission (1) according to claim 1 or 2, characterized in that the crankshaft (3) is made hollow.

11. 3. Coaxial transmission (1) according to claim 1 or 2, characterized in that the guiding unit (9) is arranged stationary with respect to the rotating shaft (2).

12. the hollow shaft (7) is locked or braked with respect to rotational movement about the axis of rotation (2); Another crank pin (21) is provided, a further piston set is provided having a plurality of pistons (23a-t) each having a meshing portion (11) with at least one tooth on a first end face (10) facing away from the rotation axis (2); a connecting rod (22) arranged in a star shape is provided for connecting the pistons (23a-t) of the other piston set to the other crank pin (21), the connecting rod and the pistons (23a-t) of the other piston set being connected; a further hollow shaft (24) having internal teeth (25) is provided, at least the internal teeth of the further hollow shaft (24) being arranged inside a cross section of the hollow shaft (7) when viewed in a plane normal to the rotation axis (2); 3. A coaxial transmission (1) according to claim 1 or 2, characterized in that the pistons (23a-t) of the further piston sets are each linearly guided in the guiding unit (9) and are reciprocatable parallel to a radial direction (12), so that, upon rotation of the guiding unit (9) about the rotation axis (2), the meshing portions (11) of the first end faces (10) of the pistons (23a-t) of the further piston sets can be successively engaged with and released from the internal teeth (25) of the further hollow shaft (24), thereby causing a further rotation of the further hollow shaft (24) about the rotation axis (2) during each engagement.

13. 13. Coaxial transmission (1) according to claim 12, characterized in that the internal teeth (8) of the hollow shaft (7) and the internal teeth (25) of the further hollow shaft (24) each have a different number of teeth.

14. 13. Coaxial transmission (1) according to claim 12, characterized in that at least one of the crank pins (4) and the further crank pin (21) have equal eccentricities.

15. 13. Coaxial transmission (1) according to claim 12, characterized in that the at least one crank pin (4) and the further crank pin (21) are arranged in rotation with respect to one another with respect to the rotation axis (2).

Images