Coaxial transmission

Abstract

The invention relates to a coaxial transmission device (1), comprising: a crankshaft (3) rotatable about a rotation axis (2) and having at least one connecting rod support (4); a plurality of, preferably at least three, pistons (5a, 5b, 5c), each of which is connected to the at least one connecting rod support by means of a connecting rod (6a, 6b, 6c), each of which has a toothed portion (11a, 11b, 11c) on a first end side (10a, 10b, 10c) facing away from the rotation axis, the toothed portion having at least A tooth; a hollow shaft (7) with an internal tooth portion (8), wherein, when viewed in a plane perpendicular to the axis of rotation, a piston is arranged inside the hollow shaft, and the coaxial transmission device also includes a guide unit (9), wherein the pistons are linearly guided in the guide units respectively, and the pistons can reciprocate parallel to a radial direction (12a, 12b, 12c) perpendicular to the axis of rotation, thereby enabling the tooth portion on the first end side of the piston to be in a state of meshing with the internal tooth portion and in a state of disengagement from the internal tooth portion successively.

Description

Technical Field

[0001] The invention relates to a coaxial transmission comprising a crankshaft rotatable about an axis of rotation and having at least one connecting rod bearing. Background Art

[0002] DE 312164 C discloses a self-locking transmission in which a plurality of arms arranged in a star shape around a drive shaft are eccentrically supported on the drive shaft with their inner ends, are located in a guide with their middle part, and mesh with a toothed ring with their outer ends. In this case, the arms are designed as two-armed levers, the pivot points of which are guided in the manner of a crosshead, and the inner ends of the levers are placed independently of one another on a driving eccentric, so that the outer ends perform a connecting rod movement and thereby mesh with the toothed ring in turn and drive the latter in the direction opposite to the rotation of the drive shaft. This results in a cycloidal movement and thus in line contact of the outer ends with the teeth of the toothed ring.

[0003] Similar transmissions are known from US Pat. No. 5,351,568 A, US Pat. No. 2005,268,872 A1 and WO 0166974 A1, in which cycloidal motions and thus line contacts occur.

[0004] A disadvantage caused by the line contact is that it limits the transmittable torque.

[0005] Transmissions without connecting rods are known from the following documents: EP 0201730 A1 relates to a reduction transmission with a toothed element that can reciprocate radially, which is driven by means of a rotatable disc arranged in an offset manner. Similarly, DE 102015105523 A1, WO 2008028540 A1 and DE 102015105520 A1 all relate to transmissions having a toothed support for accommodating teeth arranged around an axis of rotation of the transmission, wherein the gear is displaceable in a gear carrier and is arranged in a radially guided manner, and wherein a drive element that can rotate around the axis of rotation is provided for driving the gear in the form of a shaped running disc / starting disc. Summary of the invention

[0006] Therefore, the object of the present invention is to provide a transmission device which can avoid the above-mentioned disadvantages. In particular, the transmission device should be able to transmit high torques preferably with small structural dimensions. Particularly preferably, a high transmission ratio and high precision or free play should be achieved.

[0007] Introduction of the Invention

[0008] In order to achieve the above-mentioned purpose, a coaxial transmission device is provided according to the present invention, which includes a crankshaft with at least one connecting rod support part that can rotate around an axis of rotation, the coaxial transmission device also includes a plurality of, preferably at least three, pistons, the pistons are respectively connected to the at least one connecting rod support part by means of connecting rods and respectively have a toothed portion on a first end side facing away from the axis of rotation, the toothed portion having at least one tooth, the coaxial transmission device also includes a hollow shaft with an internal toothed portion, wherein the piston is arranged inside the hollow shaft when viewed in a plane perpendicular to the axis of rotation, and the coaxial transmission device also includes a guide unit, wherein the pistons are respectively linearly / straightly guided in the guide unit, the pistons can reciprocate parallel to a radial direction that is perpendicular to the axis of rotation, thereby enabling the toothed portion on the first end side of the piston to be successively in a state of meshing with the internal toothed portion and in a state of disengagement from the internal toothed portion, so that during the corresponding meshing period, the hollow shaft or the guide unit continues to rotate around the axis of rotation under surface contact between the corresponding toothed portion and the internal toothed portion.

[0009] The coaxial transmission according to the invention can also be referred to as crankshaft transmission.

[0010] Here, the crankshaft represents a drive element or can be referred to as a drive element.

[0011] Preferably, the crankshaft is arranged at least partially within the hollow shaft, viewed in a plane perpendicular to the axis of rotation.

[0012] A connecting rod bearing may also be referred to as a connecting rod journal or crank pin, wherein the connecting rod is supported on at least one connecting rod (bearing). In principle, a plurality of, preferably all, connecting rods may be supported on one connecting rod bearing, so that only a single connecting rod bearing is required. However, a plurality of connecting rod bearings or connecting rod journals or crank pins may also be provided, in particular when the connecting rods are arranged one behind the other along the axis of rotation, wherein preferably a crank pin may be provided for each connecting rod.

[0013] It should be noted that by arranging a plurality of connecting rod bearings or crank pins in succession and adapting the rotational angle offset between them, the resolution and / or the transmission ratio of the transmission can be influenced.

[0014] The hollow shaft is preferably mounted so as to be rotatable about an axis of rotation and can serve as an output element.

[0015] Alternatively, the guide unit can be used as an output element if the hollow shaft is fixed, for which purpose the guide unit must be rotatably mounted.

[0016] In order to be able to rotate the hollow shaft or a possible guide unit further in a specific direction, three pistons are preferably provided. The further rotation is caused by the first end side toothing of one of the pistons pressing against the inner toothing of the hollow shaft in a flat manner, while the other pistons exert no or almost no pressure on the inner toothing.

[0017] Typically, when three pistons are provided, one piston meshes with the inner toothing and presses against it. During this period, the other two pistons exert no pressure or only a small pressure on the inner toothing. Preferably, at least one of the other two pistons partially meshes with the inner toothing to achieve gaplessness. Preferably, at least one of the other two pistons does not contact the inner toothing at all.

[0018] In general, in the case of a plurality of pistons, the freedom from play is ensured by the simultaneous, at least partial meshing of at least two pistons with the internal toothing.

[0019] This mode of action results in very large transmission ratios. In addition, compared to solutions known from the prior art with line contact or linear toothing, very high torques can be transmitted from the crankshaft to the hollow shaft or to a possible guide unit by means of the surface contact or surface contact between the respective first end-side toothing and the inner toothing of the hollow shaft.

[0020] The number of pistons can be kept correspondingly low, or the coaxial transmission according to the invention can have correspondingly compact dimensions. Although a very large number of pistons can also be provided in the coaxial transmission according to the invention in order to be able to transmit particularly high torques, wherein a plurality of pistons are pressed simultaneously and essentially in the same manner with their first end-side toothing against the internal toothing, this is usually not necessary in practice.

[0021] The linear motion of the piston is important for the surface contact. In addition, the toothing and the internal toothing can be geometrically designed or optimized accordingly to further enhance the pressing or surface contact and thus enhance the high torque transmission.

[0022] By using at least three pistons, it can be ensured that the next piston, which presses its first end-side toothing flatly against the inner toothing, does not cause the hollow shaft or the possible guide unit to rotate in the opposite direction, and only a reciprocating oscillation of the hollow shaft or the possible guide unit about the axis of rotation occurs. While this situation cannot be excluded in principle in the case of a double piston, an additional element can be provided in the case of a double piston, such as a balance or flywheel, which only allows the hollow shaft or the possible guide unit to rotate in a specific direction, thereby enabling the hollow shaft or the possible guide unit to continue rotating even with only two pistons.

[0023] The toothing on the first end side may also be referred to as toothing formed on the first end side.

[0024] The guide unit can be designed in one piece or can be composed of a plurality of elements.

[0025] Since the pistons are linearly guided in the guide unit, the pistons accordingly only perform linear movements parallel to the respective radial direction, wherein the respective radial direction associated with the pistons is defined by the guide unit.

[0026] The linear guide can be formed in particular by a hollow cylinder in the guide unit, in which the piston is arranged. In this case, the radial direction of each piston is defined by the corresponding cylinder axis.

[0027] It should be pointed out again that, as will be explained further below, it is possible that the guide unit is not fixed but can rotate. Therefore, the radial direction of the piston will change due to the rotation of the guide unit, or strictly speaking in a mathematical sense there are an infinite number of radial directions within the time period during which the guide unit rotates.

[0028] Furthermore, the coaxial transmission according to the invention can be locked by stopping one of the pistons at the top dead center, ie at the maximum stroke of the piston in the corresponding radial direction away from the axis of rotation, thereby achieving a braking function.

[0029] A further advantage of the coaxial transmission according to the invention is that high dynamics / kinetic performance can be achieved, since at least one connecting rod journal of the crankshaft describes a circular movement about the axis of rotation and preferably itself has a circular cross-section perpendicular to the axis of rotation, so that mass balancing can be achieved very simply, for example in a known manner using balancing weights on the crankshaft.

[0030] Furthermore, the use of connecting rods and pistons allows for a modular design. By varying the number of pistons, their angular offset about the axis of rotation and their distribution on different connecting rod journals, the transmission stages can be variably adjusted. This results in different transmission ratios while also maintaining the dimensions of the transmission. The modular design of the transmission allows for large-scale production of individual components without losing product flexibility and thus ensures fast delivery.

[0031] In order to further increase the magnitude of the transmittable torque, in a preferred embodiment of the coaxial transmission according to the invention, it is provided that the toothed portion of the first end side has a plurality of teeth, preferably three teeth. As the number of teeth of the toothed portion of the first end side increases, the area that the corresponding piston can press against the inner toothed portion increases, which enables a particularly large torque to be transmitted between the crankshaft and the hollow shaft or a possible guide unit.

[0032] In a preferred embodiment of the coaxial transmission according to the present invention, it is provided that a plurality of connecting rods are arranged one behind the other along the axis of rotation. Such a coaxial transmission is advantageous in terms of manufacturing technology.

[0033] In order to achieve a particularly space-saving design, a preferred embodiment of the coaxial transmission according to the invention provides that the connecting rods are at least partially located in a common plane perpendicular to the axis of rotation. For this purpose, the connecting rods can be arranged partially nested. As a result, the dimensions of at least one connecting rod support or the crankshaft along the axis of rotation can be set shorter.

[0034] In order to be able to achieve a structurally simple solution for this arrangement, in a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that in a plane extending parallel to the axis of rotation and / or including the axis of rotation, at least one of the connecting rods, preferably at least two of the connecting rods, has a substantially "U"-shaped or "J"-shaped cross-section.

[0035] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that at least two of the pistons have different diameters, wherein the diameter is respectively measured in a transverse direction, the respective transverse direction being perpendicular to the respective radial direction. In this context, the extension (of the piston) in the transverse direction is referred to as the diameter, i.e. the piston does not in principle have to have a circular cross section in a plane perpendicular to the relevant radial direction.

[0036] In principle, each radial direction or piston provides an infinite number of transverse directions, wherein mutually corresponding transverse directions must always be considered in order to enable a meaningful comparison of the diameters, for example by the corresponding transverse directions being located in the same plane or in parallel planes. In particular, all transverse directions can extend parallel to the axis of rotation, thereby enabling a meaningful comparison in any case.

[0037] Due to the different piston sizes or different sizes of the piston diameter, a mass balance can be achieved, which is particularly advantageous primarily at high rotational speeds. Of course, it is also conceivable that the piston diameter has different sizes in addition when the connecting rod is arranged "upper and lower".

[0038] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that at least one piezoelectric element is provided in at least one of the pistons, preferably in all the pistons, in order to change the length of the respective piston measured parallel to the respective radial direction, in order to compensate for longitudinal deformations caused by heat or wear in this way.

[0039] In addition, by lengthening the piezoelectric element, an increase in pressure can be achieved, in particular an increase in the pressure of the first end-side toothing on the inner toothing. For example, this can be used to increase the braking effect (force) when one of the pistons is at top dead center.

[0040] In a preferred embodiment of the coaxial transmission device according to the present invention, it is provided that the piston has a toothing with at least one tooth on a second end side opposite to the first end side, and an inner ring with an external toothing is provided which is supported so as to be rotatable about an axis of rotation, wherein a guide unit is at least partially arranged between the inner ring and the hollow shaft, wherein the toothing on the second end side of the piston can be successively in a state of meshing with and disengaging from the external toothing, so that during the corresponding meshing period, the inner ring or the guide unit continues to rotate about the axis of rotation with surface contact between the corresponding toothing and the external toothing.

[0041] The toothing of the second end side can also be referred to as the toothing formed on the second end side. Preferably, the inner ring is supported so that it can rotate about the rotation axis, and as long as the inner ring is not locked, the inner ring has the function of a shaft in principle and can therefore also be referred to as an inner shaft. The outer toothing of the inner ring points to the inner toothing of the hollow shaft.

[0042] In principle, what has been said about the meshing of the first end-side toothing with the internal toothing of the hollow shaft applies analogously to the meshing of the second end-side toothing with the external toothing of the inner ring, to which reference is therefore made. That is, due to the surface contact or surface pressure between the second end-side toothing of the pistons and the external toothing of the inner ring, higher torques can be transmitted between the crankshaft and the inner ring or a possible guide unit in comparison with solutions with linear contact.

[0043] Furthermore, a plurality of teeth, in particular three teeth, can be provided in the toothing of the second end face in order to transmit particularly high torques between the crankshaft and the inner ring or a possible guide unit.

[0044] When the guide unit is braked or fixed, one or each piston drives the hollow shaft and the inner ring alternately. It is possible that both the inner ring and the hollow shaft are used as the driven element. It is also possible that only the hollow shaft or only the inner ring is used as the driven element, wherein the other element is braked or locked.

[0045] Since the diameter of the inner ring is smaller than that of the hollow shaft, a lower linear speed / tangential speed can be achieved or obtained on the inner ring at the same angular speed. In other words, the inner ring and the hollow shaft can provide two driven members with different speeds at the same time, thereby eliminating the possible second transmission device according to the application.

[0046] The inner ring can, but need not necessarily, be connected to the hollow shaft in a rotationally fixed manner, wherein, in this connection, on the one hand, a higher resolution of the coaxial transmission can be achieved and, on the other hand, a higher torque can be transmitted.

[0047] Furthermore, embodiment variants are conceivable which have only two pistons, in which case, due to a total of four (piston) teeth, it can be ensured by means of the inner ring that the hollow shaft or a possible guide unit can only move further in a certain direction.

[0048] Finally, it is also possible that the inner ring rotates in a direction opposite to the direction of rotation of the hollow shaft.

[0049] In a particularly preferred embodiment of the coaxial transmission according to the invention, it is provided that the inner toothing of the hollow shaft and the outer toothing of the inner ring have the same number of teeth. This ensures that the angular velocities of the hollow shaft and the inner ring are equal. The geometrical configurations or contours of the inner and outer toothing are accordingly designed differently, that is, the inner toothing of the hollow shaft is designed with relatively large teeth or tooth spacings.

[0050] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that for at least two of the pistons, the respective radial directions enclose an angle not equal to zero measured about the axis of rotation. That is, the pistons are at least partially angularly offset relative to one another. This influences the properties of the coaxial transmission. In addition to harmonic rotations, non-harmonic movements are also possible, wherein the application areas for such coaxial transmissions can be, for example, vibrators. The angular offset leads to the teeth of the internal toothing being jumped over according to the angle of the pistons relative to one another and / or a change in the direction of rotation of the hollow shaft or a possible guide unit.

[0051] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that the crankshaft is designed to be hollow so that the cable can be guided through the crankshaft, preferably along the axis of rotation, without twisting.

[0052] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that the guide unit is arranged so as to be immovable relative to the axis of rotation. In this case, the hollow shaft continues to move and serves as a driven element. If necessary, in such an embodiment variant, the inner ring (if present) can also continue to move, the inner ring can be braked again and can also serve as a driven element.

[0053] In a preferred embodiment of the coaxial transmission according to the invention, it is provided that the guide unit is supported so as to be rotatable about the axis of rotation, wherein preferably a mechanism is provided for braking the rotation of the guide unit about the axis of rotation. When the guide unit is braked, the hollow shaft can continue to rotate and can be used as a driven element. The mechanisms for braking the guide unit are known and can, for example, be braked by friction or by eddy currents.

[0054] If, however, the hollow shaft is fixed or braked in a known manner, such as the mechanism mentioned above by way of example for the guide unit (ie, for example, by means of friction or eddy currents), the guide unit serves as an output element. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The invention will now be explained in more detail with the aid of examples. The accompanying drawings are exemplary and intended to illustrate the inventive concept, but are not intended to be limiting or even exclusive. In them:

[0056] Figure 1 A schematic cross-sectional view of a coaxial transmission according to the invention is shown, wherein the connecting rods are arranged one behind the other along the axis of rotation;

[0057] Figure 2 Show according to Figure 1 A sectional view of the section line AA of FIG. 1 , wherein the arrow indicates the viewing direction;

[0058] Figure 3 A schematic sectional view shows a further embodiment of a coaxial transmission according to the invention, in which the connecting rods lie at least partially in a common plane which is perpendicular to the axis of rotation;

[0059] Figure 4 Show according to Figure 3 A sectional view of the section line BB of , wherein the arrow indicates the viewing direction;

[0060] Figure 5 Shows similar Figure 3 A schematic sectional view of a further embodiment of a coaxial transmission according to the invention of an embodiment of , wherein the toothing of the first end side of the piston has a plurality of teeth;

[0061] Figure 6 Shows similar Figure 1 A schematic sectional view of a further embodiment of a coaxial transmission according to the invention of an embodiment of , wherein the piston has a piezoelectric element;

[0062] Figure 7 Shows similar Figure 1 Schematic sectional view of a further embodiment of a coaxial transmission according to the invention of an embodiment of FIG. 1 , in which an inner ring with an external toothing is provided. DETAILED DESCRIPTION

[0063] Figure 1 A coaxial transmission 1 or crankshaft transmission according to the invention is shown schematically in a section perpendicular to the rotation axis 2. The coaxial transmission 1 comprises a crankshaft 3 rotatable about the rotation axis 2 and having at least one connecting rod bearing 4, wherein in the illustrated embodiment, exactly one connecting rod bearing 4 or exactly one connecting rod journal or crank pin is provided.

[0064] A plurality of pistons are connected to the connecting rod support 4 in a known manner, or the pistons are movably supported on the connecting rod support 4, for example, the separate connecting rod holes of the connecting rods 6a, 6b, 6c are respectively connected by means of screws 21 (see Figure 1 ) is fastened to the connecting rod support 4, and the pistons 5a, 5b, 5c are connected to the other connecting rod holes of the connecting rods 6a, 6b, 6c by means of piston pins. Figure 1 In the embodiment, a total of five pistons are provided, wherein Figure 1 Only three pistons 5a, 5b, 5c can be seen in FIG. The piston 5a is connected to the crankshaft 3 or the connecting rod support 4 via a connecting rod 6a, the piston 5b is connected via a connecting rod 6b and the piston 5c is connected via a connecting rod 6c.

[0065] All pistons 5a, 5b, 5c each have a first end face 10a, 10b, 10c facing away from the axis of rotation 2 and having a formed toothing 11a, 11b, 11c, each toothing 11a, 11b, 11c having exactly one tooth in the exemplary embodiment shown.

[0066] In the illustrated embodiment, Figure 1 As shown, the crankshaft 3 is designed to be hollow along the axis of rotation 2 , which allows, for example, cables (not shown) to be guided through without twisting.

[0067] Furthermore, a hollow shaft 7 is provided in the coaxial transmission 1, which has an internal toothing 8. Figure 1 In the plane of the drawing perpendicular to the axis of rotation 2, the pistons 5a, 5b, 5c (and the crankshaft 3 at least partially) are arranged inside the hollow shaft 7. This also applies to the guide unit 9, in which the pistons 5a, 5b, 5c are each linearly guided and can reciprocate parallel to the radial direction 12a, 12b, 12c, which is perpendicular to the axis of rotation 2. For this purpose, in the illustrated embodiment, the guide unit 9 has a hollow cylinder, which serves as a linear guide for the pistons 5a, 5b, 5c.

[0068] By the reciprocating movement of the pistons 5a, 5b, 5c, the toothings 11a, 11b, 11c of the first end sides 10a, 10b, 10c of the pistons 5a, 5b, 5c are successively in a state of meshing with the internal toothing 8 and disengaging from the internal toothing 8, wherein due to the linear movement of the pistons 5a, 5b, 5c, during the corresponding meshing, a surface contact between the corresponding toothings 11a, 11b, 11c and the internal toothing 8 can be ensured, and the corresponding toothings 11a, 11b, 11c are pressed against the internal toothing 8 in a surface manner. As a result, when the guide unit 9 is arranged so as to be immovable relative to the rotation axis 2 or when the guide unit 9 is arranged so as to be rotatable around the rotation axis 2 but is braked, the hollow shaft continues to rotate by a stroke around the rotation axis 2. On the other hand, when the hollow shaft 7 is fixed or immovable relative to the rotation axis 2 or is braked, the guide unit 9 (supported so as to be rotatable around the rotation axis 2) continues to rotate by a stroke. Due to the surface engagement or pressing, very high torques can be transmitted from the crankshaft 3 to the hollow shaft 7 or to a possible guide unit 9. Figure 1 In the embodiment of the invention, the connecting rods 6a, 6b, 6c are arranged one behind the other on the crankshaft 3 or the connecting rod support 4 along the axis of rotation 2. Figure 2 Cross-sectional view (according to Figure 1 AA, wherein the arrow indicates the viewing direction), wherein the fourth piston 5c' and the associated connecting rod 6c' and the connecting rod 6a' of the fifth piston can also be seen (the fifth piston is not shown, which is along Figure 1 The viewing direction of the drawing is Figure 1 Behind the element shown in FIG. 1 , or viewed along the axis of rotation 2 , is the last piston, wherein piston 5 a is the first piston).

[0069] In order to ensure effective and at the same time space-saving mass balancing, especially at relatively high rotational speeds, Figure 1 In the embodiment shown in FIG. 1 , different piston diameters 13 are provided, wherein the piston diameters 13 are respectively measured in a transverse direction, the respective transverse direction being perpendicular to the respective radial direction 12a, 12b, 12c. In particular, piston 5b has a piston diameter 13 which is greater than the diameters of pistons 5a and 5b, wherein all pistons except piston 5b have the same piston diameter 13 (thus, for the sake of clarity, in FIG. 1 ). Figure 1 The piston diameter 13 of the piston 5a is not shown separately.

[0070] It should be noted that in the illustrated embodiment the pistons 5a, 5b, 5c have a circular cross section in the section arranged in the hollow cylinder of the guide unit 9, wherein the respective cross section lies in a plane perpendicular to the respective radial direction 12a, 12b, 12c.

[0071] from Figure 1 and Figure 2 It can also be seen that some of the pistons 5a, 5b, 5c have an angular offset 20 measured about the axis of rotation 2 with respect to one another. That is, the radial directions 12a, 12b, 12c associated with each piston 5a, 5b, 5c respectively enclose one another at an angle not equal to zero measured about the axis of rotation 2. Specifically, in the illustrated embodiment, the angular offset 20 between the piston 5a and the piston 5b is 120°, or the angle between the radial direction 12a and the radial direction 12b is 120°. Similarly, this applies to the angular offset 20 between the piston 5b or 5c and the piston 5c or 5a, or to the angle between the radial direction 12b or 12c and the radial direction 12c or 12a.

[0072] The piston 5c' is arranged at the same angular position about the axis of rotation 2 as the piston 5c (see Figure 2 ). A fifth piston (not shown) is arranged at the same angular position about the axis of rotation 2 as the piston 5a.

[0073] Angular offset 20 can cause teeth of internal toothing 8 to jump depending on the angle of pistons 5a, 5b, 5c relative to one another and / or change the direction of rotation of hollow shaft 7 or of a possible guide unit 9. The properties of coaxial transmission 1 can therefore be influenced by angular offset 20.

[0074] Figure 3 A schematic sectional view shows a further embodiment of a coaxial transmission 1 according to the invention, which has exactly three pistons 5a, 5b, 5c and three associated connecting rods 6a, 6b, 6c, wherein the connecting rods 6a, 6b, 6c are not arranged one behind the other along the axis of rotation 2, but lie at least partially in a common plane perpendicular to the axis of rotation 2. This embodiment is accordingly very compact, since the dimensions parallel to the axis of rotation 2 can be kept correspondingly short.

[0075] Figure 3 The pistons 5a, 5b, 5c in the exemplary embodiment of have the same piston diameter 13. The mass balancing can be achieved in a known manner by means of balancing weights on the crankshaft 3, for example.

[0076] from Figure 4 Cross-sectional view (according to Figure 3As can be seen from the section line BB of FIG. 1 , in which the arrow indicates the viewing direction, this “up and down” arrangement of the connecting rods 6a, 6b, 6c is possible in that the connecting rods 6a and 6c have a substantially U-shaped cross section in a plane extending parallel to the rotation axis 2 and / or including the rotation axis 2. The connecting rod 6b has a substantially I-shaped cross section, which is arranged along the rotation axis 2 between those sections of the connecting rod 6c that form the two parallel sides of the U-shaped shape of the cross section of the connecting rod 6c. The described section of the connecting rod 6c is arranged along the rotation axis 2 between those sections of the connecting rod 6a that form the two parallel sides of the U-shaped shape of the cross section of the connecting rod 6a.

[0077] besides, Figure 3 The implementation method and Figure 1 The embodiments of are similarly applicable. In particular, Figure 3 The pistons 5 a , 5 b , 5 c of the embodiment of FIG. 5 also have an angular offset 20 of 120° with respect to one another.

[0078] In order to further increase the magnitude of the transmittable torque, the toothed sections 11a, 11b, 11c may each have a plurality of teeth. Figure 5 is shown in, which embodiment is similar to Figure 3 Specifically, in Figure 5 In the embodiment of the present invention, the toothed parts 11a, 11b, 11c respectively have three teeth, thereby Figure 3 Compared with the embodiment of the present invention, the amount of torque that can be transmitted can be significantly improved.

[0079] Figure 6 Shown with Figure 1 Schematic sectional view of another embodiment of the coaxial transmission 1 according to the invention similar to the embodiment of the present invention, in which the pistons 5a, 5b, 5c have piezoelectric elements 14a, 14b, 14c. By means of the piezoelectric elements 14a, 14b, 14c, the velocity of the respective piston 5a, 12b, 12c measured parallel to the respective radial direction (for the sake of clarity) can be changed. Figure 6 In the figure, only the piston 5b is shown in the piston length 15. In this way, longitudinal deformations / lengths of the pistons 5a, 5b, 5c caused by heat or wear can be compensated. In addition, increasing the piston length 15 by the piezoelectric elements 14a, 14b, 14c can achieve an increase in pressure, in particular the pressure of the toothing 11a, 11b, 11c of the first end side 10a, 10b, 10c acting on the inner toothing 8.

[0080] If the pistons 5a, 5b, 5c also have a toothing 17a, 17b, 17c formed on a second end side 16a, 16b, 16c opposite the first end side 10a, 10b, 10c, the pressure can optionally also be increased there by means of the piezoelectric element 14a, 14b, 14c.

[0081] Figure 7 An embodiment is shown in FIG. 1 , in which the pistons 5a, 5b, 5c have a second end side 16a, 16b, 16c with a toothed section 17a, 17b, 17c. This embodiment also has an inner ring 18 and is otherwise similar to Figure 1 The implementation method is similar. Accordingly, in principle, refer to the above Figure 1 The content of the implementation method described in the embodiment.

[0082] In the illustrated embodiment, each of the toothed portions 17 a , 17 b , 17 c has one tooth, but it is also feasible for each of the toothed portions 17 a , 17 b , 17 c to have a plurality of teeth.

[0083] The inner ring 18 has an outer toothing 19 pointing toward the inner toothing 8 and is supported so as to be rotatable about the rotation axis 2. The guide unit 9 is arranged at least partially between the inner ring 18 and the hollow shaft 7, wherein the toothing 17a, 17b, 17c of the second end sides 16a, 16b, 16c of the pistons 5a, 5b, 5c can successively be in a state of meshing with the outer toothing 19 and disengaging from the outer toothing 19.

[0084] During the respective meshing, due to the linear movement of the pistons 5a, 5b, 5c, surface contact between the respective toothing 17a, 17b, 17c and the outer toothing 19 of the inner ring 18 can be ensured and the respective toothing 17a, 17b, 17c can be pressed against the outer toothing 19 in a surface manner.

[0085] Thus, when the guide unit 9 is arranged immovably relative to the rotation axis 2 or when the guide unit 9 is arranged rotatably about the rotation axis 2 but is braked, the inner ring 18 continues to rotate by a stroke about the rotation axis 2. More precisely, when the guide unit 9 is braked or fixed, one or each piston 5a, 5b, 5c alternately drives the hollow shaft 7 and the inner ring 18. Therefore, both the inner ring 18 and the hollow shaft 7 can be used as driven elements.

[0086] It is also possible to use only the hollow shaft 7 or only the inner ring 18 as the output element, wherein the other element is braked or locked in each case.

[0087] It is of course also conceivable that both the hollow shaft 7 and the inner ring 18 are fixed, so that only the guide unit 9 moves and can serve as an output element.

[0088] In particular, compared to solutions with linear contact, very high torques can be transmitted between the crankshaft 3 and the inner ring 18 or, if applicable, the guide unit 9 .

[0089] exist Figure 7 In the embodiment of the embodiment of the present invention, the outer toothing 19 has exactly the same number of teeth as the inner toothing 8. The geometrical structures or contours of the inner toothing 8 and the outer toothing 19 are designed accordingly differently, that is to say the inner toothing 8 of the hollow shaft 7 has a relatively large tooth or tooth spacing. Accordingly, the hollow shaft 7 and the inner ring 18 rotate at the same angular speed. This same angular speed can also be achieved by a rotationally fixed connection of the hollow shaft 7 to the inner ring 18.

[0090] Since the inner ring 18 has a smaller diameter than the hollow shaft 7, a lower linear speed / tangential speed can be achieved or obtained on the inner ring at the same angular speed. That is, two driven elements with different speeds can be provided simultaneously by the inner ring 18 and the hollow shaft 7, whereby a possible second transmission can be omitted depending on the application.

[0091] List of reference numerals:

[0092] 1 Coaxial transmission

[0093] 2 Axis of rotation

[0094] 3 Crankshaft

[0095] 4 Connecting rod support

[0096] 5a, 5b, 5c, 5c' Piston

[0097] 6a, 6a', 6b, 6c, 6c' Connecting rod

[0098] 7 Hollow shaft

[0099] 8 Internal teeth of hollow shaft

[0100] 9 Guide unit

[0101] 10a, 10b, 10c First end side of the piston

[0102] 11a, 11b, 11c first end side tooth portion

[0103] 12a, 12b, 12c Radial direction

[0104] 13 Piston diameter

[0105] 14a, 14b, 14c Piezoelectric element

[0106] 15 Piston length

[0107] 16a, 16b, 16c Second end side of the piston

[0108] 17a, 17b, 17c Second end side tooth portion

[0109] 18 Inner Ring

[0110] 19 External teeth of inner ring

[0111] 20 Angle offset

[0112] 21 Screws

Claims

1. A coaxial transmission (1), comprising a crankshaft (3) rotatable about an axis of rotation (2) and having at least one connecting rod support (4), The coaxial transmission device (1) also includes a plurality of pistons (5a, 5b, 5c), each of which is connected to the at least one connecting rod support (4) by means of a connecting rod (6a, 6b, 6c), each of which has a toothed portion (11a, 11b, 11c) on a first end side (10a, 10b, 10c) facing away from the rotation axis (2), wherein the toothed portion has at least one tooth. The coaxial transmission device (1) further comprises a hollow shaft (7) having an internal toothed portion (8), wherein: The pistons (5a, 5b, 5c) are arranged inside the hollow shaft (7) when viewed in a plane perpendicular to the axis of rotation (2). The coaxial transmission device (1) also includes a guide unit (9), wherein the pistons (5a, 5b, 5c) are respectively linearly guided in the guide unit (9), and the pistons can reciprocate parallel to a radial direction (12a, 12b, 12c), which is perpendicular to the rotation axis (2), thereby enabling the toothed portions (11a, 11b, 11c) of the first end sides (10a, 10b, 10c) of the pistons (5a, 5b, 5c) to be successively in a state of meshing with the internal toothed portion (8) and in a state of disengagement from the internal toothed portion (8), so that during the corresponding meshing period, the hollow shaft (7) or the guide unit (9) continues to rotate around the rotation axis (2) with surface contact between the corresponding toothed portions (11a, 11b, 11c) and the internal toothed portion (8), and the connecting rods (6a, 6b, 6c) are at least partially located in a common plane perpendicular to the rotation axis (2).

2. The coaxial transmission device (1) according to claim 1, characterized in that: The toothed sections (11a, 11b, 11c) of the first end sides (10a, 10b, 10c) each have a plurality of teeth.

3. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: A plurality of connecting rods (6a, 6b, 6c) are arranged front and rear along the rotation axis (2).

4. The coaxial transmission device (1) according to claim 1, characterized in that: In a plane extending parallel to the rotation axis (2) and / or including the rotation axis (2), at least one of the connecting rods (6a, 6b, 6c) has a substantially "U"-shaped or "J"-shaped cross section.

5. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: At least two of the pistons (5a, 5b, 5c) have different diameters (13), wherein the diameters (13) are respectively measured along a transverse direction, the respective transverse direction being perpendicular to the respective radial direction (12a, 12b, 12c).

6. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: In at least one of the pistons (5a, 5b, 5c), at least one piezoelectric element (14a, 14b, 14c) is arranged to change the length (15) of the corresponding piston (5a, 5b, 5c) measured parallel to the corresponding radial direction (12a, 12b, 12c).

7. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: The pistons (5a, 5b, 5c) each have a toothing (17a, 17b, 17c) with at least one tooth on a second end side (16a, 16b, 16c) opposite to the first end side (10a, 10b, 10c), an inner ring (18) is provided which is supported so as to be rotatable about an axis of rotation (2), the inner ring having an external toothing (19), wherein a guide unit (9) is arranged at least partially between the inner ring (18) and the hollow shaft (7), In the process, the toothed portions (17a, 17b, 17c) of the second end sides (16a, 16b, 16c) of the pistons (5a, 5b, 5c) can be successively placed in a state of meshing with the external toothed portion (19) and disengaging from the external toothed portion (19), so that during the corresponding meshing period, the inner ring (18) or the guide unit (9) continues to rotate around the rotation axis (2) with surface contact between the corresponding toothed portions (17a, 17b, 17c) and the external toothed portion (19).

8. The coaxial transmission device (1) according to claim 7, characterized in that: The inner toothing (8) of the hollow shaft (7) and the outer toothing (19) of the inner ring (18) have the same number of teeth.

9. The coaxial transmission device (1) according to claim 1 or 2, characterized in that For at least two of the pistons (5a, 5b, 5c), the respective radial directions (12a, 12b, 12c) enclose an angle (20) not equal to zero measured about the axis of rotation (2).

10. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: The crankshaft (3) is hollow.

11. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: The guide unit (9) is arranged so as to be immovable relative to the rotation axis (2).

12. The coaxial transmission device (1) according to claim 1 or 2, characterized in that: The guide unit (9) is supported so as to be rotatable about a rotation axis (2).

13. The coaxial transmission device (1) according to claim 12, characterized in that: A mechanism is provided for braking the rotation of the guide unit (9) around the rotation axis (2).

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