Patent Application
20230112146
The present disclosure relates to a rocker pin for a rocker pin pair of a plate link chain. The present disclosure further relates to a rocker pin pair with such a rocker pin for a plate link chain of a belt transmission, a plate link chain with such a rocker pin pair for a belt transmission of a drive train, a belt transmission with such a plate link chain for a drive train, and a drive train with a such belt transmission.
Rocker pins for a rocker pin pair of a plate link chain are known from the prior art as traction devices in the form of belt elements for belt transmissions; for example, in a so-called CVT (continuous variable transmission). Such a CVT is known, for example, from DE 100 17 005 A1. Such a plate link chain is set up to transmit high torques and high speeds, as is known, for example, from motor vehicle engine construction. Because the gear noises are unfamiliar and generally perceived as annoying, it is a constant challenge to create a plate link chain that has low noise emissions. However, the object is also to provide a long service life of the plate link chain, to avoid the need for replacement over the service life of a motor vehicle, and to provide a high degree of efficiency. Furthermore, small running radii (i.e., diameters effective for the transmission) on the conical pulley pairs of a belt drive desirable so that a large transmission ratio can be achieved in a small (radial) installation space. A plate link chain with rocker pins is known, for example, from WO 2016/095 913 A1.
Noise, vibration and harshness (NVH) and strength are the dominant issues in the further development of the plate link chain. Furthermore, the efficiency and wear must also be improved and, for a large ratio spread and/or small installation space, it must be possible to achieve a small minimum running radius on the conical pulley pairs. So far, attempts have been made to keep the vibration excitation low by using different pitch lengths (implemented by two different plate link types) and their sequence (for example, as chaotic as possible). These measures have already been almost exhausted and further changes promise only little further potential. Another previously known measure is that the angle of the end faces of the rocker pins is made larger than the angle of the conical surface of the conical pulley pairs, so that when entering a conical pulley pair, the radially outer edge of the respective end face of the rocker pin first comes into engagement with the corresponding conical surface of the conical pulley pairs. Only as a result of a deformation of the rocker pin caused by the axial pressing force does a further part, e.g., the entire end face, come into contact with the corresponding surface of the conical pulley pair. However, because this measure leads to edge wear and thus to a higher load on the frictional contact, there are limits to this measure.
The present disclosure relates to a rocker pin for a rocker pin pair of a plate link chain having
In an example embodiment, the magnitude of the radial radius increases from radially outside to radially central and/or the magnitude of the azimuthal radius increases from forward with respect to the running direction to central with respect to the running direction in discrete radius portions.
In the following, if the chain running direction, axial direction, or radial direction and corresponding terms are used without explicitly indicating otherwise, reference is made to the aforementioned spatial directions. Unless explicitly stated otherwise, ordinal numbers used in the preceding and subsequent description are used only for the purposes of clear distinction and do not indicate an order or the order of designated components. An ordinal number greater than one does not necessarily mean that another such component must be present.
The rocker pin proposed here can be used in a rocker pin pair with a further rocker pin. The two rocker pins of a rocker pin pair are in use in a plate link chain with their rolling surface in force-transmitting contact with one another and in force-transmitting contact with their link-side contact surfaces with one (other) associated plate link. For this purpose, a rocker pin has a length extension which, when in use, is parallel to the axial direction. The axial direction is defined as a direction parallel to the rotation axes of the conical pulley pairs. The plate links of a plate link chain are suspended adjacent to one another in the axial direction on the rocker pin pair or the majority of rocker pin pairs of the plate link chain and each form a plate link assembly in the case of two adjacent rocker pin pairs.
Furthermore, the rocker pin has a height extension that is parallel to the radial direction. The radial direction is defined on a wrap-around loop formed by a plate link chain, and this shape is generally oval when in use, i.e., two centers (at the rotation axes of the conical pulley pairs) are formed, which are connected by a center line. The radial direction is positively defined as extending outwards (outside the wrap-around loop) from the center line (inside the wrap-around loop). Within the wrap-around loop is referred to here as radially inside, and outside of the wrap-around loop is accordingly referred to here as radially outside.
The third spatial direction is the chain running direction, which in use depends on the location in the wrap-around loop, and thus the three spatial directions mentioned here are to be regarded as a moving coordinate system. The width extension of the rocker pin is parallel to the chain running direction. In an example embodiment, a rocker pin has an oval, approximately teardrop-shaped cross portion (with the axial direction as normal), and the rocker pin is radially narrow on the inside and radially wider on the outside. The height extension is defined as the maximum extension in the radial direction and the width extension as the maximum extension in the chain running direction (in a straight portion of the plate link chain, i.e., when used in an ideally tensioned strand).
At the end, i.e., when viewed in the axial direction, an end face is provided in each case, which is set up in force-transmitting, e.g., frictional, contact with the corresponding conical surface of the conical pulley pairs. In an example embodiment, the end face is inclined axially inward in accordance with the inclination of the conical surface of the conical pulley pairs from radially outward to radially inward, but a little more, so that the end faces of the (unloaded) rocker pin are not radially parallel to the conical surface, but only the radially outwardly arranged outer edge (minus a provided rounding radius over the outer edge to the longitudinal extension of the rocker pin, for example) comes into contact with the conical surface in the unloaded state of the rocker pin, i.e., when running into a conical pulley pair.
In an example embodiment, the end face is inclined azimuthally inwards, i.e., inclined inwards in the chain running direction from forward (with respect to the running direction) to rearward (with respect to the running direction), so that the end faces of the (unloaded) rocker pins are not azimuthally parallel to the conical surface, but only the radially outwardly arranged outer edge (minus a provided rounding radius over the outer edge to the longitudinal extension of the rocker pin, for example) comes into contact with the conical surface in the unloaded state of the rocker pin, i.e., when running into a conical pulley pair. In an example embodiment, the end faces are both axially and azimuthally inclined inward from radially outside to radially inside.
For a desired point contact or line contact, the end faces may also have a curvature. This means that the inclination of the end face is overlaid by a curvature, and a radial radius describes a curvature component based on the end face inclined axially inwards from radially outside to radially inside and an azimuthal radius describes a curvature component based on the end face inclined azimuthally (inward from forward with respect to the running direction to rearward with respect to the running direction). Providing such a curvature is well known in various variants; for example, from DE 34 47 092 A1, DE 197 08 865 A1, DE 100 03 131 A1, DE 10 2007 023 277 A1, JP 2009-209 992 A and US 9,316,287 B2.
Here, it is now proposed that the magnitude of the radial radius increases from radially outside to radially central and/or the magnitude of the azimuthal radius increases from forward with respect to the running direction to central with respect to the running direction in discrete radius portions. It has been shown that a contact point between the rocker pin and the conical surface as far radially outward as possible and/or as far forward as possible in the running direction of the chain brings acoustic advantages. Thus (as already known) a large angle difference between the conical surface and the respective end face must be set. With the end face proposed here, a contact point (or a contact line) results very far radially outside or very far forward with respect to the running direction.
At the same time, a suitable pressure distribution under load results from the radius that increases towards the center of the end face. With a higher load, i.e., a deflection (of the neutral longitudinal axis along the length extension) of the rocker pin around the chain running direction or around the radial direction, the contact point is shifted further inside in the radial direction or rearward with respect to the direction of travel, where larger radii are realized and thus the contact area is increased, so that the contact pressure is reduced at least in comparison to previously known embodiments. In an example embodiment, the radius portions are configured in such a way that there is (almost) constant pressure over the course of the load. At the same time, this ensures that the contact point remains as far as possible radially on the outside or in front of the running direction, because with the increasing radius the bending-induced displacement of the contact point is shifted less strongly radially on the inside or rearward with respect to the running direction. It is also proposed here that the radius has discrete radius portions that are assigned to a respective discrete load state range. This makes the production of the end face economical.
In one embodiment, the center of the end face is the geometric centroid. In one embodiment, it is the intersection of the neutral longitudinal axis of the rocker pin. In one embodiment, it is the contact point at a medium load, and a medium load may be a load that occurs frequently; for example, a torque transmission in an efficiency optimum of the drive engine.
It is further proposed in an example embodiment of the rocker pin that the magnitude of the radial radius decreases from radially central to radially inside and/or the magnitude of the azimuthal radius decreases from central with respect to the running direction to rearward with respect to the running direction, e.g., in discrete radius portions.
In this embodiment it is proposed that the respective radius decreases again radially inwards or rearward with respect to the direction of travel. This prevents the contact point from being displaced too far radially inward or rearward with respect to the direction of travel under heavy loads and from remaining as central as possible. This means that a small running radius can be achieved in relation to the radial radius, because the radially innermost edge of the rocker pin never comes into force-transmitting contact with the conical surface. With regard to the azimuthal radius as well as the radial radius, an edge carrier under maximum load is excluded and thus low noise emissions and low wear are achieved.
In an example embodiment, the radius has discrete radius portions that are assigned to a respective discrete load range. This makes the production of the end face economical.
According to a further aspect, a rocker pin for a rocker pin pair of a plate link chain is proposed having
In an example embodiment, the magnitude of the radial radius increases from radially outside to radially central and/or the magnitude of the azimuthal radius increases from forward with respect to the running direction to central with respect to the running direction, and the magnitude of the radial radius decreases from radially central to radially inside and/or the magnitude of the azimuthal radius decreases from central with respect to the running direction to rearward with respect to the running direction.
The rocker pin proposed here largely corresponds to a combination of the aforementioned embodiments and reference is made to the previous description in this respect. In one possible embodiment of the rocker pin proposed herein, in contrast to the previously mentioned embodiments, the end face does not have discrete radius portions everywhere, e.g., none. Rather, magnitudes of such a radius change continuously up to the middle into larger magnitudes and from the middle back into smaller magnitudes.
It is further proposed in an example embodiment of the rocker pin that the radius portions merge tangentially into one another.
In this embodiment, a gentle transition is created between the radius portions, so that the surface pressure also remains low in a transition area. In an example embodiment, the tangential transition is continuously differentiable. A technical approach to a continuously differentiable transition in the context of cost-efficient manufacturing is economical. With a good approximation, jumps in pressure at the transitions between the radius portions are avoided. In addition to reduced noise emissions, the efficiency can be improved and the wear on the end faces of the rocker pins and the conical surfaces of the conical pulley pairs is reduced.
According to a further aspect, a rocker pin pair for a plate link chain of a belt transmission is proposed, having two rocker pins, at least one of which is designed according to an embodiment according to the aforementioned description, and the end faces of the rocker pins of the rocker pin pair may be designed identically.
The rocker pin pair proposed here includes two rocker pins, and at least one of the two rocker pins is designed according to an embodiment according to the aforementioned description, e.g., both rocker pins are designed according to an embodiment according to the aforementioned description. Since the rocker pins of a rocker pin pair are supported on one another during use due to the tensile force, they reinforce each other. Two load cases occur, i.e. initially only the front cradle thrust piece runs in, so that the rear rocker pin is initially not subject to any axial load. The bending of the front rocker pin in the direction of travel is partially absorbed, i.e., damped, by the rear rocker pin, which is unloaded in the axial direction. Subsequently, the rear rocker pin also runs into the conical pulley pair and is now also subject to the axial load of the two conical pulleys (fully run-in condition). In an example embodiment, the end faces of the rocker pins of the rocker pin pair are therefore identical, so that their deflection in the fully run-in state under the axial load is (almost) identical.
According to a further aspect, a plate link chain is proposed for a belt transmission of a drive train, having at least the following components:
The plate link chain proposed here is set up as a traction device for a belt transmission, for example for a CVT. In a belt transmission, a plate link chain forms a wrap-around loop portion on the transmission shafts and two strands in between, one being a tight strand or load strand and the other being a slack strand. The strands and the wrap-around loop portions together form an (oval) wrap-around loop, as explained above. A wrap-around loop does not mean a loop with a constant radius, but a circumferentially closed structure. The form is defined by the running radii (set by means of a pulley distance) of the conical pulley pairs of the belt transmission. The spatial directions are also defined here as explained above.
The plate link chain has a chain width, and across this chain width a plurality of plate links are usually arranged adjacent to one another and form a plate link assembly. In use, the chain width is oriented parallel to the orientation of the at least two transmission shafts. The chain width is defined by the width extension of the rocker pins, and the (axial) ends of the rocker pins protrude beyond the plate link assembly so that the plate links do not come into frictional contact with the corresponding surface of the pulley pairs.
The plate link chain has a large number of plate links, and a plurality of plate link types (as explained above) for reduced noise emission, for example two plate link types, namely a short plate link and a long plate link. The plate links (of a plate link assembly) each have two adjacent rocker pin pairs. A rocker pin pair has a fixed rocker pin and a free rocker pin in relation to a plate link. Two plate links are each connected to one another in a traction-transmitting manner by means of a common rocker pin pair, and the designation as a free or fixed rocker pin is reversed in each case for the other plate link. The two rocker pins of a rocker pin pair are in direct contact with one another in a force-transmitting manner as a result of the traction force transmitted during the operation of the belt transmission by the plate links of the plate link chain and thus the plate link load acting on the rocker pin pair (applying on both sides in the chain running direction). The two rocker pins of the rocker pin pair thus transfer the traction force of the plate links to one another as a pressure force and, during motion in a belt transmission, roll off one another by means of their rolling surfaces lying against one another in a force-transmitting manner. The rolling surfaces are curved or kinked and thus describe a rocking motion on one another during operation of the belt transmission.
In a CVT, for example, the end faces of the rocker pins are designed to be inclined radially outwardly to radially inwardly on the inside in order to create an approximately parallel contact surface with the (inclined conical) surfaces of the conical pulley pairs, or (as explained above) for reduced noise emission with a greater inclination of the end faces than the conical surfaces of the conical pulley pairs.
In a CVT, a torque is introduced into the plate link chain via the end faces of the rocker pins. The rocker pins are thus loaded on both sides with an axial pressing force. The plate links transmit the torque as a tensile load to the respective associated rocker pins; for example, the immediately adjacent rocker pin, at least on the currently free, i.e., not axially pressed, rocker pins (at least of the load strand). The rocker pins or rocker pin pairs are thus linked by means of the multiplicity of plate links in a manner that transmits tensile force.
In an example embodiment, the plate link chain is set up as a looping means for a continuously variable transmission and the end faces of the rocker pins of the plate link chain are frictionally engaged in force-transmitting contact with the corresponding (conical) surfaces of the conical pulley pairs.
Here it is now proposed that in the end faces of the rocker pins of the rocker pin pairs of the plate link chain the magnitude of the radial radius increases from radially outside to radially central and/or the magnitude of the azimuthal radius increases from forward with respect to the running direction to central with respect to the running direction, e.g., in discrete radius portions, and the magnitude of the radial radius decreases from radially central to radially inside and/or the magnitude of the azimuthal radius decreases from central with respect to the running direction to rearward with respect to the running direction, for example, in discrete radius portions. With low noise emissions across the load cases (e.g. depending on the gear ratio states and/or the applied torque gradient), such a plate link chain has (almost) constant pressure on the end faces and thus an exact design limit for a maximum load on the conical surfaces of the conical pulley pairs, based on which a desired wear property or service life of the plate link chain and the belt transmission can be designed. The plate link chain proposed here can be used without additional measures to replace a conventional plate link chain.
According to a further aspect, a belt transmission is proposed for a drive train, having at least the following components:
The belt transmission is set up for a drive train, for example a motor vehicle, and includes at least a first conical pulley pair arranged on a first transmission shaft, for example the transmission input shaft, and a second conical pulley pair arranged on a second transmission shaft, for example the transmission output shaft, as well as one for torque transmission between the conical pulley pairs provided loop means, namely the plate link chain described above. A conical pulley pair has two conical pulleys which are oriented with corresponding conical surfaces to each other and are axially movable relative to each other. In an example embodiment, the (first) conical pulley, also referred to as a loose pulley or movable pulley, can be displaced (axially displaced) along its rotation axis and the (second) conical pulley, also referred to as a fixed pulley, is fixed (axially fixed) in the direction of the rotation axis. In this way, the respective pulley distance of the conical pulley pair in question can be changed.
When the belt transmission is in operation, the plate link chain is displaced as a result of the conical surfaces of the two conical pulleys by means of a relative axial movement of the conical pulley of a conical pulley pair between an inner position (small or minimum running radius) and an outer position (large or maximum running radius) in a radial direction (relative to the respective rotation axis). The plate link chain thus runs on a changeable running radius. As a result, a different rotational speed transmission ratio and torque transmission ratio can be, e.g., continuously, adjusted from one conical pulley pair to the other conical pulley pair.
The belt transmission proposed here has a plate link chain according to the above description, and the rocker pins of the plate link chain, due to the curvature of the end faces according to the above description, with a low noise emission over the load cases, has (almost) constant pressure on the end faces and thus an exact design limit for a maximum load of the conical surfaces of the conical pulley pairs, on the basis of which a desired wear property or service life of the plate link chain and the belt transmission can be designed. The belt transmission proposed here can be used without additional measures to replace a conventional belt transmission.
According to a further aspect, a drive train is proposed, having at least the following components:
The drive train, for example, of a motor vehicle used to drive at least one drive wheel (consumer), is designed to transmit a torque provided by one or a plurality of drive engines, for example an internal combustion engine and/or an electric drive engine, and output via the respective machine shaft thereof, i.e., the combustion drive shaft and/or the rotor shaft, for example, for use by a consumer as required, i.e., taking into account the required speed and the required torque. One use is, for example, an electrical generator to provide electrical energy and/or the transmission of torque to a drive wheel of a motor vehicle to propel the same.
In order to transmit the torque in a targeted manner and/or by means of a manual transmission with different gear ratios, the use of the belt transmission described above is helpful as the plate link chain enables a high level of efficiency in terms of torque transmission. The plate link chain proposed here also has a long service life with a high transmissible torque while at the same time emitting low noise.
The disclosure described above is explained in detail below based on the relevant technical background with reference to the associated drawings, which show example embodiments. The disclosure is in no way restricted by the purely schematic drawings, wherein it should be noted that the drawings are not dimensionally accurate and are not suitable for defining proportions. In the figures;
The radial radius 18 (drawn in an exemplary manner) of various (e.g., directly adjacent) radial portions 20 are executed with a variable magnitude and the magnitude increases in comparison of the radial radius 18 of the end face 14 with each other from radially outside to radially central, and the radial portions 20 may run discretely. The radial radius 18 are defined pivoted about a parallel (first axis) to the chain running direction 10. The center of the end face 14 is, for example, the exit point of the neutral axis 29. The curvature of the end face 14 is so small that it is not visible in this view. An ideal tangential or (as close as technically possible or as far as economically viable) an approximation to an ideal tangential transition between the radius portions 20 is therefore not necessary in every case.
Two azimuthal radii 19 are shown pivoting about a parallel (second axis) to the radial direction 8. The magnitude of the azimuthal radius 19 is variable and increases from forward with respect to the running direction to central with respect to the running direction, wherein the radius portions 20 are discrete, for example. The center of the end face 14 is, for example, the exit point of the neutral axis 29. The curvature of the end face 14 is very small. An ideal tangential or (as close as technically possible or as far as economically viable) an approximation to an ideal tangential transition between the radius portions 20 is therefore not necessary in every case.
The end face 14 is designed for force-transmitting, e.g., exclusively frictional, contact with the conical surfaces 15 (see
The rocker pins 1, 2 each have, on the end face 14, at least two, here four, discrete radius portions 20 (shown with contour lines), which each have a magnitude-constant radial radius 18 and a constant azimuthal radius 19. The magnitude of the radial radius 18 increases from radially outside to radially central and decreases from radially central to radially inside. The magnitude of the azimuthal radius 19 also decreases from forward with respect to the running direction to central with respect to the running direction and from central with respect to the running direction to rearward with respect to the running direction.
In
In
At least two plate links 12 are linked together to form a ring by means of the large number of rocker pin pairs 3 (for the transmission of traction force in the strands 32, 33). Generally, a plurality of plate links 12 is arranged next to one another in the axial direction 6. A coordinate system is shown here in the first strand 32, which corresponds to the coordinate system according to the previous figures. The chain running direction 10 lies in the plane of the plate link chain 4 ring. The axial direction 6 (corresponding to the direction of the chain width) is oriented parallel to the rotation axes 23, 24. The radial direction 8 points outwards from the ring formed by the plate link chain 4. The position of the coordinate system shown is defined in any point of the plate link chain 4 and the orientation of the chain running direction 10 and the radial direction 8 as well as the position of the axial direction 6 change with the movement of the plate link chain 4.
For example, a drive engine 27 is connected to the first transmission shaft 30, wherein only the torque-receiving input gear is shown here. For example, a consumer 28, for example at least one drive wheel for a motor vehicle, is connected to the second transmission shaft 31, wherein only the torque-emitting output gear is shown here.
Here, a further reduction in noise emissions and an increase in service life are achieved by means of the proposed rocker pin.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 104 315.5 | Feb 2020 | DE | national |
This application is the United States National Phase of PCT Appln. No. PCT/DE2021/100010 filed Jan. 11, 2021, which claims priority to German Application No. DE102020104315.5 filed Feb. 19, 2020, the entire disclosures of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2021/100010 | 1/11/2021 | WO |
