Braced gear for a gear transmission, gear transmission for a drive device, and method for producing a braced gear
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-03
- Publication Date
- 2026-03-18
AI Technical Summary
Existing tensioning gears in gear transmissions suffer from rotational irregularities, leading to tooth lifting and repositioning, causing noise, increased wear, and reduced service life due to torque fluctuations and manufacturing tolerances, which existing solutions fail to adequately address without increasing production costs.
A tensioning gear design featuring two sub-gears arranged coaxially with a first spring arrangement in the circumferential direction to maintain tooth contact and a second spring arrangement in the axial direction to prevent tilting, ensuring continuous engagement and reducing wear through optimized bracing forces.
The design effectively reduces wear and noise, extending the service life of the tensioning gear while maintaining efficient operation by preventing tilting and ensuring continuous tooth contact, thus enhancing the reliability and longevity of the gear transmission.
Smart Images
Figure EP2024062272_14112024_PF_FP_ABST
Abstract
Description
[0001] Tensioning gear for a gear transmission, gear transmission for a drive device and method for producing a tensioning gear
[0002] DESCRIPTION:
[0003] The invention relates to a tensioning gear for a gear transmission, comprising a first partial gear and a second partial gear arranged coaxially with the first partial gear and rotatably mounted relative to the first partial gear. The first partial gear and the second partial gear share a common axis of rotation and are clamped against one another with a specific clamping force in the circumferential direction relative to the axis of rotation by means of a first spring arrangement. The invention further relates to a gear transmission for a drive device of a motor vehicle and to a method for producing a tensioning gear for a gear transmission.
[0004] For example, the prior art document DE 10 2011 102 756 A1 is known. This document describes a spur gear, in particular for a motor vehicle transmission, with helical gearing, with a main gear and a tensioning gear coupled to the main gear, each forming part of the helical gearing and designed to minimize backlash during engagement with a corresponding second spur gear, as well as with a spring that exerts a spring force on the tensioning gear to minimize the backlash. The spring is designed to push the tensioning gear away from the main gear in a linear movement to minimize the backlash. The object of the invention is to propose a tensioning gear for a gear transmission that has advantages over known tensioning gears, in particular enabling simple and cost-effective production while maintaining a long service life.
[0005] This is achieved according to the invention with a tensioning gear for a gear transmission having the features of claim 1. It is provided that the first partial gear and the second partial gear are tensioned against each other in the axial direction with respect to the axis of rotation by means of a second spring arrangement.
[0006] Advantageous embodiments with useful further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments explained in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are feasible.
[0007] The tensioning gear is preferably a component of the gear train, but can of course also be provided separately. The tensioning gear preferably meshes with another gear of the gear train, with the tensioning gear and the additional gear being arranged relative to one another such that the additional gear meshes or engages with both the first partial gear and the second partial gear of the tensioning gear. The tensioning gear serves to compensate for rotational irregularities between the tensioning gear and the additional gear, ensuring continuous contact between the gear teeth.
[0008] If the teeth of the gears lift off and then re-engage, for example due to torque fluctuations, this will at least lead to annoying noises; increased wear and thus a reduced service life can also occur. To prevent the teeth of the gears from lifting off and then re-engaging, the two partial gears are arranged coaxially to one another and clamped against one another in the circumferential direction, namely with the help of the first spring arrangement. The clamping of the partial gears occurs in such a way that a tooth of the first partial gear is forced against a first tooth of the other gear, which defines a tooth gap, and a tooth of the second partial gear is forced against a second tooth of the other gear, which defines the same tooth gap. The first tooth and the second tooth therefore delimit the tooth gap on opposite sides in the circumferential direction with respect to the axis of rotation.
[0009] In other words, the teeth of the first partial gear and the second partial gear are forced away from each other in the circumferential direction with respect to the rotational axis of the partial gears in such a way that they bear against the first tooth and the second tooth of the further gear on opposite sides of the tooth space, preferably permanently bear against them while engaging in the tooth space. To ensure proper meshing of the two partial gears with the further gear, it can - optionally - be provided that the two partial gears have toothings with identical toothing parameters. In this case, the toothing of the first partial gear is designed identically to the toothing of the second partial gear. The toothing is present in particular as spur toothing, preferably as spur toothing. In this case, the partial gears are spur gears with spur teeth.
[0010] For proper operation of the gear train, it is advantageous to optimally dimension the clamping force exerted by the first spring arrangement. If the first spring arrangement is undersized, i.e., if the clamping force between the first gear and the second gear is too small, this can still lead to lifting or re-engaging. However, if the first spring arrangement is oversized, i.e., if the clamping force is too great, high frictional power is generated between the clamping gear and the other gear, resulting in a correspondingly high power loss, which reduces the efficiency of the gear train.Since it is often not possible to arrange the first spring arrangement and couple it to the partial gears in such a way that the tensioning force is symmetrical on the partial gears in the axial direction, this can lead to tilting of the partial gears against one another, particularly during torque transmission between the tensioning gear and the other gear. This means that a first center plane of the first partial gear and a second center plane of the second partial gear are no longer arranged parallel to one another, but rather intersect at an angle that is different from 0° or greater than 0° and less than 180°. This can lead to increased wear on the tensioning gear, in particular on the teeth of the first partial gear and / or the teeth of the second partial gear.The tilting is caused in particular by the fact that the coaxial arrangement and the rotatable bearing of the second partial gear with respect to the first partial gear has a play which is necessary for the rotatable bearing on the one hand and results in particular from manufacturing tolerances on the other hand.
[0011] In principle, the tilting of the two partial gears relative to each other could be reduced or even completely prevented by improved mounting of the partial gears. However, this would require significantly reducing the manufacturing tolerances of the partial gears, which would result in high costs for the tensioning gear. To prevent this, the second spring arrangement is provided, which reduces or completely prevents this tilting even when there is play between the partial gears, which would allow them to tilt relative to each other. To this end, the second spring arrangement clamps the two partial gears relative to each other in the axial direction with respect to the axis of rotation.
[0012] While the first spring arrangement braces the two partial gears against each other in the circumferential direction, the second spring arrangement braces the two partial gears in the axial direction. This means that the second spring arrangement urges the first partial gear and the second partial gear towards each other, for example urges the first partial gear towards the second partial gear and / or urges the second partial gear towards the first partial gear, in particular urges it towards the other partial gear. To do this, the second spring arrangement acts on the one hand on the first partial gear and on the other hand on the second partial gear. The partial gears are braced in particular by a holding force caused by the second spring arrangement, which is dimensioned such that it limits the tilting of the partial gears to a desired extent, in particular prevents tilting.
[0013] The described design of the tensioning gear reduces the wear that occurs during operation of the gear train, thus extending the service life of the tensioning gear. At the same time, unwanted noise from the gear train is reliably eliminated or at least reduced.
[0014] A further development of the invention provides that the first partial gear is arranged on a first bearing projection of the first partial gear and has a second bearing projection on which the first partial gear is arranged. The two partial gears are rotatably mounted on one another via the first bearing projection and the second bearing projection. The first bearing projection extends from a base body of the first partial gear in the direction of the second partial gear, and the second bearing projection extends from a base body of the second partial gear in the direction of the first partial gear. The first bearing projection engages in a bearing recess of the second partial gear, and the second bearing projection engages in a bearing recess of the first partial gear. In other words, the second partial gear engages in the first partial gear in such a way that two plain bearings are formed, namely one radially inner and one radially outer.
[0015] The two bearing projections are preferably generally cylindrical, in particular circular-cylindrical or hollow-circular-cylindrical. In particular, the second partial gear rests continuously on the first bearing projection in the circumferential direction, and the first partial gear rests continuously on the second bearing projection in the circumferential direction, preferably in each case over the entire extent in the circumferential direction, i.e., over 360° or at least almost 360°. Viewed in the axial direction, the first bearing projection overlaps with a toothing of the second partial gear, and the second bearing projection overlaps with a toothing of the first partial gear. With the described design of the tensioning gear, the explained advantages are achieved in a structurally simple manner.
[0016] A further development of the invention provides that the second spring arrangement, on the one hand, is supported on the first bearing projection and, on the other hand, rests against the second partial gear in such a way that it compensates for a tilting moment caused by the first spring arrangement about a tilting axis that is perpendicular to an imaginary plane accommodating the common axis of rotation. The aforementioned tilting of the two partial gears relative to each other due to the play occurs about the tilting axis. Viewed in longitudinal section, this axis is perpendicular to the plane of the drawing and, to that extent, perpendicular to the imaginary plane that completely accommodates the axis of rotation.
[0017] At least during the operation of the gear transmission, i.e., while a torque is being transmitted between the tensioning gear and the other gear, the tilting moment occurs, which causes the two partial gears to tilt relative to each other around the tilting axis. The holding force, or a holding moment caused by the holding force, counteracts this tilting moment, so that the tilting of the partial gears is reduced or even completely prevented. For this purpose, the second spring arrangement engages the first bearing projection on the one hand and the second partial gear on the other.
[0018] The second spring arrangement rests against the second partial gear in certain areas, viewed in the circumferential direction, in such a way that the holding force it causes counteracts the tilting moment. It can be provided that the second spring arrangement rests against the second partial gear over at least 90° and at most 270°, at least 180° and at most 300°, or at least 270° and at most 330°, viewed in the circumferential direction. However, the second spring arrangement particularly preferably supports the second partial gear continuously in the circumferential direction, i.e., rests against it over 360°. This achieves particularly reliable support of the second partial gear while at the same time enabling simple and cost-effective production of the bracing gear.
[0019] For example, the second spring arrangement is positively secured to the first bearing projection in the direction facing away from the second partial gear. For example, it engages positively with the first bearing projection, in particular in a recess in the first bearing projection, or it is secured to the first bearing projection by means of a retaining element that is positively secured to the first bearing projection, by being supported against the first bearing projection in the direction facing away from the second partial gear. The retaining element is, for example, in the form of a retaining ring, in particular a snap ring.
[0020] A further development of the invention provides that a spring element of the second spring arrangement rests continuously against the second partial gear in the circumferential direction and urges this in the direction of the first partial gear. Such a configuration has already been mentioned. The second spring arrangement has the spring element, which ultimately produces the holding force. It can be provided that the second spring arrangement only has the spring element, i.e. consists exclusively of the spring element. Alternatively, it can of course be provided that the second spring arrangement has several spring elements, which together reduce or prevent the partial gears from tilting against one another by jointly providing the holding force. In any case, the advantages already mentioned are achieved.
[0021] A further development of the invention provides for the spring element to be designed as a disc spring. The disc spring represents a simple and cost-effective way to clamp the two partial gears against each other. Depending on the spring characteristic required to achieve the desired holding force, the spring element can also comprise several disc springs that engage each other in opposite or the same direction. With the described design of the clamping gear, the advantages explained are reliably achieved.
[0022] A further development of the invention provides that the first spring arrangement is arranged in a chamber which is delimited in the radial direction inwards by the first bearing projection and in the radial direction outwards by the second bearing projection. The chamber serves to protect the arrangement of the first spring arrangement. It is configured between the first partial gear and the second partial gear. In the radial direction it is delimited by the two bearing projections, namely in the radial direction inwards by the first bearing projection and in the radial direction outwards by the second bearing projection. Depending on an extension of the second bearing projection in the axial direction, it can be provided that the chamber is delimited in the radial direction outwards in some regions by the second bearing projection and in some regions by the first partial gear.In the axial direction, for example, the chamber is bounded on one side by the first partial gear and on the other by the second partial gear. The holding force exerted by the second spring arrangement is directed toward reducing the chamber's size in the axial direction, i.e., toward reducing the chamber's dimensions in this direction. The protected arrangement of the first spring arrangement ensures a long service life of the tensioning gear.
[0023] A further development of the invention provides that the first spring arrangement for bracing the first partial gear and the second partial gear against one another engages in a form-fitting manner on a first form-fitting projection projecting from the first partial gear into the chamber and on a second form-fitting projection projecting from the second partial gear into the chamber. The first form-fitting projection preferably extends radially outwards and the second form-fitting projection extends radially inwards. In particular, the first form-fitting projection extends from the first bearing projection and the second form-fitting projection extends from the second bearing projection. The first spring arrangement comprises, for example, a so-called omega spring or is present as such. It has an extension of at least 180°, at least 225° or at least 170° in the circumferential direction.Preferably, however, their extension is larger and amounts to at least 300°, at least 330°, or at least 360°. The described design of the tensioning gear enables the implementation of the explained advantages in a structurally simple manner.
[0024] A further development of the invention provides that a holding force exerted by the second spring arrangement on the first partial gear and the second partial gear corresponds to a first holding force value for a first bracing force value of the bracing force and to a second holding force value different from the first holding force value for a second bracing force value different from the first bracing force value. This means that the second spring arrangement is selected or designed depending on the first spring arrangement. If the bracing gear is designed such that a bracing force corresponding to the first bracing force value is generated by the first spring arrangement, a second spring arrangement is used for the bracing gear, which provides a holding force corresponding to the first holding force value.
[0025] For another embodiment of the first spring arrangement, in which it provides the clamping force with the second clamping force value, a second spring arrangement is used which provides the holding force with the second holding force value. The clamping force and the holding force can be achieved by appropriately selecting the respective spring arrangement, in particular the spring constant of the respective spring arrangement, and / or by a corresponding arrangement in the clamping gear, for example with a corresponding preload. In general, the holding force provided by the second spring arrangement must be greater the greater the clamping force generated by the first spring arrangement. In this case, the aforementioned advantages are reliably achieved.The invention further relates to a gear transmission for a drive device of a motor vehicle, with a tensioning gear, in particular a tensioning gear according to the embodiments in the context of this description, and with a gear meshing with the tensioning gear, wherein the tensioning gear has a first partial gear and a second partial gear arranged coaxially to the first partial gear and rotatably mounted with respect to the first partial gear, wherein the first partial gear and the second partial gear have a common axis of rotation and are tensioned against one another with a specific tensioning force in the circumferential direction with respect to the axis of rotation by means of a first spring arrangement. It is provided that the first partial gear and the second partial gear are tensioned against one another in the axial direction with respect to the axis of rotation by means of a second spring arrangement.
[0026] The advantages of such a design of the gear train and the tensioning gear have already been pointed out. Both the gear train and the tensioning gear can be further developed according to the explanations in this description, so reference is made to these in this regard.
[0027] The invention also relates to a method for producing a tensioning gear for a gear transmission, in particular a tensioning gear according to this description, wherein the tensioning gear has a first partial gear and a second partial gear arranged coaxially to the first partial gear and rotatably mounted with respect to the first partial gear, wherein the first partial gear and the second partial gear have a common axis of rotation and are tensioned against one another with a specific tensioning force in the circumferential direction with respect to the axis of rotation by means of a first spring arrangement. It is provided that the first partial gear and the second partial gear are tensioned against one another in the axial direction with respect to the axis of rotation by means of a second spring arrangement. With regard to the advantages and possible advantageous further developments, reference is again made to the explanations in this description.
[0028] A further development of the invention provides that a holding force exerted by the second spring arrangement on the first partial gear and the second partial gear is determined as a function of the clamping force. In other words, the second spring arrangement is designed as a function of the clamping force produced by the first spring arrangement. For example, it is provided that a holding force generated by the second spring arrangement after the clamping gear has been mounted in the gear train when the clamping gear is stationary is selected as a function of the clamping force generated by the first spring arrangement in the same state, and the clamping gear is designed accordingly.
[0029] The holding force here is understood in particular to be the minimum spring force to be generated by the second spring arrangement during operation of the gear transmission. The clamping force, on the other hand, is the maximum spring force generated by the first spring arrangement during operation of the gear transmission. This ensures that the holding force is always sufficient to reduce the tilting of the partial gears to the desired extent, in particular to prevent it completely. To determine the holding force from the clamping force, for example, an axial distance between an application point of the first spring arrangement on the first partial gear and the center of a toothing of the second partial gear is used. Additionally or alternatively, a distance between the common axis of rotation and the tilting axis is used.This approach ensures a reliable design of the tensioning gear, in which tilting is reliably reduced or prevented.
[0030] The features and feature combinations described in the description, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed by the invention that are not explicitly shown or explained in the description and / or the figures, but which follow from or can be derived from the explained embodiments.
[0031] The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawings, without limiting the invention. In the drawings:
[0032] Figure 1 is a schematic representation of a tensioning gear for a gear transmission, as well as
[0033] Figure 2 is a schematic longitudinal section through the tensioning gear arranged on a shaft.
[0034] Figure 1 shows a tensioning gear 1 for a gear transmission (not shown in detail). The tensioning gear 1 has a first partial gear 2 and a second partial gear 3. The two partial gears 2 and 3 have a common axis of rotation 4 and are mounted on one another for rotation about this axis of rotation 4. The second partial gear 3 sits on a first bearing projection 5, which extends completely through the second partial gear 3 in the axial direction and projects beyond the second partial gear 3 on the side of the latter facing away from the first partial gear 2. The second partial gear 3 is held on the first bearing projection 5 in the direction facing away from the first partial gear 2 by means of a form-fitting element 6.
[0035] The two partial gears 2 and 3 are clamped against each other in the circumferential direction by means of a first spring arrangement 7 (not visible here). In order to reduce or completely compensate for a tilting moment caused by this clamping, which is directed towards a tilting of the two partial gears 2 and 3 against each other, a second spring arrangement 8 engages the first bearing projection 5, which urges the second partial gear 3 in the axial direction towards the first partial gear 2 and correspondingly clamps the two partial gears 2 and 3 against each other in the axial direction. Figure 2 shows a schematic longitudinal sectional view of the clamping gear 1 arranged on a shaft 9. This once again clearly shows that the second partial gear 3 sits on the first bearing projection 5 of the first partial gear 2, so that the second partial gear 3 is rotatably mounted on the first partial gear 2.Furthermore, the second partial gear 3 has a second bearing projection 10, on which the first partial gear 2 sits for rotatably supporting the partial gears 2 and 3. A chamber 11, in which the first spring arrangement 7 is arranged, is created in the radial direction between the bearing projections in 5 and 10. It can also be seen that the second spring arrangement 8, in particular a disc spring 12 of the second spring arrangement 8, is arranged in the axial direction between the form-locking element 6 and the second partial gear 3, so that it is supported on the one hand on the form-locking projection 6 and on the other hand on the second partial gear 3 in order to urge the two partial gears 2 and 3 towards one another in the axial direction or to urge them against one another.
[0036] Also indicated is a distance di, which exists in the axial direction between an engagement point of the first spring arrangement 7 on the first partial gear 2 and a center of a toothing of the second partial gear 3. Furthermore, a distance d2 is indicated, which exists in the radial direction between the axis of rotation 4 and a tilting axis 13, about which the two partial gears 2 and 3 can be tilted relative to one another due to a play in their bearings. The minimum holding force to be exerted by the second spring arrangement 8 is calculated as a function of the clamping force generated by the first spring arrangement 7 and the distances di and d2, and the clamping gear 1 is designed accordingly.
[0037] The described design of the tensioning gear 1 enables a reduction in wear on the teeth of the partial gears 2 and 3, which could otherwise occur due to the tilting of the partial gears 2 and 3 relative to each other. This improves the service life of the tensioning gear 1 in a structurally simple manner. LIST OF REFERENCE SYMBOLS:
[0038] 1 tensioning gear
[0039] 2 1st gear 3 2nd gear
[0040] 4 axis of rotation
[0041] 5 1. Bearing projection
[0042] 6 Form-locking element
[0043] 7 1. Spring arrangement 8 2. Spring arrangement
[0044] 9 Wave
[0045] 10 2. Bearing projection
[0046] 11 Chamber
[0047] 12 Disc spring 13 Tilting axis
Claims
PATENT CLAIMS:
1. A tensioning gear (1) for a gear transmission, comprising a first partial gear (2) and a second partial gear (3) arranged coaxially to the first partial gear (2) and rotatably mounted with respect to the first partial gear (2), wherein the first partial gear (2) and the second partial gear (3) have a common axis of rotation (4) and are tensioned against one another with a specific tensioning force in the circumferential direction with respect to the axis of rotation (4) by means of a first spring arrangement (7), characterized in that the first partial gear (2) and the second partial gear (3) are tensioned against one another in the axial direction with respect to the axis of rotation (4) by means of a second spring arrangement (8).
2. Tensioning gear according to claim 1, characterized in that the second partial gear (3) is arranged on a first bearing projection (5) of the first partial gear (2) and has a second bearing projection (10) on which the first partial gear (2) is arranged.
3. Tensioning gear according to one of the preceding claims, characterized in that the second spring arrangement (8) is supported on the one hand on the first bearing projection (5) and on the other hand bears against the second partial gear (3) in such a way that it compensates for a tilting moment caused by the first spring arrangement (7) about a tilting axis (13) which is perpendicular to an imaginary plane receiving the common axis of rotation (4).
4. Tensioning gear according to one of the preceding claims, characterized in that a spring element of the second spring arrangement (8) bears continuously in the circumferential direction against the second partial gear (3) and urges this in the direction of the first partial gear (2).
5. Tensioning gear according to one of the preceding claims, characterized in that the spring element is designed as a disc spring (12).
6. Tensioning gear according to one of the preceding claims, characterized in that the first spring arrangement (7) is arranged in a chamber (11) which is bounded in the radially inward direction by the first bearing projection (5) and in the radially outward direction by the second bearing projection (10).
7. Tensioning gear according to one of the preceding claims, characterized in that the first spring arrangement (7) for tensioning the first partial gear (2) and the second partial gear (3) against each other engages in a form-fitting manner on a first form-fitting projection projecting from the first partial gear (2) into the chamber (11) and on a second form-fitting projection projecting from the second partial gear (3) into the chamber (11).
8. Tensioning gear according to one of the preceding claims, characterized in that a holding force exerted by the second spring arrangement (8) on the first partial gear (2) and the second partial gear (3) corresponds to a first holding force value for a first tensioning force value of the tensioning force and to a second holding force value different from the first holding force value for a second tensioning force value different from the first holding force value.
9. Gear transmission for a drive device of a motor vehicle, with a tensioning gear (1), in particular a tensioning gear (1) according to one or more of the preceding claims, and with a gear meshing with the tensioning gear (1), wherein the tensioning gear (1) has a first partial gear (2) and a second partial gear (3) arranged coaxially to the first partial gear (2) and rotatably mounted with respect to the first partial gear (2), wherein the first partial gear (2) and the second partial gear (3) have a common axis of rotation (4) and are tensioned against one another with a specific tensioning force in the circumferential direction with respect to the axis of rotation (4) by means of a first spring arrangement (7), characterized in that the first Partial gear (2) and the second partial gear (3) are braced against each other in the axial direction relative to the rotational axis (4) by means of a second spring arrangement (8). 10.Method for producing a tensioning gear (1) for a gear transmission, in particular a tensioning gear (1) according to one or more of claims 1 to 8, wherein the tensioning gear (1) has a first partial gear (2) and a second partial gear (3) arranged coaxially to the first partial gear (2) and rotatably mounted with respect to the first partial gear (2), wherein the first partial gear (2) and the second partial gear (3) have a common axis of rotation (4) and are tensioned against one another with a specific tensioning force in the circumferential direction with respect to the axis of rotation (4) by means of a first spring arrangement (7), characterized in that the first partial gear (2) and the second partial gear (3) are tensioned against one another in the axial direction with respect to the axis of rotation (4) by means of a second spring arrangement (8).