Ring gear carrier for a planetary gear and planetary gear

Abstract

Ring gear carrier (3) for receiving a ring gear (8) in a gear housing (2) of a planetary gear (1), characterized in that the ring gear carrier (3) comprises a base carrier (11), wherein at least one receiving surface (13, 14) is formed on an inner side (23) of the base carrier (11), and wherein a damping element (12) is arranged on an outer side (24) of the base carrier (11) facing away from the receiving surface (13, 14).

Description

The invention relates to a ring gear carrier for a ring gear of a planetary gear and to a planetary gear with such a ring gear carrier according to the preamble of the independent claims.In transmissions, internal vibrational excitations result in noise formation due to the system. A main noise source is tooth flanks of engaged gearwheels which roll under load, since vibrational excitations occur due to the forces and moments occurring during rolling, which are perceived as gear rattling or gear hay by an engine user, in particular by the occupants of the motor vehicle. In addition, noise can also arise at other points of the transmission, for example when rolling the rolling bodies in the rolling bearings. These noises generated in the transmission are transmitted as structure-borne sound via gears, transmission shafts and bearings to the transmission housing and from there are emitted as airborne sound to the environment or are forwarded in the form of structure-borne sound to the machine structure. In a planetary gear, a structure-borne sound transmission can additionally occur via the ring gear of the planetary gear if the latter is connected to the transmission housing or a ring gear carrier and structure-borne sound can be transmitted via the ring gear to the transmission housing.In order to reduce the generation of noise in a transmission, measures can be taken to minimize the excitations of oscillations, which are referred to as primary measures. Further, secondary measures may be taken to reduce transmission of sound waves to the transmission housing or radiation of sound waves from the transmission housing of the transmission. The primary measures include, for example, the optimization of the rigidity profile of the tooth flanks and the reduction of the deviations between the tooth flanks. However, these generally result in a marked increase in the production costs, since these measures are associated with lower production tolerances and associated higher processing times of the components. In addition, these measures cannot contribute to noise minimization in all load cases, and so these primary measures are generally not suitable as sole measures for noise reduction.Secondary measures with which the transmission of sound waves to the housing and the emission of the sound waves are to be minimized include various types of insulation and damping measures and measures which aim at a change in the natural oscillation behavior of the components which are significantly involved in the development of structure-borne noise and structure-borne noise conduction. One possibility for noise reduction is to acoustically isolate the bearing points of the transmission shafts from the transmission housing and thus to minimize a transmission of oscillations via the bearing points. In a similar manner, such decoupling and damping measures can also be carried out on other components, for example on a ring gear of a planetary gear. Such decoupling and damping measures however bring about a significant reduction in the rigidity for connecting the elastically mounted transmission components to the transmission housing. As a result of the lowering of the rigidity at the connection points, an increased displacement of the transmission components relative to one another occurs during the transmission of torque. This can lead to an increased load on the tooth flanks of meshed gears and an associated increased wear of the transmission components. In addition, the elastic mounting can lead to an increased excitation of oscillations and, associated therewith, to an increased generation of noise. The fact that only individual transmission components can be isolated can also have a disadvantageous effect. Due to the reduced rigidity at the insulated connection points, the forces resulting from the force transmission are supported more strongly at the other connection points. A large part of the structure-borne sound waves is thus redirected, so that a strong vibrational excitation of the transmission housing and a noise nuisance associated therewith continue to occur.DE 199 14 607 A1 discloses an oil pan for a vehicle transmission, in particular an automatic transmission of a motor vehicle. Here, webs are provided on the oil pan, which webs have a higher rigidity than the oil pan made of a polymer material, in order to be able to absorb corresponding load peaks.DE 10 2007 013 494 A1 discloses cast housings for a drive or a transmission, wherein a damping element is arranged on an outer surface of the cast housing in order to absorb the oscillations of the housing and thus improve the acoustic properties of the housing.DE 11 2008 004 241 T5 discloses a fastening structure for a transmission housing and a planetary transmission. An elastically deformable damping element is provided, which is arranged between a first tooth of a first gearwheel and a second gearwheel.The object of the invention is to minimize the generation of noise in a planetary gear.According to the invention, this object is achieved by a ring gear carrier for receiving a ring gear in a transmission housing of a planetary transmission, wherein the ring gear carrier comprises a base carrier, on the inner side of which at least one receiving surface is formed, and wherein a damping element is arranged on an outer side of the base carrier facing away from the receiving surface.The rigidity of the ring gear carrier can be substantially maintained by the base carrier compared to a ring gear carrier made of a metallic solid material. The vibration-damping material on the outer side of the base carrier can damp the vibrations excited in the planetary transmission, so that a transmission of vibrations from the receiving points via the ring gear carrier to the transmission housing is reduced. In particular when supporting a ring gear and / or a rolling bearing on the ring gear carrier, the receiving point and the base carrier of the ring gear carrier are in a direct force flow, so that a direct and correspondingly efficient damping of the oscillations is possible.The features listed in the dependent claims allow advantageous improvements and further developments of the ring gear carrier proposed in the independent claim.In a preferred embodiment of the ring gear carrier, it is provided that the base carrier has a U-shaped section, wherein the recess of the U-shaped section is filled with a damping material. This provides a particularly efficient possibility for damping, since the oscillations are absorbed directly by the damping element and can thus particularly efficiently smooth the ring gear carrier excited into oscillations. In addition, such a ring gear carrier can be produced comparatively easily from a manufacturing standpoint, in particular in an injection molding process, in which the recess of the U-shaped section is filled correspondingly.In a preferred embodiment of the invention, it is provided that the damping element is a damping material made of a polymer material. A polymer material, in particular a thermosetting plastic or a thermoplastic, has a highly damping effect, so that the structure-borne sound is greatly damped. Damping materials have a lower modulus of elasticity compared to metallic materials. However, by attaching the damping material to the outer side of the ring gear carrier, this does not lead to a reduction in the rigidity at the receiving surfaces.In a preferred embodiment of the invention, it is provided that the base carrier is made of a metallic material. As a result, the base carrier can be produced particularly easily and cost-effectively as a rotary, stamped or deep-drawn part. Compared to a damping material made of a polymer material, a metallic base carrier has a correspondingly higher modulus of elasticity and a higher flexural rigidity. As a result, the ring gear or a bearing, accommodated in the ring gear carrier, for a drive shaft and / or a planet carrier of the planetary gear set do not move so strongly from its position under load, so that the load on the tooth flanks in the planetary gear set is reduced. Due to the more rigid mounting of the planetary gear and / or the drive shaft, additional damping measures can be taken in order to achieve a further noise reduction of the transmission noises.In a preferred embodiment of the invention, it is provided that a receiving surface for a ring gear is formed in such a way that the ring gear can be received in the ring gear carrier in a rotationally fixed manner. In this case, the ring gear carrier supports the torque of the ring gear only in the torsional direction. In the radial direction, the planetary set is supported via the bearing points arranged in the ring gear carrier. As a result of the polymer material on the ring gear carrier, damping is introduced into the ring gear carrier both in the radial, axial and torsional direction. The structure-borne sound level can thus be minimized. In addition, a decoupling function can be implemented on the ring gear in the torsional direction, since the same rigidity of a housing cover without damping material does not have to be achieved in this direction.In an advantageous embodiment of the ring gear carrier, it is provided that the material thickness of the damping material is at least twice as high as the material thickness of the base carrier. In order to achieve a high damping effect with a reasonable weight, it is advantageous to apply the light damping material to the metallic base support to a correspondingly strong extent. Thus, on the one hand, sufficient rigidity for mounting the ring gear and / or the drive shaft is achieved, but at the same time a correspondingly high damping effect is also achieved.In a preferred embodiment of the invention, it is provided that the damping element is connected to the base carrier by means of a cohesive connection, in particular in an injection molding process or by gluing the base carrier. In this case, the damping material can be connected to the base carrier in a materially integral manner in a simple and cost-effective manner in an injection molding method or an adhesive bonding method. As a result, the additional costs in production and assembly can be kept low and efficient vibration damping on the ring gear carrier can be realized.According to the invention, a planetary gear with a ring gear carrier according to the invention, a drive shaft, a ring gear and at least one planetary gear which is accommodated on a planetary carrier is proposed, wherein the ring gear carrier comprises a basic carrier on which the ring gear and / or at least one bearing of the drive shaft and / or of the planetary carrier are supported on an accommodation surface on an inner side of the basic carrier, wherein a damping element is arranged on an outer side of the basic carrier facing away from the at least one accommodation surface.In a preferred embodiment of the planetary gear set, it is provided that the drive shaft carries a sun gear or is designed as a sun shaft. In particular in motor vehicle transmissions for the drive or the axle transmission, an advantageous rotational speed transmission can be achieved in this way in order to increase the torque and to reduce the rotational speed accordingly.In a further preferred embodiment of the planetary gear set, it is provided that an output takes place via the planetary gear or the planetary carrier. By means of an output via the planetary carrier, the torque can be delivered to an output shaft or a differential in a simple manner.According to the invention, a method for producing a ring gear carrier having a base carrier and a damping element is proposed, wherein the damping element comprises a polymer material which is applied to the base carrier of the ring gear carrier. By applying the damping material to the transmission cover, corresponding vibration damping can be achieved both in existing constructions and in new constructions and the transmission noises can be reduced.The various embodiments of the invention mentioned in this application can be combined with one another with advantage unless stated otherwise in the individual case.The invention is explained below with reference to preferred embodiments with reference to the attached figures. Identical components or components with the same function are identified with the same reference numerals. The following shows: FIG. 1 shows a first exemplary embodiment of a planetary gear according to the invention; FIG. 2 shows a ring gear carrier according to the invention for such a planetary transmission; FIG. 3 shows a further exemplary embodiment of a planetary transmission according to the invention; and FIG. 4 shows a further exemplary embodiment of a ring gear carrier for such a planetary transmission.FIG. 1 shows an exemplary embodiment of a planetary gear 1 according to the invention. The planetary transmission 1 has a transmission housing 2, in which a ring gear carrier 3 is accommodated. The transmission housing 2 is preferably closed by a housing cover, not shown. In the transmission housing 4 there is arranged a drive shaft 4 which is designed as a sun shaft 26. The drive shaft 4 is in engagement with a set of planet gears 6 which are arranged on a planet carrier 7. In this case, a toothing 18 on the planetary gears 6 engages both with a toothing 19 on the ring gear 8 and with a toothing 27 of the sun shaft 26. The planetary gear 1 further comprises a ring gear 8, which is accommodated on a first accommodation surface 13 on the ring gear carrier 3. The drive shaft 4 is rotatably mounted in a ring gear carrier 3 by means of a first rolling bearing 10. The rolling bearing 10 comprises an inner ring 16 which is arranged on the drive shaft 4 and an outer ring 17 which bears against the second receiving surface 14 of the ring gear carrier 3. A plurality of rolling elements 20 are arranged between the inner ring 16 and the outer ring 17. The planet carrier 7 is preferably mounted rotatably on the drive shaft 4 both in the axial direction and in the radial direction. The output 9 of the planetary gear 1 takes place via the planet gears 6 or the planet carrier 7. Alternatively, the drive shaft 4 can also carry a sun gear 5, which is in engagement with the planet gears 6. Threaded bores 21 are formed on the transmission housing 2 in order to screw the housing cover to the transmission housing 2.The ring gear carrier 3 comprises a metallic base carrier 11, on the inner side 23 of which the receiving surfaces 13, 14 are formed. The base carrier 11 preferably has a rotationally symmetrical geometry, wherein the base carrier has a radial end section of the ring gear carrier 3 a U-shaped section 30. On the outer side 24 of the metallic base support 11, at least in the region of the U-shaped section 30, a damping element 12 in the form of a damping material 25 is applied to the metallic base support 11 in order to damp the oscillations transmitted to the receiving surfaces 13, 14. The metallic base support 11 is preferably produced as a stamped and bent part, as a turned part or as a deep-drawn part. In this case, in particular a metal sheet 22 can be brought into the shape of the base carriers 11 by a comparatively simple and cost-effective forming process. At least one connection point 29, in particular a screw connection, is provided between the transmission housing 2 and the ring gear carrier 3, which connection points are formed parallel to a central axis 28 of the planetary gear 1 with threaded bores, at which the ring gear carrier can be fixed by means of fastening means, in particular by means of screws. For this purpose, corresponding fastening openings are formed in the metallic base carrier 11 of the ring gear carrier 3, through which the fastening means are guided in order to produce a force-fit and / or form-fit connection between the ring gear carrier 3 and the transmission housing 2.FIG. 2 shows a ring gear carrier 3 for such a planetary gear 1 in a single-part drawing. The receiving surfaces 13, 14 on the metallic base carrier 11 run parallel to the central axis 28 of the planetary gearing 1, while the further surfaces run substantially perpendicular thereto. In this case, a damping material 25 is applied to the outer side 24 of the metallic base carrier 11, which damping material firstly reinforces the metallic base carrier 11 in the region of the receiving surface 13, 14 and secondly brings about a damping of the oscillations transmitted to the ring gear carrier 3. In this case, the base support 11 has, in a radially outer region, a U-shaped course 30 with a recess 31, which is completely filled by the damping material 25.FIG. 3 shows an alternative exemplary embodiment of a planetary transmission 1 according to the invention. With substantially the same construction as set out in FIG. 1, only the differences will be discussed below. In this embodiment, the drive and output 9 take place on the same side of the planetary gearing. The drive shaft 4 is rotatably mounted in the planet carrier 7 of the planetary gear 1 by means of a roller bearing 10. The planet carrier 7 is rotatably mounted in the ring gear carrier 3 via a further rolling bearing on the second receiving surface 14, which is also referred to as bearing surface 15. The drive takes place, as explained in FIG. 1, via the drive shaft 4 designed as a sun shaft 5, while the output takes place via the planetary carrier 7.FIG. 4 shows a ring gear carrier 3 for the embodiment variant of a planetary gear mechanism 1 shown in FIG. 3. The geometry of the receiving surface 13, 14 and of the metallic base carrier 11 is correspondingly adapted, so that the ring gear 8 can be received on the first receiving surface 13 and a rolling bearing 10 for rotatably mounting the planetary carrier 7 on the second receiving surface 14. Furthermore, a third receiving surface can be formed on the ring gear carrier 3 in order to receive and / or support a further bearing for the drive shaft 4.Instead of a metallic base carrier 11, a base carrier 11 made of another material with sufficient bending stiffness, in particular made of a ceramic material or a fiber-reinforced plastic, can also be used.List of reference characters1 Planetary gear 2 Transmission housing 3 Ring gear carrier 4 Drive shaft 5 Sun gear 6 Planetary gear 7 Planetary carrier 8 Ring gear 9 Output 10 Rolling bearing 11 (metallic) Basic carrier 12 Damping element 13 First receiving surface 14 Second receiving surface 15 Bearing point 16 Inner ring 17 Outer ring 18 Toothing (on the planetary gear) 19 Toothing (on the ring gear) 20 Rolling bodies 21 Threaded bore 22 Sheet metal 23 Inner side 24 Outer side 25 Damping material 26 Sun shaft 27 Toothing (on the sun gear) 28 Central axis 29 Connection point 30 U-shape 31 Recess

Claims

Ring gear carrier (3) for receiving a ring gear (8) in a transmission housing (2) of a planetary transmission (1), characterized in that the ring gear carrier (3) comprises a base carrier (11), wherein at least one receiving surface (13, 14) is formed on an inner side (23) of the base carrier (11), and wherein a damping element (12) is arranged on an outer side (24) of the base carrier (11) facing away from the receiving surface (13, 14).Ring gear carrier (3) according to Claim 1, characterized in that the basic carrier has a U-shaped section (30), the recess (31) of the U-shaped section (30) being filled with a damping material (25).Ring gear carrier (3) according to Claim 1 or 2, characterized in that the damping element (12) is a damping material (26) made of a polymer material.Ring gear carrier (3) according to one of Claims 1 to 3, characterized in that the basic carrier (11) is made of a metallic material.Ring gear carrier (3) according to one of Claims 1 to 4, characterized in that a receiving surface (13) for a ring gear (8) is formed in such a way that the ring gear (8) can be received in the ring gear carrier (3) in a rotationally fixed manner.Ring gear carrier (3) according to one of Claims 1 to 5, characterized in that the material thickness of the damping material (25) is at least twice as high as the material thickness of the base carrier (11).Ring gear carrier (3) according to one of Claims 1 to 6, characterized in that the damping element (25) is connected to the base carrier (11) by means of a materially bonded connection.Planetary transmission (1) with a ring gear carrier (3) according to one of Claims 1 to 7, comprising a drive shaft (4), a ring gear (8) and at least one planetary gear (6) which is accommodated on a planetary carrier (7), wherein the ring gear carrier (3) comprises a basic carrier (11), on which the ring gear and / or at least one bearing of the drive shaft (4) and / or of the planetary carrier are supported on an accommodation surface (13, 14) on an inner side (23) of the basic carrier (11), wherein a damping element (12) is arranged on an outer side (24) of the basic carrier (11) which is remote from the at least one accommodation surface (13, 14).Planetary transmission (1) according to claim 8, characterised in that an output (9) takes place via the planetary gear (6) or the planetary carrier (7).Planetary transmission (1) according to one of Claims 8 or 9, characterized in that the drive shaft (4) carries a sun wheel (5) or is designed as a sun shaft (26).

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