Planetary gear with spacer sleeve

Abstract

Planetary gear (1) with at least one first and one second planetary stage (2,3), wherein the first planetary stage (2) comprises a first sun wheel (7) and a plurality of first planetary wheels (8) and the second planetary stage (3) comprises a second sun wheel (9) and a plurality of second planetary wheels (10), wherein the sun gears (7,9) are arranged coaxially with respect to a main axis of rotation (H) of the planetary gear set (1) and wherein the first planet gears (8) are arranged offset in the direction of rotation about the main axis of rotation (H) to the second planet gears (10), with a plurality of bolts (11), wherein the second planet gears (10) are arranged on the bolts (11), and with a first housing section (5), wherein the first housing section (5) is arranged in the axial direction to the main axis of rotation (H) adjacent to the first sun gear (7) and wherein the bolts (11) are arranged on the first housing section (5), with a plurality of spacer sleeves (12), wherein the spacer sleeves (12) are arranged on the bolts (11) between the second planet gears (10) and the first housing section (5), wherein the spacer sleeves (12) each have an inner rim (16) and an outer rim (15), characterized by a plurality of bushing parts (13), wherein the bushing parts (13) are arranged in the first housing section (5) and the bolts (11) are arranged in the bushing parts (13) and the spacer sleeves (12) are supported on the bushing parts (13), wherein the bushing parts (13) have a bearing edge (18), wherein the outer edge (15) and the bearing edge (18) together form an annular, outer bearing area (19).

Description

Field of invention

[0001] The invention relates to a planetary gear set with at least a first and a second planetary stage, wherein the first planetary stage comprises a first sun gear and a plurality of first planet gears, and the second planetary stage comprises a second sun gear and a plurality of second planet gears, wherein the sun gears are arranged coaxially with respect to a main axis of rotation of the planetary gear set, and wherein the first planet gears are arranged offset in the direction of rotation about the main axis of rotation relative to the second planet gears, with a plurality of bolts, wherein the second planet gears are arranged on the bolts, and with a first housing section, wherein the first housing section is arranged adjacent to the first sun gear in the axial direction to the main axis of rotation, and wherein the bolts are arranged on the first housing section, and with a plurality of spacer sleeves.the spacer sleeves are arranged on the bolts between the second planetary gears and the first housing section.

[0002] Planetary gears are used, for example, in the automotive industry to divide, combine, or increase torque in the vehicle's drivetrain. Planetary gears typically have at least one central gear, also called the sun gear, and several other gears, also called planets, with the other gears arranged around the central gear and meshing with it.

[0003] The publication DE 10 2010 047 139 A1 discloses a planetary drive with planet gears rotatably mounted on planet bolts, wherein each planet bolt sits in a receptacle of a planet carrier and is held axially at a distance from the planet carrier by a spacer sitting on the respective planet bolt.

[0004] German patent application DE 10 2010 032 252 A1 relates to a transmission device with at least one planet gear and at least one planet carrier, wherein the planet gear is rotatably mounted on the planet carrier about a planetary rotation axis at a radial distance from a central axis of the transmission device via at least one pin received on the planet carrier, and wherein the planet gear is kept at a distance from the planet carrier in the axial direction by means of at least one axial stop. German patent application DE 10 2010 047 143 A1 describes a further planetary gear.

[0005] The unpublished DE 10 2011 087 574 A1 shows a spur gear differential for a motor vehicle, with two sun gears housed in a planet carrier in which at least one planet gear is rotatably mounted via a bolt, wherein the bolt is located in a sleeve in an opening of the planet carrier and the bolt completely penetrates the planet gear, the sleeve having two radially outwardly projecting flange sections.

[0006] German patent application DE 10 2009 058 543 A1, which represents the closest prior art, discloses, for example, a planetary gear set designed as a differential. The differential comprises a planet carrier with a first and a second planet set, each planet set having planet gears, the planet gears of the first and second planet sets meshing in pairs. The planet gears are mounted on bolts fixedly arranged in the planet carrier, with the planet gears being spaced apart from the planet carrier at least on one side. The patent discloses a spacer that is fixedly arranged on the bolt and that spaces the planet gear away from the planet carrier. In a first embodiment, the spacer is frictionally engaged on the bolt so that it is fixedly arranged in the axial direction relative to the axis of rotation of the bolt.The position and length of the spacer are chosen such that, firstly, the planet gear is securely guided, and secondly, the spacer sleeve is spaced apart from the planet carrier. Thus, friction occurs only between the end of the spacer sleeve facing the planet gear and the planet gear itself. In a second embodiment, the fixed spacer is additionally supported against the planet carrier and is therefore better secured with respect to the axial direction. In this second embodiment as well, friction occurs between the end of the spacer facing the planet gear and the planet gear.

[0007] The invention is based on the objective of proposing a new planetary gear with reduced wear.

[0008] This problem is solved by a planetary gear unit having the features of claim 1. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description, and the accompanying figures.

[0009] The invention proposes a planetary gear unit suitable and / or designed for use in a motor vehicle, particularly in the vehicle's drivetrain. Specifically, the planetary gear unit serves to combine, distribute, translate, or reduce a drive torque within the vehicle's drivetrain. The drive torque can be a primary torque or an auxiliary torque for propelling the vehicle.

[0010] The planetary gear set comprises at least a first and a second planetary stage. The first planetary stage comprises a first sun gear, preferably configured as an output gear, and a plurality of first planet gears, wherein the first planet gears mesh with the first sun gear. The second planetary stage comprises a second sun gear, preferably configured as an output gear, and a plurality of second planet gears, wherein the second planet gears mesh with the second sun gear.

[0011] The two sun gears are arranged coaxially with respect to a main axis of rotation of the planetary gear set. Preferably, the sun gears are arranged adjacent to each other, in particular directly adjoining one another. For example, the sun gears may be supported axially against each other, optionally with the interposition of bearing elements.

[0012] The axes of rotation of the first and second planet gears are arranged parallel to the main axis of rotation, but spaced apart from it. It is possible for the axes of rotation of the first and second planet gears to be arranged on a common pitch circle diameter or on two different pitch circle diameters around the main axis of rotation.

[0013] From a design perspective, the first planet gears are arranged offset from the second planet gears in the direction of rotation around the main axis of rotation. In particular, the axes of rotation of the first and second planet gears are positioned offset from each other in the direction of rotation around the main axis of rotation.

[0014] The planetary gear set is specifically designed as a spur gear planetary gear set, which features continuously toothed gears as sun gears and planet gears. In this configuration, the planetary gear set can be built very compactly with respect to its axial dimensions.

[0015] The planetary gear set comprises a plurality of bolts, with the second planet gears arranged on the bolts. The bolts are positioned coaxially to the axes of rotation of the second planet gears. Preferably, the first planet gears are mounted on further bolts.

[0016] The planetary gear set comprises a first housing section, which is preferably designed as a planet carrier for at least the second planet gears, and preferably for both the first and second planet gears. The first housing section is arranged axially adjacent to the main axis, particularly adjacent to the first sun gear. Thus, the first sun gear is positioned between the first housing section and the second sun gear. The first housing section can, for example, be a formed cup that encompasses the first and / or second planetary stage. Alternatively, it can be a cover that closes such a cup in the axial direction. In particular, the first housing section is designed as a portion of a formed part.

[0017] The bolts on which the second planet gears are mounted are located on the first housing section. The second planet gear on the bolt is spaced apart from the first housing section. Preferably, the second planet gears extend axially only far enough that, viewed radially, they are arranged without overlap with the first sun gear, in particular with the teeth of the first sun gear. This design ensures that the second planet gears cannot mesh with the first sun gear. Consequently, space remains in the axial direction on the bolt between the second planet gears and the first housing section.

[0018] To bridge the axial distance between the second planet gear and the first housing section, the planetary gear has a plurality of spacer sleeves, the spacer sleeves being arranged on the bolts between the second planet gears and the first housing section.

[0019] The invention proposes that the spacer sleeves each have an inner flange and an outer flange – hereinafter collectively referred to as flanges. The flanges are designed as flange sections, extending in a radial plane perpendicular to the main axis of rotation. The advantage of this flange design is that the spacer sleeves can be supported over a large area on both axial sides in annular support areas, thereby reducing wear in the planetary gear.

[0020] According to the invention, the planetary gear unit comprises a plurality of bushing parts, wherein the bushing parts are arranged in the first housing section, the bolts are arranged in the bushing parts, and the spacer sleeves are supported against the bushing parts. Because the spacer sleeves are supported against the bushing parts and thus only indirectly and not directly against the first housing section, it is ensured that the spacer sleeves cannot wear into the first housing section during operation of the planetary gear unit. The bushing parts thus provide wear protection for the first housing section against wear that could otherwise be caused by the spacer sleeves. This design therefore ensures that the planetary gear unit can be operated advantageously with low or no wear at this position.

[0021] Another advantage is the improved repairability of the planetary gear. Without the bushing component, in the event of wear, the first housing section, and thus the entire planetary gear housing, would have to be replaced. With the bushing components, only these components may need to be replaced.

[0022] In a preferred embodiment of the invention, the spacer sleeves are designed as formed parts. This allows the spacer sleeves to be manufactured very cost-effectively. Furthermore, formed parts are very lightweight due to their thin material, thus keeping the overall weight and therefore the moving mass of the planetary gear low. Additionally, a material with particularly low wear resistance can be selected. Preferably, the formed parts are produced by a drawing process and / or cold forming. Optionally, the spacer sleeves can be hardened, particularly in the areas subject to friction, or completely hardened, to further reduce wear.

[0023] In a preferred embodiment of the invention, the first sun gear is guided by the inner and outer edges of the spacer sleeves with respect to the axial direction of the main axis of rotation. The inner and / or outer edges thus form a starting point for the first sun gear. In this configuration, the first and second planetary stages are coupled to each other with respect to the axial positioning of the components, so that they self-align correctly. This correct alignment optimizes the operation of the planetary gear set, thereby reducing wear. For example, if the second planetary gear rotates towards the first sun gear, it presses against the inner edge. The inner edge may then press against the first sun gear, causing it to shift in the same direction during operation.

[0024] In a particularly preferred embodiment of the invention, the spacer sleeves are mounted on the bolts so as to be freely rotatable. This can be achieved, for example, by mounting the spacer sleeves on the bolts with at least some clearance or with at least some interference. In particular, the spacer sleeves are mounted on the bolts in a sliding bearing configuration. This design ensures that when one of the second planet gears is supported against the first housing section, two support areas can be used as moving friction zones. Firstly, a support area is formed between the second planet gear and the spacer sleeve, and secondly, a support area is formed in the region between the spacer sleeve and the first housing section.The wear load on both support areas is reduced by half compared to designs where only one support area can be used as a friction zone, thus reducing wear on the planetary gear in this area. Further advantages arise from the fact that the freely rotating spacer sleeves prevent jamming and therefore also more extensive damage to the planetary gear during operation.

[0025] It is preferred that the functional surfaces, in particular the support areas, of the spacer sleeves are machined to minimize friction on the inner and outer contact areas.

[0026] In a preferred embodiment of the invention, the inner ring extends in an axial region with respect to the main axis of rotation, wherein the axial region extends between the first and second planet gears and / or between the first and second sun gears. The axial region is defined by radial planes that are arranged perpendicular to the main axis of rotation and form intersection planes with it.

[0027] In a preferred embodiment of the invention, the radial extension of the inner flange is such that the inner flange acts as a separating element between the second planet gear and the first sun gear, thus preventing meshing of these two gears by the inner flange. In this way, both wear optimization and operational reliability are improved.

[0028] Considering the second planet gear, it can be conceptually divided into a hollow cylindrical base body and a circumferential toothed section. The boundary between the base body and the toothed section is formed as a hollow cylindrical surface and is defined by the bases of the tooth gaps of the toothed section. In a preferred embodiment, the ring width of the inner ring, defined as the difference between the outer radius and the inner radius of the inner flange (i.e., as a simple ring width), is at least 50%, preferably at least 75%, and specifically at least 95% of the ring width (with the same definition) of the base body. Such a large overlap results in a large annular area in the support region between the second planet gear and the spacer sleeve, ensuring that the surface pressures are kept low, thus minimizing wear in the support region.

[0029] Alternatively or optionally, the inner flange is designed to overlap the first sun gear in axial projection, with the overlap extending over at least 50%, preferably at least 75%, and particularly at least 95% of the first sun gear's toothing. The overlap is defined as the length of the maximum overlap in the radial direction to the main axis of rotation. This substantial overlap ensures reliable guidance of the first sun gear by the spacer sleeve.

[0030] It is particularly preferred that the housing section in the receiving area of ​​the bushing parts is made of an unhardened material. This allows the first housing section to be manufactured cost-effectively, while the wear resistance is ensured by the bushing parts.

[0031] In a preferred design embodiment of the invention, the bushing parts are also designed as formed parts analogous to the spacer sleeves and may be machined and / or hardened.

[0032] In a preferred embodiment of the invention, the bushing components each have a contact flange, wherein the contact flanges are designed as flange sections extending in a radial plane perpendicular to the main axis of rotation. The outer flange and the contact flange are arranged parallel to each other and together form an annular outer contact area for each bolt. The two flanges increase the contact surfaces between the spacer sleeve and the bushing components, thus reducing the load in the outer contact area, which acts as a support. Optionally, the outer contact area can be additionally lubricated to further reduce wear.

[0033] In a first possible implementation of the invention, the bolts are fixedly mounted in the bushing sections. In this embodiment, the second planet gears are rotatably mounted on the bolts. For example, they are rotatably mounted on the bolts via a sliding bearing or a rolling bearing. In this embodiment, the second planet gears are supported against the first housing section via the spacer sleeves and the bushing section.

[0034] In another design embodiment, the bolts are rotatably mounted in the bushing parts and / or the bushing parts are designed as sliding bearings for the bolts. In this embodiment, the bolts rotate together with the second planetary gears, resulting again in two support areas and thus two rotation ranges.

[0035] After the bushing parts are firmly received in the first housing section, but the spacer sleeves are preferably mounted freely rotatable on the bolts and thus also have a certain amount of play in the radial direction, it is preferred that the diameter of the outer edge is designed differently from the diameter of the contact edge, so that it is ensured that, despite a certain radial tolerance of the spacer sleeve, the outer contact area, which is the same in terms of area, is always provided as a support area.

[0036] In a preferred embodiment of the invention, the planetary gear set is designed as a differential, wherein the first housing section, in particular designed as a planet carrier, is rotationally fixed to a toothed connection, and wherein the first and second planet gears mesh with each other in pairs. In this embodiment, the three connections of the differential are formed by the housing section, in particular the planet carrier, and the two sun gears. Particularly preferably, the housing section, in particular the planet carrier, forms a differential input and the two sun gears each form a differential output. As already explained, the planet gears and / or the sun gears are preferably designed as spur gears, in particular spur gears, so that the differential can be designed to be very narrow in the axial direction.

[0037] In a further development of the invention, the planet gears and the sun gear of a planetary stage are provided with a Wildhaber-Novikov toothing, wherein convex, semicircular teeth of one gear engage in similarly shaped, but concave, gaps between the teeth of the other gear. This design has the advantage that the teeth only need to be half as high as, for example, involute teeth, thus saving space in the radial direction.

[0038] Exemplary embodiments of the invention are explained in more detail in the following description of the figures, which show: Fig. 1 a schematic longitudinal section through a planetary gear set designed as a differential as an embodiment of the invention; Fig. 2 a spacer sleeve from the planetary gear in the Fig. 1 in three-dimensional representation and Fig. 3 a bushing part from the planetary gear in the Fig. 1, also in schematic three-dimensional representation.

[0039] The Fig. Figure 1 shows a schematic longitudinal section of a planetary gear 1, which is designed as a differential, as an embodiment of the invention. The planetary gear 1 serves to distribute a drive torque from one input device to two output devices. In particular, the planetary gear 1 is designed for use in a vehicle.

[0040] The planetary gear set 1 comprises a first planetary gear set 2 and a second planetary gear set 3. The planetary gear sets 2 and 3 are arranged in a housing 4, which is formed by a first housing section 5 and a second housing section 6. The first housing section 5 is designed as a cover, and the second housing section 6 is designed as a pot. Alternatively, both housing sections 5 and 6 can be designed as pots.

[0041] The first planetary set 2 comprises a first sun gear 7 and a plurality of first planet gears 8, which are shown in the representation in the Fig. 1 are shown almost hidden. The second planetary set 3 comprises a second sun gear 9 and a plurality of second planet gears 10. The first planet gears 8 mesh with the first sun gear 7, the second planet gears 10 mesh with the second sun gear 9. The first planet gears 8 mesh in pairs with the second planet gears 10, with each first planet gear 8 meshing with both the first sun gear 7 and one of the second planet gears 10.

[0042] The first sun gear 7 and the second sun gear 9 are arranged coaxially with each other and with respect to a main axis of rotation H of the planetary gear set 1. In particular, the sun gears 7 and 9 are arranged directly adjacent to each other. Furthermore, the first sun gear 7 is located directly adjacent to the first housing section 5 and the second sun gear 9 is located directly adjacent to the second housing section 6.

[0043] Each of the second planet gears 10 is arranged on a bolt 11, which is located in the housing 4, in particular on the first housing section 5 and on the second housing section 6. The second planet gears 10 are designed as short planet gears with respect to their axial width, extending only in the area of ​​the second sun gear 9 and, in particular, not overlapping or meshing with the first sun gear 7.

[0044] To space the second sun gear 10 from the first housing section 5, the planetary gear 1 includes a spacer sleeve 12, which is located in the Fig. 2 is shown in a schematic three-dimensional representation. Furthermore, the planetary gear 1 has bushing parts 13, which are arranged in the first housing section 5 and which support the bolt 11. One such bushing part 13 is shown in a three-dimensional representation in the Fig. 3 shown. On the opposite side of the bolt 11, identical bushing parts 14 are arranged in the second housing section 6, which support the bolt 11 on this side.

[0045] The spacer sleeve 12 has an outer flange 15 and an inner flange 16, which are designed as radially projecting flanges. In particular, the inner flange 15 and the outer flange 16 extend in a radial plane perpendicular to the main axis of rotation H of the planetary gear 1.

[0046] The bushing part 13 is inserted into the first housing section 5, in particular pressed in, and is secured there by friction. The bushing part 13 has a radially inwardly directed end limit 17 in the form of a circumferential edge, which forms an axial stop for the bolt 11. Furthermore, the bushing part 13 has a contact flange 18, which is also designed as a flange in a radial plane perpendicular to the main axis of rotation H of the planetary gear 1. The contact flange 18 is designed in particular parallel to the outer flange 15, so that they form a common outer contact area 19, which is annular in shape. On the side opposite the spacer sleeve 12, the contact flange 18 rests flat against an inner surface of the first housing section 5.

[0047] In contrast, the inner board 16, together with an end face of the second planet gear 10 facing the inner board 16, forms an inner contact area 20, which is also circular in shape and forms an axial run-up for the second planet gear 10.

[0048] In the Fig. In the illustrated embodiment 1, the second planet gear 10 is rotatably mounted on the bolt 11 via a sliding bearing. The bolt 11, on the other hand, is fixedly mounted in the bushing parts 13, 14. The spacer sleeve 12 rests rotatably, and in particular freely rotatably, on the bolt 11.

[0049] During operation of the planetary gear 1, the second planet gear 10 can shift axially. If it shifts to the right, it contacts the bushing part 14, specifically a contact flange 21, which is identical in design to the contact flange 18, and is guided axially by it. If, on the other hand, the second planet gear 10 shifts towards the first housing section 5, it contacts the spacer sleeve 12, which in turn is supported by the bushing part 13. Since the spacer sleeve 12 is freely rotatable on the bolt 11, a relative rotation can occur either between the second planet gear 10 and the sleeve part 12 or between the sleeve part 12 and the bushing part 13. Due to the annular contact surfaces 19, 20, friction is low in both areas, and the surface load is low, thus minimizing wear.

[0050] The spacer sleeve 12 and the bushing parts 13, 14 are each designed as a formed part, in particular as a drawn part. These components are therefore inexpensive to manufacture and are lightweight. The first housing section 5 and the second housing section 6 are unhardened in the area of ​​the bushing parts 13, 14, whereby the bushing parts 13, 14 ensure that no wear occurs on the housing sections 5, 6. To further reduce friction, the contact surfaces in the bearing areas 19 and 20 of the spacer sleeve 12 and the bushing part 13 are machined.

[0051] The first sun gear 7 is arranged between the inner rim 16 and the outer rim 15 and is positioned overlapping in axial projection. In this way, the first sun gear 7 can be guided by the spacer sleeve 12 in both axial directions, or rather, it forms a starting point on both sides for the first sun gear 7. The overlap of the inner rim 16 with the first sun gear 7 is – as can be seen from the Fig. As can be seen from Figure 1, the overlap is very large. The inner flange 16 overlaps almost 100% with the teeth of the first sun gear in the radial direction shown. The overlap between the inner flange 16 and the second planet gear 10 is also large. If the second planet gear 10 is divided into teeth and a base body, as indicated by the dotted lines, the ring width R of the inner flange 16 is larger than the ring width defined by the base body of the second planet gear 10.

[0052] The toothing of the sun gears 7, 9 and the planet gears 8, 10 is designed as Wildhaber / Novikov toothing, so that the radial expansion of the gears is small. Reference symbol list 1 planetary gear 2 first planetary theorem 3 second planetary set 4 cases 5 first housing section 6 second housing section 7 first sun wheel 8 first planetary gears 9 second sun wheel 10 second planetary gears 11 bolts 12 Spacer sleeve 13 Bushing part 14 Bushing part 15 Outboard 16 Inboard 17 End limit 18 Attachment board 19 Investment area 20 Investment area H Main axis of rotation R Ring width

Claims

[1] Planetary gear (1) with at least a first and a second planetary stage (2, 3), wherein the first planetary stage (2) comprises a first sun gear (7) and a plurality of first planetary gears (8) and the second planetary stage (3) comprises a second sun gear (9) and a plurality of second planetary gears (10), wherein the sun gears (7, 9) are arranged coaxially with respect to a main axis of rotation (H) of the planetary gear (1) and wherein the first planet gears (8) are arranged offset from the second planet gears (10) in the direction of rotation around the main axis of rotation (H), with a plurality of bolts (11), wherein the second planetary gears (10) are arranged on the bolts (11), and with a first housing section (5), wherein the first housing section (5) is arranged in the axial direction to the main axis of rotation (H) adjacent to the first sun gear (7) and wherein the bolts (11) are arranged on the first housing section (5), with a plurality of spacer sleeves (12), wherein the spacer sleeves (12) are arranged on the bolts (11) between the second planetary gears (10) and the first housing section (5), wherein the spacer sleeves (12) each have an inner board (16) and an outer board (15), characterized by a plurality of bushing parts (13), wherein the bushing parts (13) are arranged in the first housing section (5) and the bolts (11) are arranged in the bushing parts (13) and the spacer sleeves (12) are supported on the bushing parts (13), wherein the bushing parts (13) have a contact edge (18), wherein the outer edge (15) and the contact edge (18) together form a circular, outer contact area (19). [2] Planetary gear (1) according to claim 1, characterized by that the second sun gear (7) is arranged between the inboard (16) and the outboard (15) and is guided laterally by them. [3] Planetary gear (1) according to claim 1 or 2, characterized by that the spacer sleeves (12) are arranged freely rotatably on the bolts (11). [4] Planetary gear (1) according to one of the preceding claims, characterized by that the inner board (16) extends in an axial region between the first and the second planetary gears (8, 10) and / or in an axial region between the first (7) and the second sun gear (9). [5] Planetary gear (1) according to one of the preceding claims, characterized by that the inboard (16) forms a boundary between the first and the second planetary stage (2,3), wherein the inboard is arranged as a separating element between the second planetary gear (10) and the first sun gear (7) and separates them from one another. [6] Planetary gear (1) according to one of the preceding claims, characterized bythat the second planetary gear (10) can be conceptually divided into a hollow cylindrical base body and a circumferential toothing, wherein the ring width (R) of the inner rim (16) takes up more than 50%, preferably more than 75% and in particular more than 95% of the ring width of the hollow cylindrical base body. [7] Planetary gear (1) according to one of the preceding claims, characterized by that the inboard (16) overlaps with the first sun gear (7) in axial projection, wherein the overlap extends over at least 50%, preferably over at least 75% and in particular over at least 95% of the toothing of the first sun gear (7). [8] Planetary gear (1) according to one of the preceding claims, characterized bythat the planetary gear (1) is designed as a differential, wherein the first and the second planet gears (8, 10) mesh with each other in pairs and the first housing section (5) is connected as a planet carrier in a rotationally fixed manner to a rotating toothing. [9] Planetary gear (1) according to one of the preceding claims, characterized by that the planetary stages (2,3) are designed with a Novikov / Wildhaber toothing.

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