Planetary gear assembly

Abstract

Planetary gear set assembly (10) for a transmission, wherein the planetary gear set assembly (10) comprises the following: a planet carrier assembly comprising a carrier part (210), a web part (212) and a plurality of planet gears (30), rotatably mounted by pinion shafts (40) each with an axial passage (44), wherein the carrier part (210) of the planet gear assembly is engaged with a first rotating element for common rotation; a sun wheel (16) with a first and a second axial end (85, 88), wherein the sun wheel (16) engages with a second rotating element for common rotation; an engaging toothed ring (22) for common rotation with a third rotating element, wherein the toothed ring (22) and the sun gear (16) engage with each of the several planet gears (30) of the planet carrier; a bearing plate (70) which is held by the web part (212) of the planetary gear carrier; and a first and second thrust bearing (80, 82), wherein the first thrust bearing (80) is arranged between the support part (210) of the planet carrier assembly and the first axial end (85) of the sun gear (16), and the second thrust bearing (82) is arranged between the bearing plate (70) and the second axial end (88) of the sun gear (16); characterized by the fact that the bearing plate (70) has several radial extensions (72) on its outer circumference, each of which covers the axial passage (44) of a respective pinion shaft (40), and has a recess (74) radially within each radial extension (72); wherein the web part (212) has an inner circumferential edge (218) which includes several semicircular recesses (222), wherein each radial extension (72) of the bearing plate (70) is arranged in a corresponding semicircular recess (222) of the web part (212); and wherein the recesses (74) of the bearing plate (70) cooperate with the pinion shaft (40) to form a lubrication passage (45) which communicates with the passage (44) of the pinion shaft (40).

Description

TECHNICAL AREA

[0001] The present invention relates to a planetary gear assembly according to the preamble of claim 1, as is known essentially from US 5 533 943 A.

[0002] A similar planetary gear assembly is essentially derived from US 2013 / 0 337 959 A1. BACKGROUND

[0003] Planetary gear assemblies are remarkably versatile and adaptable devices. Various motor vehicle powertrain components, such as transmissions, differentials, and transaxles, frequently and widely utilize planetary gear assemblies. Typically, they are used individually to provide speed reduction and torque multiplication, or they are arranged in series and used in conjunction with clutches and brakes that connect or ground different elements of the planetary gear assemblies to enable multiple speed reductions and torque multiplications.

[0004] A simple planetary gear assembly comprises a centrally located sun gear, a planet carrier generally arranged around the sun gear, and a ring gear arranged around the carrier. Several planet gears, rotatably mounted on shafts in the carrier, mesh with both the sun gear and the ring gears.

[0005] There are, of course, many technical challenges regarding the design and manufacturing of planetary gear assemblies. One relates to how multiple planetary gear assemblies are arranged or packed within a gearbox housing that includes clutches, brakes, connecting elements, and shafts. Ever-increasing power and torque requirements, improved fuel economy, and the need for longer service life and greater robustness also demand more stringent specifications and a smaller footprint for the designs.

[0006] Another technical issue concerns lubrication. In certain configurations and vehicle speed ranges, the planetary or pinion gears of a given planetary gear assembly can reach significant rotational speeds, i.e., many thousands of rpm. The rotational speed of the planetary carrier can also be relatively high. High planetary or pinion gear speeds are not inherently problematic, but they do require adequate lubrication, not only to lubricate the interface between the pinion, bearing, and pinion shaft, but also to dissipate the heat generated at this interface by such high speeds.

[0007] The present invention relates to an improved planetary gear set assembly which not only provides a more robust assembly but also improved lubricating oil channels to the planetary bearings. SUMMARY

[0008] The present invention provides a planetary gear set assembly for a transmission, characterized by the features of claim 1.

[0009] In another example of the present invention, the planetary gear set assembly further comprises a lubrication passage for supplying pressurized hydraulic fluid for lubricating the planet gears of the planet carrier assembly. The lubrication passage comprises an axial bore intersecting a radial bore in the second rotating element, a second thrust bearing, a lubrication passage between the web part and the bearing plate of the planet carrier assembly, and an axial bore in each of the pinion shafts.

[0010] In yet another example of the present invention, the bearing plate also comprises a bearing surface. The bearing surface is an axial end face adjacent to the inner circumference of the bearing plate. The second thrust bearing is arranged on the bearing surface. The plurality of lubrication recesses are arranged radially outward from the bearing surface near the pinion shafts of the planetary carrier assembly.

[0011] In yet another example of the present invention, the bearing plate is arranged in a groove on the inner circumference of the web part of the planet carrier assembly, and a snap ring is arranged in the groove to fasten the bearing plate to the web part of the planet carrier assembly.

[0012] In yet another example of the present invention, the planetary gear set assembly also includes a needle bearing assembly arranged on each pinion shaft for rotatably supporting the planetary gear.

[0013] In yet another example of the present invention, the carrier part and the web part of the planetary carrier assembly have a plurality of pinion bores. Each plurality of pinion bores of the carrier part is arranged coaxially with one of the plurality of bores of the web part. A first end of each of the pinion shafts is arranged in one of the plurality of pinion bores of the carrier part. A second end of each of the pinion shafts is arranged in one of the plurality of bores of the web part.

[0014] In yet another example of the present invention, an inner surface of the lubrication recesses in combination with an outer surface of the web part of the planet carrier assembly forms a lubrication passage which is connected to the second thrust bearing and an axial bore of each of the pinion shafts.

[0015] Further goals, advantages, and areas of application will become apparent from the description presented here. It is understood that the description and specific examples serve only as illustrations. DRAWINGS

[0016] The drawings described herein serve only as illustrations. Fig. 1 is a fragmented cross-sectional view of a planetary gear set assembly, according to an example of the present invention; and Fig. Figure 2 is a perspective view of a support element of a planetary gear set assembly, according to an example of the present invention. DETAILED DESCRIPTION

[0017] The following description is merely exemplary.

[0018] With reference to Fig. Figure 1 is a first example of the present invention in conjunction with part of a planetary gear assembly, characterized by reference number 10. The planetary gear assembly 10 comprises a drive hollow shaft or input shaft 12, a sun gear 16, a planet carrier 20, and a ring gear 22. The input shaft 12 has external teeth 14 that engage with and drive the sun gear 16. The sun gear 16 has teeth 18 on its outer surface. The planet carrier 20 is preferably a welded construction comprising forged or cold-formed components and is generally aligned with the sun gear 16. The planet carrier 20 includes an annular extension 24 with external teeth or teeth that engage with corresponding driving or driven elements (not shown).The toothed ring 22 also includes an annular extension 26 which engages in any way to enable a common rotation with a corresponding driving or driven element 28.

[0019] The planet carrier 20 also includes a multitude of planet gears or pinion gears 30 (one of which is located on Fig. 1), which are rotatably mounted by rolling bearings, such as cage roller bearing or needle roller bearing assemblies 32. The roller bearing or needle roller bearing assemblies 32 are in turn supported by a corresponding plurality of pinion shafts 40, which are received within several pairs of spaced-apart, aligned bores 42 in the planet carrier 20, see Fig. 1. The number of planetary or pinion gears 30, bearing assemblies 32, stub shafts or pinion shafts 40, and pairs of aligned bores 42 can be three, four, five, six, or more, depending on the torque load on the planetary gear assembly 10 and other design parameters. The plurality of pairs of aligned bores 42, the stub shafts or pinion shafts 40, the bearing assemblies 32, and the planetary or pinion gears 30 are typically and preferably arranged or mounted parallel to and at equal angular intervals around the common axis of the input shaft 12 and the planet carrier 20. For example, if four of each of the aforementioned components are present, as in Fig. As shown in Figure 2, these are preferably arranged at intervals of 90° around the common axis of the input shaft 12 and the planet carrier 20.

[0020] As in Fig. As shown in Figure 1, the pinion shafts 40 each comprise a concentric, axial bore or passage 44, with an opening at each end of the shaft 40, extending along the axis of the shaft 40. The bores 42 of the planet carrier 20 may have a closed end, or the end may be open, for communication between the passage 44 and the outside of the planet carrier.

[0021] With reference to Fig. 2 and further with reference to Fig. Figure 1 shows a planetary gear carrier 200 in accordance with an example of the present invention and describes it below. The planetary gear carrier 200 comprises a carrier part or plate 210 and a web part or element 212. As shown in Figure 1, the planetary gear carrier 200 comprises a carrier part or plate 210 and a web part or element 212. Fig. As shown in Figure 2, the support plate 210 comprises a plurality of coaxially aligned bores 214, each aligned with one of the several coaxially aligned bores 216 of the web element 212, which are only in the Fig. 1 are recognizable. The bridge element 212 also includes an inner circumference or rim 218, which forms a bore 220 coaxial to the input shaft 12.

[0022] The inner circumference or edge 218 of the web element comprises a plurality of semicircular recesses 222 and a snap-ring groove 224. One of the multiple recesses 222 is arranged adjacent to each of the bores 216 of the web element 212. The recesses 222 provide relief or passage, thus enabling communication of the passage 44 of the pinion shaft 40 outside the planet carrier element 20, 200. The snap-ring groove 224 is arranged on the inner circumference or edge 218 of the web element 212.

[0023] The planet carrier element 20, 200 further comprises a bearing plate 70. The bearing plate 70 is a largely flat, stamped plate having several radial extensions 72 and a plurality of recesses 74. The bearing plate 70 is attached to the web element 212 such that one of the several radial extensions 72 and recesses 74 is located adjacent to each of the several bores 216. The recesses 74 of the bearing plate 70 cooperate with the pinion shaft 40 to form a lubrication passage 45 that communicates with the passage 44 of the pinion shaft 40. The bearing plate 70 is held in position by a snap ring 76 located in the snap ring groove 224 of the web element 212 and, when assembled with the rest of the planet gear set 10, extends radially inward toward the input shaft 12.

[0024] The planetary gear set assembly 10 and the transmission in general comprise a series of thrust bearings that allow adjacent transmission elements to rotate freely relative to one another, while axial loads are transferred from one element to the adjacent element. For example, the planetary gear set assembly 10 comprises a first thrust bearing 80, a second thrust bearing 82, a third thrust bearing 84, and a fourth thrust bearing 86. In particular, the first thrust bearing 80 is arranged between a first end 85 of the sun gear 16 and the annular extension 24 of the carrier plate 210 of the planet carrier segment 20, 200. The second thrust bearing 82 is arranged between a second end 88 of the sun gear 16 and a first or inner surface 90 of the bearing plate 70. The third thrust bearing 84 is arranged between a second or outer surface 92 of the bearing plate and the driving or driven element 28, connected to the ring gear 22.The fourth thrust bearing 86 is arranged between the driving or driven element 28, connected to the gear ring 22 and another element or gear housing 94.

[0025] As mentioned above, the input shaft 12 is hollow and pressurized with lubricating oil or hydraulic fluid. A radial opening 102 in the wall of the input shaft 12 directs pressurized fluid into a radial passage 104. The lubricating fluid is guided radially outward to the second thrust bearing 82, through the thrust bearing 82, and into the passage 45, which is formed by the recess 74 of the bearing plate 70 and the passage 44 of the pinion shaft 40. Thus, the interface between the pinion, bearing, and shaft is directly supplied with lubricant. Furthermore, the radial passage 45, which provides the lubrication, remains in a radially outward orientation, thereby minimizing the influence of the rapid rotation of the planet carrier 20 on the lubrication flow.

Claims

[1] Planetary gear set assembly (10) for a transmission, wherein the planetary gear set assembly (10) comprises the following: a planet carrier assembly comprising a carrier part (210), a web part (212) and a plurality of planet gears (30), rotatably mounted by pinion shafts (40) each with an axial passage (44), wherein the carrier part (210) of the planet gear assembly is engaged with a first rotating element for common rotation; a sun wheel (16) with a first and a second axial end (85, 88), wherein the sun wheel (16) engages with a second rotating element for common rotation; an engaging toothed ring (22) for common rotation with a third rotating element, wherein the toothed ring (22) and the sun gear (16) engage with each of the several planet gears (30) of the planet carrier; a bearing plate (70) which is held by the web part (212) of the planetary gear carrier; and a first and second thrust bearing (80, 82), wherein the first thrust bearing (80) is arranged between the support part (210) of the planet carrier assembly and the first axial end (85) of the sun gear (16), and the second thrust bearing (82) is arranged between the bearing plate (70) and the second axial end (88) of the sun gear (16); characterized by , that the bearing plate (70) has several radial extensions (72) on its outer circumference, each of which covers the axial passage (44) of a respective pinion shaft (40), and has a recess (74) radially within each radial extension (72); wherein the web part (212) has an inner circumferential edge (218) which includes several semicircular recesses (222), wherein each radial extension (72) of the bearing plate (70) is arranged in a corresponding semicircular recess (222) of the web part (212); and wherein the recesses (74) of the bearing plate (70) cooperate with the pinion shaft (40) to form a lubrication passage (45) which communicates with the passage (44) of the pinion shaft (40).

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