SE539396C2

SE539396C2 - Lubrication system for a planetary gear

Info

Publication number: SE539396C2
Application number: SE1551030A
Authority: SE
Inventors: Forsberg Jörgen; Hallgren Richard; Ishaq Fady
Original assignee: Scania Cv Ab
Priority date: 2015-07-17
Filing date: 2015-07-17
Publication date: 2017-09-12
Also published as: DE102016006716A1; SE1551030A1

Abstract

12 Abstract The present invention relates to a lubrication system for a planetary gear. Theplanetary gear comprises a sun Wheel (1) rotationally fixedly arranged on an inlet shaft(2), a number of planetary Wheels (7) rotatably supported by planetary Wheel bearings(9) and a planetary carrier (3) rotationally fixedly arranged on an outlet shaft (4). Thelubrication system comprises a primary lubrication passage (12) directing lubricantfrom one of the shafts (2, 4) to the planetary Wheel bearings (9). The primarylubrication passage (12) comprises a first part (12b) extending through the sun Wheel(1) from an inlet opening (12a) to an outlet opening (12c) located at a longer radial distance from a rotation axis (5) of the sun Wheel (1) than the inlet opening (l2a). (Pig. 1)

Description

Lubrication system for a planetary gear BACKGROUND TO THE INVENTION AND PRIOR ART The present invention relates to lubrication system for a planetary gear according to the preamble of claim 1.

A planetary gear comprises a sun wheel, a ring wheel and a number of planetarywheels supported by a planetary carrier. The planetary gear can be used in a hybridpower train in a vehicle. The sun wheel is rotationally ﬁxedly arranged on an inletshaft and the planetary carrier is rotationally ﬁxedly arranged on an outlet shaftcoaxially arranged with the inlet shaft. The components of the planetary gear is usuallylubricated and cooled by a lubrication system supplying lubricant via a lubricationchannel in one of the shafts to a lubrication passage in the planetary carrier. Thelubricant is forced radially outwardly in the lubrication passage by means of thecentrifugal force of the rotating planetary carrier. The lubrication passage in theplanetary carrier delivers lubricant to the planetary wheel bearings. During certainoperating conditions, the rotational speed of the planetary carrier is very low. In thiscases, the centrifugal force is not high enough to force the lubricant all the way radially outwardly to the planetary wheel bearings.

JP 2010149764 shows a power transmission device of a hybrid vehicle capable ofsupplying oil toward a planetary pinion by using rotation of a sun gear. The powertransmission device can transmit channel of mechanical power output from an intemalcombustion engine to a driving shaft by dividing the mechanical power by a planetarygear mechanism. A ring gear rotates by interlocking with the driving shaft, and aplanetary carrier has a sun gear shaft j oined to an engine output shaft of the intemalcombustion engine and joining the sun gear and a rotor of an electric motor. The sun gear shaft is formed with an oil outflow hole capable of making the oil existing in an inside space ﬂow out to a pinion side space When the sun gear shaft rotates bycommunicating the inside space of the sun gear shaft With the pinion side space faced With a planetary pinion supported by the planetary carrier.

SUMMARY OF THE INVENTION The object of the invention is to ensure a required lubricant flow to the planetary Wheel bearings of a planetary gear during substantially all operating condition.

This object is achieved With the arrangement of the kind mentioned in the introductionWhich is characterized by the features indicated in the characterizing part of claim l.The planetary gear comprises a sun Wheel connected to an inlet shaft and a planetarycarrier connected to an outlet shaft. The planetary gear provides two operatingconditions. At a first operating condition, the inlet shaft is locked to the planetarycarrier. In this case, the sun Wheel and the planetary carrier rotate With the samerotational speed. At a second operating condition, the rotary movement of the inletshaft is transmitted to the outlet shaft via the sun Wheel, the planetary Wheels and theplanet carrier. In this case, the planetary carrier usually rotates With a lower rotationalspeed than the sun Wheel. The lubricant is forced by the centrifugal force radiallyoutWardly through the lubrication passage to the planetary Wheel bearings. The size ofthe centrifugal force is related to the rotational speed of the sun Wheel. Since therotation speed of the sun Wheel in most cases is higher or equal to the rotational speedof the planetary carrier, it is favorable to arrange a first part of the primary lubricationpassage in the sun Wheel. The relatively high speed of the sun Wheel duringsubstantially all operating conditions ensures a required lubrication flow through the lubricant passage all the Way radially outWardly to the planetary Wheel bearings.

According to an embodiment of the present invention, the inlet opening of the first partof the primary lubrication passage may be arranged at an inner periphery of the sunWheel and the outlet opening may be arranged in a side surface of the sun Wheel.Preferably, the outlet opening is arranged in the side surface in vicinity of an outerperiphery of the sun Wheel. In this case, the first channel of the lubrication passage obtains an optimal extension in a radial direction in the sun Wheel.

According to an embodiment of the present invention, said first part of the primary lubrication passage comprises a zone having a lubrication guiding surface forrning an angle of at least 45 degrees in relation the rotation axis of the sun Wheel. Preferably,the lubrication guiding surface forrns an angle in the range of 50-70 degrees in relationthe rotation axis of the sun Wheel. The presence of such a radially outWardly directedguiding surface results in a high Velocity radially outWardly of the lubricant ﬂoWWhich further ensures that the lubricant reaches the planetary Wheel bearings. Saidzone may comprise the outlet opening in the sun Wheel. In this case, the lubricant ﬂoWWill have a high Velocity radially outWardly When it leaves the first part of the primary lubrication passage and the sun Wheel.

According to the present invention, the primary lubrication passage comprises asecond part in Which the lubricant is directed from said first part to a third part of theprimary lubrication passage arranged in the planetary carrier. The planetary Wheelbearings supports the planetary Wheels in a radially outWardly position of the sunWheel. Thus, the primary lubrication passage has to have a final third part in theplanetary carrier directing lubricant to the bearings and a second interrnediate partdirecting the lubricant ﬂoW from the first part in the sun Wheel to the third part in theplanetary carrier. Said second part of the primary lubrication passage may be formed ina radial plane extending through the sun Wheel and the planetary carrier. Preferably,the second part of the primary lubrication passage may be design in a manner such thatit directs the lubricant ﬂoW radially outWardly in the second part of the primarylubrication passage from the first part in the sun Wheel to the third part of the primarylubrication passage in the planetary carrier. In this case, the lubrication ﬂoW Will not hit any surfaces in the second part of the primary lubrication passage.

According to an embodiment of the present invention, said third part of the primarylubrication passage comprises an annular groove provided With an opening via Which itreceives lubricant from said second part of the primary lubrication passage. Such anannular groove extends around the rotation axis of the shafts. The opening of thegroove may be arranged in a plane forrning an angle to the rotation axis of the shafts.The angle may be in the range of l-5°. Such an inclination of the opening of the groovefacilitates the reception of the lubricant ﬂoW in the groove. The opening of the groovein the third part of the primary lubrication passage may be arranged in a commonradial plane as the outlet opening of the first part of the primary lubrication passage. Inthis case, a radially outWardly directed lubricant ﬂow is provided in the second part of the primary lubrication from the outlet opening in the sun Wheel to the groove in the planetary Carrier.

According to an embodiment of the present invention, said third part of the primarylubrication passage comprises channels directing lubricant from the groove to therespective planetary Wheel and the planetary Wheel bearings. The third part of theprimary lubrication passage may comprises a number of channels having inletopenings at regular intervals along the annular groove. The lubricant received in thegroove Will ﬂoW along the annular groove until it reaches such an inlet opening. Theplanetary carrier may comprise a hub for each planetary Wheel, Wherein said third partof the primary lubrication passage comprises a channel directing lubricant to an innerspace of the hub and a channel directing lubricant from the inner space of the hub to the planetary Wheel bearing.

According to the present invention, the lubrication system comprises a secondarylubrication passage directing lubricant to an engagement area between the sun Wheeland the planetary Wheels. The secondary lubrication passage may extend through thesun Wheel between an inlet opening arranged at an inner periphery of the sun Wheeland an outlet opening arranged at an outer periphery of the sun Wheel in anengagement area With the planetary Wheels. The primary lubrication passage and thesecondary lubrication passage may have at least partly a parallel extension in the sunWheel.

According to the present invention, the primary lubrication passage and the secondarylubrication passage may receive lubricant from a common radial channel in one of theshafts. In this case, the number of radial oil channels in the shaft Will be reduced. Theshaft With the radial oil channel can be the inlet shaft or the outlet shaft. Thelubrication system comprises a disc shaped member arranged inside the sun WheelWhere it divides the primary lubrication passage from the secondary lubricationpassage. Such a disc shape member may have a relative simple design. The discshaped member may comprise an inner edge portion arranged at an outer radialposition of an outlet opening of said radial channel in the shaft and at an axial positionin Which it distributes the lubricant ﬂoW from the radial channel in predeterrnined properties to the respective lubrication passages.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention is described below by an example with reference to the attached drawing, on which: Fig. l shows a cross section view of a planetary gear comprising a lubrication systern according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THEINVENTION Fig. l shows a cross section view of a planetary gear. The planetary gear comprises asun wheel l which is rotationally fixedly arranged on a first rotatable shaft 2 and aplanet wheel carrier 3 which is rotationally fixedly arranged on an outlet shaft 4. Theinlet shaft 2 and the outlet shaft 4 are coaxially arranged. The inlet shaft 2 and theoutlet shaft 4 are parts of a drivetrain D of a vehicle. The inlet shaft 2, the sun wheel l,the outlet shaft 4 and the planetary carrier 3 are rotationally arranged around acommon rotation axis 5. A part of the outlet shaft 4 is rotatably arranged inside theinlet shaft 2 by means of a partially shown bearing 6. The planetary carrier 3 compriseshubs 8 supporting the respective planetary wheels 7. The planetary wheels 7 arerotatably arranged on the hub 8 by means of planetary wheel bearings 9. The planetarywheel 7comprises teeth engaged with teeth of the radially inwardly arranged sun wheel l and teeth of a radially outwardly arranged ring wheel l0.

The planetary carrier 3 comprises a locking portion 3a. The locking portion 3a is to beengaged by a not shown locking member. The locking member is rotationally fixedlyarranged on the inlet shaft 2. The locking member is movably arranged in an axialdirection in relation to the inlet shaft 2 between a first operating condition and a secondoperating condition. In the first operating condition, the locking member is inengagement with the locking portion 3a of the planet wheel carrier 3. The rotationalmovement of the inlet shaft 2 is transmitted to the outlet shaft 4 via the planetarycarrier 3. In this operating condition, the secondary shaft 4 and the planetary carrier 3rotate at the same rotational speed as the inlet shaft 2 and the sun wheel l. In thesecond operating condition, the locking member is out of engagement with the lockingportion 3a of the planet wheel carrier 3. The rotational movement of the inlet shaft 2 is transmitted to the outlet shaft 4 via the sun wheel l, the planetary wheels 7, the ring wheel 10 and the planetary carrier 3. In this operating condition, the secondary shaft 4and the planetary carrier 3 usually achieve a lower rotational speed than the inlet shaft 2 and the sun wheel 1.

The planetary gear is provided with a lubrication system. The lubrication systemcomprises an elongated axial lubrication channel 1 la arranged in a central portion ofthe outlet shaft 4. The lubrication system comprises at least one radial lubricationchannel llb directing lubricant from the axial lubrication channel 11 radiallyoutwardly and out of the outlet shaft 4 via an outlet opening llc. The outlet openingllc is arranged in a position radially inwardly of the sun wheel 1. An annular disc-shaped member 14 is arranged in the sun wheel 1. The disc-shaped member 14comprises an outer edge portion l4a f1xedly connected to the sun wheel 1 and a freeinner edge portion l4b arranged in a position radially outwardly of the outlet openingllc of the radial lubrication channel llb in the outlet shaft 4.The annular disc 14 formsa dividing wall between a primary lubrication passage 12 and a secondary lubricationpassage 13 in the sun wheel 1. The axial position of the inner edge portion l4b of thedisc-shaped member 14 def1nes the proportions of the lubricant ﬂow to be directedfrom the radial lubrication channel 1 lb to the primary lubricant passage 12 and thesecondary lubricant passage 13. Thus, a predeterrnined part of the lubricant ﬂowleaving the radial channel 1 lb is directed into an inlet opening 12a of the primarylubrication passage 12 and a remaining part of the lubricant ﬂow is directed into an inlet opening 13a of the secondary lubrication passage 13.

The primary lubrication passage 12 comprises a f1rst part comprising an inner spacel2b formed in the sun wheel 1. The inner space l2b has an extension between the inletopening 12a arranged at an inner periphery of the sun wheel 1 and an outlet opening12c arranged in a side surface of the sun wheel 1. The outlet opening 12c is arranged inthe vicinity of an outer periphery of the sun wheel 1. Thus, the inner space l2b has aradial extension essentially corresponding to the radial extension of the sun wheel 1.The rotational movement of the sun wheel 1 creates a centrifugal force forcing thelubricant in the inner space l2b radially outwardly. The inner space l2b comprise azone with a lubrication guiding surface 12b1 forrning an angle of at least 45 degrees inrelation to the rotation axes 5 of the sun wheel 1. The lubrication guiding surface 12b1extends to the outlet opening 12c. The lubrication ﬂow receives a velocity in an axialdirection along the guiding surface l2b1 ensuring that the lubricant ﬂow leaves the sun wheel 1. Furthermore, the lubrication ﬂow receives a relatively high velocity in a radial direction along the outwardly sloping guiding surface 12b1 ensuring that thelubrication ﬂow leaves the sun wheel 1 with a high Velocity in a radial direction. Thelubricant ﬂow leaving the outlet opening 12c ﬂows substantially radially outwardly ina second part of the primary lubrication passage 12. The second part of the lubricationpassage 12 comprises a second annular channel 12d forrned in an axial space between the sun wheel 1 and the planetary carrier 3.

The primary lubrication passage 12 comprises a third part in the planet wheel carrier 3.The third part of the primary lubrication passage 12 comprises an annular groove 12eextending around the rotation axis 5. An inlet opening 12e1of the annular groove 12e isarranged in a common radial plane as the outlet opening 12c of the sun wheel 1. Thus,the lubricant leaving the outlet opening 12c of the sun wheel 1 in a radially outwardlydirection will be received in the annular groove 12e via the inlet opening 12e1.Furthermore, the opening 12e1 of the annular groove 12e forms an angle in the rangeof 1- 5° in relation to the rotation axis 5. The third part of the primary lubricationpassage 12 comprises a number of third channels 12f receiving lubricant from theannular groove 12e. The third channels 12f has inlet opening arranged at regularintervals in the annular groove 12e. The third channels 12f directs the lubrication ﬂowradially outwardly to the respective hubs 8. Each hub 8 comprises a fourth channel 12gdirecting the lubricant to an empty inner space 8a of hub 8. Each hub 8 comprises atleast one f1fth channel 12h directing the lubrication from said inner space 8a to theplanetary wheel bearings 9. The planetary wheels 7 rotates with a low friction on thehub 8 by means of the planetary wheel bearings 9. The lubricant ﬂow distributed bythe primary lubrication passage 12 provides an effective cooling and lubrication planetary wheel bearing 9.

The secondary lubrication passage 13 comprises a lubrication channel 13b receivinglubricant, via the inlet opening 13a, from the radial channel 1 lb in the outlet shaft 4.Also in this case, the rotation movement of the sun wheel 1 creates a centrifugal forceforcing the lubricant in the secondary lubrication passage 13 radially outwardly. Theradially outwardly forced lubricant is received in a plurality of outlet channels 13c.Each outlet channel 13c comprises an outlet opening in a periphery portion of the sunwheel 1. The periphery portion of the sun wheel constitutes an engagement area withthe planetary wheel 7. The secondary lubrication passage provides an effective supplyof lubrication to the engagement area between the sun wheel 1 and the planetary wheels 7.

Thus, the primary lubrication passage 12 comprises a f1rst part in the form of an innerspace 12b arranged inside the sun Wheel 1. The lubricant in the inner space 12b isforced radially outWardly by the centrifugal force created by the rotational movementof the sun Wheel 1. It is favorable to arrange a f1rst part of the primary lubricationpassage 12 in the sun Wheel 1 instead of in the planetary carrier 3 since the sun Wheel 1usually has a higher rotational speed When the planetary carrier 3 in the secondoperating condition. Consequently, the lubricant in the f1rst channel 12b is usuallyforced radially outWardly by a larger centrifugal force than in a corresponding channelin the planetary carrier 3 When the planetary gear is in the in the f1rst operatingcondition. The radially outWardly sloping guiding surface 12b1 in the inner space 12bof the primary lubrication passage 12 provides a Velocity of the lubricant ﬂoW in anaxial direction ensuring that the lubricant ﬂoW leaves the sun Wheel 1. Furthermore,the radially outWardly sloping guiding surface 12b1 in the inner space 12b of theprimary lubrication passage 12 provides a high velocity of the lubricant ﬂoW in aradially outWardly direction. As a consequence, the lubrication ﬂoW leaving the innerspace 12b has a high velocity radially outWardly. The high velocity radially outWardlyof the lubrication ﬂoW 2 ensures that the planetary Wheel bearings 9 achieves arequired cooling and lubrication during substantially all operating conditions. ThesomeWhat inclined opening 12e 1 of the annular groove 12e in the planetary carrier 3 facilitates the reception of the lubricant ﬂoW in the annular groove 12e.

The invention is in no Way limited to the embodiment to Which the draWing refers but may be varied freely Within the scopes of the claims.

Claims

1. A lubrication system for a planetary gear comprising a sun Wheel (1) rotationallyfixedly arranged on an inlet shaft (2), a number of planetary Wheels (7) rotatablysupported by planetary Wheel bearings (9) and a planetary carrier (3) rotationallyfixedly arranged on an outlet shaft (4), Wherein the lubrication system comprises aprimary lubrication passage (12) directing lubricant from one of the shafts (2, 4) to theplanetary Wheel bearings (9), Wherein the primary lubrication passage (12) comprises afirst part (12b) extending through the sun Wheel (1) from an inlet opening (12a) to anoutlet opening (12c) located at a longer radial distance from a rotation axis (5) of thesun Wheel (1) than the inlet opening (12a), Wherein the primary lubrication passagecomprises a second part (l2d) in Which the lubricant is directed from said first part(12b) of the primary lubrication passage to a third part (12e-h) of the primarylubrication passage Which extends through the planetary carrier (3), and Wherein thelubrication system comprises a secondary lubrication passage directing lubricant to anengagement area between the sun Wheel (1) and the planetary Wheels (7), characterizedm that the primary lubrication passage and the secondary lubrication passage receivelubricant from a common radial channel (1 lb) in one of the shafts (2, 4) and that thelubrication system comprises a disc shaped member (14) arranged inside the sun WheelWhere it divides the primary lubrication passage (12) from the secondary lubrication passage (13).

2. A lubrication system according to claim 1, characterized in that the inlet opening(12a) of the first part of the primary lubrication passage is arranged at an innerperiphery of the sun Wheel (1) and the outlet opening (12c) of the first part of the primary lubrication passage is arranged in a side surface of the sun Wheel (1).

3. A lubrication system according to claim 1 or 2, characterized in that the first part(12b) of the primary lubrication passage comprises a zone With a lubrication guidingsurface (12b1) forrning an angle of at least 45 degrees to rotation axis (5) of the sunWheel (1).

4. A lubrication system according to claim 3, characterized in that said zone (12b1)comprises the outlet opening (12c) of the first part (12b) of the primary lubrication passage.

5. A lubrication system according to any one of the preceding claims, characterized inthat said second part (12d) of the primary lubrication passage is forrned in a space between the sun Wheel (1) and the planetary carrier (3).

6. A lubrication system according to any one of the preceding claims, characterized inthat said third part (12e-h) of the primary lubrication passage comprises an annulargroove (12e) provided With an opening (12e1) via Which it receives lubricant from said second part (12d) of the primary lubrication passage.

7. A lubrication system according to claim 6, characterized in that the opening (12e1)of the groove (12e) and the outlet opening (12c) of the first part (12b) of the primarylubrication passage is arranged in a common radial plane in relation to the rotation axis(5) ofthe sun Wheel (1).

8. A lubrication system according to claim 6 or 7, characterized in that the opening (12e1) of the groove (12e) forms an angle to the rotation axis (5) of the sun Wheel (1).

9. A lubrication system according to any one of the claims 6 to 8, characterized in thatthe third part (12e-h) of the primary lubrication passage comprises channels (12f-h)directing lubricant from the groove (12e) to the planetary Wheel bearing (9) of the respective planet Wheels (7).

10. A lubrication system according to claim 9, characterized in that the planetarycarrier (3) comprises a hub (8) for each planetary Wheel (7), Wherein the third part(12e-h) of the primary lubrication passage comprises a channel (l2g) directinglubricant to an inner space (8a) of the hub and a channel (12h) directing lubricant from the inner space (8a) of the hub to the planetary Wheel bearing (9).

11. A lubrication system according to claim 10, characterized in that the secondarylubrication passage extends through the sun Wheel (1) between an inlet opening (13a)arranged at an inner periphery of the sun Wheel (1) and an outlet opening (13c) arranged in an engagement area between the sun Wheel (1) and the planetary Wheels (7)-

12. A 1ubrication systen1 according to any one of the preceding c1ain1s, characterized inthat the disc shaped member (14) coniprises an inner edge portion (14b) arranged at anouter radia1 position of an out1et opening (11c) said radia1 channel (11b) in the shaft (4)and at an axia1 position in Which it distributes the 1ubricant ﬂow from the radia1channe1 (11b) in predeterrnined proportions to the respective lubrication passages (12, 13).

13. A drivetrain (D) coniprising a 1ubrication system according to any one of the c1ain1s 1-12.