DE102015218544A1 - Planetary gear with planetary gears with different helix angles - Google Patents

Abstract

Transmission sections in planetary gear design are widely used. For example, these are used in automatic transmissions, differential devices, etc. A common design of such transmissions includes a central sun gear, a coaxial with internally toothed ring gear, and a planet carrier having a plurality of planetary gears disposed thereon, the planet gears meshing with the sun gear and the ring gear on the one hand. In a widespread embodiment, the gears are each helically toothed. It is proposed a planetary gear 1 with a sun gear 2, with a ring gear 3, with a planet carrier and with a plurality of planet gears 4, wherein the planetary gears 4 are rotatably mounted on the planet carrier and wherein the planet gears 4 with the sun gear 2 and with the ring gear 3 as Radpartner comb, wherein the planet gears 4 each have a helical toothing 7, wherein the teeth 8 of the helical toothing 7 have a first flank 9 and a second flank 10, wherein the first flank 9 at least partially with a first helix angle beta_1 and the second flank 10th at least partially formed with a second helix angle beta_2, and wherein the first and the second helix angle beta_1, beta_2 are formed differently.

Description

The invention relates to a planetary gear with a sun gear, a ring gear and a planet carrier and a plurality of planetary gears, wherein the planetary gears are arranged on the planet carrier and wherein the planetary gears mesh with the sun gear and with the ring gear as Radpartner, the planetary gears respectively a helical toothing, wherein the teeth of the helical toothing have a first flank and a second flank, wherein the first flank is at least partially formed with a first helix angle and the second flank at least partially with a second helix angle.

Transmission sections in planetary gear design are widely used. For example, these are used in automatic transmissions, differential devices, etc. A common design of such transmissions includes a central sun gear, a coaxial with internally toothed ring gear, and a planet carrier having a plurality of planetary gears disposed thereon, the planet gears meshing with the sun gear and the ring gear on the one hand. In a widespread embodiment, the gears are each helically toothed. Such a helical toothing generates an axial force in addition to the actual power transmission. However, if one looks at the planet gears, they are based on the one on the ring gear and the other on the sun gear, wherein the axial forces generated are directed against and substantially cancel.

In the publication DE 11 2005 003 077 B4 For example, it is proposed to prevent reverse installation of planetary gears with asymmetrically shaped teeth. The publication DE 2320340 A For gearboxes that transmit maximum power in one direction only, the tooth flanks under load receive a larger meshing angle than the less loaded counter flanks. In the publication DE 4410042 A1 For example, an involute gear planetary gear is proposed in which the tooth surfaces of the planets meshing with the sun gear and the tooth surfaces on the other side have different amounts of correction. In the publication DE 2402631 B1 a planetary gear for a wind turbine is presented in which the flanks of the teeth of the teeth of the sun and the planet gears are formed asymmetrically. In a planetary drive according to the publication DE 69308437 C2 are different operating pressure angle between the planetary gears and the ring gear on the one hand and the planetary gears and the sun gear on the other hand formed. According to the document WO2011 / 067633 A1 a transmission with gears is proposed, wherein the flank angles of the teeth differ from each other.

It is an object of the present invention to propose a planetary gear, which is improved in performance. This object is achieved by a planetary gear with 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 drawings.

In the context of the invention, a planetary gear is proposed, which is e.g. can be used in a motor vehicle transmission in the drive train. The planetary gear is designed as a Stirnzahnradplanetengetriebe, the individual wheels of the planetary gear are circumferentially toothed.

The planetary gear has a sun gear, a ring gear and a planet carrier with a plurality of planetary gears. Sun gear, ring gear and planet carrier are preferably arranged concentrically and / or coaxially to each other. In particular, the planetary gear, in particular the sun gear, the ring gear and / or the planet carrier defines a main axis of rotation of the planetary gear. For example, the planetary gear comprises at least or exactly three planet gears.

The planet gears are arranged rotatably in a common pitch circle coaxially with the main axis of rotation and preferably equally spaced on the planet carrier. The planet gears mesh with the sun gear on one side and with the ring gear on the other side. Sun gear and ring gear are also referred to as Radpartner the planetary gears. Sun gear, ring gear and planet carrier can also be referred to as shafts of the planetary gear, it being possible to provide during operation that one of the shafts is arranged stationary.

The planet gears each have a helical toothing, in particular a straight helical toothing, on. In a helical gearing, the teeth of the helical gearing do not run parallel to the axis of rotation of the planetary gear in a radial plan view from the outside. The teeth of the helical teeth run in particular in the radial plan view of the planetary gear at a helix angle beta. The helix angle beta is generally more than 2 degrees, preferably more than 5 degrees and in particular more than 10 degrees. Furthermore, it is preferred that the helix angle beta is less than 30 degrees, preferably less than 25 degrees.

The teeth of the helical gearing have a first flank and a second flank. Preferably, the first edge is formed as a leading edge and the second edge as a trailing edge. The first flank extends at least in sections with a first helix angle, the second flank extends at least in sections with a second helix angle.

In the context of the invention it is proposed that the first and the second helix angle are formed differently. Thus, the first and second helix angles differ. In particular, the teeth are asymmetrical with respect to a central plane of symmetry running along the teeth. In particular, the first and second flanks are over a common axial section of the tooth 7 formed with different helix angles. The axial section preferably extends over a region of the tooth in the longitudinal extent of more than 80%. Preferably, the axial section extends over the entire length of the tooth in the longitudinal extent. The helix angles are preferably constant over the axial section. Alternatively, the helix angles may change over the course.

It is a consideration of the invention that on the helix angle of the first flank and the second flank, the axial forces arising during operation can be adjusted specifically. So it is in principle possible to choose the first and the second helix angle such that e.g. a resulting axial force is generated in a constructively predeterminable direction. Alternatively, it is possible for the first and the second helix angle to be selected such that the axial forces cancel out not only essentially, but completely or at least significantly more accurately than is known from the prior art.

Considering the cancellation of the axial forces somewhat more precisely, it is preferred that the helix angles differ by an angular amount which, although larger than 0.1 degrees, preferably greater than 0.3 degrees, is smaller than 2 degrees, in particular smaller is measured as 1 degree. Preferably, the amount is 0.5 degrees. By this comparatively small correction of the helix angle, the planetary gear can be adjusted without axial force. The planetary gear is preferably operable only in one direction of rotation. The reason is that due to the correction of the helix angles in a reversal of the direction of rotation, the resulting axial force would be greater than with an uncorrected planetary gear. In particular, the planetary gear is optimized for one direction of rotation.

Structurally, the teeth may each be divided into a first tooth flank half and a second tooth flank half, the first tooth flank half is as a first partial tooth, in particular part of a tooth, with the first helix angle and the second tooth flank half is as a partial tooth, in particular part of a tooth with the formed second helix angle. In this way, the planetary gear or its helical toothing can be constructed in a simple manner.

With the aim of obtaining the planetary gear friction and / or wear, it is preferred that one of the wheel partners teeth with the first helix angle and the other wheel partner has teeth with the second helix angle. In particular, the helix angles of the wheel partners differ from one another by the same amount as the first and second helix angles of the planet gears.

It is preferred that the transmission is designed for a main operating direction of rotation, so that all wheels in the planetary gear during operation rotate significantly or even exclusively in a direction associated with them. In this embodiment, it is preferred that the wheel partner, which meets a power transmitting edge of the planet gear, takes over the helix angle of this flank. Thus, the power transmitting wheel contacts are each formed with the same helix angle.

In a preferred embodiment of the invention, in a reference system in which the planet carrier is, the sun gear is a relative power input shaft and the ring gear is a relative power output shaft. Alternatively or additionally, a relative power flow relative to the planet carrier results from the sun gear to the ring gear. Via the second flanks, the relative power output shaft is driven, wherein the second helix angle is formed greater than the first helix angle. Alternatively or additionally, in one or the reference system in which the planet carrier is, the sun gear in the reference system is a relative power output shaft and the ring gear in the reference system is a relative power input shaft, the relative power output shaft being driven via the second edges and the second skew angle being larger is formed as the first helix angle. Alternatively or additionally, a relative power flow relative to the planet carrier results from the ring gear to the sun gear.

It is preferable that one of the shafts, that is, the sun gear, the ring gear or the planetary carrier is formed as a power input shaft and another of the shafts as a power output shaft is. The third wave may be stationary, braked and / or accelerated. In particular, the third wave may be fixed, forming another power input or another power output. It is envisaged that the power output shaft is driven via the second flanks of the planet gears, wherein the second helix angle is formed greater than the first helix angle. Background of this training is that in a planetary gear due to losses, especially friction losses, no equal torques at the power input shaft and the power output shaft or at the power input and power output of the planet gears are present. Thus, the toothing forces on the two interventions on the two wheel partners are not the same, so that a delta arises from the axial forces acting on the planetary bearing. In particular, the torques at the power output of the planet are smaller than at the power input. Thus, the resulting axial forces at the power output of the planet are also smaller than those at the power input. By increasing the helix angle at the power output, the axial forces generated there are increased, so that the delta can be eliminated from the axial forces or at least reduced.

For example, the planetary gear is designed so that by losses acting on the power input circumferential force is 3% higher than the force acting on the power output circumferential force. The same percentage difference would result for the axial forces if the first and second flanks each had the same helix angle. However, if the first and second flanks are corrected differently at the helix angle, in this example with a difference of 0.5 degrees, equal axial forces will be produced even at the different circumferential forces. As a result, the storage of planetary gears is relieved and losses are avoided. Overall, the performance of the planetary gear can be improved by this adjustment.

In the event that the sun gear as a power input shaft and the planet carrier are designed as a power output shaft and the sun gear drives the planetary gears over the first edge and the planetary wheels supported on the second edge on the preferably stationary ring gear, it is preferred that the second Bevel angle greater than the first helix angle is formed.

In another case, the planet carrier forms a power input shaft and the sun gear forms a power output shaft. The ring gear supports the planet gears via the first flank, the planetary gears drive the sun gear via the second flank. The second helix angle is preferably larger than the first helix angle.

In another possible configuration, the ring gear is formed as a power input shaft and the sun gear as a power output shaft. Preferably, the planet carrier is stationary. The ring gear drives the planet gears via the first flanks, the planet gears drive the sun gear via the second flanks. Preferably, the second skew angle is greater than the first skew angle is formed.

In another configuration, the sun gear is configured as a power input shaft and the ring gear as a power output shaft. The sun gear drives the planet gears over the first flanks. The planet gears drive the ring gear on the second flanks. Preferably, the second helix angle is greater than the first helix angle formed.

In another configuration, the ring gear is configured as a power input shaft and the planet carrier as a power output shaft. The ring gear drives the planet gears over the first flanks. The planet gears are based on the second flanks on the sun gear. Preferably, the second helix angle is greater than the first helix angle formed.

In another configuration, the planet carrier is configured as a power input shaft and the ring gear as a power output shaft, the planetary gears are supported on the sun gear via the first flanks. Furthermore, the planet wheels for the second flanks drive the ring gear. Preferably, the second skew angle is greater than the first skew angle is formed.

Preferably, the power input shaft with a torque generator and / or motor, in particular with an electric motor or internal combustion engine operatively connected or operatively connected. Optionally, the torque generator or motor forms part of the planetary gear.

Further features, advantages and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying drawings. Showing:

1 a schematic three-dimensional representation of a planetary gear as a first embodiment of the invention;

2 one of the planetary gears of the 1 in a schematic three-dimensional representation;

3 a radial plan view of a section of the planetary gear of the preceding figures;

4 a schematic edge view of the planetary gear of the preceding figures.

The 1 shows in a schematic three-dimensional representation of a planetary gear 1 as an embodiment of the invention. The planetary gear 1 is used for example in a motor vehicle as part of the drive train.

For example, the planetary gear 1 form a translation stage in the driveline in the transmission of a traction torque for the vehicle.

The planetary gear 1 has a sun wheel 2 , a ring gear 3 and a plurality of planetary gears 4 on, which are rotatably mounted on a planet carrier, not shown. The planetary gear 1 or the sun wheel 2 and / or the ring gear 3 define a main axis of rotation H. The planet gears 4 each define their own axes of rotation D, which are arranged on a common pitch circle diameter about the main axis of rotation H.

The planet wheels 4 , the sun wheel 2 and the ring gear 3 are each formed as gears. The sun wheel 2 is radially outside and / or front side with a Sonnenradschrägverzahnung 5 educated. The ring gear 3 is radially inside with a Hohlradschrägverzahnung 6 educated. The planet wheels 4 each have radially outwardly helical teeth 7 on. The helical gears 7 are each designed as straight helical gears. The Hohlradschrägverzahnung 6 has a helix angle beta_Hohlrad, Sonnenradschrägverzahnung 5 has a helix angle beta_sunner. The helix angles are in each case the intermediate angle between the course of the tooth and a parallel to the main axis of rotation H 'on a development, in particular on the pitch circle

The helix angles of the planet gears 4 are explained in the following figures. To define the helix angle is on the 3 directed.

The helical toothing 7 the planet wheels 4 has a plurality of teeth 8th on. Each of the teeth 8th has a first edge 9 and a second flank 10 on. Looking at the planetary gear 1 For example, in one embodiment, wherein the power input to the sun gear 2 and the power output on the planet carrier are. The ring gear 3 is stationary in a first embodiment. Furthermore, the sun wheel rotates 2 counterclockwise. This drives the sun wheel 2 the planet wheels 4 over the first flank 9 at. At the ring gear 3 the planetary gears are supported 4 with the second flank 10 from. The first flank 9 forms a leading edge, the second flank 10 forms a trailing edge of the respective tooth 8th ,

The sun wheel 2 or more generally, the power input shaft is always operated in one direction only. During operation of the planetary gear 1 Axialkräfte arise, whereby by the first engagement between the power input shaft - in this case the sun gear 2 - An axial force on the planet gears 4 arises. At the second engagement of the planet gears 4 opposite to the other wheel partner - in this case the ring gear 3 - creates a second axial force, which counteracts the first axial force. Without loss of power in the planetary gearbox 1 would the axial forces compensate exactly. However, the torques acting on the first engagement are due to power losses in the planetary gear 1 greater than the axial forces acting on the second engagement, with the resulting axial forces also being different. Thus remains a resultant axial force, which is a storage of the planetary gears 4 loaded.

To eliminate this load is provided that a helix angle on the first flank 9 is smaller than a second helix angle at the second flank 10 ,

Thoughtfully one can get one of the teeth 8th imagine two partial teeth, with the first flank 9 through a first partial tooth 11a a reference tooth with the first helix angle and the second flank 10 through a second partial tooth 11b a reference tooth is formed with the second helix angle.

In the 2 is the planetary gear 4 with its straight helical toothing 7 shown again in a three-dimensional representation. In the head area of the tooth 7 is with a first line 12 the course of the tooth 7 on the first flank 9 visualized. By contrast, by the second line 13 the course of the tooth 7 on the second flank 10 shown. The third line 14 shows the change from a tooth having a common helix angle to the tooth 7 which shows two different helix angles. The first and the second line 12 . 13 each extend in the longitudinal direction of the tooth 7 on the first and on the second partial tooth 11a , b, wherein the course corresponds to the respective helix angle. For example, the first and the second line 12 . 13 at the height of the profile reference line or at the head line.

It is possible, on the one hand, that only one of the flanks 9 . 10 is modified. However, it is also possible that the first and the second flank 9 . 10 are adjusted accordingly.

In the 3 is a radial plan view of the tooth 8th one of the planet wheels 4 shown. Furthermore, in the 3 a rotation axis D of the planetary gear 4 or a parallel D 'of the axis of rotation D shown in the sheet plane. With the outer contour lines are the contours 16a , b of a comparative tooth 15 shown. For example, the contours 16a , b the contours of the comparative tooth 15 at the head line or at the profile reference line. The comparison tooth 15 assumes a helix angle beta with respect to the axis of rotation D or the parallel D '. The helix angle is defined as the angle that exists between the longitudinal course of the respective tooth 7 . 15 and the axis of rotation D projected as a parallel D 'results in a common plane, wherein the common plane forms a settlement.

The one with the contours 17a , tooth illustrated 8th however, has different helix angles. The contour 17a corresponds to the first line 12 and / or the first partial tooth 11a the first flank 9 , The contour 17a and / or the first line 12 and / or the first flank 9 and / or the first partial tooth 11a closes with the rotation axis D or the parallel D 'the first helix angle beta_1. The contour 17b corresponds to the second line 13 and / or the second partial tooth 11b the second flank 10 , The contour 17b and / or the second line 13 and / or the second flank 10 and / or the second partial tooth 11b closes with the rotation axis D or the parallel D 'the second helix angle beta_2.

The helix angle beta_1 at the first flank 9 is smaller than the helix angle beta of the reference tooth 16 , By contrast, the helix angle beta_2 is the second flank 10 formed larger than the helix angle beta of the reference tooth 16 , Relative to each other, the helix angles differ by an amount formed by the difference between beta_1 and beta_2.

Thus, it is possible the first and the second edge 9 . 10 with different helix angles beta_1 and beta_2 form by only one flank 9 or 10 or both flanks 9 and 10 be modified accordingly. By way of example, the tooth width decreases in the direction of rotation about the axis of rotation D at the head line in the first part tooth 11a and / at the first flank 9 by the amount d1 = 20 microns and the tooth width in the direction of rotation about the axis of rotation D at the head line in the second partial tooth 11b and / on the second flank 10 by the amount d1 = 20 microns and that at the same end of the tooth 8th , The tooth 8th has a conical shape in plan view.

In the 4 is a three-dimensional representation of the planetary gear 4 shown, with the teeth 8th each on the first and the second flank 9 . 10 have different helix angles beta_1 and beta_2. The teeth 8th are formed so that they have on one end side - in this example, the rear end side - a wider area in the circumferential direction than at the other end of the same tooth 7 ,

LIST OF REFERENCE NUMBERS

1

 planetary gear

2

 sun

3

 ring gear

4

 planet

5

 Sonnenradschrägverzahnung

6

 Hohlradschrägverzahnung

7

 helical teeth

8th

 tooth

9

 first flank

10

 second flank

11a, b

 first and second partial tooth

12

first line

13

 second line

14

 third line

15

 Compare tooth

16a, b

 Contours of the comparative tooth

17a, b

Contours of the tooth 7

H

 Main axis of rotation

H'

 Parallel to the main axis of rotation

D

 axis of rotation

D '

 Parallel to the axis of rotation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 112005003077 B4 [0003]
• DE 2320340 A [0003]
• DE 4410042 A1 [0003]
• DE 2402631 B1 [0003]
• DE 69308437 C2 [0003]
• WO 2011/067633 A1 [0003]

Claims (12)

Planetary gear ( 1 ) with a sun wheel ( 2 ), with a ring gear ( 3 ), with a planetary carrier and with a plurality of planetary gears ( 4 ), the planetary gears ( 4 ) are rotatably mounted on the planet carrier and wherein the planet gears ( 4 ) with the sun wheel ( 2 ) and with the ring gear ( 3 ) as Radpartner, the planetary gears ( 4 ) each have a helical toothing ( 7 ), wherein the teeth ( 8th ) of helical gearing ( 7 ) a first edge ( 9 ) and a second flank ( 10 ), wherein the first edge ( 9 ) at least in sections with a first helix angle (beta_1) and the second flank ( 10 ) are at least partially formed with a second helix angle (beta_2), characterized in that the first and the second helix angle (beta_1, beta_2) are formed differently. Planetary gear ( 1 ) according to claim 1, characterized in that the helix angles (beat_1, beta_2) differ by an amount which is greater than 0.1 degrees and / or less than 2 degrees. Planetary gear ( 1 ) according to claim 1 or 2, characterized in that the teeth ( 8th ) each have a first tooth flank half and a second tooth flank half, wherein the first tooth flank half as a partial tooth ( 11a ) with the first helix angle (beta_1) and with the second tooth flank half as a partial tooth ( 11b ) is formed with the second helix angle (beta_2). Planetary gear ( 1 ) according to one of the preceding claims, characterized in that one of the wheel partners has a helical toothing with the first helix angle (beta_1) and the other wheel partner helical toothing with the second helix angle (beta_2). Planetary gear ( 1 ) according to one of the preceding claims, characterized in that in a reference system in which the planet carrier is, the sun gear ( 2 ) in the reference system, a relative power input shaft and the ring gear ( 3 ) forms in the reference frame a relative power output shaft, wherein over the second edges ( 10 ) the relative power output shaft is driven and wherein the second helix angle (beta_2) is greater than the first helix angle (beta_1) is formed and / or that in a reference system in which the planet carrier is, the sun gear ( 2 ) in the reference system, a relative power output shaft and the ring gear ( 3 ) forms in the reference frame a relative power input shaft, wherein over the second edges ( 10 ), the relative power output shaft is driven, and wherein the second skew angle (beta_2) is made larger than the first skew angle (beta_1). Planetary gear ( 1 ) according to one of the preceding claims, characterized in that the sun gear ( 2 ), the ring gear ( 3 ) and the planet carrier each form a shaft, wherein one of the waves is formed as a power input shaft and another of the waves as a power output shaft, wherein over the second flanks ( 10 ), the power output shaft is driven, and wherein the second skew angle (beta_2) is made larger than the first skew angle (beta_1). Planetary gear ( 1 ) according to one of the preceding claims, characterized in that the sun gear ( 2 ) is formed as a power input shaft and the planet carrier as a power output shaft, wherein the sun gear ( 2 ) the planet wheels ( 4 ) over the first flank ( 9 ) drives and the planetary gears ( 4 ) over the second flank ( 10 ) on the ring gear ( 3 ), wherein the second skew angle (beta_2) is greater than the first skew angle (beta_1) is formed. Planetary gear ( 1 ) according to one of the preceding claims 1 to 6, characterized in that the planet carrier as a power input shaft and the sun gear ( 2 ) is formed as a power output shaft, wherein the ring gear ( 3 ) the planet wheels ( 4 ) over the first flanks ( 9 ) and the planet gears ( 4 ) over the second flanks ( 10 ) the sun wheel ( 2 ), wherein the second skew angle (beta_2) is formed larger than the first skew angle (beta_1). Planetary gear ( 1 ) according to one of the preceding claims 1 to 6, characterized in that the ring gear ( 3 ) as a power input shaft and the sun gear ( 2 ) is formed as a power output shaft, wherein the ring gear ( 3 ) the planet wheels ( 4 ) over the first flanks ( 9 ) and the planet gears ( 4 ) over the second flanks ( 10 ) the sun wheel ( 2 ), wherein the second skew angle (beta_2) is formed larger than the first skew angle (beta_1). Planetary gear ( 1 ) according to one of the preceding claims 1 to 6, characterized in that the sun gear ( 2 ) as a power input shaft and the ring gear ( 3 ) is formed as a power output shaft, wherein the sun gear ( 2 ) the planet wheels ( 4 ) over the first flanks ( 9 ) and the planet gears ( 4 ) over the second flanks ( 10 ) the ring gear ( 3 ), wherein the second skew angle (beta_2) is formed larger than the first skew angle (beta_1). Planetary gear ( 1 ) according to one of the preceding claims 1 to 6, characterized in that the ring gear ( 3 ) is formed as a power input shaft and the planet carrier as a power output shaft, wherein the ring gear ( 3 ) the planet wheels ( 4 ) over the first flanks ( 9 ) and the planet gears ( 4 ) over the second flanks ( 10 ) on the sun wheel ( 2 ), wherein the second skew angle (beta_2) is greater than the first skew angle (beta_1) is formed. Planetary gear ( 1 ) according to one of the preceding claims 1 to 6, characterized in that the planet carrier as a power input shaft and the ring gear ( 3 ) is formed as a power output shaft, wherein the planetary gears ( 4 ) over the first flanks ( 9 ) on the sun wheel ( 2 ) and the planetary gears ( 4 ) over the second flanks ( 10 ) the ring gear ( 3 ), wherein the second skew angle (beta_2) is formed larger than the first skew angle (beta_1).

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