WO2007138000A1

WO2007138000A1 - Transmission for transmitting a drive torque from one drive shaft to two output shafts

Info

Publication number: WO2007138000A1
Application number: PCT/EP2007/055080
Authority: WO
Inventors: Alois BÖCK; Detlef Baasch; Robert Peter; Florian Knedler
Original assignee: Zf Friedrichshafen Ag
Priority date: 2006-05-30
Filing date: 2007-05-25
Publication date: 2007-12-06
Also published as: DE102006025072A1; EP2024663A1

Abstract

The invention relates to a transmission, in particular a rear axle transmission for transmitting a drive torque from one drive shaft (2) to two output shafts (3, 5) by means of a differential unit (15) and a continuously variable device (14) for influencing the distribution rate of the drive torque to the output shafts (3, 5), said device being activated by means of at least one motor (37). The differential unit (15) comprises a differential (17) and a differential cage (19) that is operatively connected to the drive shaft (2) and the device (14) for influencing the distribution rate of the drive torque has at least one planetary gear set (39) as the transmission ratio stage, which is operatively connected to the differential cage (19) and an associated output shaft (3 and 5) and which can be activated by means of a shifting element (77). The planetary gear set (39) has a first sun gear (61) that is connected to the differential cage (19), a second sun gear (63) that is connected to the respective output shaft (3, 5), planetary gears (69, 71) that interact with the two sun gears (61, 63) and a planetary carrier that is in the form of a strut (65). According to the invention, each planetary gear (69, 71) has axially continuous teeth, with which both the first sun gear (61) and the second sun gear (63) engage.

Description

Transmission unit for guiding a drive torque from a drive shaft to two output shafts

The invention relates to a Getriebeeinheif for guiding a drive torque from a drive shaft to two output shafts according to the closer defined in the preamble of claim 1. Art.

Such a transmission unit is z. B. from FR 2 864 190 known. It describes an asymmetrical transfer case which distributes a drive torque generated by a drive motor by means of a differential unit to two wheels connected to an output shaft. A differential of the differential unit distributes the drive torque equally to the two output shafts.

In order to achieve a different torque distribution required, for example, due to cornering, each of the two output shafts is associated with a so-called torque vectoring unit with a planetary set, which is arranged between a differential cage of the differential unit and the respective output shaft and with which to the respective Output shaft acting drive torque can be influenced.

The web of the planetary gearset can be braked by means of a brake relative to a transmission housing for generating a so-called torque-vectoring torque, whereby the gearbox housing supporting Torque Vectαring torque by means of a realized with the planetary gears and the sun gears of the planetary gear ratio stage to the respective Bike is guided. The respective output shaft and the differential cage are in each case fixedly connected to a sun gear of the planetary gear set, the sun gears each having a gear arranged on the planet carrier. th planetary gear interact and thus two planetary gears are arranged on each planet carrier.

In such a gear unit with two in each case with a sun gear engaged on a planet carrier planetary gears disadvantageously a large width for the planetary gears is required because of a teeth of the planet gears due to their different design data must be provided an undercut. In addition, the mounting of the planetary gears on the planet carrier can make difficult, since the arrangement of the planet gears must be taken to each other. Furthermore, a jamming of the teeth of the planetary gears with a toothing of the sun gears is possible, and the production of the teeth of the planet gears is very costly.

The present invention has for its object to make a transmission unit of the type mentioned in such a way that planetary gears Qbersetzungsstufe with safe protection against tilting of the teeth of the planetary gears with sun gears are inexpensively manufacturable and easy to assemble.

According to the invention this object is achieved with a gear unit for guiding a drive torque to two output shafts with the features of claim 1

It is thus a transmission unit, in particular Hinterachsgetriebeeinheit, provided for guiding a drive torque from a drive shaft to two output shafts via a differential unit and a switchable by means of at least one motor, continuously adjustable device for influencing the degree of distribution of the drive torque to the output shafts, wherein the differential unit is a differential and one with the drive shaft having operatively connected differential cage and the device for influencing the degree of distribution of the drive torque has at least one Planetensaϊz as a translation stage, which is operatively connected to the differential cage and an associated output shaft and which is switchable by means of a switching element, and wherein the planetary gear set connected to the differential cage first sun , An associated with the respective output shaft second sun gear, with the two sun gears interacting planetary gears and a web designed as a planet carrier. It is inventively provided that each planetary gear has an axially continuous toothing, with which both the first sun gear and the second sun gear is engaged

With an inventively designed gear unit jamming of the teeth of the sun gears can be avoided with the planetary gears in an advantageous manner, with the assembly of planetary wheels also very simple by the use of a single planetary gear meshing with both sun gears is the width of the planetary gear compared to the use of two interacting with the two sun gears planet wheels by the elimination of an undercut between the two planetary gears advantageously very low. Furthermore, a cost-effective production of the planetary toothing is possible by the inventive gear unit.

If the first sun gear and the second sun gear formed with different numbers of teeth, so it can be easily created a translation in the device for influencing the degree of distribution of the drive torque to the output shafts.

By opposing forces acting on the planetary gear teeth creates a so-called S-shock on the Planetenradverzahnung. This Impact can be avoided by having at least one planetary gear in a region between the interaction zones with the first sun gear and the second sun gear a groove. The width of the planetary gear is advantageously lower than in the use of two planetary gears per planet carrier, since the groove can be selected narrower than the case of two planetary carriers necessary undercut.

A particularly good torque distribution can be achieved in that the device for influencing the degree of distribution of the drive torque with two with respect to a transmission center axis which is perpendicular to a longitudinal axis of the output shafts, at least approximately symmetrically arranged torque vectoring units is formed.

A very accurate adjustment of the influencing torque on the respective output shaft is achieved if the at least one transmission stage with a non-rotating, with respect to the transmission capability infinitely adjustable, in particular frictional switching element of the respective Torque vectoring unit is connectable wherein the transmission capability of the respective Schaltelemenfs on the at least one motor is adjustable

Conveniently, the switching element is designed as a multi-disc brake, which can be actuated by means of an operable by the at least one motor for axial adjustment.

A simple and safe operation of the Lamellenschaltelemenfes can be achieved in that a drive shaft of the motor interacts with a pivot wheel of the means for axial adjustment wherein the pivot wheel by means of particular designed as balls rolling elements, which in deep-varying grooves of the pivot wheel and arranged in corresponding depth-varying grooves of a fixed to the housing Ball ramp disk of the axial adjustment device cooperates with the ball ramp disk.

If the drive shaft of the motor interacts with the swivel wheel of the axial adjustment device by means of an at least single-stage spur gear stage, a very simple mechanism for actuating the multidisk switch element is realized.

The at least one motor can basically be an electric or hydraulic drive unit, but it is particularly advantageous if the motor is designed as an electric motor, as a result high positioning accuracy, high dynamics, a very variable design and a low noise level at low cost the engine can be reached,

Further advantages and advantageous developments of the invention will become apparent from the claims and the embodiment described in principle with reference to the drawings. It shows:

1 is a schematic sectional view of a Hinterachsgetriebeeinheit a motor vehicle with a translation stage having device for influencing the Verteilungsgra- of the drive torque to the output shafts. and

Fig. 2 is a simplified schematic diagram of the translation stage of the device for influencing the degree of distribution of the drive torque to the output shafts of Fig. 1 with a formed with a continuous toothing planetary gear. FIG. 1 shows a region of a gear unit 1, which has a drive torque transmitted by a drive shaft 2 and shown only schematically by a drive shaft 2 to a first output shaft 3 and a second output shaft 5 arranged coaxially therewith and symmetrically with respect to the drive shaft 2 distributed.

The gear unit 1 is provided for installation in a motor vehicle and is designed in the embodiment shown as Hinterachsgetriebeeinheit, but it is also conceivable that a substantially analog gear unit is used as Vorderachsgetriebeeinheit. It is also conceivable to use the present transmission unit both as a front axle transmission unit and as a rear axle transmission unit, for example in the case of a swollen motor vehicle.

The output shafts 3 and 5, which are rotatably mounted about a common longitudinal axis X, are connected at their free ends in each case with a vehicle wheel, not shown, wherein in the installed state of the Hinterachsgetriebeeinheit 1 a vehicle with respect to the output shaft 3 on a viewed in the vehicle front left Transmission side 7 and a vehicle wheel with respect to the output shaft δ on a right side gear 9 is located.

The Hinterachsgetriebeeinheit 1 includes a gear housing 11, which with a substantially surrounding the drive shaft 2 front gear housing part 12, with one of the left side gear 7 associated side gear housing part 13 from which the first output shaft 3 projects laterally, and with a not shown the right transmission side 9 associated lateral gear housing part, from which the second output shaft 5 protrudes laterally, is formed. The rear axle transmission unit 1 distributes the drive torque transmitted from the drive shaft 2 to the two output shafts 3 and 5 and can thereby also effect an uneven torque distribution on the two output shafts 3 and 5 and thus actively improve the driving characteristics. The Antriebsmornent of the drive shaft 2 is introduced into a differential unit 15, which is formed with a differential 17 and a differential cage 19 and connected to a device 14 for influencing the drive torque to the output shafts 3 and 5.

1, the active connection between the drive shaft 2 and the differential basket 19 is a fixed to the drive shaft 2 connected drive pinion 21 with a fixed connected to the differential cage 19 ring gear 23 into engagement, wherein the differential cage 19 rotatable about the The differential 17 is in a known construction with two connected to the respective output shaft 3 and 5 output side bevel gears 25 and 27 and with two with the two bevel gears 25 and 27 meshing drive side. bevel gears 29 and 31 formed. The two drive-side bevel gears 29 and 31 are fixedly arranged on a pin 33 which is fixed in the differential cage 19 with respect to a rotation about the longitudinal axis X and rotatably supported with respect to a rotation about a perpendicular to the longitudinal axis X through the bolt 33 extending gear center axis Y.

Fig. 1 shows two embodiments of the drive side bevel gears 29 and 31 and the cooperating output side bevel gears 25 and 27, which are each engaged with each other and between which the expert can select an alternative according to the particular application.

If a drive torque is transmitted by the fuel-cooking machine 10 via the drive shaft 2, this is transmitted to the drive via the drive pinion 21 Dividing wheel 23 and the fixedly connected differential cage 19 transmitted. By means of the bolt 33 of the differential 17 connected to the differential cage 19, the drive torque is transmitted to the drive-side bevel gears 29 and 31 of the differential 17, which in turn guide the drive torque to the driven-side bevel gears 25 and 27 of the differential 17 and thus the output shafts 3 and 5 drive.

If there is no differential speed between the two output shafts 3 and 5, the bevel gears 29 and 31 rotate with the bolt 33 exclusively about the longitudinal axis X. Should an output shaft in the installed state, for example, rotate faster than when cornering at different speeds rotating vehicle wheels the other, then rotate the drive side bevel gears 29 and 31 to compensate for the speed difference about the axis Y of the bolt 33, wherein the bolt 33 further passes the drive torque about its rotation about the longitudinal axis X on the two output shafts 3, 5.

In addition to balancing a different rotational speed of the two output shafts 3 and 5, a different torque distribution to the two output shafts 3 and 5 can be achieved with the rear axle transmission unit 1. For this purpose, the device 14 for influencing the drive torque is provided on the output shafts 3 and 5 with two identical torque vectoring units arranged symmetrically with respect to the gear center axis Y, wherein of the two torque vectoring units in FIG. 1, only the left transmission side 7 associated torque vectoring unit 35 is shown, which will be described below.

The torque vectoring units are arranged in the gear housing 11 and are in the present case continuously adjusted and actuated by a respective, switchable electric motor 37. As can be seen in the illustrated torque vectoring unit SS, this has a gear set 39 designed as a planetary gear set without ring gear and an actuatable by the electric motor 37 brake device 51.

The transmission stage 39 shown in principle in FIG. 2 has a first sun gear 61 and a second sun gear 63, a planetary carrier 65 and in the present case three or more rotatably arranged on the planet carrier 65, each formed with a planetary planet, of which in Fig. 1 two Planetary gears 69 and 71 are visible and in Fig. 2, the planetary gear 69 is visible.

The first sun gear 61 is fixedly connected to the differential cage 19 and the second sun gear 63 fixed to the one output shaft 3. The stationary with the sun gears 61, 63 meshing planet gears 69, 71 each have a running in the axial direction of the respective planetary gear 69 and 71 through teeth 73, which both with a toothing 62 of the first sun gear 61 and with a toothing 64 of the second Sun gear 63 is engaged.

Such trained planet gears 69, 71 can not jam with the sun gears 61, 63, due to positional error with separate teeth, whereby the reliability of the transmission unit 1 is particularly high. In addition, the continuous teeth 73 of the planet is very easy to manufacture, whereby the production costs are very low.

By opposing forces acting on the toothing 73 of the planetary gears 69, 71, a so-called S-stroke, ie, in the radial direction of a tooth of a planetary gear 61 or 63 S-shaped extending line of force, arise at the teeth 73 of the planetary gears. To counteract this, have the planetary gears 69, 71 a not shown groove in a region between the engagement zones of the two sun gears 61, 63, with which the S-beat is eliminated.

The translation of the differential cage 19 to the first output shaft 3 is realized with a different ZahnΣahl the two sun gears 61 and 63, wherein the tooth number difference of the sun gears 61, 63 because of the same distance of the two sun gears 61 and 63 from the longitudinal axis X via a profile displacement is compensated within the sun gears 61, 63.

In the present translation stage 39, the first sun gear 61 has a number of 32 teeth and the second sun gear 63 has a number of 35 teeth. The number of teeth is designed in such a way that the geometric changes to the sun gears 61, 63 compared to a design with two planet wheels per planet carrier offer the opportunity to work with the same distance of the sun gears 61, 63 from the longitudinal axis X.

It remains up to the expert to choose according to the particular application, a corresponding number of teeth of the sun gears.

The brake device 51 has a lamellae brake 77 designed as a lamellae. The with respect to their transfer capability infinitely adjustable multi-disc brake 77 has arranged as fins on the planet carrier 65 inner fins 75 which cooperate with defined in the gear housing 11 outer fins 79 by their axial adjustability such that they can be brought into or out of frictional contact.

In the present case, the electric motor 37 actuates the brake device 51 via a transmission housing fixedly mounted by its drive shaft 83 Intermediate gear 85, which is in engagement with the drive shaft 83 of the electric motor 37 and actuates a device 87 for axial adjustment of the multi-disc brake 77. The means 87 for axial adjustment of the multi-disc brake 77 is in the embodiment shown from a pivot wheel 89 which is in engagement with the intermediate 85 and how the idler 85 is disposed on the transmission center axis Y side facing away from the multi-disc brake 77, and one between the pivot wheel 89th and the multi-disc brake 77 arranged ball ramp plate 91 constructed. The intermediate gear 85 serves to bridge the center distance between the electric motor 37 and the swivel wheel 89. The ratio is determined by a number of teeth of the electric motor 37 and a number of teeth of the swivel wheel 89.

It is left to the skilled person to use for bridging the distance between the electric motor and the longitudinal axis in addition to the embodiment formed as an intermediate single-stage spur gear according to the particular space conditions also a two-stage or multi-stage spur gear.

The ball ramp disk 91, which is rotatably mounted and axially displaceable in the gear housing 11 and as the pivot wheel 89 is seated on the drive shaft 3, has distributed over its radius three in depth varying grooves 93. In grooves 93 of the ball ramp disc 91 corresponding also varying in their depths grooves 95 of the pivot wheel 89 are three trained as balls 97 rolling elements, which results in a caused by the electric motor 37 turning the pivot wheel 89 axial movement of the ball ramp disk 91, such that upon axial movement in the direction of the Y-axis, the housing-fixed outer disks 79, after overcoming a clearance of the device for axial position 87, enter into a friction connection with the inner disks 75 of the coupling device 51. In an open state of the multi-disc brake 77, the translation stage 39 runs around the longitudinal axis X without torque transmission in the block. If a friction connection in the multi-disc brake 77 is triggered via the electric motor 37, a torque vectoring torque acting on the respective output shaft 3 or 5 is generated from the drive torque. This is done by a support of the planet carrier 65 via the braking device 51 in the gear housing 11, It is thus a torque transmission from the drive shaft 2 via the differential cage 19 and from there by means of the planet carrier 65 from the first sun gear 61 to the respective output shaft 3 and 5 connected second sun gear 63 generates, by means of which a different torque distribution to the left output shaft 3 and the right output shaft 5 can be achieved.

reference numeral

1 rear axle unit

2 drive shaft

3 first output shaft

5 second output shaft

7 left transmission side

9 right transmission side

10 internal combustion engine

11 gearbox housing

12 front gear housing part

13 lateral gear housing part

14 device for influencing the drive torque on the output shafts

15 differential unit

17 differential

19 differential basket

21 drive pinions

23 ring gear

25 left output side bevel gear

27 right driven bevel gear

29 upper drive side bevel gear

31 lower drive side bevel gear

33 bolts

35 left torque vectoring unit

37 electric motor

39 translation level

51 brake device

61 first sun 62 toothing first sun gear

63 second sun wheel

64 toothing second sun gear

65 planet carrier

69 planetary gear

71 planetary gear

73 toothing planet rad

75 inner fins

77 Multi-disc brake of the left torque vectoring unit

79 outer fins

83 Drive shaft Elektrσ-Motσr

85 intermediate wheel

87 Device for axial adjustment

89 Pivoting wheel

91 Ball ramp disc

93 grooves of the ball ramp disc

95 grooves of the swivel wheel

97 balls

X longitudinal axis

Y gear center axis

Claims

claims

1. gear unit, in particular Hinterachsgetriebeeinheit, for guiding a drive torque from a drive shaft (2) on two output shafts (3, 5) via a differential unit (15} and by means of at least one motor (37) switchable, continuously adjustable device (14) for influencing the degree of distribution of the drive torque to the output shafts (3, 5), wherein the differential unit (15) has a differential (17) and a differential cage (19) operatively connected to the drive shaft (2) and the device (14) for influencing the degree of distribution of the drive torque has at least one planetary gear set (39) as a translation stage, which with the differential cage (19) and an associated output shaft (3 or, 5) is operatively connected and which by means of a switching element (77) is switchable, and wherein the planetary gear set (39) with the Differential basket (19) connected to the first sun gear (61), one with the respective output shaft (3, 5) connected to two ites sun wheel (63). with the two sun gears (61, 63) interacting planet wheels (69, 71) and designed as a web (65) planet carrier, characterized in that each planet gear (89.71) has an axially continuous toothing (73), with both the first Sun gear (61) and the second sun gear (63) is engaged.

2. Transmission unit according to claim 1, characterized in that the first sun gear (61) and the second sun gear (63) are formed with different numbers of teeth.

3. Transmission unit according to one of claims 1 or 2, characterized in that at least one planetary gear (69, 71) in a region between the interaction zones with the first sun gear (61) and the second sun gear (63) has a groove.

4. Transmission unit according to one of claims 1 to 3, characterized in that the device (14) for influencing the degree of distribution of the drive torque with two relative to a Getriebemittelachse (Y), which perpendicular to a longitudinal axis (X) of the output shafts (3, 5) runs, at least approximately symmetrically arranged torque vectoring units (35) is formed.

5. Transmission unit according to claim 4, characterized in that the at least one transmission stage (39) with a non-rotating, with respect to the transfer capability continuously adjustable, in particular frictional switching element (77) of the respective torque vectoring unit (35) is connectable, the transmission capability of the respective switching element (77) via the at least one motor (37) is adjustable.

6. Gefriebeeinheit according to claim 5, characterized in that the switching element is designed as a multi-disc brake (77) which is actuated by means of one of the at least one motor (37) actuatable means for axial adjustment (87)

7. A transmission unit according to claim 6, characterized in that a drive shaft (83) of the motor (37) with a pivot wheel (89) of the

Interacting means (87) for axial adjustment, wherein the swivel wheel (89) by means of rolling elements (97) which in depth-varying grooves (95) of the pivot wheel (89) and in correspondingly arranged grooves (93) of a housing-fixed ball ramp disc (91) of the device ( 87) for axial adjustment, cooperates with the ball ramp disc (91).

8. Transmission unit according to claim 7, characterized in that the drive shaft (83) of the motor (37) with the swivel wheel (89) by means of an at least single-stage spur gear (85) cooperates

9. Gefriebeeinheit according to any one of claims 7 or 8, characterized in that the rolling elements are designed as balls (97).

10. Transmission unit according to one of claims 1 to 9, characterized in that the at least one motor is designed as an electric motor (37).