Differential gearing, in particular axle gearing

Abstract

An epicyclic gearing for splitting output drive power from a power input to a first power output and a second power output, comprising a superposition gearing stage, including a first sun gear, a first planetary gear set, a first planetary carrier, and a first ring gear, and a reverse gearing stage, including a second sun gear, a second planetary gear set, a second planetary carrier, and a second ring gear, wherein, the superposition gearing stage and the reverse gearing stage are kinematically coupled, and the epicyclic gearing is operatively arranged to operate in a first switching state or a second switching state, wherein the first switching state and the second switching state have different gear ratios.

Claims

1. An epicyclic gearing for splitting output drive power from a power input to a first power output and a second power output, comprising: a superposition gearing stage, comprising: a first sun gear; a first planetary gear set; a first planetary carrier non-rotatably connected to the first power output; and, a first ring gear; and, a reverse gearing stage, comprising: a second sun gear non-rotatably connected to the first ring gear; a second planetary gear set; a second planetary carrier; and, a second ring gear non-rotatably connected to the second power output; wherein, the superposition gearing stage and the reverse gearing stage are kinematically coupled, and the epicyclic gearing is operatively arranged to operate in a first switching state or a second switching state, wherein the first switching state and the second switching state have different gear ratios.

2. The epicyclic gearing recited in claim 1, wherein the first switching state is a purely differential motion without an added gear ratio.

3. The epicyclic gearing recited in claim 2, wherein in the second switching state, the epicyclic gearing operates as a rolling differential gearing and includes a slower speed gear ratio.

4. The epicyclic gearing recited in claim 3, wherein shifting between the first switching state and second switching state occurs when the second planetary carrier is coupled to either the power input or non-rotatably coupled to the gear housing.

5. The epicyclic gearing device recited in claim 1, wherein the first sun gear is driven by the power input, and the second planetary carrier is operatively arranged to be non-rotatably coupled to the first sun gear via a first coupling device or to the gear housing via a second coupling device.

6. The epicyclic gearing device recited in claim 5, wherein the first and/or second coupling devices couple in a positive-locking manner.

7. The epicyclic gearing device recited in claim 5, wherein the first and/or second coupling devices couple in a friction-locking manner.

8. The epicyclic gearing device recited in claim 1, wherein a partial gear ratio of the superposition gearing stage and a partial gear ratio of the reverse gearing stage sync with another, providing a symmetrical torque distribution to the first power output and the second power output.

9. The epicyclic gearing device recited in claim 1, wherein the first ring gear and the second ring gear include the same number of teeth.

10. The epicyclic gearing device recited in claim 1, wherein the superposition gearing stage and the reverse gearing stage are spur gearings, and the first sun gear and the second sun gear are coaxially arranged on a gear axle in axially successive rolling planes.

11. An epicyclic gearing for splitting output drive power from a power input to a first power output and a second power output, comprising: a superposition gearing stage, comprising: a first sun gear; a first planetary gear set; a first planetary carrier; and, a first ring gear; and, a reverse gearing stage, comprising: a second sun gear; a second planetary gear set; a second planetary carrier; and, a second ring gear; wherein: the superposition gearing stage and the reverse gearing stage are kinematically coupled, and the epicyclic gearing is operatively arranged to operate in a first switching state or a second switching state; and, the second planetary carrier is operatively arranged to be non-rotatably coupled to the first sun gear via a first coupling device or to the gear housing via a second coupling device.

12. An epicyclic gearing for splitting output drive power from a power input to a first power output and a second power output, comprising: a superposition gearing stage, comprising: a first sun gear; a first planetary gear set; a first planetary carrier; and, a first ring gear; and, a reverse gearing stage, comprising: a second sun gear; a second planetary gear set; a second planetary carrier; and, a second ring gear; wherein: the epicyclic gearing is operatively arranged to operate in a first switching state or a second switching state; the first switching state is a purely differential motion without an added gear ratio, and in the second switching state, the epicyclic gearing operates as a rolling differential gearing and includes a slower speed gear ratio than the first switching state; and, shifting between the first switching state and second switching state occurs when the second planetary carrier is coupled to either the power input or non-rotatably coupled to the gear housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various embodiments are disclosed, by way of example only, with reference to the accompanying drawing in which corresponding reference symbols indicate corresponding parts, in which:

(2) FIG. 1 is a schematic view of an epicyclic gearing of the present invention which can be operated in two different modes of operation.

DETAILED DESCRIPTION

(3) At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the disclosure. It is to be understood that the disclosure as claimed is not limited to the disclosed aspects.

(4) Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure.

(5) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure.

(6) In the form of a schematic diagram, the depiction according to FIG. 1 shows an example embodiment of an epicyclic gearing according to the invention, realized here as an axle gearing for a motor vehicle. This inventive epicyclic gearing serves to split the drive power present at power input I to first and second power output O1, O2. The epicyclic gearing comprises superposition gearing G1, which includes first sun gear S1, first planetary gear set P1, first planetary carrier C1 and first ring gear H1.

(7) The epicyclic gearing further comprises reverse gearing stage G2, which includes second sun gear S2, second planetary gear set P2, second planetary carrier C2 and second ring gear H2. First sun gear S1 functions as a power input, or is non-rotatably coupled to the power input. The epicyclic gearing according to the invention is characterized in that superposition gearing G1 and reverse gearing stage G2 are kinematically coupled, and the epicyclic gearing is configured in such a way that it is operable in a first and in a second switching state, whereby the first and the second switching state differ with respect to the resulting overall gear ratio between power input I and power outputs O1, O2.

(8) In the first switching state a purely differential action without a gear ratio is provided. In the second switching state the differential gearing is operated as a rolling differential gearing, causing a gear ratio to a slower speed (underdrive). Shifting between the first and the second switching state is effected by second planetary carrier C2 being non-rotatably coupled either to power input I via first coupling device K1 or to gear housing G via second coupling device K2.

(9) Power input I is non-rotatably coupled to first sun gear S1 of superposition gearing stage G1. First ring gear H1 is permanently non-rotatably coupled to second sun gear S2. First planetary carrier C1 directly drives first power output O1. Second ring gear H2 directly drives second power output O2.

(10) The switching option according to the invention is achieved in that second planetary carrier C2 is operatively arranged to non-rotatably coupled to first sun gear S1 via first coupling device K1 or to gear housing G via second coupling device K2. First and/or second coupling devices K1, K2 are exemplified here as multi-plate clutch devices which connect in a friction-locking manner. They can, however, also be configured as coupling devices which connect in a positive-locking manner.

(11) The partial gear ratio of superposition gearing and the partial gear ratio of reverse gearing G2 are matched to one another in such a way that a symmetrical torque distribution to power outputs O1, O2 results.

(12) In an example embodiment, first and second ring gear H1, H2 exhibit the same number of teeth. Planets P1a, P2a of first and second planetary gear sets P1, P2 likewise exhibit the same number of teeth. First sun gear S1 and second sun gear S2 also exhibit the same number of teeth. Superposition gearing G1 and reverse gearing G2 are respectively designed as a spur gearing, whereby first and second sun gear S1, S2 are coaxially disposed to gear axle X in axially successive rolling planes E1, E2. The power pick-up from first planetary carrier C1 is accomplished via shaft journal 4, which is passed coaxially through first sun gear S1.

(13) The propulsion of first sun gear S1 occurs via hollow shaft journal 5. Hollow shaft journal 5 is driven by means of an input gear (not shown). In an example embodiment, the input gear can be a sprocket and driven by a drive chain, which establishes a kinematic connection between the epicyclic gearing and upstream gearing, in particular an automatic or manual transmission, or where appropriate also an electromechanical drive.

(14) In an example embodiment, first coupling device K1 is positioned operatively arranged on hollow shaft journal 5, allowing the coupling of second planetary carrier C2 to hollow shaft journal 5. Bell structure C2a, which overlaps first ring gear H1, is provided between first coupling device K1 and second planetary carrier C2. The torque pick-up from first planetary carrier C1 to output shaft OS1 occurs in an interior region lying between gearing planes E1, E2.

(15) The propulsion of second power output O2 occurs via the coupling of a drive shaft OS2, representing this power output, to second ring gear H2. It should be appreciated that the gearing components can be centered and braced against one another by means of numerous bearing points realized in the interior of the gearing. For example, first sun gear S1 and output shaft OS1 can be radially braced against one another by a needle bearing. Output shaft OS1 and the structure (not show supporting first ring gear H1 and second sun gear S2 can be centered in relation to one another via a bearing point, for example, by an end section of output shaft OS1 being radially braced by means of a roller bearing in the disc body supporting first ring gear H1. Second sun gear S2 and second output shaft OS2 can likewise be radially braced against one another by a roller bearing.

(16) The unit represents a combination of differential and final drive ratio stages. The differential can be used in the area of the drive axle, when an additional gear ratio is temporarily called for.

(17) In order to operate the gearing according to the invention in a purely differential gearing mode without an additional gear ratio effect, coupling device K1 is closed and coupling device K2 is opened. In this switching state, second planetary carrier C2 is coupled to power input and first sun gear S1 in a torsionally rigid manner. The two gearing stages G1 and G2 ensure that output shafts OS1, OS2 are reversely rotatably coupled to one another, and are thus carried along by the second planetary carrier C2 with a symmetrical distribution of torque.

(18) The gearing mechanics provided by gearing stages G1, G2 is a pure splitting differential without an additional gear ratio effect.

(19) In order to operate the gearing according to the invention as a rolling differential in high gear ratio mode, first coupling device K1 is opened and second coupling device K2 is closed. Second planetary carrier C2 is then non-rotatably coupled to gearing housing G. Reverse gearing stage G2 now functions as a spur gearing stage with a gear ratio to a slower speed (underdrive). First sun gear S1 engages radially from the inside into planets P1a of first planetary gear set P1. Planets P1a in turn engage radially from the inside into first ring gear H1. First ring gear H1 drives second sun gear S2. Second sun gear S2 engages radially from the inside into planets P2a of second planetary gear set P2. Planets P2a engage radially from the inside into second ring gear H2. This again results in a reversely rotatable coupling of output shafts OS1, OS2, which yields, however, with respect to the input I or rather first sun gear S1, a resulting gear ratio effect to a slower speed (underdrive) with continued symmetrical torque distribution.

(20) It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.