Planetary support arrangement for a hybrid transmission

Abstract

A hybrid powertrain having an engine, wherein the hybrid power transmission includes a housing, a first electric machine, a second electric machine and an input shaft configured to receive power from the engine. A power distribution unit including a planetary gearset includes a sun gear rotatable with a first rotor of the first electric machine, a carrier coupled to the input shaft and rotatable therewith, a plurality of pinion gears supported for rotation on the carrier and in meshed engagement with the sun gear, and a ring gear coupled to a ring gear body, the ring gear in meshed engagement with the pinion gears. The ring gear body is rotatable relative to the housing and is supported on an external diameter by a set of bearings installed into the housing. The ring gear may be two pieces and have a reduced diameter portion supported by one of the bearings.

Description

Attorney Docket No. 25065-2231 (713682PCT)PLANETARY SUPPORT ARRANGEMENT FOR A HYBRID TRANSMISSIONFIELD

[0001] The present disclosure is related to a hybrid powertrain for a motor vehicle with an engine and a hybrid power transmission including a first and second motor / generator unit, a power distribution unit, a gearset arrangement, and a differential. The power distribution unit includes a planetary gear arrangement where the ring gear is supported externally to housings by bearings at each end. The planetary of the power distribution unit will include a carrier coupled to an input shaft with an extending feature for mounting a support bearing. The extending feature allows the oil passage to be axially aligned with the support bearing providing a compact arrangement.BACKGROUND OF THE INVENTION

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] Power transmission devices for a hybrid vehicle including an engine and a power distribution unit in which two electrical machines are connected are known. In these hybrid systems the power distribution unit in the form of a planetary is used to efficiently split power between the gasoline engine, electric motor-generators, and the wheels, essentially acting as a continuously variable transmission (CVT) by dynamically adjusting power distribution based on driving conditions, allowing for optimal fuel economy and smooth acceleration. In these arrangements the planetary gearset acts as a power splitter, allowing the engine and electric motor to contribute to the drive power simultaneously, or independently depending on the situation. These power transmissions typically use two motor-generators, one primarily for propulsion (MG2) and another for engine start / stop and charging the battery (MG1). A benefit of thisAttorney Docket No. 25065-2231 (713682PCT) arrangement is the overall mechanical simplicity of the geartrain, where specific controlling of the motor-generators are used to influence the overall functionality to provide hybrid and electric driving modes, although with some limitations. Typical arrangements of these power transmission devices are considered to be a parallel hybrid. A parallel hybrid utilizes the arrangement where both the gasoline engine and electric motor are directly connected to the drivetrain, allowing both power sources to power the wheels simultaneously or independently, depending on driving conditions. Improvements to the supportive structure and arrangement of the components of the power distribution unit may be made to provide a compact arrangement.SUMMARY OF INVENTION

[0004] It is an aspect of the present disclosure to provide a hybrid power transmission driven by an engine with a first electric motor and a second electric motor providing power to a power distribution unit, wherein power from the distribution device is provided to a gearset arrangement and differential to distribute power to a pair of ground engaging wheels.

[0005] In a related aspect, the power distribution device includes a planetary gearset with a ring gear supported in a housing by bearings on the outer side of the ring gear body.

[0006] In a related aspect of the present disclosure, the ring gear body has a bearing supporting the body at an outer surface of a first end and an outer surface of a second end, with the ring gear body including an inner gear form engaging a planetary pinion and outer gear from in meshed engagement with a layshaft.

[0007] In a related aspect of the present disclosure, the ring gear body is bell-shaped.

[0008] In another aspect of the present disclosure, the ring gear has a two-piece construction with a first closed end and a second closed end, allowing a reduction of the bearingAttorney Docket No. 25065-2231 (713682PCT) diameter at the second end while still supporting the ring gear on the outer surface of the second end

[0009] It is an aspect of the present disclosure for an input shaft and planetary carrier of the planetary to be coupled together and supported by a bearing, where the bearing supports the carrier on an extended portion and an oil passage exiting the input shaft is provided radially inward of the extension. In one aspect, the oil passage and the extension overlap along the rotational axis of the input shaft. In one aspect, the extension is spaced away from an outlet of the oil passage and radially covers the outlet.

[0010] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appending drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure. The inventive concepts associated with the present disclosure will be more readily understood by reference to the following description in combination with the accompanying drawings wherein:

[0012] FIG. 1 illustrates a diagram of the hybrid powertrain;

[0013] FIG. 2 shows a detailed cross-section view of the power distribution unit of a hybrid transmission;

[0014] FIG. 3 provides a detailed view of an alternative arrangement of the power distribution unit with a reduced diameter bearing support structure.Attorney Docket No. 25065-2231 (713682PCT)DETAILED DESCRIPTION

[0015] Referring to FIG. 1, hybrid powertrain 10 is shown including an engine ENG, a first electric machine MG1, and a second electric machine MG2 as power sources. Engine ENG may be an internal-combustion engine with an output 12 that provides power to a damper 14. Damper 14 is coupled to an input shaft 16 of the hybrid transmission 18 and transfers power provided by the engine to the input shaft 16. First electric machine MG1 and second electric machine MG2 are motor / generators which are configured to function as a motor in a powerproviding operative state and as a generator in a regeneration operative state. The operations of the first and second electrical machines MG1 and MG2 are each provided with a controlled power by an inverter 20 and 22, respectively. The first and second electric machines MG1 and MG2 are connected to a battery 24 via the inverters 20 and 22 and may convert the mechanical energy that is backdriven through the transmission 18 into electric energy to replenish the battery 24. The first and second electric machines MG1 and MG2 may also convert the electric energy supplied from the battery 24 or the electric energy generated by the other electric machines into mechanical energy to drive the vehicle.

[0016] The first motor-generator MG1 includes a first stator 26 that is fixed to the housing of hybrid transmission 18, and a first rotor 30 that is rotatably supported on the radially inner side of the first stator 26. The first rotor 30 is drivingly connected to a sun gear 32 of the power distribution unit 34. Connection between sun gear 32 and first rotor 30 is provided by MG1 rotor shaft 36, such that the first rotor 30 rotates together with the sun gear 32. MG1 may function as a motor (i.e., an electric motor) that receives a supply of electric power from battery 24 and generates power (i.e., providing a driving force), as well as function as a generator (i.e., an electric generator) that receives a mechanical rotation and generates electric power back to battery 24. In this example,Attorney Docket No. 25065-2231 (713682PCT) battery 24 is used as the power storage device, but other storage devices including a capacitor may also be used. In one aspect, MG1 may function mainly as a generator that generates electric power due to rotation from power distribution unit 34. The electrical power created by MG1 is provided to charge battery 24 or supply electric power for driving to the second motor-generator MG2. Under certain operating conditions, MG1 may also provide a driving force to power distribution unit 34. MG1 is used to effectively influence the functionality of power distribution unit 34 by controlling the power split within it, essentially creating a continuously variable transmission effect, allowing for optimal power delivery depending on driving conditions. MG1 may be used to adjust the power distribution between the engine ENG and MG1 to achieve the best efficiency across different speeds and accelerations.

[0017] The second motor-generator MG2 has a second stator 36 that is fixed to the housing of hybrid transmission 18, and a second rotor 40 that is rotatably supported on the radially inner side of the first stator 36. The second rotor 40 is drivingly connected to a MG2 output gear 42 via MG2 rotor shaft 44. MG2 may function as a motor (i.e., an electric motor) that receives a supply of electric power from battery 24 and generates power (i.e., providing a driving force), and may also function as a generator (i.e., an electric generator) that receives a mechanical rotation and generates electric power back to battery 24. In this example, the MG2 may mostly function as a motor that assists with providing driving a force for propelling the vehicle. Under low vehicle operating speeds, MG2 may also function as a generator that regenerates the inertia force of the vehicle as electric energy back to battery 24.

[0018] Power distribution unit 34 includes a planetary gear set 35 that is arranged and centered on the same rotational axis as the input shaft 16. Planetary gear set 35 includes a sun gear 32, a carrier 46 supporting a plurality of pinion gears 48, and a ring gear 50. The sun gear 32,Attorney Docket No. 25065-2231 (713682PCT) pinion gears 48, and ring gear 50 are in mesh together. The sun gear 32 is drivingly connected to MG1 rotor shaft 36 of MG1. The carrier 46 is drivingly connected to the input shaft 16 that receives power from the engine ENG. The ring gear 50 may be integrally formed or coupled with an output gear 52 (that is in mesh with the layshaft) via ring gear body 54. Ring gear body 54 is a generally bell-shaped member that provides the radially outer side of the planetary gear set 35 in this embodiment. The ring gear 50 of the power distribution unit 34 is provided on a radially inner surface of ring gear body 54. The output gear 52 is provided on a radially outer surface of ring gear body 54. In one aspect, the axial positioning of output gear 52 and ring gear 50 are generally aligned and may overlap at least partially. A third gear, parking gear 56, may also be provided integrally or coupled to the outer surface of ring gear body 54 to receive a parking pawl in the direction of MG1 when the vehicle is in a parked condition. As a result, power that has been provided by engine ENG or motor generator MG1 to power distribution unit 34 is transmitted to the output gear 52 via ring gear 50 and ring gear body 54.

[0019] The power delivered to MG2 output gear 42 and the power delivered to the power distribution unit 34 output gear 52 are provided to a layshaft gear assembly 58 via meshed engagement with a layshaft input gear 60. Layshaft gear assembly 58 is positioned on its own rotational axis that is offset from the rotation axis of MG1 and MG2. Layshaft input gear 60 and layshaft output gear 62 are disposed about the same axis and coupled together for rotation. The layshaft output gear 62 of layshaft assembly 58 is in meshed engagement to drive a differential input gear 64 and differential unit 66. Differential unit 66 distributes and transmits torque that is transmitted to the differential input gear 64 to a plurality of wheels 68. Differential unit 66 may be a differential gear mechanism with a plurality of bevel gears that are in mesh with each other.Attorney Docket No. 25065-2231 (713682PCT)

[0020] FIG. 2 provides a detailed view of the power distribution unit 34 of hybrid transmission 18. Power distribution unit 34 includes a planetary gearset 35 and is located within a housing, specifically a first housing 70 on the MG1 axial side and a second housing 72 towards the engine ENG axial side. Housings 70 and 72 are fastened together outside of the view. MG1 rotor shaft 36 is supported by and rotatable relative to housing 70 by bearing 74 located between MG1 rotor 30 and housing 70. MG1 rotor shaft is supported by a second bearing on the opposite side of MG1 rotor 30 not in view. MG1 rotor shaft 36 includes a central hollow portion 76. Sun gear 32 of the planetary gear set 35 is shown integrally formed into the end portion of MG1 rotor shaft 36, but may also be an attached component. Input shaft 16, provided on the same axis as MG1 rotor shaft 36, includes a first end 78 that is coupled to damper 14 via spline 80. The second end 82 of input shaft 16 extends into hollow portion 76 and supported by MG1 rotor shaft 36 via needle bearing 84. A carrier 46 is coupled to input shaft 16, either with a splined arrangement or joined by a weld at location 86, resulting in input shaft 16 and carrier 46 to be operable as a unitary structured component and to rotate together. The carrier 46 may be a powder metal or stamped component made of a first half 46A and a second half 46B. Portion 46A is the half directly connected to input shaft 16 at location 86. A pinion shaft 88 is provided between the carrier halves 46A and 46B to support a plurality of pinion gears 48 rotatable on pinion shaft 88 via pinion bearings 90. Pinion gears 48 are located radially outward and in meshed engagement with sun gear 32 on an inner side and meshed with ring gear 50 on an outer side. An axial bearing 92 is provided between the axial end of the MG1 rotor shaft 36 and face of carrier half 46A to maintain the axial location of planetary 35. In the embodiment shown in FIG. 2, ring gear body 54 is provided as a bell-shaped component, where at a first end 94 the body 54 has a reduced diameter and at a second end 96 the diameter is increased relative to the first end 94 to surround and allow insertion ofAttorney Docket No. 25065-2231 (713682PCT) planetary 35. Ring gear body 54 is supported on an outer diameter on a first end 94 by bearing 98 which is installed into housing 70. Ring gear body 54 is further supported by bearing 100 on the outer diameter at second end 96. Bearing 100 is installed into housing 72. Towards the first end 94 and adjacent to bearing 98, a park gear 56 is shown coupled to ring gear body 54. Park gear 56 is configured to receive a parking pawl to provide a vehicle park lock function. Park gear 56 may be a separate component attached to ring gear body 54 as shown, or integrated into ring gear body 54. Ring gear body 54 may be a single piece constructed component with the gear forms of ring gear 50 and output gear 52 integrally provided. As shown, ring gear body 54 is a two-piece construction with a first piece 54A arranged as a tubular part including the gear forms of ring gear 50 and output gear 52, and a second piece 54B being L shaped and joined to part 54A at location 102. The joining method at location 102 may be welding, or other structural, torque transmitting connections may be utilized. Park gear 56 attaches to or is integral with the L shaped portion. The arrangement shown in FIG. 2 illustrates bearing 100 being larger than the gear form pitch diameter of the internal gear teeth of ring gear 50.

[0021] Another construction of ring gear body 54’, shown in FIG. 3, may include a modification of the tubular shaped portion 54A of FIG. 2, being modified to provide a reduction of bearing 100’ diameter. As shown, a revised ring gear body 54C with a reduced bearing diameter support section 104 is provided at a diameter less than the pitch diameter of ring gear 50. This arrangement of bearing 100’ still supports ring gear body 54 on the outer diameter, but provides for a reduction in the diameter of bearing 100’. This arrangement may be beneficial to provide reduced parasitic drag losses and a less expensive bearing, and the construction of ring gear body 54 accordingly is modified. Ring gear body 54 is the two-piece construction in this arrangement, and with a non-permanent connection at location 102 that allows for the installation of planetaryAttorney Docket No. 25065-2231 (713682PCT)35, because both ring gear bodies 54B and 54C provide a closed end arrangement instead of the open bell-shaped arrangement of FIG. 2.

[0022] In each of the arrangements previously described of ring gear body 54 or 54’, the gear forms of park gear 56, ring gear 50, and output gear 52 may also be provided as separate components and not integral to ring gear body 54, but instead attached in a fixed torque transmitting manner to adapt to various manufacturing processes. Ring gear body 54 must be well located and supported because the ring gear body 54, in conjunction with the various gear features described, is used to transfer power between power distribution unit 34 and layshaft input gear 64.

[0023] Within the power distribution unit 34, various components require a lubricant such as oil to be provided to maintain smooth running operation and to remove heat generated by the meshing gearsets. Hybrid transmission 18 includes a pressurized oil cooling and lubrication system to distribute oil throughout the transmission 18 to cool the electric motors and the lubricate and cool the geared components. Features to effectively lubricate and support power distribution unit 34 will now be discussed in reference to FIG. 2. It should be understood the lubricating oil is pressurized and will further distribute within power distribution unit 36 due to the centrifugal forces as the components rotate during operation.

[0024] Input shaft 16 includes oil passages 100 to receive and distribute lubricating oil from a tube 112 positioned within the hollow portion 76 of MG1 rotor shaft 36, thereby providing the oil into power distribution unit 34. Input shaft 16 also includes a main central axially extending lubrication channel 110 that receives pressurized oil delivered by tube 112 that is located within the hollow portion 76. Pressurized oil enters tube 112 and delivers oil first to lubrication delivery openings 112B and 112C. First radial delivery opening 112B allows oil to exit radially outward towards MG1 rotor shaft 36 for purposes to cool rotor 30. The rotor shaft 36 may also includeAttorney Docket No. 25065-2231 (713682PCT) radial openings. Remaining oil will continue to travel through tube 1 12 towards power distribution unit 34, and additional oil exits at second opening 112C. Opening 112C is aligned with a cross drilling 114 in rotor shaft 36 to provide a passage of oil to MG1 rotor shaft support bearing 74 and ring gear body support bearing 98.

[0025] Tube 112 delivers remaining oil toward center oil channel 110 of input shaft 16. Lubricating oil provided to central channel 110 exits the input shaft 16 via a first radial passage HOB and a second radial passage 110C that is downstream from the first radial passage HOB. Oil exiting passage HOB is distributed into power distribution unit 34 via a cross drilled passage 116 and is directed into baffle 118 fixed to carrier half 46B, directing oil towards pinion gears 48 and also pinion shaft bearings 90 via a passage in pinion shaft 88. The second radial passage HOC, arranged near the end of the cavity 110 towards the engine ENG side of input shaft 16, delivers oil to a cavity 120 defined outside of the input ger 16 within housing 72, and provides lubricating oil to seal 122 and carrier support bearing 124 that are adjacent the cavity 120.

[0026] Carrier half 46A includes an axial extension 46C to receive the inner race of carrier support bearing 124. The outer race of carrier support bearing 124 is installed into housing 72. The use of extension 46C allows second oil passage 110C to be located under and axially aligned with carrier support bearing 124. This arrangement reduces the axial space, relative to extension 46C not being provided, where carrier support bearing 124 would need to be positioned adjacent and axially separated from oil passage HOC. Extension 46C has a ledge formation with a minimum diameter larger than input shaft 16 outer diameter 126, allowing an annular ring of space 128 to be created and preventing blockage of oil exiting passage 110C. A chamfer 130 on the inner end of extension 46C further provides a passage for oil to enter cavity 120 from passage HOC with reduced restriction. Lubricating oil also passes through carrier support bearing 124 and radiallyAttorney Docket No. 25065-2231 (713682PCT) travel towards power distribution unit 34 along carrier half 46B due to gravitational and centrifugal forces of the rotating components, thereby eventually reaching and lubricating bearing 100. Lubricating oil provided to power distribution unit 34 returns to an oil sump disposed lower in the hybrid transmission 18 via gravity, and the oil is re-used.

[0027] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varies in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of disclosure.

Claims

Attorney Docket No. 25065-2231 (713682PCT)CLAIMS1. A hybrid powertrain having an engine and hybrid power transmission for a motor vehicle, the hybrid power transmission comprising: a housing; a first electric machine; a second electric machine; an input shaft configured to receive power from the engine; a power distribution unit including a planetary gearset; wherein the planetary gearset includes: a sun gear coupled to the first electric machine and rotatable with a first rotor of the first electric machine, a carrier coupled to the input shaft and rotatable therewith, and a plurality of pinion gears supported for rotation on the carrier and in meshed engagement with the sun gear; and a ring gear coupled to a ring gear body, the ring gear in meshed engagement with the pinion gears; wherein the ring gear body is supported on an external diameter thereof by a set of bearings installed into said housing, wherein the ring gear body is rotatable relative to the housing.

2. The hybrid powertrain of claim 1, wherein the ring gear body is a two-piece structure including a first piece fixedly secured to a second piece such that the first and second piece rotate together as a unitary component.Attorney Docket No. 25065-2231 (713682PCT)3. The hybrid powertrain of claim 2, wherein the first piece is disposed toward the engine and the second piece is disposed toward the first electric machine.

4. The hybrid powertrain of claim 3, wherein the first piece has an open end facing the engine and the second piece has an open end facing the first electric machine.

5. The hybrid powertrain of claim 4, wherein the open end of the first piece has a diameter greater than a pitch diameter of ring gear inner teeth that are in meshed engagement with the pinion gears.

6. The hybrid powertrain of claim 4, wherein the open end of the first piece has a diameter smaller than a pitch diameter of ring gear inner teeth that are in meshed engagement with the pinion gears.

7. The hybrid powertrain of claim 6, wherein the first piece includes an enlarged diameter portion and a reduced diameter portion, where the ring gear inner teeth are disposed on the enlarged diameter portion, wearing a first bearing of the set of bearings is disposed on an outer diameter of the reduced diameter portion, wherein ring gear outer teeth are disposed on the enlarged diameter portion and in meshed engagement with a layshaft assembly that is drivingly connected to the second electric machineAttorney Docket No. 25065-2231 (713682PCT)8. The hybrid powertrain of claim 1, wherein the ring gear includes inner teeth that are in meshed engagement with the pinion gears and ring gear outer teeth in meshed engagement with a layshaft assembly that is drivingly connected to the second electric machine.

9. The hybrid powertrain of claim 1, wherein the set of bearings are each disposed on an outer rotational surface of the ring gear body.

10. The hybrid powertrain of claim 1, wherein the first rotor is rotationally fixed to a rotor shaft, wherein the sun gear is fixed for rotation to the rotor shaft, wherein the ring gear is rotatable relative to the rotor shaft.

11. The hybrid powertrain of claim 10, wherein the rotor shaft includes a hollow portion extending axially therethrough, wherein the input shaft is received within the hollow portion and supported for rotation relative to the rotor shaft, wherein the input shaft is fixed for rotation with the carrier of the planetary gearset.

12. The hybrid powertrain of claim 11, wherein the carrier is supported for rotation relative to the housing via a carrier bearing disposed on an outer rotational surface of the carrier, and wherein the rotor shaft is supported for rotation relative to the housing via a rotor shaft bearing disposed on an outer rotational surface of the rotor shaft.Attorney Docket No. 25065-2231 (713682PCT)13. The hybrid powertrain of claim 12, wherein the rotor shaft and input shaft combine to define an oil distribution path including a plurality of oil outlet passages, wherein the carrier includes a carrier extension portion that axially overlaps and is radially spaced from at least one of the oil outlet passages, wherein the carrier bearing is disposed on the carrier extension.

14. The hybrid powertrain of claim 13, wherein an oil distribution tube extends through the hollow portion of the rotor shaft and into the input shaft, wherein oil passes through the tube and into the input shaft.

15. A hybrid powertrain including an engine and hybrid power transmission for a motor vehicle, the hybrid power transmission comprising: a housing; a first electric machine; a second electric machine operably connected to the first electric machine; a power distribution unit operably connected to the first electric machine and including a planetary gearset disposed within the housing; an input shaft that receives power from an engine and being operably connected to the planetary gearset, the input shaft having an oil distribution cavity; a pressurized oil source in fluid communication with the oil distribution cavity; wherein the planetary gearset includes a carrier coupled for common rotation to said input shaft;Attorney Docket No. 25065-2231 (713682PCT) wherein the housing includes a carrier support bearing that supports the carrier for rotation relative to the housing, wherein the carrier bearing is disposed on an extension portion of the carrier; wherein the input shaft includes a radial oil passage formed in the input shaft, wherein the radial oil passage is axially aligned with the carrier support bearing to provide lubrication to the power distribution unit.

16. The hybrid powertrain of claim 15, wherein a rotor shaft is drivingly connected to the first electric machine and is fixed to a sun gear of the planetary gearset, wherein the rotor shaft includes a hollow portion coupled to the input shaft and rotatable relative to the input shaft.

17. The hybrid powertrain of claim 16, wherein an oil distribution tube extends through the hollow portion and is fluidly coupled to the oil distribution cavity of the input shaft, wherein the oil distribution tube receives pressurized oil from the pressurized oil source.

18. The hybrid powertrain of claim 17, wherein the radial oil passage is a first radial oil passage, wherein a second radial oil passage is formed in the input shaft and disposed axially upstream from the first radial oil passage, wherein the second radial oil passage provides oil into an annular space between the input shaft and the rotor shaft and thereafter radially through the rotor shaft toward pinion gears of the planetary gearset.Attorney Docket No. 25065-2231 (713682PCT)19. The hybrid powertrain of claim 18 , wherein a third radial oil passage is disposed upstream of the second radial oil passage, wherein the third radial oil passage includes a delivery opening formed in the distribution tube and radial bore formed in the rotor shaft, wherein oil exits the bore and is delivered to a ring gear bearing that supports the planetary gearset.

20. The hybrid powertrain of claim 19, wherein a fourth radial oil passage is disposed upstream of the third radial oil passage, wherein the fourth radial oil passage includes a further delivery opening formed in the tube and a further radial bore formed in the input shaft, wherein oil exits the further radial bore and delivered to the first electric machine.

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