Electric drive unit for a hybrid drive vehicle

Abstract

An electric drive unit configured for use with a hybrid-drive vehicle includes a first gear stage including a layshaft input gear rotatable about a layshaft axis and a rotor output gear rotatable about an output axis, and a second gear stage including a first layshaft output gear and a second layshaft output gear each rotatable about the layshaft axis and a first cluster gear and a second cluster gear each rotatable about the output axis. The first layshaft output gear is engaged with first cluster gear and the second layshaft output gear engaged with the second cluster gear to transmit a load generated from rotational motion of an electric motor. Further, the electronic drive unit includes a layshaft coupled the layshaft input gear and the first and second layshaft output gear such that the first gear stage and the second gear stage are operatively coupled to each other.

Description

Attorney Docket No.: 027873-03489ELECTRIC DRIVE UNIT FOR HYBRID DRIVE VEHICLERELATED APPLICATIONS

[0001] The present disclosure claims priority to and the benefit of U.S. Provisional Application 63 / 748,077, filed on January 22, 2025 and U.S. Provisional Application 63 / 829,330, filed June 24, 2025, the entire contents of each of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present application relates to vehicles and, more particularly, to vehicles propelled at least partially with a rotating electrical machine.BACKGROUND

[0003] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0004] In the past, vehicles have relied solely on internal combustion engines (ICEs) for propulsion. Modern vehicles now are often at least partially propelled by a rotating electrical machine (also referred to as an electric motor), in addition to or in lieu of an ICE. Vehicles that are partially propelled by an ICE as well as an electric motor are often referred to variously or interchangeably as a hybrid-drive vehicle, a hybrid-electric vehicle (HEV), or a plug-in hybrid-electric vehicle (PHEV). As modern vehicles include components for two different propulsion systems — both for the electric motor and the ICE — space allocated within the vehicle for each propulsion system is precious. As a result, it is helpful to decrease the packaging footprint for components of a propulsion system for a hybrid-drive vehicle.SUMMARY

[0005] According to an aspect of the present disclosure, an electric drive unit configured for use with a hybrid-drive vehicle includes a first gear stage including a layshaft input gear rotatable about a layshaft axis and a rotor output gear rotatable aboutAttorney Docket No.: 027873-03489an output axis that offset from the layshaft axis, the layshaft input gear engaged with the rotor output gear to receive rotational motion from an electric motor, a second gear stage including a first layshaft output gear and a second layshaft output gear each rotatable about the output axis, the first layshaft output gear engaged with the first cluster gear and the second layshaft output gear engaged with the second cluster gear to transmit a load generated from the rotational motion, and a layshaft coupled to the layshaft input gear, the first layshaft output gear, and the second layshaft gear such that the first gear stage and the second gear stage are operatively coupled to each other.

[0006] According to a further aspect of the present disclosure, the layshaft is formed with a single component or multiple components operable as a one-piece part. The first cluster gear and the second cluster gear have a same diameter, have an equal number of teeth, and are axially adjacent to each other.

[0007] According to a further aspect of the present disclosure, the first cluster gear has gear teeth formed with a first helix angle engaged with a corresponding gear teeth formed in the first layshaft output gear and the second cluster gear has gear teeth formed with a second helix angle engaged with a corresponding gear teeth in the second layshaft output gear. The first helix angle and the second helix angle are different from each other and also oppositely angled from each other. The first helix angle is larger than the second helix angle. A first module determined in the first cluster gear and a second module determined in the second cluster gear are different from each other. The first and second helix angles and / or the first and second modules are configured to be adjustable to achieve substantially same lives of the first and second cluster gears.

[0008] According to a further aspect of the present disclosure, the second gear stage includes a first gear mesh between the first cluster gear and the first layshaft output gear and a second gear mesh between the second cluster gear and the second layshaft output gear, and a first torque generated on the first gear mesh and a second torque generated on the second gear mesh are different from each other.

[0009] According to another aspect of the present disclosure, an electric drive unit configured for use with a hybrid-drive vehicle comprises a layshaft gearbox assembly including a layshaft input gear, a first layshaft output gear, and a second layshaft output gear each rotatable about a layshaft axis, the layshaft input gear engaged with a rotorAttorney Docket No.: 027873-03489output gear to receive rotational motion from an electric motor defined in a first gear stage, and a cluster gearbox assembly including a first cluster gear engaged with the first layshaft output gear, a second cluster gear engaged with the second layshaft output gear, and a cluster gear shaft coupled to the first and second cluster gears, rotating about an output axis that offset from the layshaft axis defined as a second gear stage. Further, the layshaft gearbox assembly includes a layshaft coupled to the layshaft input gear, and the first and second layshaft output gears such that the first gear stage and the second gear stage are operatively coupled to each other for transmitting a load generated from the rotational motion.

[0010] According to another aspect of the present disclosure, an electric drive unit configured for use with a hybrid-drive vehicle includes a layshaft gearbox assembly implementing a first gear ratio, including a layshaft input gear configured to receive rotational motion from an electric motor, a first layshaft output gear, and a second layshaft output gear, the layshaft input gear, the first layshaft output gear, and the second layshaft output gear each rotatable about a layshaft axis; and a cluster gearbox assembly implementing a second gear ratio, including a first cluster gear having angled gear teeth engaged with the first layshaft output gear, a second cluster gear having oppositely angled gear teeth, axially adjacent to and having a diameter equal to the first cluster gear, engaged with the second layshaft output gear, and a cluster gear shaft, coupled to the first cluster gear and the second cluster gear, rotating about an output axis that is offset from the layshaft axis and communicating rotational motion from the electric motor to wheels on the hybrid-drive vehicle.

[0011] According to another aspect of the present disclosure, an electric drive unit configured for use with a hybrid-drive vehicle includes a layshaft gearbox assembly implementing a first gear ratio, including a layshaft input gear configured to receive rotational motion from an electric motor, a first layshaft output gear, and a second layshaft output gear, the layshaft input gear, the first layshaft output gear, and the second layshaft output gear rotatable about a layshaft axis; a cluster gearbox assembly implementing a second gear ratio, including a first cluster gear having angled gear teeth engaged with the first layshaft output gear, a second cluster gear having oppositely angled gear teeth and the same diameter as the first cluster gear, axially adjacent the first cluster gear,Attorney Docket No.: 027873-03489engaged with the second layshaft output gear, and a cluster gear shaft, coupled to the first cluster gear and the second cluster gear, rotating about an output axis that is offset from the layshaft axis; and a planetary gearbox implementing a third gear ratio, coupled to the cluster gear shaft and rotating coaxially with the output axis and the cluster gearbox assembly, communicating rotational motion from the electric motor to wheels on the hybrid-drive vehicle.

[0012] According to another aspect of the present disclosure, an electric drive unit configured for use with a hybrid-drive vehicle includes a layshaft gearbox assembly implementing a first gear ratio, including a layshaft input gear configured to receive rotational motion from an electric motor, a first layshaft output gear, and a second layshaft output gear, the layshaft input gear, the first layshaft output gear, and the second layshaft output gear rotatable about a layshaft axis; a cluster gearbox assembly implementing a second gear ratio, including a first cluster gear having angled gear teeth engaged with the first layshaft output gear, a second cluster gear having oppositely angled gear teeth, axially adjacent the first cluster gear, engaged with the second layshaft output gear, and a cluster gear shaft, coupled to the first cluster gear and the second cluster gear, rotating about an output axis that is offset from the layshaft axis and communicating rotational motion from the electric motor to wheels on the hybrid-drive vehicle; and a housing assembly having a cavity that receives the layshaft gearbox assembly, the cluster gearbox assembly, and an electric motor assembly, wherein the housing assembly is configured to couple to a portion of the hybrid-electric vehicle.

[0013] Further details and benefits will become apparent from the following detailed description of the appended drawings. The drawings are provided herewith purely for illustrative purposes and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order that the disclosure may be well understood, there will not be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

[0015] FIG. 1 is a perspective view depicting an implementation of an electric drive unit configured to be included in a hybrid-drive vehicle;Attorney Docket No.: 027873-03489

[0016] FIG. 2 is a cross-sectional view depicting an implementation of an electric drive unit configured to be included in a hybrid-drive vehicle;

[0017] FIG. 3 is a cross-sectional view depicting an implementation of a portion of an electric drive unit configured to be included in a hybrid-drive vehicle;

[0018] FIG. 4 is a perspective view depicting an implementation of a portion of an electric drive unit configured to be included in a hybrid-drive vehicle;

[0019] FIG. 5 is a cross-sectional view depicting an implementation of a portion of an electric drive unit configured to be included in a hybrid-drive vehicle;

[0020] FIG. 6 is a perspective view depicting an implementation of an electric drive unit included with a portion of a hybrid-drive vehicle;

[0021] FIG. 7 is a perspective view depicting an implementation of a portion of an electric drive unit configured to be included in a hybrid-drive vehicle;

[0022] FIG. 8 is a perspective view depicting an implementation of a portion of an electric drive unit configured to be included in a hybrid-drive vehicle;

[0023] FIG. 9 is a perspective view depicting an implementation of an electric drive unit included with a portion of a hybrid-drive vehicle;

[0024] FIG. 10 is a perspective view depicting a portion of a hybrid-drive vehicle configured to couple to the electric drive unit;

[0025] FIG. 11 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit;

[0026] FIG. 12 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit;

[0027] FIG. 13 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit;

[0028] FIG. 14 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit;

[0029] FIG. 15 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit;

[0030] FIG. 16 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit; andAttorney Docket No.: 027873-03489

[0031] FIG. 17 is a detailed view depicting a portion of the layshaft gearbox assembly and the cluster gearbox assembly of the electric drive unit.

[0032] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.DETAILED DESCRIPTION

[0033] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0034] An electric drive unit configured for use with a hybrid-drive vehicle can have a minimized or reduced outer diameter, including an electric motor having a rotor shaft, as well as a layshaft assembly that is parallel and offset from the rotor shaft receiving rotational output from the rotor shaft, and a cluster gear assembly meshingly engaged with the layshaft assembly rotating coaxially with the rotor shaft. The cluster gear assembly can include two gears, axially adjacent to each other and having the same diameter. The two axially-adjacent gears can use gear teeth that are angled relative to each other having equal and opposite angled gear teeth relative to each other. This arrangement can help reduce lateral offset and axial length of the gear face of each gear.

[0035] A first gear ratio can exist between the rotor shaft and the layshaft assembly and a second gear ratio can exist between the layshaft assembly and the cluster gear assembly. In some implementations, the electric drive unit can include a third gear ratio between an output of the cluster gear assembly and a planetary gear assembly couple to the cluster gear assembly. The planetary gear assembly can be configured to couple with a differential gearbox used with the hybrid-drive vehicle. The electric drive unit can include a closed circuit cooling system having its own fluid circuit and heat exchanger. Or in other implementations, the electric drive unit can have a housing with an opening that rigidly couples with a corresponding opening on an ICE so that the ICE shares cooling fluid, such as engine oil or transmission fluid, with the electric drive unit assembly as part of a shared cooling circuit. In one implementation, the electric drive unit can propel theAttorney Docket No.: 027873-03489front wheels of the hybrid-drive vehicle and an ICE can propel the rear wheels. However, it should be appreciated that other configurations are possible.

[0036] In brief, as shown in Figure 1, an electric drive unit 10 can include a housing assembly 12, an electric motor assembly 14, a differential gearbox assembly 16 (shown in Figure 2), and a pair of output shafts 18, which are rotatable about an output axis 24. The housing assembly 12 can define one or more cavities (not specifically shown) in which the electric motor assembly 14, the differential gearbox assembly 16, and the output shafts 18 can be at least partly housed.

[0037] Turning to Figures 2-5, the electric drive unit 10 can also include a layshaft assembly 22, positioned parallel to and offset from an output axis 24 of the electric motor assembly 14 or vehicle wheel rotation that receives rotational output from the electric motor assembly 14. A geared connection between the electric motor assembly 14 and the layshaft assembly 22 can implement a first gear ratio. The layshaft assembly 22 can engage a cluster gearbox assembly 26 that is coaxial with the output axis 24 via another geared connection. The geared connection between the layshaft assembly 22 and the cluster gearbox assembly 26 can implement a second gear ratio. The cluster gearbox assembly 26 includes a first cluster gear 28 and a second cluster gear 30 having equal diameters that receive rotational input from the layshaft assembly 22. In some implementations the cluster gearbox assembly 26 can fixedly couple to the differential gearbox assembly 16 positioned coaxial with the output axis 24, which is configured to couple with the output shafts 18. The geared connection between the cluster gearbox assembly 26 and the differential gearbox assembly 16 can implement a third gear ratio.

[0038] The electric motor assembly 14 can include a stator assembly 32 and a rotor assembly 34. The stator assembly 32 includes a stator core 36 having stator slots (not shown) that receive stator windings 38. The stator windings 38 extend axially outside of the stator slots to form end turns 40 that are exposed outside of the stator core 36. The stator windings 38 are configured to receive electrical current controlled by an inverter (not shown). The flow of electrical current through the stator windings 38 can induce the angular displacement of the rotor assembly 34 relative to the stator assembly 32 about the output axis 24. The rotor assembly 34 can include a rotor 42 with an outer diameter that is received concentrically within the stator core 36 and an inner diameter 44 thatAttorney Docket No.: 027873-03489fixedly couples to a rotor shaft 46 in a way that prevents the angular displacement of the rotor shaft 46 relative to the rotor 42. The rotor shaft 46 can rotate coaxially about the output axis 24 and extend axially along the output axis 24 toward the differential gearbox assembly 16. In this implementation, an outer diameter of the rotor shaft 46 can be slightly larger than the inner diameter 44 of the rotor 42 such that the rotor shaft 46 may be press fit into the rotor 42. In other implementations, the outer diameter of the rotor shaft can have a splined surface that engages corresponding splined surface on the inner diameter of the rotor 42. The rotor shaft 46 can include rotor shaft bearings 48 on opposite sides of the stator core 36 that are each received in journals 50 formed within a surface of the housing assembly 12 and have radial surfaces 52 that engage shoulders 54 formed on an outer surface of the rotor shaft 46. The shoulders 54 can help manage axial thrust of the rotor shaft 46 during operation.

[0039] A distal end of the rotor shaft 46 includes a rotor output gear 56 having radially-outwardly-facing gear teeth shaped to engage and impart rotational motion from the rotor shaft 46 to the layshaft gearbox assembly 22. The layshaft gearbox assembly 22 is positioned parallel to and offset from the rotor shaft 46 and includes a layshaft input gear 58 that is rotatably fixed to a first layshaft output gear 60 and a second layshaft output gear 62 rotating about a layshaft axis 64. The layshaft gearbox assembly 22 can be supported within the housing assembly 12 with a first layshaft bearing 66 positioned on a proximate side 68 of the layshaft input gear 58. A second layshaft bearing 70 can also support the layshaft gearbox assembly 22 toward an opposite or distal side 72 of the layshaft input gear 58. The first layshaft bearing 66 and the second layshaft bearing 70 can be axially constrained relative to the housing assembly 12 and the layshaft input gear 58 to prevent the axial movement of the layshaft gearbox assembly 22 relative to the housing assembly 12. In one implementation, the layshaft input gear 58 can include radially-extending surfaces 74 that abut radial surfaces of the first and second layshaft bearings 66, 70. The housing assembly 12 can include shoulders 76 or protuberances that also engage radial surfaces of the first and second layshaft bearings 66, 70. In some implementation, the housing assembly 12 can include a groove 78a configured to receive a radially-outwardly-expanding snap ring 80 that also engages a corresponding groove 78b formed in an axially-extending outer surface of the first layshaft bearing 66, such thatAttorney Docket No.: 027873-03489the snap ring 80 is compressible to selectively reduce the diameter of the snap ring 80 permitting assembly / disassembly. The rotor output gear 56 and the layshaft input gear 58 can each have a diameter selected to implement a first gear ratio. The selected pitch diameters of the rotor output gear 56 and the layshaft input gear 58 can be related as a first center distance. The axially-directed thrust exerted by the torque from the rotor shaft 46 along the layshaft axis 64 can be controlled by the rotor shaft bearings 48, the first layshaft bearing 66, and the second layshaft bearing 70. These bearings can be implemented in a variety of ways, such as drawn cup needle roller bearings for example.

[0040] The layshaft input gear 58 is fixedly coupled to the first layshaft output gear 60 and the second layshaft output gear 62 to prevent angular displacement between the gears 58, 60, 62. The first layshaft output gear 60 is positioned axially adjacent to the second layshaft output gear 62; both the first layshaft output gear 60 and the second layshaft output gear 62 are axially spaced from the layshaft input gear 58. The layshaft input gear 58, the first layshaft output gear 60, and the second layshaft output gear 62 rotate about the layshaft axis 64. The first layshaft output gear 60 and the second layshaft output gear 62 have the same diameter and can be formed using helical gears having opposite angled helix gear teeth. That is, the first layshaft output gear 60 has gear teeth angled relative to the layshaft axis 64 at a first angle and the second layshaft output gear 62 has gear teeth angled relative to the layshaft axis 64 at a second, different angle. The first angle and the second angle can be selected such that when the first layshaft output gear 60 and the second layshaft output gear 62 are coupled together axially adjacent to each other, the gear teeth of the second layshaft output gear 62 can be a mirrored opposite shape of the gear teeth of the first layshaft output gear 60. Put differently, the first layshaft output gear 60 can have gear teeth for left-handed gearing whereas the second layshaft output gear 62 can have gear teeth for right-handed gearing.

[0041] The layshaft input gear 58 can be rotationally coupled to the first layshaft output gear 60 and the second layshaft output gear 62 in any one of a variety of ways. In one implementation, the first layshaft output gear 60 and the second layshaft output gear 62 can be formed on an outer surface of a half shaft 82 that can be received within an inner diameter 84 of the layshaft input gear 58. The half shaft 82 can have an inner diameter 86 shaped to receive a torsionally-compliant shaft 88 that extends from a proximal endAttorney Docket No.: 027873-0348968 of the layshaft input gear 58 where it is received within the inner diameter 84 of the layshaft input gear 58, concentric to the first layshaft bearing 66, via a splined connection. The torsionally-compliant shaft 88 can extend from the proximal end 68 of the layshaft input gear 58 to a distal end 92 of the half shaft 82, within the inner diameter 86 of the half shaft 82, to engage another splined connection within the inner diameter 86 of the half shaft 82. For example, in the layshaft assembly 22, the torsionally-compliant shaft 88 is formed with one-piece, solid shaft. In another approach, the torsionally-compliant shaft 88 may be an assembled layshaft that becomes effectively one piece shaft. The splined connections can prevent angular displacement of the half shaft 82 relative to the layshaft input gear 58 yet permit limited axial movement of the half shaft 82 relative to the layshaft input gear 58. However, it should be appreciated that other implementations are possible such that the layshaft input gear, the first layshaft output gear, and the second layshaft output gear are rigidly coupled together, either as individual components joined together using known fasteners or formed as a unitary component.

[0042] The first layshaft output gear 60 and the second layshaft output gear 62 can meshingly engage with the cluster gearbox assembly 26. The cluster gearbox assembly 26 can include a cluster gear shaft 94, the first cluster gear 28, and a second cluster gear 30. The cluster gearbox assembly 26 is positioned within the housing assembly 12 to rotate about the output axis 24. The first and second cluster gears 28, 30 are axially adjacent to each other and each have gear teeth shaped to mesh with and receive rotational movement from the first layshaft output gear 60 and the second layshaft output gear 62, respectively. The diameters of the first layshaft output gear 60 and second layshaft output gear 62 relative to the diameters of the first cluster gear 28 and the second cluster gear 30 can be chosen to implement a second gear ratio. The diameters of the first layshaft output gear 60 and the second layshaft output gear 62 can be less than an outer diameter of the stator assembly 32. The diameters of the first layshaft output gear 60 and the second layshaft output gear 62 as they relate to the diameters of the first cluster gear 28 and the second cluster gear 30 can be related as a second center distance. The first center distance and the second center distance in the electric drive unit 10 are equal. The use of a first layshaft output gear 60 and second layshaft output gear 62 engaging a first cluster gear 28 and a second cluster gear 30 can reduceAttorney Docket No.: 027873-03489limitations existing on width of a gear relative to a chosen pitch diameter relative to other implementations using only a single input gear meshing with a single output gear. The distribution of load over two cluster gears can reduce the overall diameter of the gears thereby decreasing the overall diameter of the electric drive unit. Given the orientation of the gear teeth of the first and second layshaft output gears 60, 62 at equal and opposing angles, as well as the corresponding gear teeth of the first and second cluster gears 28, 30 engaging the layshaft output gears 60, 62 can cancel out the axial thrust created by the first layshaft output gear 60 engaging the first cluster gear 28 relative to the axial thrust created by the second layshaft output gear 62 engaging the second cluster gear 30.

[0043] Turning to FIGS. 11 through 17, the first gear ratio existed between the rotor assembly 34 and the layshaft assembly 22 is defined as a first gear stage 150, and the second gear ratio existed between the layshaft assembly 34 and the cluster gear assembly 26 is defined as a second gear stage 152. In the first gear stage 150, the rotor output gear 56 of the rotor assembly 34 and the layshaft input gear 58 of the layshaft gear assembly 22 may each have a diameter selected to implement the first gear ratio and meshed with each other. In the second gear stage 152, the first and second cluster gears 28 and 30 of the cluster gear assembly 26 have gear teeth shaped to mesh with and receive rotational movement from the first and second layshaft output gears 60 and 62, respectively. Further, in the second stage 152, the diameters of the first layshaft output gear 60 and second layshaft output gear 62 relative to the diameters of the first cluster gear 28 and the second cluster gear 30 may be chosen to implement the second gear ratio (also defined as a first gear mesh 154 and a second gear mesh 156).

[0044] In one implementation, in the first gear stage 150, the rotor output gear 56 and the layshaft input gear 58 are each formed with a helical gear shape. The helical gear pair of the rotor output gear 56 and the layshaft input gear 58 may create an axial thrust on the rotor assembly 34 and also an axial thrust on the layshaft assembly 22. The axial thrust forces on both gears are generally equal and opposite. The axial thrusts may be a function of the normal tooth force and the helix angle. In FIG. 12, for example, when the rotor output gear 56 transmits 405 Nm of torque, the axial thrust of 4,092 N is generated on the rotor assembly along the output axis 24 ( i . e. , a left direction in FIG. 12) and anotherAttorney Docket No.: 027873-03489axial thrust of 4,092 N is generated on the layshaft assembly towards the layshaft assembly along the layshaft axis 64 (i.e. , a right direction in FIG. 12). Accordingly, the axial thrusts on both the rotor assembly and the layshaft assembly are equal and opposite. This results that the system in the first gear stage remains balanced with respect to the axial thrust forces.

[0045] As shown in an example of FIG. 13, in the second gear stage 152 isolated from the first gear stage 150, two meshes (the first gear mesh 154 and the second gear mesh 156) between the first and second layshaft output gears 60 and 62, and the first and second cluster gears 28 and 30 each generate axial thrusts in an opposite direction (see arrows). For example, the first and second layshaft output gears 60 and 62 are each formed with 30° helix angle with the opposite direction from each other and also the first and second cluster gears 28 and 30 are each formed with 30° helix angle with the opposite direction from each other. Further, the first layshaft output gear 60 and the first cluster gear 28 are meshed with each other and the second layshaft output gear 62 and the second cluster gear 30 are meshed with each other. In the second gear stage 152 isolated from the first gear stage 150, accordingly, the axial thrust forces on both the first gear mesh 154 and the second gear mesh 156 may be canceled because the gears are mirror images of each other (i.e., the axial thrust forces are equal and opposite). In FIG.13, for example, when the layshaft 88 transmits 1 ,237 Nm of an input torque, each of the first gear mesh 154 and the second gear mesh 156 generates 3,151 Nm of torque, respectively. Further, the first axial thrust of 14,946 N is generated on the first gear mesh 154 toward the first layshaft input gear 58 (i.e., a left direction shown in FIG. 13) and the second axial thrust of 14,946 N is generated on the second mesh 156 toward the opposite direction from the first axial thrust (i.e., a right direction shown in FIG. 13) such that the first and second axial thrusts may be canceled.

[0046] As shown in FIGS. 14 through 17, however, the second gear stage 152 does not exist in isolation of the first gear stage 150 when the layshaft 88 is formed with a one-piece part as shown in the present disclosure or is an assembled layshaft that becomes effectively a one-piece part. So, the net axial force on the one-piece layshaft 88 may be zero, but the first gear mesh 154 and the second gear mesh 156 in the second gear stage 152 may not have equal axial force. To accomplish this balance, accordingly, the normalAttorney Docket No.: 027873-03489forces on the gear teeth (i.e. , the first and second gear meshes) in the second gear stage 152 may be different, which means that the torque that generated in each gear mesh of the second gear stage 152 may have to be different since the helix angles of the two gears are the same.

[0047] In FIG. 14, for example, when the axial thrust force of 4,092 N is transmitted towards the layshaft assembly along the layshaft axis 64 from the first gear stage 150 (i.e., a right direction in FIG. 14), the axial thrust forces on each of the first and second layshaft output gears 60 and 62 are different in the second gear stage 152. The first axial thrust force of 16,992 N is generated on the first layshaft output gear 60 (i.e., a left direction in FIG. 14) and the second axial thrust force of 12,990 N is generated on the second layshaft output gear 62 in the opposite direction (i.e., a left direction) from the first axial thrust force. Further, the torque values generated on each of the first and second gear meshes 154 and 156 are also different because the layshaft 88 is formed as a single piece and the second gear stage 152 is not isolated from the first gear stage 150. Accordingly, the torque of 3,582 Nm is generated on the first gear mesh 154 defined between the first layshaft output gear 60 and the first cluster gear 28 and the torque of 2,772 Nm is generated on the second gear mesh 156 defined between the second layshaft output gear 62 and the second cluster gear 30. In this case, for example, the first and second cluster gears are each formed with the same module (i.e., 1.97 module) and 30° helix angle with the opposite direction from each other.

[0048] In the present disclosure, further, since both the first and second gear meshes 154 and 156 in the second gear stage 153 may carry an equal amount of torque, the helix angles of the two cluster gears need to be different in the second gear stage 152. Further, since both gears need to have the same center distance and the number of teeth to fit in the limited space of the gearbox assembly, the two gears may have different modules as well. In FIG. 15, when the first axial thrust of 16,992 N is generated on the first layshaft output gear 60 and the second axial thrust of 12,900 N is generated on the second layshaft output gear 62 in the second gear stage 152, the helix angle and module of the first and second cluster gears 28 and 30 may be different from each other to carry the equal amount of torque (i.e., 3,151 Nm) on each of the first and second gear meshes 154 and 156. In this case, for example, the first cluster gear 28 may have 33.235° helix angleAttorney Docket No.: 027873-03489and 1.9 module, and the second cluster gear 30 may have 26.495° helix angle and 2.036 module. Accordingly, the helix angles and the modules of each gear may be adjusted based on the axial thrust forces and torques generated or transmitted in the first gear stage 150 and / or the second gear stage 152.

[0049] Due to the different helix angles and modules of the first and second cluster gears 28 and 30, the gears 28 and 30 may have slightly different lives (i.e. , the life spans of the gears). For example, in the example of FIG. 16, the first cluster gear 28 formed with 33.235° helix angle and 1.9 module has 100 hrs. lives, but the second cluster gear 30 formed with 26.495° helix angle and 2.036 module has 130 hrs. lives. Accordingly, to achieve the same lives of the first and second cluster gears 28 and 30 in the second gear stage 152, the first and second gear meshes 154 and 156 may have slightly different torques instead of the equal torque values shown in FIG. 16. For example, as shown in FIG. 17, to keep the same lives (e.g., 115 hrs.) of the first and second cluster gears 28 and 30, the first torque of the first gear mesh 154 may be 3, 176 Nm and the second torque of the second gear mesh 156 is 3,126 Nm such that the first and second gear meshes 154 and 156 may have slightly different torques. Further, compared to the exemplary form of FIG. 16, the helix angle of the first and second cluster gears 28 and 30 may be slightly modified further to keep the balance of the lives. For example, in FIG. 17, the first cluster gear 28 may have 33.5° helix angle and the second cluster gear 30 may have 26.285° helix angle.

[0050] As shown in FIGS. 14 through 17, accordingly, in the second gear stage 152 integrated (i.e. operatively coupled) from the first gear stage 150, to keep the balance of the torques (i.e. , same torques or slightly different torques) in each of the first and second gear meshes 154 and 156 and / or the same or slightly different lives of the first and second cluster gears 28 and 30, the first cluster gear 28 and the second cluster gear 30 in the second gear stage 152 may have different helix angles. Further, since the first and second cluster gears 28 and 30 need to have the same center distance and tooth counts, both have different modules as well to keep the balance of torques and / or also lives of the first and second cluster gears. In the present disclosure, as described above, the helix angles and / or modules of the cluster gears in the second gear stage may be adjusted to allowAttorney Docket No.: 027873-03489for balanced load sharing, thereby improving the overall lifespan of the cluster gears in the second gear stage.

[0051] In one implementation, the proximal end 96 of the cluster gear shaft 94 abuts a distal end of the rotor shaft 46. The cluster gear shaft 94 can be supported within the housing assembly 12 by cluster shaft bearings 98 that fit over an outer diameter of the cluster gear shaft 94. The cluster gear shaft 94 can include a radially-outwardly extending flange 100 that abuts a radial surface 102 of the first cluster gear 28 on one side of the flange 100 and abuts a radial surface 104 of the second cluster gear 30 on an opposite side of the flange 100. The flange 100 as well as the radial surfaces 102, 104 of the first cluster gear 28 and the second cluster gear 30 can include apertures that, when angularly aligned, can receive threaded fasteners 90 for rigidly coupling the first cluster gear 28 and the second cluster gear 30 to the cluster gear shaft 94 and to prevent angular displacement of the first and second cluster gears 28, 30 relative to the cluster gear shaft 94. The cluster gear shaft 94 can include an output 106 configured to communicate rotational motion from the cluster gearbox assembly 26 ultimately to the wheels of the vehicle. In one implementation, the cluster gear shaft 94 can include splines on an outer surface of the output 106 shaped to transmit rotational motion from the electric motor assembly 14 through the layshaft gearbox assembly 22 and the cluster gearbox assembly 26.

[0052] Some implementations of the electric drive unit 10 can include a third gear ratio implemented using a planetary gearbox assembly 108 coupled to the distal end 110 of the cluster gear shaft 94. The planetary gearbox assembly 108 can include a sun gear 112 and a plurality of planet gears 114 engaging the sun gear 112 and a ring gear 116 formed in the housing assembly 12. The planetary gearbox 108 can rotatably couple the cluster gear shaft 94 to the differential gearbox assembly 16 and implement a third gear ratio. The diameter of the sun gear 112 and the diameter of the planet gears 114 can be selected to effectuate the third gear ratio. The sun gear 112 can have an inner diameter 118 that engages with the cluster gear shaft 94 to prevent angular displacement of the sun gear 112 relative to the cluster gear shaft 94. In one implementation, the inner diameter 118 of the sun gear 112 includes a splined surface to engage the splines on the outer surface of the cluster gear shaft 94. The planet gears 114 can be positioned aroundAttorney Docket No.: 027873-03489the sun gear 112 and held in meshing engagement with the sun gear 112 via a planetary carrier 120 that may be incorporated into the differential gearbox assembly 16. A plurality of pins 122 can extend axially parallel to the output axis 24 from a radial surface 124 of the differential gearbox assembly 16. The pins 122 can have an outer diameter close in size to an inner diameter of the planet gears 114 such that the pins 122 carry the planet gears 114 and permit the planet gears 114 to rotate relative to the sun gear 112 and the ring gear 116. Rotational or angular motion from the cluster gear shaft 94 can be translated into rotational motion to the sun gear 112, which then imparts that motion to the planet gears 114 positioned between the sun gear 112 and the ring gear 116. The planet gears 114 then communicate the rotational movement to the pins 122 rigidly affixed to the differential gearbox assembly 16. It should be appreciated that implementations of electric drive units that omit the planetary gearbox assembly 108 are possible.

[0053] The differential gearbox assembly 16 receives the rotational movement from the planet gears 114 through the pins 122 and includes a differential gearbox housing 126 carrying a first output gear 128 and a second output gear 130 coupled to the output shafts 18, and pinion gears 132 rotatable perpendicularly about a pinion 134 relative to the output axis 24. The first output gear 128 and second output gear 130 are rotatable about the output axis 24. The first output gear 128 can be rigidly coupled to one output shaft 18a such that first output gear 128 is not angularly displaced relative to the output shaft 18a. The second output gear 130 is also rotatable about the output axis 24 and can be rigidly coupled to another output shaft 18b such that second output gear 130 is not angularly displaced relative to the output shaft 18b. The pinion gears 132 can be pivotably carried by the differential gearbox housing 126 and positioned axially along the output axis 24 in between the first output gear 128 and the second output gear 130 engaging both the first output gear 128 and the second output gear 130. Angular displacement of the output shafts 18 relative to each other can cause the pinion gears 132 to rotate about the pinion 134 and permit relative rotational movement.

[0054] Turning to Figures 6-10, an implementation of the hybrid electric gearbox assembly 10 is shown as a modular element that can be affixed to an outer surface of the ICE, such as an oil pan 136. In this implementation, the hybrid electric gearbox assembly 10 can include its own fluid cooling circuit having a fluid pump 138 than draws fluid fromAttorney Docket No.: 027873-03489inside the housing assembly 12 at an intake 140 and communicates the fluid through a fluid conduit 146 that deposits the fluid over components within the housing assembly 12, such as the end turns 40. The housing assembly 12 can be coupled to the oil pan 136 via a plurality of oil pan mounting bosses 142 that can receive threaded fasteners 144. However, it should be appreciated that other implementations of the hybrid electric gearbox assemblies can include housing assemblies that have an opening configured to fluidly couple to the ICE such that the lubrication or cooling fluids used by the ICE can also be used to cool the components of the planetary gearbox assembly located inside of the housing assembly. A number of fluids used to lubricate and or cool components of an ICE could be used, such as engine oil, transmission fluid, or water ethylene glycol (WEG) are a few examples.

[0055] It is to be understood that the foregoing is a description of one or more embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0056] As used in this specification and claims, the terms "e.g. " “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

Claims

Attorney Docket No.: 027873-03489CLAIMSWhat is claimed is:

1. An electric drive unit configured for use with a hybrid-drive vehicle, comprising: a first gear stage including a layshaft input gear rotatable about a layshaft axis, and a rotor output gear rotatable about an output axis that offset from the layshaft axis, the layshaft input gear engaged with the rotor output gear to receive rotational motion from an electric motor;a second gear stage including a first layshaft output gear and a second layshaft output gear each rotatable about the layshaft axis, and a first cluster gear and a second cluster gear each rotatable about the output axis, the first layshaft output gear engaged with the first cluster gear and the second layshaft output gear engaged with the second cluster gear to transmit a load generated from the rotational motion; anda layshaft coupled to the layshaft input gear, the first layshaft output gear, and the second layshaft output gear such that the first gear stage and the second gear stage are operatively coupled to each other.

2. The electric drive unit of claim 1, wherein the layshaft is formed with a single component.

3. The electric drive unit of claim 1, wherein the layshaft is formed with multiple components operable as a one-piece part.

4. The electric drive unit of claim 1, wherein the first cluster gear and the second cluster gear have a same diameter, have an equal number of teeth, and are axially adjacent to each other.

5. The electric drive unit of claim 1 , wherein the first cluster gear has gear teeth formed with a first helix angle engaged with a corresponding gear teeth formed in the first layshaft output gear and the second cluster gear has gear teeth formed with a secondAttorney Docket No.: 027873-03489helix angle engaged with a corresponding gear teeth formed in the second layshaft output gear.

6. The electric drive unit of claim 5, wherein the first helix angle and the second helix angle are different and also oppositely angled from each other.

7. The electric drive unit of claim 5, wherein the first helix angle is larger than the second helix angle.

8. The electric drive unit of claim 5, wherein a first module determined in the first cluster gear and a second module determined in the second cluster gear are different from each other.

9. The electric drive unit of claim 8, where the first and second helix angles and / or the first and second modules are configured to be adjustable to achieve substantially same life span of the first and second cluster gears.

10. The electric drive unit of claim 1, wherein the second gear stage includes a first gear mesh between the first cluster gear and the first layshaft output gear and a second gear mesh between the second cluster gear and the second layshaft output gear, and a first torque generated on the first gear mesh and a second torque generated on the second gear mesh are different from each other.

11. An electric drive unit configured for use with a hybrid-drive vehicle, comprising: a layshaft gearbox assembly including a layshaft input gear, a first layshaft output gear, and a second layshaft output gear each rotatable about a layshaft axis, the layshaft input gear engaged with a rotor output gear to receive rotational motion from an electric motor defined as a first gear stage; anda cluster gearbox assembly including a first cluster gear engaged with the first layshaft output gear, a second cluster gear engaged with the second layshaft output gear,Attorney Docket No.: 027873-03489and a cluster gear shaft coupled to the first and second cluster gears, rotating about an output axis that offset from the layshaft axis defined as a second gear stage, wherein the layshaft gearbox assembly further includes a layshaft coupled to the layshaft input gear, and the first and second layshaft output gears such that the first gear stage and the second gear stage are operatively coupled to each other for transmitting a load generated from the rotational motion.

12. The electric drive unit of claim 11, wherein the layshaft is formed with a single component.

13. The electric drive unit of claim 11, wherein the layshaft is formed with multiple components operable as a one-piece part.

14. The electric drive unit of claim 11 , wherein the first cluster gear and the second cluster gear have a same diameter, have an equal number of teeth, and are axially adjacent to each other.

15. The electric drive unit of claim 11 , wherein the first cluster gear has gear teeth with a first angle engaged with the first layshaft output gear and the second cluster gear has gear teeth with a second angle engaged with the second layshaft output gear.

16. The electric drive unit of claim 15, wherein the first angle of the first cluster gear teeth and the second angle of the second cluster gear teeth are different and also oppositely angled from each other to generate substantially similar torque or slightly different torque on each of the first cluster gear and the second cluster gear.

17. The electric drive unit of claim 15, wherein the first teeth angle of the first cluster gear is larger than the second teeth angle of the second cluster gear.Attorney Docket No.: 027873-0348918. The electric drive unit of claim 16, wherein a first module determined in the first cluster gear and a second module determined in the second cluster gear are different from each other.

19. The electric drive unit of claim 18, wherein the first module of the first cluster gear is smaller than the second module of the second cluster gear.

20. The electric drive unit of claim 18, wherein the torques generated on each of the first cluster gear and the second cluster gear, the respective first and second teeth angles of the first cluster gear and second cluster gear, and / or the respective first and second modules of the first cluster gear and second cluster gear are configured to be adjustable to achieve substantially same lives of the first and second cluster gears.

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