WO2025072972A1

WO2025072972A1 - 3-pinion reinforced differential cross shaft support

Info

Publication number: WO2025072972A1
Application number: PCT/US2024/049339
Authority: WO
Inventors: Chad LABELLE
Original assignee: Linamar Corporation
Priority date: 2023-09-29
Filing date: 2024-09-30
Publication date: 2025-04-03

Abstract

A differential assembly includes a carrier having a central cavity, first, second, and third pinion gears, and a cross shaft assembly. The cross shaft assembly includes a cross shaft support having a central body with a center hole extending axially therethrough, and first, second, and third support holes spaced circumferentially apart and extending radially outward from the center hole. The cross shaft support also includes first, second, and third spokes projecting radially from the central body and including respective spoke end portions fixedly coupled to the carrier. The first, second, and third spokes are spaced circumferentially apart and offset from the first, second, and third support holes in an alternating arrangement. The first, second, and third cross shafts are mounted into the respective first, second, and third support holes, extend through the respective first, second, and third pinion gears, and fixedly coupled to the carrier.

Description

3-PINION REINFORCED DIFFERENTIAL CROSS SHAFT SUPPORT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application 63/541,300, filed on September 29, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to a single speed stepped planetary coaxial gear reduction subassembly for use in an electrified transmission for an automotive vehicle. More specifically, the present invention relates to a single speed stepped planetary coaxial gear reduction subassembly which includes a differential having a cross shaft.

DESCRIPTION OF RELATED ART

[0003] Many vehicles today have an electric drive comprising an electric motor operatively coupled to an axle gearbox in lieu of and/or in addition to an internal combustion engine. An axle gearbox operatively coupled to an electric motor is generically described as an electrified drive axle. The electrified drive axle is typically operatively coupled to one or more wheels for propelling the vehicle.

[0004] One type of electrified drive axle is a single speed stepped planetary coaxial electrified drive axle. The coaxial electrified drive axle typically includes an electric motor having a motor shaft that is coaxial with left-hand and right-hand output shafts. Typically, the electric motor of the coaxial electrified drive axle includes a stator and a rotor contained and supported within a housing. The motor shaft is supported and contained by opposing inboard and outboard motor bearings inserted into the housing. Further, the motor shaft is operatively coupled through a differential assembly to the left-hand and right-hand output shafts. The left-hand and right-hand output shafts are typically operatively coupled to respective wheels of the vehicle.

[0005] In certain electrified drive axles, the motor shaft of the electric motor is operatively coupled to the differential assembly through a stepped planetary gear set. One end of the motor shaft is fixedly coupled to a sun gear of the stepped planetary transmission. The stepped planetary transmission includes a plurality of stepped planetary gears attached to a carrier through needle bearings and planetary pins. Typically, the carrier is supported by an inboard carrier support bearing and an outboard carrier support bearing. Often, the carrier includes an inboard carrier fixedly coupled to an outboard carrier along a carrier split line.

[0006] Further, the differential assembly is integrated within the carrier and includes a plurality of differential pinion gears meshingly engaged with opposing inboard and outboard differential side gears mounted within the carrier. Typically, the differential pinion gears are rotationally supported by a 1-piece cross shaft fixedly coupled to the carrier when the carrier split line is aligned with the 1 -piece cross shaft. The 1-piece cross shaft typically includes a plurality of cross shaft legs extending from a central ring. The cross shaft legs extend axially through the respective differential pinion gears and have a distal end fixedly coupled to the carrier. The 1-piece cross shaft is resistant to bending during operation of the electrified drive axle since the cross shaft legs are integrally formed with the central ring. However, the 1-piece cross shaft can not be used when the carrier split line is spaced apart from the cross shaft legs.

[0007] Typically, a 4-piece cross shaft assembly is used when the position of the carrier split line within the carrier prevents using a 1-piece cross shaft. The 4-piece cross shaft assembly includes a cross shaft support and a plurality of cross shafts. The cross shaft support typically includes a side wall extending between opposing end walls and a plurality of support holes spaced circumferentially apart in the side wall. Each cross shaft extends axially through the respective differential pinion gear and includes a distal end fixedly coupled to the carrier. In addition, each cross shaft includes a proximal end inserted into the respective support hole in the cross shaft support. However, loads applied to the differential pinion gears during operation of the electrified drive axle apply a rotational load onto the cross shaft support. The rotational load applied to the cross shaft support can cause the cross shaft support to rotate within the carrier, causing the proximal ends of the cross shafts to shift within the support holes. The rotation of the cross shaft support can cause the cross shafts to bend, which can deflect the differential pinion gears causing damage to the differential pinion gears.

[0008] It is desirable, therefore, to prevent the rotation of the cross shaft support during operation of the electrified drive axle when the position of the carrier split line prevents using a 1-piece cross shaft. Further, it is desirable to reduce the amount of deflection of the differential pinion gears to improve the reliability and durability of the electrified drive axle.

SUMMARY OF THE INVENTION

[0009] According to one embodiment, there is provided a differential assembly which includes a carrier having a central cavity for substantially enclosing a first pinion gear, a second pinion gear, a third pinion gear, and a cross shaft assembly. The cross shaft assembly includes a cross shaft support fixedly coupled to a first cross shaft, a second cross shaft, and a third cross shaft. The cross shaft support includes a central body with a center hole extending axially therethrough, a first side wall, a second side wall, and a third side wall spaced circumferentially apart, and a first support hole, a second support hole, and a third support hole spaced circumferentially apart and which extend radially between the center hole and a respective one of the first, second, and third side walls. The cross shaft support also includes a first spoke, a second spoke, and a third spoke projecting radially from the central body, each of the first, second, and third spokes including respective spoke end portions fixedly coupled to the carrier. The first, second, and third spokes are spaced circumferentially apart and offset from the first, second, and third support holes in an alternating arrangement. Further, the first cross shaft is mounted in the first support hole, passes through the first pinion gear, and is fixedly coupled to the carrier. Also, the second cross shaft is mounted in the second support hole, and passes through the second pinion gear, and is fixedly coupled to the carrier. In addition, the third cross shaft is mounted in the third support hole, passes through the third pinion gear, and is fixedly coupled to the carrier.

[0010] According to a second embodiment, there is provided a gear reduction subassembly for use in an electrified transmission for an automotive vehicle. The gear reduction subassembly includes a gearbox housing, a single speed stepped planetary gear set, and a differential assembly. The single speed stepped planetary gear set and the differential assembly are contained within and supported by the gearbox housing. The single speed stepped planetary gear set includes a sun gear, a ring gear, a carrier having a central cavity, and a plurality of stepped planetary gears. Each one of the plurality of stepped planetary gears includes a driven planet gear and a driving planet gear rotationally supported by a planet pin mechanically coupled to the carrier. The driven planet gear is meshingly engaged with the sun gear and the driving planet gear is meshingly engaged with the ring gear. The differential assembly includes a cross shaft assembly and a plurality of pinion gears meshingly engaged with an inboard side gear and an outboard side gear. The cross shaft assembly includes a cross shaft support and a plurality of cross shafts. The cross shaft support includes a central body, a center hole extending axially therethrough, a plurality of support holes spaced circumferentially apart and extending radially outward from the center hole, a plurality of spokes spaced circumferentially apart and projecting radially outward from the central body and including respective spoke end portions fixedly coupled to the carrier. The plurality of spokes is spaced between the plurality of support holes in an alternating arrangement. The plurality of cross shafts extends through a respective one of the plurality of pinion gears with a distal end fixedly coupled to the carrier and a proximal end mounted in a respective one of the plurality of support holes.

[0011] According to a third embodiment, there is provided a coaxial electrified drive axle. The coaxial electrified drive axle includes a gear reduction subassembly. The gear reduction subassembly includes a single speed stepped planetary gear set and a differential assembly contained and supported within a gearbox housing. The single speed stepped planetary gear set includes a sun gear, a ring gear, a carrier having a central cavity, a plurality of stepped planetary gears, and a sun gear shaft. Each one of the plurality of stepped planetary gears includes a driven planet gear and a driving planet gear rotationally supported by a planet pin mechanically coupled to the carrier. The driven planet gear is meshingly engaged with the sun gear and the driving planet gear is meshingly engaged with the ring gear. The carrier further includes an inboard opening and an outboard opening. The sun gear shaft extends axially from the sun gear through the inboard opening and includes a sun shaft bore extending axially therethrough. The differential assembly includes a cross shaft assembly and a plurality of pinion gears meshingly engaged with an inboard side gear and an outboard side gear. The cross shaft assembly includes a cross shaft support and a plurality of cross shafts. The cross shaft support includes a central body, a center hole extending axially therethrough, and a plurality of support holes spaced circumferentially apart and extending radially outward from the center hole. The cross shaft support also includes a plurality of spokes spaced circumferentially apart and projecting radially outward from the central body and which includes respective spoke end portions fixedly coupled to the carrier. The plurality of spokes is spaced between the plurality of support holes in an alternating arrangement. The plurality of cross shafts extends through a respective one of the plurality of pinion gears with a distal end fixedly coupled to the carrier and a proximal end mounted in a respective one of the plurality of support holes. The coaxial electrified drive axle also includes a motor housing fixedly coupled to the gearbox housing and having an interior cavity therebetween and an electric motor positioned within the interior cavity. The electric motor includes a stator fixedly coupled to the motor housing and includes a passageway extending axially therethrough, a rotor positioned within the passageway, and a rotor shaft fixedly coupled to the rotor and including a rotor shaft bore extending axially through the rotor shaft and through the rotor. The rotor shaft is rotationally supported and contained by the motor housing and driveably coupled to the sun gear shaft. The coaxial electrified drive axle also includes a left-hand output shaft and a right-hand output shaft driveably coupled to the inboard side gear and the outboard side gear, respectively. The left-hand output shaft extends axially through the sun shaft bore and the rotor shaft bore. The right-hand output shaft extends axially through the outboard opening in the carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0013] Figure 1 is a cross-sectional view of a portion of a coaxial electrified drive axle which includes a cross shaft support, according to one embodiment of the present invention;

[0014] Figure 2 is an enlarged cross-sectional view of portion 2 of the coaxial electrified drive axle of Figure 1;

[0015] Figure 3 is a cross-sectional view of the coaxial electrified drive axle of Figure 1 taken along line 3-3;

[0016] Figure 4 is perspective view of the cross shaft support of Figure 1;

[0017] Figure 5 is a cross-sectional view of a known coaxial electrified drive axle;

[0018] Figure 6 is an enlarged cross-sectional view of portion 6 of the known coaxial electrified drive axle of Figure 5; [0019] Figure 7 is a cross-sectional view of the known coaxial electrified drive axle of Figure 5 taken along line 7-7 and including a known cross shaft assembly;

[0020] Figure 8 is a front view of a known 1 -piece cross shaft;

[0021] Figure 9 is a front semi-transparent view of the known cross shaft assembly of Figure 7 which includes a known cross shaft support;

[0022] Figure 10 is a perspective view of the known cross shaft support of Figure 9;

[0023] Figure 11 is a semi-transparent front view of the known cross shaft assembly of Figure 9; and

[0024] Figure 12 is a semi-transparent perspective view of the known cross shaft assembly of Figure 11.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Figures 1-4 illustrate a coaxial electrified drive axle 10 for a vehicle, according to embodiments described herein. Directional references employed or shown in the description, figures or claims, such as top, bottom, upper, lower, upward, downward, lengthwise, widthwise, left, right, and the like, are relative terms employed for ease of description and are not intended to limit the scope of the invention in any respect. Referring to the Figures, like numerals indicate like or corresponding parts throughout the several views.

[0026] Referring to Figures 1 and 2, the coaxial electrified drive axle 10 (hereinafter, “electrified drive axle”) includes an electric motor 12 operatively coupled to opposing left-hand and righthand output shafts 14, 16 through a single speed stepped planetary gear set 18 and a differential assembly 20. A rear portion of the electrified drive axle 10 is omitted from the Figures for simplicity. The opposing left-hand and right-hand output shafts 14, 16 extend in an axial direction and are aligned along a rotational axis 22.

[0027] The electrified drive axle 10 also includes a motor housing 24 fixedly coupled to a gearbox housing 26 and having an interior cavity 28 defined between the motor housing 24 and the gearbox housing 26. The motor housing 24 is has a generally cylindrical shape and includes an outer wall 30, a mounting wall 32, a housing end wall (not shown), a motor opening 34, and a divider wall 36. The outer wall 30 has an interior surface 38 that extends circumferentially around the rotational axis 22 and extends axially between the mounting wall 32 and the housing end wall (not shown). The mounting wall 32 includes the motor opening 34 aligned with the rotational axis 22 and which is fluidically connected to the interior cavity 28. The mounting wall 32 is fixedly coupled to the gearbox housing 26, enclosing the interior cavity 28 within the motor housing 24 and the gearbox housing 26. The divider wall 36 projects radially from the outer wall 30 and is spaced axially apart from the mounting wall 32. The divider wall 36 includes a recessed cavity 40 aligned with the rotational axis 22. In addition, the recessed cavity 40 includes a shaft opening 42 extending axially therethrough having a centerline generally aligned with the rotational axis 22. The electrified drive axle 10 also includes an outboard motor bearing (not shown) and an inboard motor bearing 44. The outboard motor bearing (not shown) is supported by the housing end wall (not shown) and having a centerline aligned with the rotational axis 22. The inboard motor bearing 44 is inserted into the recessed cavity 40 in the divider wall 36 and includes a centerline aligned with the rotational axis 22.

[0028] The electrified drive axle 10 also includes a stator 46, a rotor 48, and a rotor shaft 50. The stator 46 is attached to the interior surface 38 of the outer wall 30 and includes a stator passageway 52 extending longitudinally through the stator 46 aligned with the rotational axis 22. The rotor 48 is positioned within the stator passageway 52 through the stator 46 and fixedly coupled to the rotor shaft 50. The rotor 48 has a centerline aligned with the rotational axis 22 such that the rotor 48 rotates about the rotational axis 22. In addition, the rotor shaft 50 includes a rotor shaft bore 54 extending axially between opposing outboard and inboard shaft ends 56, 58. The outboard shaft end 56 is rotationally supported and contained by the outboard motor bearing (not shown). In addition, the inboard shaft end 58 is rotationally supported and contained by the inboard motor bearing 44. In the embodiment shown in Figure 1, a portion 60 of the rotor shaft 50 adjacent the inboard shaft end 58 extends into and/or through the shaft opening 42 in the divider wall 36. The rotor shaft 50 is essentially part of the rotor 48 in the embodiment shown in Figure 1. However, in alternate embodiments, the rotor shaft 50 is a separate component attached to and/or passing through the rotor 48. Further, in certain embodiments, the rotor shaft 50 extends entirely through the rotor 48. In other embodiments, the rotor shaft 50 is split into two short rotor shafts with each of the short rotor shafts extending from respective first and second rotor ends 62, 64 without passing entirely through the rotor 48.

[0029] Also shown in Figure 1, the single speed stepped planetary gear set 18 (hereinafter “planetary gear set”) and the differential assembly 20 are generally contained within and supported by the gearbox housing 26. The planetary gear set 18, the differential assembly 20, and the gearbox housing 26 may alternatively be described as a single speed stepped planetary coaxial gear reduction subassembly 66, hereinafter “gear reduction subassembly”.

[0030] The planetary gear set 18 includes a sun gear 68, a plurality of stepped planetary gears 70, a ring gear 72, and a carrier 73. Each of the plurality of stepped planetary gears 70 include a driven planet gear 74, a driving planet gear 76, one or more radial needle bearings 78, and a planet pin 80 passing axially through the respective driven planet gears 74 and the respective driving planet gears 76. Each of the driven planet gears 74 is meshingly engaged with the sun gear 68. Further, each of the driving planet gears 76 is meshingly engaged with the ring gear 72. In certain embodiments, the stepped planetary gears 70 are supported to the planet pin 80 by a pair of radial needle bearings 78 separated by a sleeve 81. In addition, each of the planet pins 80 is mechanically coupled to the carrier 73.

[0031] As shown in Figure 1, the carrier 73 extends between an inboard carrier end 82 and an opposing outboard carrier end 83. The inboard carrier end 82 is supported and contained within the motor housing 24 by an inboard carrier support bearing 84 operatively coupled between the inboard carrier end 82 and the divider wall 36 in the motor housing 24. The outboard carrier end 83 is supported and contained within the gearbox housing 26 by an outboard carrier support bearing 85. The carrier 73 includes an inboard carrier 86 fixedly coupled to an outboard carrier 88 along a carrier split line 90. The inboard carrier 86 and the outboard carrier 88 include an inboard opening 91 and an outboard opening 92, respectively, extending through the inboard carrier end 82 and the outboard carrier end 83, respectively, and which are aligned with the rotational axis 22. The carrier 73 also includes a central cavity 93 extending between the inboard and outboard openings 91, 92.

[0032] Referring to Figures 2 and 3, the outboard carrier 88 includes a plurality of radial holes 94 and a plurality of pin holes 95. The plurality of radial holes 94 includes first, second, and third radial holes 94 which are circumferentially spaced apart. Tn addition, the plurality of pin holes 95 includes first, second, and third pin holes 95 extending axially through the respective one of the plurality of radial holes 94. Further, the planetary gear set 18 includes a plurality of connecting pins 96. The plurality of connecting pins 96 include first, second, and third connecting pins 96 extending through the respective one of the plurality radial holes 94.

[0033] The outboard carrier 88 also includes a plurality of slots 97. The plurality of slots 97 include first, second, and third slots 97 which are circumferentially spaced apart and extending in a radial direction. Each of the plurality of slots 97 include opposing first and second slot walls 98, 99 extending inwardly from an end wall 100 and extending generally parallel to and offset from a slot axis 101. The plurality of radial holes 94 and the plurality of slots 97 are arranged circumferentially around the outboard carrier 88 in an alternating arrangement with each of the plurality of radial holes 94 spaced circumferentially between adjacent ones of the plurality of radial holes 94. Certain embodiments include thrust washers at each end of the stepped planetary gears 70 to support thrust loads against the carrier 73.

[0034] The planetary gear set 18 also includes a sun gear shaft 102 which extends from the sun gear 68 and is aligned with the rotational axis 22 of the sun gear 68, as shown in Figure 1. The sun gear shaft 102 is generally cylindrically-shaped with a sun shaft bore 103 extending longitudinally through both the sun gear shaft 102 and the sun gear 68. In the embodiment shown in Figure 1 , the rotor shaft bore 54 through the rotor shaft 50 includes a recessed inlet portion 104 sized and shaped to matingly engage with the sun gear shaft 102 such that the rotor shaft 50 is driveably coupled to the sun gear shaft 102. The sun shaft bore 103 extending through the sun gear shaft 102 is aligned with the rotor shaft bore 54. More specifically, the longitudinal axis of the sun gear shaft 102 is generally aligned with the rotational axis 22. Rotation of the rotor shaft 50 about the rotational axis 22 causes the sun gear 68 to rotate, which in turn causes the driven planet gears 74 to rotate. Rotation of the driven planet gears 74 cause each of the respective driving planet gears 76 to rotate and travel along the ring gear 72, resulting in rotation of the carrier 73 about the rotational axis 22.

[0035] In addition, the differential assembly 20, shown in Figures 1-3, is integrated within the carrier 73 forming part of the single speed stepped planetary coaxial gear reduction subassembly 66. The differential assembly 20 includes a plurality of pinion gears 105 as well as an inboard side gear 108 and an opposing outboard side gear 109 mounted within the carrier 73. The differential assembly 20 includes first, second, and third pinion gears 105 in order to nest the differential assembly 20 between the driving planet gears 76 to reduce the axial length of the gear reduction subassembly 66. The_plurality of pinion gears 105 include pinion gear teeth 110 which are meshingly engaged with both the inboard and outboard side gears 108, 109. It will be appreciated that the plurality of pinion gears 105 may vary in number without altering the scope of the present invention.

[0036] The inboard and outboard side gears 108, 109 are driveably coupled to the respective lefthand and right-hand output shafts 14, 16 and rotate with the respective left-hand and right-hand output shafts 14, 16. The left-hand and right-hand output shafts 14, 16 are aligned with the rotational axis 22 of the inboard and outboard side gears 108, 109. The left-hand output shaft 14 extends through the inboard opening 91 in the carrier 73, extends through the sun shaft bore 103 in the sun gear 68 and the sun gear shaft 102, and extends through the rotor shaft bore 54. The lefthand output shaft 14 has a proximal shaft end 112 fixedly coupled to the inboard side gear 108. In addition, the left-hand output shaft 14 has an opposing distal shaft end 113 configured to be operatively coupled to a first wheel of the vehicle. The left-hand output shaft 14 is generally cylindrical and extends longitudinally along the rotational axis 22 of the rotor shaft 50. Further, the left-hand output shaft 14 has an outer surface 115 having a diameter less than an inner diameter of the rotor shaft bore 54 through the rotor shaft 50.

[0037] The right-hand output shaft 16 has a first shaft end 116 fixedly coupled to the outboard side gear 109, as shown in Figure 1. The right-hand output shaft 16 is generally cylindrical and extends longitudinally along the rotational axis 22. The cylindrical-shaped portion 117 of the righthand output shaft 16 extends through the outboard opening 92 in the carrier 73 and through an outboard aperture 118 in the gearbox housing 26. The right-hand output shaft 16 has a second shaft end 119 opposing the first shaft end 116 and configured to be operatively coupled to an opposing second wheel of the vehicle. In the embodiment shown in Figure 1, rotation of the inboard and outboard side gears 108, 109 about the rotational axis 22 result in rotation of the left-hand and right-hand output shafts 14, 16, respectively, as well rotation of operatively coupled first and second wheels of the vehicle. During use, the vehicle is propelled by the electrified drive axle 10 rotating the left-hand and right-hand output shafts 14, 16. [0038] Also shown in Figure 1 , the differential assembly 20 includes a cross shaft assembly 120 inserted into the central cavity 93 in the carrier 73. Referring to Figures 2 and 3, the cross shaft assembly 120 includes a plurality of cross shafts 121 fixedly coupled to a cross shaft support 122. The plurality of cross shafts 121 corresponds numerically with the plurality of radial holes 94 in the outboard carrier 88. It will be appreciated that the plurality of cross shafts 121 can vary in number without altering the scope of the present invention. In the first embodiment, the plurality of cross shafts 121 includes first, second, and third cross shafts 121. The plurality of cross shafts 121 are generally cylindrically-shaped and include a cross shaft axis 123 extending in a longitudinal direction between a distal end 124 and an opposing proximal end 125.

[0039] Referring to Figures 1, 2, and 3, the plurality of cross shafts 121 are assembled with the carrier 73 such that each cross shaft axis 123 is generally perpendicular to the rotational axis 22 of the rotor shaft 50. In addition, each one of the plurality of cross shafts 121 include a pin aperture 126 extending radially therethrough and adjacent the distal end 124. The first, second, and third cross shafts 121 joined by the cross shaft support 122 in the middle is commonly described as a 4- piece cross shaft assembly. The differential assembly 20 includes the cross shaft assembly 120 instead of a known 1 -piece cross shaft 127 (Figure 8) since the carrier split line 90 does not go through the cross shaft assembly 120 which prevents assembly of the 1 -piece cross shaft 127 within the carrier 73. The cross shaft assembly 120 requires three individual cross shafts 121 (one for each of the first, second, and third pinion gears 105) since the carrier 73 includes a carrier split line 90 which is axially offset from the cross shaft assembly 120 within the carrier 73 and the differential assembly 20 is a 3-pinion differential.

[0040] Depicted in Figures 3 and 4, the cross shaft support 122 includes a central body 128 having a generally triangular shape with opposing front and rear faces 129, 130. In addition, the cross shaft support 122 includes a plurality of side walls 131 circumferentially spaced apart and extending axially between the front and rear faces 129, 130. In the first embodiment, the plurality of side walls 131 includes first, second, and third side walls 131 which correspond numerically to the plurality of cross shafts 121. Further, the cross shaft support 122 includes a center hole 132 extending axially through the central body 128 between the front and rear faces 129, 130 and defining an axis of rotation 134 of the cross shaft support 122. The axis of rotation 134 of the cross shaft support 122 is aligned with the rotational axis 22 after the cross shaft support 122 is assembled with the carrier 73. The cross shaft support 122 also includes a plurality of support holes 136 extending radially through the respective one of the plurality of side walls 131 and adjoin the center hole 132. In the first embodiment, the plurality of support holes 136 includes first, second, and third support holes 136 which correspond numerically to the plurality of cross shafts 121. In more detail, the first, second, and third support holes 136 extend radially from the center hole 132 and through the respective one of the first, second, and third side walls 131. The plurality of support holes 136 have a respective hole axis 138 perpendicular to the axis of rotation 134 of the cross shaft support 122. Further, the plurality of support holes 136 are sized and shaped to matingly engage with the proximal end 125 of the plurality of cross shafts 121, respectively.

[0041] Referring to Figure 4, the cross shaft support 122 also includes a plurality of spokes 140 spaced circumferentially apart and projecting radially outward from the central body 128. In the first embodiment, the plurality of spokes 140 includes first, second, and third spokes 140.,. It will be appreciated that the plurality of spokes 140 might vary in number without altering the scope of the present invention. Each of the plurality of spokes 140 extend radially between adjacent ones of the plurality of pinion gears 105 up to respective one of the plurality of slots 97 in the carrier 73. Each one of the plurality of spokes 140 includes opposing first and second spoke walls 148, 150 extending axially between opposing third and fourth spoke walls 152, 154 and terminates at a respective spoke end portion 156. The spoke end portions 156 are configured to matingly engage with the respective plurality of slots 97 in the outboard carrier 88. In addition, each of the plurality of spokes 140 includes a respective spoke axis 168 which is perpendicular to the axis of rotation 134. The slot axis 101 is configured to align with the respective spoke axis 168 when the cross shaft support 122 is assembled with the outboard carrier 88. It will be appreciated that the spoke end portions 156 and the plurality of slots 97 might vary in shape and size without altering the scope of the present invention. In addition, the plurality of slots 97 in the carrier 73 might include an axial shoulder (not shown) in order to axially locate the cross shaft support 122 during assembly. Further, the plurality of slots 97 in the carrier 73 have a close fit with the respective spoke end portions 156 and a sufficiently substantial contact area in the rotational direction to resist torsional deflections caused by forces transmitted from the plurality of pinion gears 105 through the plurality of cross shafts 121 into the cross shaft support 122. [0042] In the first embodiment, the plurality of spokes 140 and the plurality of support holes 136 are arranged circumferentially around the central body 128 in an alternating arrangement. In more detail, each one of the plurality of spokes 140 is spaced circumferentially between adjacent ones of the plurality of support holes 136. It will be appreciated that the plurality of spokes 140 of the cross shaft support 122 are sized and shaped sufficiently narrow in order to provide adequate clearance to the pinion gear teeth 110. Also, the plurality of pinion gears 105 are mounted on the respective one of the plurality of cross shafts 121 and rotate relative to the respective cross shaft axis 123. Further, the inboard and outboard side gears 108, 109 rotate relative to the carrier 73. Rotation of the carrier 73 about the rotational axis 22 of the rotor shaft 50 results in rotation of the cross shaft assembly 120 about the rotational axis 22 causing the plurality of pinion gears 105 to orbit about that same rotational axis 22. In the event that the right-hand and left-hand wheels rotate at different speeds, the inboard and outboard side gears 108, 109 will also rotate at different speeds causing the plurality of pinion gears 105 to also rotate about the cross shaft axis 123 of the associated one of the plurality of cross shafts 121.

[0043] Referring to Figures 2 and 3, the cross shaft assembly 120 and the plurality of pinion gears 105 are assembled with the outboard carrier 88 by inserting the cross shaft support 122 into the central cavity 93 in the outboard carrier 88. Next, the spoke end portions 156 of the plurality of spokes 140 are inserted into the respective one of the plurality of slots 97. Next, the plurality of pinion gears 105 are inserted into a respective gap between the plurality of spokes 140. Next, the proximal end 125 of the plurality of cross shafts are inserted through the respective one of the plurality of radial holes 94 in the outboard carrier 88 and through the respective one of the plurality of gears 105. Next, the proximal end 125 of the plurality of cross shafts 121 is mounted in the respective one of the plurality of support holes 136 in the cross shaft support 122. Next, the plurality of connecting pins 96 are inserted into the respective one of the plurality of pin holes 95 in the outboard carrier 88 and through the respective pin apertures 126 in the respective one of the plurality of cross shafts 121. As assembled, the plurality of cross shafts 121 have a respective centerline aligned with the hole axis 138 of the respective plurality of support holes 136. The cross shaft support 122 is prevented from twisting during operation by sliding the plurality of spokes 140 of the cross shaft support 122 into the respective one of the plurality of slots 97 in the carrier 73. The plurality of connecting pins 96 fixedly coupling the plurality of cross shafts 121 to the carrier 73 also axially fixes the cross shaft support 122 in place within the plurality of slots 97 in the carrier 73.

[0044] A known coaxial electrified drive axle 10P is shown in Figures 5-12. Elements in Figures 5-12 that are the same or similar to those used above in the embodiment shown in Figures 1-4 have the same reference numbers for simplicity. Only the significant differences in relation to Figure 1 are highlighted below. One difference substantially involves a known cross shaft assembly 220 inserted within a known carrier 73P having the carrier split line 90 spaced axially apart from the plurality of cross shafts 121. When the carrier split line 90 aligns with the plurality of cross shafts 121, a known 1-piece cross shaft 127 (Figure 8). However, the known 1-piece cross shaft 127 (Figure 8) is unsuitable for use in a carrier 73P having a carrier split line 90 spaced apart from the plurality of cross shafts 121 because the 1-piece cross shaft 127 cannot be inserted into the carrier 73P during assembly.

[0045] Referring to Figures 5-7 and 9, the known cross shaft assembly 220 includes three cross shafts 121 and a known cross shaft support 222, which is alternately described as a “4-piece cross shaft assembly”. Referring to Figures 9 and 10, the known cross shaft support 222 has a generally cylindrical shape with a plurality of arcuate walls 224 circumferentially spaced apart and extending in an axial direction. The known cross shaft support 222 also includes a plurality of support walls 230 circumferentially spaced apart and extending circumferentially between the adjacent ones of the plurality of actuate walls 224. In addition, the known cross shaft support 222 includes a passageway 236 extending axially therethrough and a plurality of support holes 238 extending radially through a respective one of the plurality of support walls 230 and adjoining the passageway 236.

[0046] In the conventional architecture shown in Figures 5-7, the known cross shaft assembly 220 is assembled with the carrier 73P by inserting the known cross shaft support 222 into the central cavity 93 in the carrier 73P, inserting the plurality of cross shafts 121 into the respective one of the plurality radial holes 94 in the carrier 73P, through the respective one of the plurality f of pinion gears 105, and inserting the proximal end 125 of the plurality of cross shafts 121 into the respective one of the plurality of support holes 238 in the known cross shaft support 222. Next, connecting pins 96 are inserted through the respective pin holes 95 in the carrier 73P and into the pin apertures 126 in the respective one of the plurality of cross shafts 121.

[0047] Depicted in Figure 9, the plurality of cross shafts 121 have an unloaded cross shaft axis 123 which extends longitudinally between the distal and proximal ends 124, 125 and aligns with the hole axis 138 of the respective one of the plurality of support holes 238. Referring to Figure 11, loads applied to the plurality of pinion gears 105 during operation apply a rotational load onto the known cross shaft support 222, as illustrated by arrow 240. The rotational load (arrow 240) causes the known cross shaft support 222 to rotate in the counterclockwise direction as viewed in Figure 11, which causes the proximal ends 125 of the plurality of cross shafts 121 to shift within the respective one of the plurality of support holes 238. The shifting of the proximal ends 125 cause the plurality of cross shafts 121 to bend since the distal end 124 of the plurality of cross shafts 121 are fixedly coupled to the carrier 73P by the connecting pins 96. In response to the applied load (arrow 240), the proximal ends 125 of the plurality of cross shafts 121 are displaced away from the unloaded cross shaft axis 123 and the plurality of cross shafts 121 are bent, as illustrated by angle 242 between the unloaded cross shaft axis 123 and the loaded cross shaft axis 123'.

[0048] Referring to Figure 12, the load (arrow 240) applied to the known cross shaft assembly 220 during operation causes excess bending and higher stress in portion 246 of the plurality of cross shafts 121 adjacent the known cross shaft support 222. The bending of the plurality of cross shafts 121 cause higher deflections of the plurality of pinion gears 105 than observed when the known 1 -piece cross shaft 127 is used in place of the known cross shaft assembly 220. The higher amount of bending in the plurality of cross shafts 121 of the known cross shaft assembly 220 during operation results in higher stress and higher gear deflections than within the 1 -piece cross shaft 127 (Figure 8). The excess bending in the f plurality of cross shafts 121 occurs because the known cross shaft support 222 is not constrained from rotation.

[0049] Depicted in Figure 8, the known 1 -piece cross shaft 127 includes three cross shaft legs 248 which are circumferentially spaced apart and extend radially from and integrally formed with a central ring 250. As such, the known 1-piece cross shaft 127 is more resistant to bending in response to the load (arrow 240) applied during operation because a proximal end 252 of the cross shaft legs 248 are integrally formed with the central ring 250. However, the known 1 -piece cross shaft 127 is unsuitable for use in a carrier 73P having a carrier split line 90 spaced axially apart from the cross shaft legs 248 since the 1-piece cross shaft 127 cannot be assembled within the carrier 73P.

[0050] In contrast, the cross shaft assembly 120 of the electrified drive axle 10 of Figure 1-4 resists excess bending in the plurality of cross shafts 121 during operation since the cross shaft support 122 is rotationally constrained by the plurality of spokes 140 inserted into respective one of the plurality of slots 97 in the carrier 73. As such, the amount of gear deflection is reduced in the electrified drive axle 10 in comparison to the known coaxial electrified drive axle 10P having a known 4-piece cross shaft assembly 220 with the known cross shaft support 222 that is rotationally unsupported.

[0051] As discussed above, the coaxial electrified drive axle 10 of the present invention includes an electric motor 12 operatively coupled to opposing left-hand and right-hand output shafts 14, 16 through a single speed stepped planetary gear set 18 and a differential assembly 20. The planetary gear set 18 includes a sun gear 68, a plurality of stepped planetary gears 70, a ring gear 72, and a carrier 73. Each of the stepped planetary gears 70 include a driven planet gear 74, a driving planet gear 76, and a planet pin 80 which is mechanically coupled to the carrier 73 and which passes axially through the driven planet gear 74 and the driving planet gear 76. The driven planet gears 74 are meshingly engaged with the sun gear 68. The driving planet gears 76 are meshingly engaged with the ring gear 72. The differential assembly 20 includes a cross shaft assembly 120 inserted into a central cavity 93 in the carrier 73. The cross shaft assembly 120 includes a plurality of cross shafts 121 fixedly coupled to the carrier 73 at a distal end 124 and joined at a proximal end 125 by a cross shaft support 122 in the middle. The cross shaft support 122 includes a plurality of spokes 140 which are circumferentially spaced apart and extend radially outward from a central body 128 and include respective spoke end portions 156 fixedly coupled to the carrier 73. The differential assembly 20 also includes a plurality of pinion gears 105 rotationally supported on the respective one of the plurality of cross shafts 121. Further, the differential assembly 20 also includes inboard and outboard side gears 108, 109 which are meshing engaged with the plurality of pinion gears 105 and driveably coupled to respective left-hand and right-hand output shafts 14, 16. The plurality of spokes 140 on the cross shaft support 122 which are fixedly coupled to the carrier 73 prevent rotation of the cross shaft support 122 when load is applied to the plurality of pinion gears 105 during operation of the electrified drive axle 10. In addition, the plurality of spokes 140 prevent bending of the plurality of cross shafts 121 by preventing rotation of the cross shaft support 122. As such, the plurality of spokes 140 also reduce the amount of deflection of the plurality of pinion gears 105 during operation of the electrified drive axle 10. The reduction in the amount of deflection improves the reliability and durability of the plurality of pinion gears 105.

[0052] The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.

Claims

What is claimed is:

1. A differential assembly comprising: a carrier including a central cavity for substantially enclosing: a first pinion gear, a second pinion gear, and a third pinion gear; and a cross shaft assembly comprising a cross shaft support fixedly coupled to a first cross shaft, a second cross shaft, and a third cross shaft; wherein the cross shaft support comprises a central body including a center hole extending axially therethrough, a first side wall, a second side wall, and a third side wall spaced circumferentially apart, and a first support hole, a second support hole, and a third support hole spaced circumferentially apart and extending radially between the center hole and a respective one of the first, second, and third side walls; wherein the cross shaft support also comprises a first spoke, a second spoke, and a third spoke projecting radially from the central body, each of the first, second, and third spokes including respective spoke end portions fixedly coupled to the carrier, wherein the first, second, and third spokes are spaced circumferentially apart and offset from the first, second, and third support holes in an alternating arrangement; and wherein the first cross shaft is mounted in the first support hole, passes through the first pinion gear, and fixedly coupled to the carrier, the second cross shaft is mounted in the second support hole, passes through the second pinion gear, and fixedly coupled to the carrier, and the third cross shaft is mounted in the third support hole, passes through the third pinion gear, and fixedly coupled to the carrier.

2. The differential assembly as set forth in claim 1, further comprising a first connecting pin, a second connecting pin, and a third connecting pin, wherein: the carrier further comprises a first radial hole, a second radial hole, and a third radial hole extending in a radial direction and adjoining the central cavity, and includes a first pin hole, a second pin hole, and a third pin hole extending axially through the first, second, and third radial holes, respectively; the first, second, and third cross shafts include a respective pin aperture extending radially therethrough; the first, second, and third cross shafts extend through a respective one of the first, second, and third radial holes; and the first, second, and third connecting pins extend through the respective first, second, and third pin holes and through the respective pin apertures in the first, second, and third cross shafts such that the first, second, and third cross shafts are fixedly coupled to the carrier and to the cross shaft support.

3. The differential assembly as set forth in claim 2, the carrier further comprising a first slot, a second slot, and a third slot spaced circumferentially apart and extending in the radial direction; wherein the spoke end portions of the first, second, and third spokes are matingly engaged with a respective one of the first, second, and third slots.

4. The differential assembly as set forth in claim 3, wherein each of the first, second, and third spokes extend radially between the first, second, and third pinion gears, respectively, and matingly engaged with the first, second, and third slots, respectively, in the carrier.

5. The differential assembly as set forth in claim 4, the carrier further comprising an inboard carrier fixedly coupled to an outboard carrier along a carrier split line; wherein the carrier split line is spaced axially apart from the first, second, and third cross shafts.

6. A gear reduction subassembly for use in an electrified transmission for an automotive vehicle, comprising: a gearbox housing; a single speed stepped planetary gear set and a differential assembly contained within and supported by the gearbox housing; the single speed stepped planetary gear set comprising a sun gear, a ring gear, a carrier having a central cavity, and a plurality of stepped planetary gears, each one of the plurality of stepped planetary gears comprising a driven planet gear and a driving planet gear rotationally supported by a planet pin mechanically coupled to the carrier, wherein the driven planet gear is meshingly engaged with the sun gear and the driving planet gear is meshingly engaged with the ring gear; the differential assembly comprising a cross shaft assembly and a plurality of pinion gears meshingly engaged with an inboard side gear and an outboard side gear; and the cross shaft assembly including a cross shaft support and a plurality of cross shafts, the cross shaft support comprising a central body, a center hole extending axially therethrough, a plurality of support holes spaced circumferentially apart and extending radially outward from the center hole, a plurality of spokes spaced circumferentially apart and projecting radially outward from the central body and including respective spoke end portions fixedly coupled to the carrier, wherein the plurality of spokes are spaced between the plurality of support holes in an alternating arrangement, the plurality of cross shafts extend through a respective one of the plurality of pinion gears with a distal end fixedly coupled to the carrier and a proximal end mounted in a respective one of the plurality of support holes.

7. The gear reduction subassembly as set forth in claim 6, further comprising a plurality of connecting pins, wherein: the carrier further comprises a plurality of radial holes spaced circumferentially apart, extending in a radial direction, and adjoining the central cavity, the carrier further comprises a plurality of pin holes extending axially through a respective one of the plurality of radial holes; each of the plurality of cross shafts includes a respective pin aperture extending radially therethrough, the plurality of cross shafts extends through the plurality of radial holes, respectively; and the plurality of connecting pins extend through the plurality of pin holes, respectively, and the pin aperture in the plurality of cross shafts, respectively, such that the plurality of cross shafts is fixedly coupled to the carrier and to the cross shaft support.

8. The gear reduction subassembly as set forth in claim 7, the carrier further comprising a plurality of slots spaced circumferentially apart and extending in the radial direction; wherein the spoke end portions of the plurality of spokes are matingly engaged with a respective one of the plurality of slots.

9. The gear reduction subassembly as set forth in claim 8, wherein the plurality of spokes extends radially between the plurality of pinion gears and the plurality of slots, respectively, in the carrier.

10. The gear reduction subassembly as set forth in claim 9, the carrier further comprising an inboard carrier fixedly coupled to an outboard carrier along a carrier split line; wherein the carrier split line is spaced axially apart from the plurality of cross shafts.

11. The gear reduction subassembly as set forth in claim 10, wherein: the plurality of pinion gears comprises a first pinion gear, a second pinion gear, and a third pinion gear; the plurality of cross shafts comprises a first cross shaft, a second cross shaft, and a third cross shaft; and the plurality of support holes comprises a first support hole, a second support hole, and a third support hole.

12. The gear reduction subassembly as set forth in claim 11, wherein: the plurality of spokes comprises a first spoke, a second spoke, and a third spoke; the plurality of connecting pins comprises a first connecting pin, a second connecting pin, and a third connecting pin; the plurality of radial holes comprises a first radial hole, a second radial hole, and a third radial hole; the plurality of pin holes comprises a first pin hole, a second pin hole, and a third pin hole; and the plurality of slots comprises a first slot, a second slot, and a third slot.

13. A coaxial electrified drive axle comprising: the gear reduction subassembly according to claim 6 further comprising a sun gear shaft extending axially from the sun gear and including a sun shaft bore extending axially through the sun gear shaft, wherein the carrier further comprises an inboard opening and an outboard opening, and the sun gear shaft extends through the inboard opening; a motor housing fixedly coupled to the gearbox housing and having an interior cavity therebetween; an electric motor positioned within the interior cavity and including a stator fixedly coupled to the motor housing and including a passageway extending axially therethrough, a rotor positioned within the passageway, and a rotor shaft fixedly coupled to the rotor and including a rotor shaft bore extending axially through the rotor shaft and through the rotor, wherein the rotor shaft is rotationally supported and contained by the motor housing, and wherein the rotor shaft is driveably coupled to the sun gear shaft; and a left-hand output shaft and a right-hand output shaft driveably coupled to the inboard side gear and the outboard side gear, respectively, wherein the left-hand output shaft extends axially through the sun shaft bore and the rotor shaft bore, and the right-hand output shaft extends axially through the outboard opening in the carrier.

14. The coaxial electrified drive axle according to claim 13, the gear reduction subassembly further comprising a plurality of connecting pins, wherein: the carrier further comprises a plurality of radial holes spaced circumferentially apart, extending in a radial direction, and adjoining the central cavity, the carrier further comprises a plurality of pin holes extending axially through a respective one of the plurality of radial holes; each of the plurality of cross shafts includes a respective pin aperture extending radially therethrough, the plurality of cross shafts is inserted into the plurality of radial holes, respectively; and the plurality of connecting pins extend through the plurality of pin holes, respectively, and the pin aperture in the plurality of cross shafts, respectively, such that the plurality of cross shafts is fixedly coupled to the carrier and the cross shaft support.

15. The coaxial electrified drive axle according to claim 14, the carrier further comprising a plurality of slots spaced circumferentially apart and extending in the radial direction; wherein the spoke end portions of the plurality of spokes are matingly engaged with a respective one of the plurality of slots.

16. The coaxial electrified drive axle according to claim 15, wherein the plurality of spokes extends radially between the plurality of pinion gears and are matingly engaged with the plurality of slots, respectively, in the carrier.

17. The coaxial electrified drive axle according to claim 16, the carrier further comprising an inboard carrier fixedly coupled to an outboard carrier along a carrier split line, wherein the carrier split line is spaced axially apart from the plurality of cross shafts.

18. The coaxial electrified drive axle according to claim 17, wherein: the plurality of pinion gears comprises a first pinion gear, a second pinion gear, and a third pinion gear; the plurality of cross shafts comprises a first cross shaft, a second cross shaft, and a third cross shaft; the plurality of support holes comprises a first support hole, a second support hole, and a third support hole; the plurality of spokes comprises a first spoke, a second spoke, and a third spoke; the plurality of connecting pins comprises a first connecting pin, a second connecting pin, and a third connecting pin; the plurality of radial holes comprises a first radial hole, a second radial hole, and a third radial hole; the plurality of pin holes comprises a first pin hole, a second pin hole, and a third pin hole; and the plurality of slots comprises a first slot, a second slot, and a third slot.