Axle assembly of frame rail vehicle

Abstract

An axle assembly for a frame rail vehicle is described herein. The axle assembly includes a drive unit including a first drive unit assembly, a second drive unit assembly, a first axle shaft, and a second axle shaft. The first drive unit assembly includes a first motor, a first output assembly, and a first offset gear reduction assembly. The second drive unit assembly includes a second motor, a second output assembly, and a second offset gear reduction assembly. The first motor and the second motor are oriented in the same direction and spaced apart such that the axle centerline axis is positioned between the first motor and the second motor. The first offset gear reduction assembly is spaced apart from the second offset gear reduction assembly such that the axle centerline axis is positioned between the first offset gear reduction assembly and the second offset gear reduction assembly.

Description

[0001] This application is a divisional application of the invention patent application with the invention name “Axle assembly of frame rail vehicle” and application number: 201880061560.4 filed on March 23, 2020.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Application No. 62 / 546,459, filed on August 16, 2017, the disclosure of which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0004] The present invention relates to vehicle axle assemblies, and more particularly, to an axle assembly for a frame rail vehicle. Background Art

[0005] At least some known frame rail trucks include dual axle systems for increasing the load hauling capabilities of the frame rail truck. Manufacturers are increasingly turning to electric and hybrid propulsion systems to improve performance and efficiency.

[0006] Therefore, there is a need to provide an axle assembly that allows for packaging into the narrow space between chassis rails while maintaining independent wheel drive and multi-speed gear reduction capabilities.

[0007] The present invention addresses one or more of the above problems. Summary of the invention

[0008] Thus, the present invention provides a drive unit and axle assembly for a vehicle having improved performance and efficiency.

[0009] In one embodiment of the present invention, a drive unit for an axle assembly is provided. The drive unit includes a drive unit housing, a first drive unit and a second drive unit positioned in the drive unit housing, a first axle shaft, and a second axle shaft. The first axle shaft is oriented along the axle centerline axis and extends outward from the drive unit housing in a first direction defined along the axle centerline axis. The second axle shaft is oriented coaxially with the first axle shaft along the axle centerline axis and extends outward from the drive unit housing in a second direction opposite to the first direction. The first drive unit includes a first motor and a first gear assembly for transmitting torque from the first motor to the first axle shaft. The first gear assembly includes a first output assembly coupled to the first axle shaft and a first offset gear reduction assembly coupled to the first output assembly and the first motor. The second drive unit includes a second motor and a second gear assembly for transmitting torque from the second motor to the second axle shaft. The second gear assembly includes a second output assembly coupled to the second axle shaft and a second offset gear reduction assembly coupled to the second output assembly and the second motor. The first motor and the second motor are oriented in the same direction. The first motor is spaced apart from the second motor such that the axle centerline axis is positioned between the first motor and the second motor. The first offset gear reduction assembly is spaced apart from the second offset gear reduction assembly such that the axle centerline axis is positioned between the first offset gear reduction assembly and the second offset gear reduction assembly.

[0010] In another embodiment of the present invention, an axle assembly is provided. The axle assembly includes a first wheel end assembly, a second wheel end assembly, and a drive unit coupled to the first wheel end assembly and the second wheel end assembly. The drive unit includes a drive unit housing, a first drive unit and a second drive unit positioned in the drive unit housing, a first axle shaft, and a second axle shaft. The first axle shaft is oriented along the axle centerline axis and extends outward from the drive unit housing in a first direction defined along the axle centerline axis. The first axle shaft is coupled to the first wheel end assembly so that the first wheel end assembly is spaced apart from the drive unit housing. The second axle shaft is oriented coaxially with the first axle shaft along the axle centerline axis and extends outward from the drive unit housing in a second direction opposite to the first direction. The second axle shaft is coupled to the second wheel end assembly so that the second wheel end assembly is spaced apart from the drive unit housing. The first drive unit includes a first motor and a first gear assembly for transmitting torque from the first motor to the first axle shaft. The first gear assembly includes a first output assembly coupled to the first axle shaft and a first offset gear reduction assembly coupled to the first output assembly and the first motor. The second drive unit includes a second motor and a second gear assembly for transmitting torque from the second motor to the second axle shaft. The second gear assembly includes a second output assembly coupled to the second axle shaft and a second offset gear reduction assembly coupled to the second output assembly and the second motor. The first motor and the second motor are oriented in the same direction. The first motor is spaced apart from the second motor so that the axle centerline axis is positioned between the first motor and the second motor. The first offset gear reduction assembly is spaced apart from the second offset gear reduction assembly so that the axle centerline axis is positioned between the first offset gear reducer and the second offset gear reducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Advantages of the present invention will become readily appreciated as they become better understood by referring to the following detailed description when considered in conjunction with the accompanying drawings.

[0012] Figure 1 is a perspective view of a vehicle including an axle assembly according to an embodiment of the present invention.

[0013] Figure 2-3 yes Figure 1 Another perspective view of the vehicle shown in FIG.

[0014] Figure 4 yes Figure 1-3 A perspective view of the axle assembly shown in FIG.

[0015] Figure 5yes Figure 4 Another perspective view of the axle assembly shown in .

[0016] Figure 6-9 It is available for Figure 1-13 Various perspective views of the housing of the axle assembly are shown in FIG.

[0017] Fig.10 yes Figure 4 A top view of the axle assembly is shown in FIG. 1 with the housing removed.

[0018] Fig.11 yes Fig.10 A side view of the axle assembly shown in FIG.

[0019] Fig.12 It is available for Figure 1-11 A perspective view of a drive unit of an axle assembly is shown in FIG.

[0020] Fig.13 and Fig.14 yes Fig.12 A further perspective view of the drive unit is shown in .

[0021] Fig.15 yes Fig.12 Front view of the drive unit shown in .

[0022] Fig.16 yes Fig.12 Rear view of the drive unit shown in .

[0023] Fig.17 yes Fig.10 A perspective view of a portion of an axle assembly is shown in FIG.

[0024] Fig.18 yes Fig.12 A schematic diagram of a drive unit shown in FIG. 1 , showing a node layout in the form of a basic gear in a “W” configuration, comprising a first drive unit assembly in an opposing arm “V” configuration and a second drive unit assembly in a rear arm “V” configuration. DETAILED DESCRIPTION

[0025] Referring to the drawings, wherein like reference numerals refer to like parts throughout the several views, the present invention includes an electric axle assembly 10 for a vehicle 12 (eg, a frame rail truck). Figure 1-5In the illustrated embodiment, the vehicle 12 includes a frame rail system 14. A wheel assembly 16 is coupled to the electric axle assembly 10 for supporting the electric axle assembly 10 from the ground. A mounting assembly 18 is coupled to the frame rail system 14 and the electric axle assembly 10 so that the frame rail system 14 is supported from the ground by the electric axle assembly 10 and the wheel assembly 16. The mounting assembly 18 may include a cantilever coupled to one or more mounting brackets to movably attach the axle assembly 10 to the vehicle 12. The vehicle may be an electric vehicle or a hybrid vehicle having an electric motor and an internal combustion generator / motor. Advantageously, the mounting assembly 18 may be configured to retrofit the axle assembly 10 to the vehicle. For example, a frame rail truck originally equipped with a conventional axle assembly may utilize the axle assembly 10 in place of the conventional axle assembly.

[0026] In the illustrated embodiment, the electric axle assembly 10 includes a drive unit housing 20, a wheel drive unit 22 positioned within the drive unit housing 20, a pair of axle shafts 24 coupled to the wheel drive unit 22 and extending radially outward from opposite (opposite) ends of the wheel drive unit 22 along an axle centerline axis 26, and a pair of wheel end assemblies 28. Each wheel end assembly 28 is coupled to an end of a corresponding axle shaft 24. The wheel assembly 16 includes one or more wheels 30 coupled to each end of the electric axle assembly 10 to support the vehicle 12 and transmit power to the ground. For example, the electric axle assembly 10 includes: a first axle shaft 32, the first axle shaft 32 is coupled between the drive unit 22 and a first wheel end assembly 34, the first wheel end assembly 34 is coupled to a first pair of wheels 36 of the wheels 30; and a second axle shaft 38, the second axle shaft 38 is coupled between the drive unit 22 and a second wheel end assembly 40, the second wheel end assembly 40 is coupled to a second pair of wheels 42 of the wheels 30. The axle assembly 10 may further include a brake system for the vehicle, which may include a cylinder, a brake hose, a brake drum, a brake rotor, a brake caliper, and the like.

[0027] In the illustrated embodiment, the wheel assembly 16 includes a dual wheel configuration having a pair of wheels 30 coupled to each end of the axle assembly 10. Each wheel 30 defines an axis of rotation 44. The axis of rotation 44 of each wheel 30 is generally aligned along the axle centerline axis 26. The vehicle 12 may include multiple electric axle assemblies 10. Each wheel drive unit 22 may be configured to independently drive a wheel 30, and may operate the respective wheel 30 at different speeds during a turning maneuver of the vehicle, or may operate the respective wheel 30 in response to available traction at each wheel 30.

[0028] refer to Figure 10-18The wheel drive unit 22 includes a pair of motors 46 and a transmission assembly 48 coupled to each of the pair of motors 46 and each axle shaft 24. The transmission assembly 48 is coupled to each motor 46 and the first and second axle shafts 32, 38. As such, the torque generated by each motor 46 is transmitted to each wheel end assembly 28 through the transmission assembly 48 and then to the wheels 30. In one embodiment, the transmission assembly 48 has two reduction ratios that can be selectively engaged by an operator of the vehicle or a transmission controller.

[0029] Each motor 46 generates torque to drive the wheels 30. Each motor 46 includes an electric motor 49, a rotor shaft 50 protruding from the electric motor 49, and a drive shaft gear 52 fixed to the rotor shaft 50. The rotor shaft 50 extends along a rotor centerline axis 51, which defines a motor rotation axis 54 extending through the motor 46. The motor 46 can be a brushed or brushless DC or AC motor, as well as other types of motors known in the art.

[0030] In the illustrated embodiment, the pair of electric machines 46 includes a first electric machine 56 and a second electric machine 58, each oriented in the same direction and arranged in parallel so that each rotor centerline axis 51 is oriented parallel to each other. The axle output shaft 24 is oriented along the same coincident axis and extends in opposite directions. The first and second electric machines 56, 58 are oriented in a parallel translational arrangement along a lateral direction on the vehicle 12 and are oriented such that the first electric machine 56 is positioned behind the second electric machine 58 along a longitudinal axis 59 of the vehicle 12.

[0031] The transmission assembly 48 includes a first gear assembly 60 and a second gear assembly 62. The first gear assembly 60 is coupled to the first motor 56 and the first axle output shaft 32. The second gear assembly 62 is coupled to the second motor 58 and the second axle output shaft 38. The first gear assembly 60 and the second gear assembly 62 respectively include an idler shaft 64, an output shaft 66, and a shift mechanism 68 (such as Fig.17 ). The drive wheel 70 is fixed to the idler shaft 64 and meshes with the corresponding drive shaft gear 52. The drive wheel 70 transfers torque from the corresponding drive shaft gear 52 to the idler shaft 64. The shift mechanism 68 is configured to transfer torque between the idler shaft 64 and the output shaft 66. Each output shaft 66 is coupled to a corresponding axle shaft 32, 38.

[0032] In the illustrated embodiment, the wheel drive unit 22 includes a first drive unit assembly 80 and a second drive unit assembly 82. The first drive unit assembly 80 includes a first motor 56 and a first gear assembly 60 for transmitting torque from the first motor 56 to the first axle shaft 32. The first gear assembly 60 includes a first output assembly 84 coupled to a proximal end 86 of the first axle shaft 32 and a first offset gear reduction assembly 88 coupled to the first output assembly 84 and the first motor 56. The first offset gear reduction assembly 88 is coupled to the drive shaft gear 52 of the first motor 56 to transmit torque from the first motor 56 to the first output assembly 84.

[0033] The first output assembly 84 includes a first output shaft 90 extending along a first output shaft centerline axis 92 and a first plurality of output gears 94 fixedly coupled to the first output shaft 90 and spaced apart along the first output shaft centerline axis 92. The output gears 94 are rotatably (non-rotatably) fixed to the first output shaft 90 so that the output gears 94 and the first output shaft 90 rotate at the same speed. The first output shaft 90 defines a hole extending therethrough. The hole is configured to receive the proximal end 86 of the first axle shaft 32 and can be splined or keyed so that the first axle shaft 32 and the first output shaft 90 rotate at the same speed.

[0034] The first offset gear reduction assembly 88 includes a first idler shaft 96 extending along a first idler shaft centerline axis 98, a first plurality of idler gears 100 rotatably coupled to the first idler shaft 96 and spaced apart along the first idler shaft centerline axis 98, and a shift mechanism 68 ( Fig.17 shown).

[0035] The first idler shaft 96 is oriented substantially parallel to the first output shaft 90. Each idler gear 100 is configured to mesh with a corresponding output gear 94 so that rotation of the idler gear 100 causes rotation of the corresponding output gear 94. Each idler gear 100 includes a spline portion engageable with the shift mechanism 68 to rotatably (non-rotatably) couple the idler gear 100 to the first idler shaft 96. The shift mechanism 68 is coupled to the first idler shaft 96 to selectively transfer torque from the first idler shaft 96 to each of the first plurality of idler gears 100.

[0036] The first idler shaft 96 and the first output shaft 90 each have both ends rotatably supported by bearings in the drive unit housing 20. The first drive wheel 102 is fixed to the first idler shaft 96 and meshes with the drive shaft gear 52 of the first motor 56. The first drive wheel 102 transmits torque from the drive shaft gear 52 of the first motor 56 to the first idler shaft 96.

[0037] refer to Fig.17In the illustrated embodiment, the shift mechanism 68 includes a shift ring 104, a shift fork 106, and a shift actuator 108. The shift ring 104 is slidable along the first idler shaft 96 between the idler gears 100 and is rotatably (non-rotatably) coupled to the first idler shaft 96 so that the shift ring 104 and the first idler shaft 96 rotate at the same speed. The shift ring 104 includes at least one spline portion that can engage with a spline portion of any one of the idler gears 100. In addition, the shift ring 104 defines a groove that is sized and shaped to engage with the shift fork 106. The shift fork 106 is coupled to the shift actuator 108 and is movable relative to the first idler shaft 96. The shift fork 106 engages with the shift ring 104 so that the shift fork 106 can move the shift ring 104 into engagement with one of the idler gears 100. Additionally, the shift fork 106 may be moved to a neutral position in which neither idler gear 100 is engaged with the shift ring 104 .

[0038] In one embodiment, the first gear assembly 60 includes a two-speed transmission having a first reduction ratio and a second reduction ratio. The two-speed transmission includes a first pair of output gears 94 spaced apart along the first output shaft 90, and a corresponding first pair of idler gears 100 spaced apart along the first idler shaft 96. Each idler gear in the first pair of idler gears 100 is configured to mesh with a corresponding output gear in the first pair of output gears 94. One idler gear 100 in the first pair of idler gears 100 corresponds to the first reduction ratio, and the other idler gear 100 in the first pair of idler gears 100 corresponds to the second reduction ratio. The shift actuator 108 moves the shift fork 106, thereby moving the shift ring 104 along the first idler shaft 96, thereby selectively engaging the idler gears 100 to select the first reduction ratio and the second reduction ratio. Each idler gear 100 can rotate freely on the first idler shaft 96, so that when the corresponding reduction ratio is not engaged, no torque is transmitted between the first idler shaft 96 and the corresponding idler gear 100.

[0039] The second drive unit assembly 82 is similar to the first drive unit assembly 80 and includes a second motor 58 and a second gear assembly 62 for transferring torque from the second motor 58 to the second axle shaft 38. The second gear assembly 62 includes a second output assembly 110 coupled to a proximal end 112 of the second axle shaft 38 and a second offset gear reduction assembly 114 coupled to the second output assembly 110 and the second motor 58. The second offset gear reduction assembly 114 is coupled to the drive shaft gear 52 of the second motor 58 to transfer torque from the second motor 58 to the second output assembly 110.

[0040] The second output assembly 110 includes a second output shaft 116 extending along a second output shaft centerline axis 118 and a second plurality of output gears 120 spaced apart along the second output shaft centerline axis 118. The output gears 120 are rotatably (non-rotatably) fixed to the second output shaft 116 so that the output gears 120 and the second output shaft 116 rotate at the same speed. The second output shaft 116 defines a hole that is configured to receive the proximal end 112 of the second axle shaft 38 and can be splined or keyed so that the second axle shaft 38 and the second output shaft 116 rotate at the same speed.

[0041] The second offset gear reduction assembly 114 includes a second idler shaft 122 extending along a second idler shaft centerline axis 124 and a second plurality of idler gears 126 rotatably coupled to the second idler shaft 122 and spaced apart along the second idler shaft centerline axis 124. The second idler shaft 122 is oriented substantially parallel to the second output shaft 116. Each idler gear 126 is configured to mesh with a corresponding output gear 120 so that rotation of the idler gear 126 causes rotation of the corresponding output gear 120. The second shifting mechanism 68 is coupled to the second idler shaft 122 for selectively transmitting torque from the second idler shaft 122 to each of the second plurality of idler gears 126. Each idler gear 126 includes a spline portion engageable with the second shifting mechanism 68 to rotatably (non-rotatably) couple the idler gear 126 to the second idler shaft 122. In the illustrated embodiment, the second offset gear reduction assembly 114 includes a separate second shifting mechanism 68 to enable the second drive unit assembly 82 to operate independently of the first drive unit assembly 80. In another embodiment, a single shifting mechanism may be used to operate the first and second drive unit assemblies 80, 82.

[0042] In the illustrated embodiment, the second idler shaft 122 and the second output shaft 116 each have two ends rotatably supported by bearings in the drive unit housing 20. The second drive wheel 128 is fixed to the second idler shaft 122 and meshes with the drive shaft gear 52 of the second motor 58. The second drive wheel 128 transmits torque from the drive shaft gear 52 of the second motor 58 to the second idler shaft 122. The first drive wheel 102 includes a first diameter 130, and the second drive wheel 128 includes a second diameter 132, which is substantially equal to the first diameter 130.

[0043] The second shift mechanism 68 is similar to the first shift mechanism 68 and includes a second shift ring 104, a shift fork 106, and a shift actuator 108. The second shift ring 104 is slidable along the second idler shaft 122 between the idler gears 126 and is rotatably (non-rotatably) coupled to the second idler shaft 122 so that the second shift ring 104 and the second idler shaft 122 rotate at the same speed. The second shift ring 104 includes at least one spline portion that can engage with a spline portion of any of the idler gears 126 and defines a groove that is sized and shaped to engage with the shift fork 106.

[0044] In one embodiment, the second gear assembly 62 includes a two-speed transmission including a first reduction ratio and a second reduction ratio. The two-speed transmission includes a second pair of output gears 120 spaced apart along the second output shaft 116, and a corresponding second pair of idle gears 126 spaced apart along the second idler shaft 122. Each idle gear in the second pair of idle gears 126 is configured to mesh with a corresponding output gear in the second pair of output gears 120. One idle gear 126 in the second pair of idle gears 126 corresponds to the first reduction ratio, and the other idle gear 126 in the second pair of idle gears 126 corresponds to the second reduction ratio. The shift actuator 108 moves the shift fork 106, thereby moving the second shift ring 104 along the second idler shaft 122 to selectively engage the idle gears 126 to select the first reduction ratio and the second reduction ratio. Each idle gear 126 can rotate freely on the second idler shaft 122 so that when the corresponding reduction ratio is not engaged, no torque is transmitted between the second idler shaft 122 and the corresponding idle gear 126.

[0045] The shift mechanism may also include a synchronizer to assist in shifting. The shift actuator may be manually or automatically controlled. The shift actuator may be responsive to a hydraulic, pneumatic or electronic signal generated by a transmission control module. Alternatively, the shift actuator may include a mechanical linkage controlled by a vehicle operator.

[0046] The first wheel end assembly 34 is coupled to the distal end 134 of the first axle shaft 32, and the second wheel end assembly 40 is coupled to the distal end 136 of the second axle shaft 38. The first axle shaft 32 is disposed in the first main shaft 138 (at Figure 5 ), the first main shaft 138 is coupled to the drive unit housing 20. The second axle shaft 38 is arranged in the second main shaft 140, and the second main shaft 140 is coupled to the drive unit housing 20. Fig.17In the illustrated embodiment, each wheel end assembly 34, 40 includes a hub 142 having a wheel flange 144. The hub 142 is rotatably supported on the corresponding main shaft 138, 140 by a pair of hub bearings. The wheel 30 can be fixed to the wheel flange 144 using bolts, nuts and other fasteners known in the art. Each wheel end assembly 34, 40 includes a planetary gear reducer 146, which increases torque to drive the wheel 30. The planetary gear reducer 146 includes a sun gear 148, a planet gear carrier 150, a plurality of planet gears 152 and a ring gear 154. The ring gear 154 is coupled to the corresponding main shaft 138, 140. The sun gear 148 is coupled to the distal end of the corresponding axle shaft 32, 38 and is disposed in the ring gear 154. The ring gear 154 is fixed relative to the sun gear 148. The plurality of planet gears 152 are rotatably coupled to the planet gear carrier 150. The planet gear carrier 150 is arranged adjacent to the ring gear 154, wherein each planet gear 152 is disposed in the ring gear 154. Each planet gear 152 engages with the ring gear 154 and the sun gear 148. When the axle shaft rotates the sun gear 148, the sun gear 148 rotates each planet gear 152, and the planet gears 152 in turn rotate the planet gear carrier 150. The planet gear carrier 150 is coupled to the wheel hub 142 so that the planet gear carrier 150 and the wheel hub 142 rotate at the same speed.

[0047] In the illustrated embodiment, the first drive unit assembly 80 is configured to drive the first wheel-end assembly 34 and the second drive unit assembly 82 is configured to drive the second wheel-end assembly 40 independently of the first drive unit assembly 80, thereby operating the first wheel-end assembly 34 and the second wheel-end assembly 40 at different speeds during a turning maneuver of the vehicle, or in response to the traction available at each wheel 30.

[0048] refer to Figure 6-9In the illustrated embodiment, the drive unit housing 20 includes a plurality of walls 160 including an inner surface defining a chamber 162. The first drive unit assembly 80 and the second drive unit assembly 82 are completely disposed within the chamber 162 of the drive unit housing 20. The drive unit housing 20 includes a housing shell 164 and a cover 166 removably coupled to the housing shell 164. The housing shell 164 includes a body including a plurality of walls 160 having an inner surface and an outer surface 168. The inner surface defines the chamber 162, which is sized and shaped to receive the drive unit 22 therein. The outer surface 168 extends between a front side portion 170 and a rear side portion 172 along the axle centerline axis 26. The housing shell 164 includes a first end wall 174 defined at the front side portion 170 and a second end wall 176 defined at the rear side portion 172. The first end wall 174 includes a substantially heart-shaped cross-sectional shape 178. The outer surface 168 of the housing shell 164 includes a plurality of arcuate surfaces extending between the first end wall 174 and the second end wall 176 such that a heart-shaped cross-sectional shape 178 extends between the first end wall 174 and the second end wall 176. A first shaft opening 180 extends through the first end wall 174 and is sized and shaped to receive the first axle shaft 32 therethrough.

[0049] The second end wall 176 includes a mounting shoulder extending around the perimeter of the second end wall 176 and including a planar front surface. A plurality of holes are defined along the front surface for receiving corresponding fasteners therein to couple the cover 166 to the housing shell 164.

[0050] The cover 166 is coupled to the second end wall 176 and includes a second axle opening 182 extending through an outer surface of the cover 166. The second axle opening 182 is sized and shaped to receive the second axle shaft 38 therethrough.

[0051] The cover 166 includes a cover body and a mounting flange extending outwardly from the cover body. The mounting flange includes an outer surface having a cross-sectional shape that substantially matches the cross-sectional shape of the periphery of the second end wall 176. The mounting flange includes a plurality of openings extending around the periphery of the mounting flange, the plurality of openings being sized and shaped to receive fasteners therethrough to couple the cover 166 to the housing shell 164. The cover 166 is adapted to be coupled to the housing shell 164 to enclose the drive unit 22 within the gearbox chamber 162. The first axle shaft 32 is disposed in the first spindle 138 coupled to the housing shell 164. The second axle shaft 38 is disposed in the second spindle 140 coupled to the cover 166. One or more tie rods are coupled to the housing shell 164 for supporting the drive unit 22 from the frame rail system 14.

[0052] refer to Figure 10-18 , in the exemplary embodiment, three mutually perpendicular axes X, Y and Z extend through the axle assembly 10 and are used to define a three-dimensional Cartesian coordinate system relative to the axle assembly 10. Specifically, the Z axis is oriented to extend substantially parallel to the axle centerline axis 26, the X axis is oriented to extend substantially perpendicular to the Z axis and substantially parallel to the longitudinal axis 59, and the Y axis is oriented to extend substantially perpendicular to the X and Y axes. In the illustrated embodiment, the gear arrangement of the drive unit 22 includes a family unit that includes a gear orientation that allows drive to be applied to each wheel 30 while packaging the two motors 46 in the same orientation direction with one motor behind the other motor along the longitudinal axis 59. The basic (primary) gear form is in a "W" configuration relative to the XY plane (such as Fig.18 ) wherein the output shafts 90, 116 have the same coincident axis but are in opposite directions relative to the axle centerline axis 26. The motors 34, 40 are not opposed but have been rotated (translated) to impart a parallel translational arrangement in a transverse direction on the vehicle with one motor behind the other along the longitudinal axis 59.

[0053] In one embodiment, the input reduction gear pair provided by the motor has large diameter gears that will not allow the shaft to pass through. This feature necessitates the need to configure the independent wheel drive unit system 22 with an offset axle shaft 64. Fig.18 , the configuration is arranged in two "V" shapes relative to the XY plane to form a "W" shape. One of the "V" shapes has a longitudinal arm configuration along the Z axis, and the other of the "V" shapes has an opposite arm configuration along the Z axis. When arranged together, the "W" shape includes side-by-side (aligned) inputs (motors with the same orientation) and opposite outputs. The outputs are connected in opposite directions to connect the drive shaft to the wheel end. The configuration shape allows the two motor axle configuration to be packaged into the narrow space between the chassis rails while maintaining independent wheel drive and multi-speed gear reduction capabilities. By utilizing the accompanying wheel-end planetary gear reducer, the configuration also exploits the adaptability of axle ratios and vehicle product types.

[0054] refer to Figure 10-16 In the illustrated embodiment, the first axle shaft 32 is oriented along the axle centerline axis 26 and in a first direction 200 defined along the axle centerline axis 26 ( Fig.10 The second axle shaft 38 is oriented coaxially with the first axle shaft 32 along the axle centerline axis 26 and extends outwardly from the drive unit housing 20 in a second direction 202 defined along the axle centerline axis 26 opposite to the first direction 200.

[0055] The first drive unit assembly 80 is coupled to the first axle shaft 32 to drive the first wheel-end assembly 34 coupled to the first axle shaft 32. The second drive unit assembly 82 is coupled to the second axle shaft 38 to drive the second wheel-end assembly 40 coupled to the second axle shaft 38. The first motor 56 and the second motor 58 are oriented in the same direction relative to the axle centerline axis 26. In addition, each rotor shaft 50 of the first motor 56 and the second motor 58 is oriented parallel to the axle centerline axis 26. The first motor 56 is spaced apart from the second motor 58 by a distance 204 defined along the X-axis so that the axle centerline axis 26 is positioned between the rotor centerline axis 51 of the first motor 56 and the rotor centerline axis 51 of the second motor 58. For example, in one embodiment, the first motor 56 and the second motor 58 are oriented along a horizontal plane (such as Fig.15 ), wherein the first motor 56 is spaced apart from the second motor 58 along the longitudinal axis 59 so that the axle centerline axis 26 is positioned between the rotor centerline axis 51 of the first motor 56 and the rotor centerline axis 51 of the second motor 58. In other embodiments, the first and second motors 56, 58 may be oriented and spaced apart vertically along the Y axis so that the axle centerline axis 26 is positioned between the rotor centerline axes 51 of the first and second motors 56, 58, or the first and second motors 56, 58 may be oriented along any axis perpendicular to the axle centerline axis 26 so that the rotor centerline axes 51 of the first and second motors 56, 58 are oriented in the same plane. In addition, each rotor shaft 50 of the first motor 56 and the second motor 58 is spaced apart from the axle centerline axis 26 by the same radial distance 206.

[0056] In the illustrated embodiment, the first gear assembly 60 and the second gear assembly 62 are in a mirror-symmetrical relationship about the Y axis. The first gear assembly 60 extends along a first direction 200 , and the second gear assembly 62 extends along an opposite second direction 202 .

[0057] The first output shaft 90 and the second output shaft 116 are oriented along the axle centerline axis 26. The first output shaft 90 is coupled to the proximal end 86 of the first axle shaft 32 and is oriented coaxially with the first axle shaft 32 along the axle centerline axis 26. The second output shaft 116 is coupled to the proximal end 112 of the second axle shaft 38 and is oriented coaxially with the second axle shaft 38 along the axle centerline axis 26. The first output shaft 90 extends in a first direction 200 along the axle centerline axis 26 and the second output shaft 116 extends in an opposite second direction 202 along the axle centerline axis 26.

[0058] The first output shaft 90 is positioned along the axle centerline axis 26 such that the first output shaft 90 is positioned between the first and second electric machines 56, 58 relative to the X-axis. The second output shaft 116 is positioned along the axle centerline axis 26 such that the second output shaft 116 is spaced apart from the first and second electric machines 56, 58 by a distance 208 measured along the axle centerline axis 26.

[0059] The first offset gear reduction assembly 88 is offset relative to the second offset gear reduction assembly 114 such that the axle centerline axis 26 is positioned between the first offset gear reduction assembly 88 and the second offset gear reduction assembly 114. For example, the first idler shaft 96 is spaced apart from the second idler shaft 122 by a distance 210 ( Fig.15 2 (shown in FIG. 2 ) such that the axle centerline axis 26 extends between the first idler shaft 96 and the second idler shaft 122. The axle centerline axis 26 is positioned between the first and second idler shafts 96, 122 along the X-axis. The first idler shaft 96 is oriented parallel to the second idler shaft 122, and each of the first idler shaft 96 and the second idler shaft 122 is oriented parallel to the axle centerline axis 26. Additionally, the first idler shaft 96 and the second idler shaft 122 are spaced apart from the axle centerline axis 26 by the same radial distance 212.

[0060] The first drive wheel 102 is positioned adjacent to the second drive wheel 128 relative to the Z-axis. Each drive wheel 102, 128 has the same diameter such that a portion of an outer surface of the first drive wheel 102 overlaps an outer surface of the second drive wheel 128. The first idler shaft 96 extends from the first drive wheel 102 in a first direction 200, and the second idler shaft 122 extends from the second drive wheel 128 in an opposite second direction 202.

[0061] The first idler shaft 96 is spaced apart from the first electric machine 56 by a first distance 214 measured along the Y-axis such that the axle centerline axis 26 is positioned between the first idler shaft 96 and the first electric machine 56. Similarly, the second idler shaft 122 is spaced apart from the second electric machine 58 by a second distance 216 measured along the Y-axis such that the axle centerline axis 26 is positioned between the second idler shaft 122 and the second electric machine 58. In the illustrated embodiment, the first distance 214 is substantially equal to the second distance 216.

[0062] In one embodiment, an electric motor with a rotor shaft will drive the offset gear reducer. The output of the offset gear reducer will input power to a shaft with several bearings, an optional synchronizer / dog clutch, and two gears, which are paired with two gears on the output shaft of the transmission. The synchronizer or dog clutch will select two speed ratios, which will transmit power to the output shaft through two gear pairs in the transmission. The output shaft of the transmission will be coupled to the input of the sun gear of the hub planetary gear drive. In the hub planetary gear drive, the ring gear will remain fixed, and the planetary gear carrier will output power to the wheel like the planetary gear carrier in a conventional hub drive. Two electric motors, two two-speed transmission units, and two planetary gear hub drives are required on one axle. The housing integrates the electric motor and the transmission compactly, provides cooling for heat dissipation, and transmits vehicle loads to suspension components. Startup performance and speed performance are achieved by utilizing two medium-speed motors with moderate performance, and startup performance and speed performance are given by combining two speed reducer configurations.

[0063] The present invention may be used with a single axle system for box-sized applications and / or a dual axle system for heavy products.

[0064] The axle architecture configuration of the electric axle assembly 10 allows a two motor electric axle to be packaged within the chassis rails of a standard truck with a standard suspension. The dual motors provide enough power for the system to start with the smaller motor.

[0065] In one embodiment, the present invention provides an electric drive axle for a low-floor or ultra-low-floor (pedal-free) vehicle. The vehicle is typically a high occupancy vehicle or a heavy vehicle with electric (full battery or hybrid) propulsion. The present invention will allow for compact packaging of two two-speed transmission units, two electric motors and two hub reduction gears for a rail frame vehicle. Having a two-speed gear in the transmission unit will allow for improved vehicle performance, such as top speed and motor efficiency. In addition, integrating the electric motor on the side of the transmission unit (i.e., parallel and adjacent) helps to compactly package the system. Using a set of parallel shaft gears for speed reduction allows for offset packaging of the motor. The two-speed transmission unit will be integrated into the axle housing. Therefore, the electric drive axle includes two motors, two two-speed transmission units, two hub reduction gears and an external axle housing, wherein the motors are used to provide power to drive each wheel.

[0066] The present invention has been described in an illustrative manner, and it should be understood that the terms used are intended to have the nature of descriptive words rather than restrictive words. In view of the above teachings, many modifications and variations of the present invention are possible, and the present invention may be practiced in a manner different from the specifically described manner.

Claims

1. A vehicle axle assembly, comprising: Drive unit housing; a first motor located in the drive unit housing and having a first drive shaft gear extending in a first direction; a first axle shaft coupled to the drive unit housing at a proximal end of the first axle shaft, the first axle shaft extending from the drive unit housing in a first direction along an axle centerline axis; a first wheel-end assembly coupled to a distal end of the first axle shaft; a first output assembly coupled to a proximal end of the first axle shaft and positioned within the drive unit housing, the first output assembly comprising a first output gear and a second output gear; a first offset gear reduction assembly located in the drive unit housing and including a first drive wheel gear-engaged with a first shaft of the first motor, a first idler shaft extending from the first drive wheel in the first direction, a first idler gear rotatably coupled to the first idler shaft and meshed with a first output gear of the first output assembly, a second idler gear rotatably coupled to the first idler shaft and meshed with a second output gear of the first output assembly, and a first shift mechanism coupled to the first idler shaft; a second motor located in the drive unit housing and having a second drive shaft gear extending in the first direction; a second axle shaft coupled to the drive unit housing at a proximal end of the second axle shaft, the second axle shaft extending from the drive unit housing along the axle centerline axis in a second direction opposite the first direction; a second wheel-end assembly coupled to a distal end of the second axle shaft; a second output assembly coupled to a proximal end of the second axle shaft and located in the drive unit housing coaxially with the first output assembly along the axle centerline axis, the second output assembly including a third output gear and a fourth output gear; as well as a second offset gear reduction assembly, the second offset gear reduction assembly being located in the drive unit housing and comprising a second drive wheel gear-engaged with the second shaft of the second motor, a second idler shaft extending from the second drive wheel along the second direction, a third idler gear rotatably coupled to the second idler shaft and meshed with the third output gear of the second output assembly, a fourth idler gear rotatably coupled to the second idler shaft and meshed with the fourth output gear of the second output assembly, and a second shift mechanism coupled to the second idler shaft, wherein the first shift mechanism is operable to selectively engage one of the first idler gear or the second idler gear with the first idler shaft to transfer torque from the first idler shaft to one of the first output gear or the second output gear through the selected first idler gear or the second idler gear, Wherein, the second shift mechanism is operable to selectively engage one of the third idler gear or the fourth idler gear with the second idler shaft to transfer torque from the second idler shaft to one of the third output gear or the fourth output gear through the selected third idler gear or the fourth idler gear.

2. The axle assembly of claim 1, wherein: The first drive wheel and the second drive wheel are positioned such that a portion of the first drive wheel and a portion of the second drive wheel are adjacent along the axle centerline axis and overlap when viewed along the axle centerline axis, The first output assembly, the first offset gear reduction assembly and the first offset gear reduction assembly are located on a first side of the first drive wheel, The second output assembly, the second offset gear reduction assembly and the second offset gear reduction assembly are located on a second side of the second drive wheel, the second side being opposite to the first side, a second axis is perpendicular to each of the first axis and the axle centerline axis, and In a plane defined by the first axis and the second axis, the axle centerline axis is (i) located between the rotation axis of the first motor and the rotation axis of the first drive wheel along the second axis, and between the rotation axis of the second motor and the rotation axis of the second drive wheel along the second axis, and (ii) located between the rotation axis of the first motor and the rotation axis of the second motor along the first axis, and between the rotation axis of the first drive wheel and the rotation axis of the second drive wheel along the first axis, so that the axle centerline axis, the first motor, the second motor, the first drive wheel and the second drive wheel are arranged in a W shape in the plane defined by the first axis and the second axis.

3. The axle assembly according to claim 1, wherein: The first drive wheel and the second drive wheel are positioned such that a portion of the first drive wheel and a portion of the second drive wheel are adjacent along the axle centerline axis and overlap when viewed along the axle centerline axis.

4. The axle assembly according to claim 1, wherein: The first output assembly, the first offset gear reduction assembly and the first offset gear reduction assembly are located on a first side of the first drive wheel, and The second output assembly, the second offset gear reduction assembly and the second offset gear reduction assembly are located on a second side of the second driving wheel, and the second side is opposite to the first side.

5. The axle assembly according to claim 1, wherein: The first electric machine is spaced apart from the second electric machine along a first axis that is perpendicular to the axle centerline axis.

6. The axle assembly according to claim 5, wherein: a second axis is perpendicular to each of the first axis and the axle centerline axis, and Wherein, in a plane defined by the first axis and the second axis, the axle centerline axis (i) is located between the rotation axis of the first motor and the rotation axis of the first drive wheel along the second axis, and between the rotation axis of the second motor and the rotation axis of the second drive wheel along the second axis, and (ii) is located between the rotation axis of the first motor and the rotation axis of the second motor along the first axis, and between the rotation axis of the first drive wheel and the rotation axis of the second drive wheel along the first axis, so that the axle centerline axis, the first motor, the second motor, the first drive wheel and the second drive wheel are arranged in a W shape in the plane defined by the first axis and the second axis.

7. The axle assembly of claim 1, wherein: The first motor, the second motor, and the second output assembly are coplanar with each other.

8. The axle assembly of claim 1, wherein: The first idler shaft extends in the first direction along a first idler shaft centerline axis, and the second idler shaft extends in a second direction opposite to the first direction along a second idler shaft centerline axis, and Wherein, the axle centerline axis, the first idler centerline axis and the second idler centerline axis are not coplanar with each other.

9. The axle assembly of claim 1, wherein: The first motor and the second motor are oriented in the same direction.

10. The axle assembly of claim 1, wherein: Each of the first and second electric machines includes a rotor shaft and an electric motor for rotating the rotor shaft, each rotor shaft being oriented parallel to the axle centerline axis.

11. The axle assembly according to claim 10, wherein: Each rotor shaft is spaced a same radial distance from the axle centerline axis.

12. The axle assembly of claim 1, wherein: The axle centerline axis is positioned between the first idler shaft and the second idler shaft.

13. The axle assembly of claim 12, wherein: The first idler shaft is spaced apart from the first electric machine such that the axle centerline axis is positioned between the first idler shaft and the first electric machine.

14. The axle assembly of claim 13, wherein: The second idler shaft is spaced apart from the second electric machine such that the axle centerline axis is positioned between the second idler shaft and the second electric machine.

15. The axle assembly of claim 14, wherein: The first idler shaft and the second idler shaft are spaced a same radial distance from the axle centerline axis.

16. The axle assembly of claim 1, wherein: The first output assembly includes a first output shaft coupled to the first axle shaft and oriented coaxially with the first axle shaft along the axle centerline axis.

17. The axle assembly of claim 16, wherein: The second output assembly includes a second output shaft coupled to the second axle shaft and oriented coaxially with the second axle shaft along the axle centerline axis.

18. The axle assembly of claim 17, wherein: The first output shaft is positioned along the axle centerline axis such that the first output shaft is positioned between the first electric machine and the second electric machine.

19. The axle assembly of claim 18, wherein: The second output shaft is positioned along the axle centerline axis such that the second output shaft is spaced apart from the first and second electric machines by a distance measured along the axle centerline axis.

20. The axle assembly of claim 1, wherein: The drive unit housing includes a plurality of walls including an inner surface defining a chamber, and wherein each of the first motor, the first output assembly, the first output assembly, the second motor, the second output assembly, and the second output assembly is completely located within the chamber of the drive unit housing.

21. An axle assembly comprising: Drive unit housing; a first motor located in the drive unit housing and having a first drive shaft gear extending in a first direction; a first axle shaft coupled to the drive unit housing at a proximal end of the first axle shaft, the first axle shaft extending from the drive unit housing in a first direction along an axle centerline axis; a first wheel-end assembly coupled to a distal end of the first axle shaft; a first output assembly coupled to a proximal end of the first axle shaft and positioned within the drive unit housing, the first output assembly comprising a first output gear and a second output gear; a first offset gear reduction assembly located in the drive unit housing and comprising a first drive wheel geared with the first shaft of the first motor, a first idler shaft extending from the first drive wheel in the first direction, a first idler gear rotatably coupled to the first idler shaft and meshed with the first output gear of the first output assembly, a second idler gear rotatably coupled to the first idler shaft and meshed with the second output gear of the first output assembly; a second motor located in the drive unit housing and having a second drive shaft gear extending in the first direction; a second axle shaft coupled to the drive unit housing at a proximal end of the second axle shaft, the second axle shaft extending from the drive unit housing along the axle centerline axis in a second direction opposite the first direction; a second wheel-end assembly coupled to a distal end of the second axle shaft; a second output assembly coupled to a proximal end of the second axle shaft and located in the drive unit housing coaxially with the first output assembly along the axle centerline axis, the second output assembly including a third output gear and a fourth output gear; a second offset gear reduction assembly located in the drive unit housing and including a second drive wheel gear-engaged with the second shaft of the second motor, a second idler shaft extending from the second drive wheel in the second direction, a third idler gear rotatably coupled to the second idler shaft and meshed with the third output gear of the second output assembly, a fourth idler gear rotatably coupled to the second idler shaft and meshed with the fourth output gear of the second output assembly; as well as A shift mechanism, which is operable to selectively (i) engage the first idler gear with the first idler shaft and the second idler gear with the second idler shaft, or (ii) engage the second idler gear with the first idler shaft and the third idler gear with the second idler shaft to transfer torque from the first idler shaft to one of the first output gear or the second output gear through the selected first idler gear or the second idler gear, and transfer torque from the second idler shaft to one of the third output gear or the fourth output gear through the selected third idler gear or the fourth idler gear.

22. The axle assembly of claim 21, wherein: The first drive wheel and the second drive wheel are positioned such that a portion of the first drive wheel and a portion of the second drive wheel are adjacent along the axle centerline axis and overlap when viewed along the axle centerline axis, The first output assembly, the first offset gear reduction assembly and the first offset gear reduction assembly are located on a first side of the first drive wheel, The second output assembly, the second offset gear reduction assembly and the second offset gear reduction assembly are located on a second side of the second drive wheel, the second side being opposite to the first side, a second axis is perpendicular to each of the first axis and the axle centerline axis, and In a plane defined by the first axis and the second axis, the axle centerline axis is (i) located between the rotation axis of the first motor and the rotation axis of the first drive wheel along the second axis, and between the rotation axis of the second motor and the rotation axis of the second drive wheel along the second axis, and (ii) located between the rotation axis of the first motor and the rotation axis of the second motor along the first axis, and between the rotation axis of the first drive wheel and the rotation axis of the second drive wheel along the first axis, so that the axle centerline axis, the first motor, the second motor, the first drive wheel and the second drive wheel are arranged in a W shape in the plane defined by the first axis and the second axis.

23. The axle assembly of claim 1, wherein: The first drive wheel and the second drive wheel are positioned such that a portion of the first drive wheel and a portion of the second drive wheel are adjacent along the axle centerline axis and overlap when viewed along the axle centerline axis.

24. The axle assembly of claim 21, wherein: The first output assembly, the first offset gear reduction assembly and the first offset gear reduction assembly are located on a first side of the first drive wheel, and The second output assembly, the second offset gear reduction assembly and the second offset gear reduction assembly are located on a second side of the second driving wheel, and the second side is opposite to the first side.

25. The axle assembly of claim 21, wherein: The first electric machine is spaced apart from the second electric machine along a first axis that is perpendicular to the axle centerline axis.

26. The axle assembly of claim 25, wherein: The second axis is perpendicular to each of the first axis and the axle centerline axis, and Wherein, in a plane defined by the first axis and the second axis, the axle centerline axis (i) is located between the rotation axis of the first motor and the rotation axis of the first drive wheel along the second axis, and between the rotation axis of the second motor and the rotation axis of the second drive wheel along the second axis, and (ii) is located between the rotation axis of the first motor and the rotation axis of the second motor along the first axis, and between the rotation axis of the first drive wheel and the rotation axis of the second drive wheel along the first axis, so that the axle centerline axis, the first motor, the second motor, the first drive wheel and the second drive wheel are arranged in a W shape in the plane defined by the first axis and the second axis.

27. The axle assembly of claim 21, wherein: The first motor, the second motor, and the second output assembly are coplanar with each other.

28. The axle assembly of claim 21, wherein: The first idler shaft extends in the first direction along a first idler shaft centerline axis, and the second idler shaft extends in a second direction opposite to the first direction along a second idler shaft centerline axis, and Wherein, the axle centerline axis, the first idler centerline axis and the second idler centerline axis are not coplanar with each other.

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