All-wheel drive system for electric vehicle

Abstract

An all-wheel drive system for a vehicle having a longitudinal axis includes an electric motor. The electric motor has an output shaft extending along a first axis, and the first axis is substantially perpendicular to the longitudinal axis. The all-wheel drive system includes a first drive system including a first clutch and a first differential system configured to be coupled to a second drive system and to transfer torque to a first wheel of the vehicle in a first state of the first clutch. The second drive system includes a second drive shaft and a second differential system. A second drive shaft is coupled to the output shaft and configured to transfer torque to a second differential system. The second differential system is configured to transfer torque to a second wheel of the vehicle, and the second differential system extends along a second axis substantially parallel to the first axis.

Description

[0001] TECHNICAL FIELD The field relates generally to all-wheel drive systems for electric vehicles, and more particularly to all-wheel drive systems for electric vehicles having a transversely mounted electric motor. Background Art

[0002] Typically, a vehicle includes at least one drive system that transmits torque from a propulsion system to one or more wheels of the vehicle. In the example of an electric vehicle, the drive system transfers torque from an electric motor to one or more wheels. Typically, the drive system employs one or more gears that are arranged to transfer torque from the electric motor to the one or more wheels. In some instances, the arrangement of the gears may result in additional torque being required from the electric motor to drive the one or more wheels. The additional torque may reduce the range associated with the electric vehicle, or may require the use of additional or larger capacity batteries to power the electric motor.

[0003] Therefore, it is desirable to provide an all-wheel drive system for an electric vehicle having improved efficiency, thereby increasing the driving range of the electric vehicle or enabling a reduction in the capacity of a battery associated with the electric vehicle. In addition, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. Summary of the invention

[0004] According to various embodiments, an all-wheel drive system for a vehicle having a longitudinal axis is provided. The all-wheel drive system includes an electric motor configured to generate torque. The electric motor has an output shaft extending along a first axis, and the first axis is substantially perpendicular to the longitudinal axis. The all-wheel drive system includes a first drive system, the first drive system includes a first clutch and a first differential system, the first differential system is configured to be coupled to a second drive system and transmit torque to a first wheel of the vehicle in a first state of the first clutch. The all-wheel drive system includes a second drive system, the second drive system includes a second drive shaft and a second differential system. The second drive shaft is coupled to the output shaft and is configured to transmit torque to the second differential system. The second differential system is configured to transmit torque to a second wheel of the vehicle, and the second differential system extends along a second axis substantially parallel to the first axis.

[0005] The second drive shaft is coupled to the output shaft via a planetary gear set. The planetary gear set includes a sun gear coupled to the output shaft, a plurality of planetary gears coupled to a planet carrier, and a ring gear, and the planet carrier is coupled to the second transfer shaft. The ring gear is coupled to the ring carrier and a brake, and the brake is configured to lock the ring gear relative to a motor housing associated with the motor. The ring carrier includes a bevel gear, the bevel gear is configured to be coupled to a first transfer pinion of a transmission shaft, and the transmission shaft is configured to couple the second drive system to the first drive system. The second drive shaft extends along a first axis. The second drive shaft extends along a third axis parallel to the first axis and the second axis. The output shaft is coupled to the second drive shaft by a gear arranged substantially perpendicular to the third axis. The second drive shaft is configured to be coupled to the first drive system via a second clutch. The second drive shaft defines a gear, and the gear is coupled to the ring gear of the second differential system. The first differential system includes a first differential ring gear and a differential housing, the differential housing including a plurality of spider gears configured to drive a pair of side gears, each side gear being coupled to a corresponding first axle, and a first clutch coupled to the first differential ring gear and configured to connect the first differential ring gear with the differential housing in a first state. In a second state, the first clutch is configured to disconnect the first differential ring gear from the differential housing.

[0006] A vehicle having a longitudinal axis is also provided. The vehicle includes an electric motor configured to generate torque. The electric motor has an output shaft extending along a first axis, and the first axis is substantially perpendicular to the longitudinal axis. The vehicle includes a rear drive system, and the rear drive system includes a rear drive shaft and a rear differential system. The rear drive shaft is coupled to the output shaft through a planetary gear set and is configured to transfer torque to the rear differential system. The rear differential system is configured to transfer torque to the rear wheels of the vehicle, and the rear differential system extends along a second axis substantially parallel to the first axis. The vehicle includes a front drive system, the front drive system includes a front clutch and a front differential system, and the front differential system is configured to be coupled to the rear drive system and transfer torque to the front wheels of the vehicle in a first state of the front clutch.

[0007] The planetary gear set includes a sun gear coupled to an output shaft, a plurality of planetary gears coupled to a planetary carrier, and a ring gear, and the planetary carrier is coupled to a rear transfer shaft. The ring gear is coupled to the ring carrier and a brake, and the brake is configured to lock the ring gear relative to a motor housing associated with the electric motor. The ring carrier includes a bevel gear, and the bevel gear is configured to be coupled to a first transfer pinion of a transmission shaft, and the transmission shaft is configured to couple the rear drive system to the front drive system. The rear drive shaft defines a gear, and the gear is coupled to the ring gear of the rear differential system. The front differential system includes a front differential ring gear and a differential housing, the differential housing includes a plurality of star gears configured to drive a pair of side gears, each side gear is coupled to a corresponding front wheel shaft, and a front clutch is coupled to the front differential ring gear and is configured to connect the front differential ring gear with the differential housing in a first state. In a second state, the front clutch is configured to disconnect the front differential ring gear from the differential housing. The rear drive shaft extends along a first axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Exemplary embodiments will be described below with reference to the following drawings, wherein like numerals represent like elements, and wherein:

[0009] Figure 1 is a schematic diagram of an electric vehicle including an all-wheel drive system according to various embodiments;

[0010] Figure 2 According to various embodiments Figure 1 A cross-sectional view of an exemplary second or rear drive system of an all-wheel drive system;

[0011] Figure 3 According to various embodiments Figure 1 A cross-sectional view of another exemplary second or rear drive system of an all-wheel drive system of FIG. 1 ; and

[0012] Figure 4 According to various embodiments Figure 1 A cross-sectional view of yet another exemplary second or rear drive system of an all-wheel drive system. DETAILED DESCRIPTION

[0013] The following detailed description is merely exemplary in nature and is not intended to limit application and use. In addition, there is no intention to be bound by any express or implied theory presented in the preceding introduction, brief overview, or detailed description below. As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic and / or processor device, alone or in any combination, including but not limited to: application specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or groups) and memories that execute one or more software or firmware programs, combinational logic circuits, and / or other suitable components that provide the described functions.

[0014] Embodiments of the present disclosure may be described herein in terms of functional and / or logical block components and various processing steps. It should be understood that such block components may be implemented by any number of hardware, software, and / or firmware components configured to perform a specified function. For example, embodiments of the present disclosure may employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc., which may perform various functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and the systems described herein are merely exemplary embodiments of the present disclosure.

[0015] For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, machine learning models, radar, lidar, image analysis, and other functional aspects of the system (and the various operating components of the system) may not be described in detail herein. In addition, the connecting lines shown in the various figures included herein are intended to represent example functional relationships and / or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of the present disclosure.

[0016] As used herein, the term "axial" refers to a direction that is generally parallel to or coincident with the axis of rotation, axis of symmetry, or centerline of one or more components. For example, in a cylinder or disk having a centerline and generally circular ends or opposing faces, the "axial" direction may refer to a direction that extends generally parallel to the centerline between the opposing ends or opposing faces. In some instances, the term "axial" may be used for components that are not cylindrical (or otherwise radially symmetrical). For example, the "axial" direction of a rectangular housing containing a rotating axis may be considered to be a direction that is generally parallel to or coincident with the axis of rotation of the axis. In addition, the term "radial" as used herein may refer to the direction or relationship of a component relative to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane perpendicular to the centerline or axis of a cylinder or disk. In some instances, components may be considered to be "radially" aligned even if one or two of the components may not be cylindrical (or otherwise radially symmetrical). Furthermore, the terms "axial" and "radial" (and any derivatives) may include directional relationships that are not precisely aligned (e.g., skewed) with the true axial and radial dimensions, as long as the relationship is primarily in the corresponding nominal axial or radial direction. As used herein, the term "approximately" means within 10% to account for manufacturing tolerances. Additionally, the term "substantially" means within 10% to account for manufacturing tolerances.

[0017] refer to Figure 1 According to various embodiments, an all-wheel drive system, generally shown at 100, is associated with a vehicle 10. In one example, the vehicle 10 is an electric vehicle, however, it should be understood that the following disclosure may be applicable to other electric motor drive devices. Figure 1 As depicted in , the vehicle 10 generally includes a chassis 12, a body 14, a first or front wheel 16, and a second or rear wheel 18. The body 14 is disposed on the chassis 12 and substantially surrounds the components of the vehicle 10. The body 14 and the chassis 12 may together form a frame. The wheels 16-18 are each rotationally coupled to the chassis 12 near a corresponding corner of the body 14. In various embodiments, the vehicle 10 is an autonomous vehicle or a semi-autonomous vehicle. It will be appreciated that the all-wheel drive system 100 may be implemented in other non-autonomous systems and is not limited to the present embodiment. In the illustrated embodiment, the vehicle 10 is depicted as an electric passenger car, but it will be appreciated that any other vehicle may also be used, including a truck, a sport utility vehicle (SUV), a recreational vehicle (RV), etc.

[0018] As shown, the vehicle 10 generally includes a propulsion system 20, an all-wheel drive system 100, a steering system 24, a braking system 26, a sensor system 28, an actuator system 30, and at least one controller 34. In this example, the propulsion system 20 is mounted near the rear wheels 18 so as to be located near the rear of the vehicle 10. In other embodiments, the propulsion system 20 may be mounted near the front wheels 16 so as to be located near the front of the vehicle 10.

[0019] Braking system 26 is configured to provide braking torque to wheels 16 and 18. In various embodiments, braking system 26 may include friction brakes, brake-by-wire brakes, a regenerative braking system such as an electric motor, and / or other suitable braking systems.

[0020] The steering system 24 affects the position of the wheels 16 and / or 18. The steering system 24 may include a steering wheel, however, in some embodiments contemplated within the scope of the present disclosure, the steering system 24 may not include a steering wheel.

[0021] The sensor system 28 includes one or more sensing devices 40a-40n that sense observable conditions of the external environment and / or the internal environment of the vehicle 10. In various embodiments, the sensing devices 40a-40n include, but are not limited to, radar (e.g., long-range, medium-range, short-range), lidar, global positioning system, optical camera (e.g., forward, 360 degrees, rearward, side, stereo, etc.), thermal (e.g., infrared) camera, ultrasonic sensor, odometer sensor (e.g., encoder) and / or other sensors that can be used in conjunction with the systems and methods according to the present subject matter. The sensor system 28 communicates with the controller 34 via a communication medium.

[0022] The actuator system 30 includes one or more actuator devices 42a-42n that control one or more vehicle features such as, but not limited to, the propulsion system 20, the steering system 24, and the braking system 26. In various embodiments, the vehicle 10 may also include Figure 1 Interior and / or exterior vehicle features not shown, such as various doors, trunks, and cabin features such as air, music, lighting, touch screen display components, active safety seats or haptic seats, etc.

[0023] The controller 34 includes at least one processor 44 and a computer readable storage device or medium 46. The processor 44 can be any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC) (e.g., a custom ASIC that implements a neural network), a field programmable gate array (FPGA), an auxiliary processor of several processors associated with the controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), any combination thereof, or any device generally used to execute instructions. For example, the computer readable storage device or medium 46 can include volatile and non-volatile storage in read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the processor 44 is powered off. The computer readable storage device or medium 46 may be implemented using any of a number of known memory devices, such as a PROM (programmable read-only memory), an EPROM (electrical PROM), an EEPROM (electrically erasable PROM), flash memory, or any other electrical, magnetic, optical, or combination memory device capable of storing data, some of which represents executable instructions used by the controller 34 in controlling the vehicle 10. The controller 34 may receive input via a human-machine interface (such as a touch screen display component, buttons, etc.) to switch the all-wheel drive system 100 between all-wheel drive and two-wheel drive. Alternatively, the all-wheel drive system 100 may be manually switched between all-wheel drive and two-wheel drive via operator input.

[0024] Additional references Figure 2 In various embodiments, the propulsion system 20 can include an electric machine, such as an electric motor or a traction motor. In this example, the propulsion system 20 is an electric motor 48 that receives power from a power source 50 associated with the vehicle 10. In one example, the power source 50 includes one or more batteries and an inverter. The inverter converts DC power from the battery to AC power to drive the electric motor 48. The electric motor 48 can have any suitable configuration for use with the vehicle 10. In short, the electric motor 48 includes a rotor 52, a stator 54, and an output shaft 56. In this example, the electric motor 48 is arranged relative to the motor axis A1 or is substantially symmetrical relative to the motor axis A1. As shown in FIG. Figure 1As shown in , the motor axis A1 is substantially transverse or perpendicular to the longitudinal axis L of the vehicle 10. The stator 54 surrounds the rotor 52 and includes two or more conductors that generate a magnetic field to rotate the rotor 52. The rotor 52 includes one or more magnets or conductors that also generate a magnetic field. The output shaft 56 is coupled to the rotor 52 and rotates with the rotor 52. The output shaft 56 can be supported for rotation by one or more bearings 58. The electric motor 48 can be contained in a motor housing 60, and the output shaft 56 can extend outward from the motor housing 60. Typically, the bearing 58 is coupled to the motor housing 60 and is retained by the motor housing 60.

[0025] In one example, the all-wheel drive system 100 includes a first or front drive system 102 and a second or rear drive system 104. As will be discussed, when both the front drive system 102 and the rear drive system 104 work together to drive the wheels 16, 18, the all-wheel drive system 100 is in all-wheel drive. When the front drive system 102 is disconnected from the rear drive system 104, such that the rear drive system 104 drives only the wheel 18, the all-wheel drive system 100 is in two-wheel drive. Thus, the all-wheel drive system 100 can operate in both all-wheel drive and two-wheel drive. It should be noted that in all-wheel drive, the wheels 16, 18 are driven in the same direction.

[0026] refer to Figure 1 , a front drive system 102 is shown. In one example, the front drive system 102 includes a first or front differential gear set 110, a first or front clutch 112, a pair of first or front axles or a first front axle 114 and a second front axle 116. The front differential gear set 110 is any suitable differential gear set. In one example, the front differential gear set 110 includes a front differential ring gear 122, a pair of side gears 124, 126, and a plurality of star gears 128. The front differential ring gear 122 is a bevel gear having a plurality of bevel gear teeth defined around an outer circumference of the front differential ring gear 122 along a first face 122a of the front differential ring gear 122. The front differential ring gear 122 is coupled to, engaged with, or driven by a transfer pinion 118 of a propeller shaft 120. Typically, the side gears 124 , 126 and spider gear 128 are mounted for rotation within a differential housing 129 , and the front clutch 112 connects or disconnects the front differential ring gear 122 to the differential housing 129 .

[0027] In this regard, in the connected first state, the front differential ring gear 122 is connected to the differential case 129, and the front differential ring gear 122 is coupled to, engages with, or drives the spider gear 128. In the disconnected second state, the front differential ring gear 122 is disconnected from the differential case 129, and the spider gear 128 and the side gears 124, 126 are all able to rotate with the differential case 129, but the torque from the motor 48 is not transmitted to the differential case 129 to drive the front wheels 16. In other words, when the front differential ring gear 122 is in the disconnected second state and is disconnected from the differential case 129 by the front clutch 112, the front wheels 16 are able to rotate or "freewheel" while the rear wheels 18 are driven by the rear drive system 104 in two-wheel drive.

[0028] It should be noted that in other embodiments, the front clutch 112 can be configured differently. In one example, the front clutch 112 can disconnect one of the first front axle 114 or the second front axle 116 in the disconnected second state. For example, the front clutch 112 can disconnect the first front axle 114 from the first side gear 124, which allows the first side gear 124 to rotate freely. With the first side gear 124 disconnected from the first front axle 114, the first side gear 124 rotates at an equal and opposite speed to the second side gear 126, and the combination of the side gear speeds averages to zero, and allows the differential case 129 to stop rotating, thereby enabling the front wheels 16 to rotate while being driven by the rear drive system 104.

[0029] refer to Figure 1 , the front differential gear set 110 includes four star gears 128, which are spaced approximately 90 degrees apart and are coupled to rotate within a differential housing 129. Each star gear 128 is a bevel gear and includes a plurality of bevel gear teeth. Each star gear 128 is coupled to, engages with, or drives a side gear 124, 126. The side gears 124, 126 are each coupled to the differential housing 129. The side gears 124, 126 are each a bevel gear having a plurality of bevel gear teeth. The side gear 124 is coupled to the first front wheel shaft 114 to drive the first front wheel shaft 114, and thus drive one of the front wheels 16. The side gear 126 is coupled to the second front wheel shaft 116 to drive the second front wheel shaft 116, and thus drive the other of the front wheels 16.

[0030] The front clutch 112 is any suitable clutch capable of disconnecting or connecting the front differential ring gear 122 with the differential housing 129. In one example, the front clutch 112 is a plate clutch and includes at least a first plate 130, a second pressure plate 132, and an actuation system 134. Figure 1In an example of the embodiment of the present invention, the first plate 130 is coupled to the second face 122b of the front differential ring gear 122. The second face 122b is opposite the first face 122a. The pressure plate 132 can be moved by the actuation system 134 to contact the first plate 130 and move the front differential ring gear 122 to the first state of connection and engage the front differential ring gear 122 with the differential housing 129. In one example, the actuation system 134 includes a hydraulic actuator 136, a control valve 138, at least one biasing member or spring 140, and a hydraulic fluid source 142. The hydraulic actuator 136 is coupled to the pressure plate 132 and is fluidly coupled to the control valve 138 via a pipe, tube, hose, etc. The hydraulic actuator 136 extends and retracts in response to the hydraulic fluid (received from the control valve 138). Extension of the hydraulic actuator 136 moves the pressure plate 132 to connect the front differential ring gear 122 to the differential housing 129 in the connected first state. Retraction of the hydraulic actuator 136 disconnects the front differential ring gear 122 from the differential housing 129 in the disconnected second state. In this regard, the spring 140 biases the front differential ring gear 122 in the disconnected state. The spring 140 can be coupled between the front differential ring gear 122 and the differential housing 129 so that in the connected first state, the hydraulic actuator 136 overcomes the spring force to connect or engage the front differential ring gear 122 with the differential housing 129. The spring 140 can be a leaf spring or any suitable biasing member. It should be noted that although the front clutch 112 is described as including a plate clutch, the front clutch 112 can also be a band clutch, a dog clutch, a lockable overrunning clutch, etc. Additionally, it should be noted that while the actuation system 134 is described as including a hydraulic actuator, in other embodiments, the actuation system 134 may also include an electromechanical system including an electric motor, actuator bearings, and ball ramps, among other things.

[0031] The control valve 138 is fluidly coupled to the hydraulic actuator 136 and the source of hydraulic fluid source 142 via a pipe, tube, hose, etc. The control valve 138 is typically a two-way valve, however, any valve may be employed. The control valve 138 communicates with the controller 34, for example, via a communication bus, and responds to one or more control signals from the controller 34 to enable hydraulic fluid to flow to the hydraulic actuator 136 or to enable hydraulic fluid to flow from the hydraulic actuator 136 to the hydraulic fluid source 142. When hydraulic fluid from the hydraulic fluid source 142 flows to the hydraulic actuator 136, the hydraulic actuator 136 extends to move the front differential ring gear 122 to a first state of connection. When hydraulic fluid flows from the hydraulic actuator 136 to the hydraulic fluid source 142, the hydraulic actuator 136 retracts, and the spring 140 moves the front differential ring gear 122 to a second state of disconnection.

[0032] In one example, the hydraulic fluid source 142 is a fluid tank containing a predetermined amount of hydraulic fluid. The hydraulic fluid source 142 can be positioned anywhere on the vehicle 10, and the location shown is merely exemplary. The hydraulic fluid source 142 can also supply hydraulic fluid to other systems associated with the vehicle 10.

[0033] The first front axle 114 is coupled to one of the front wheels 16, and the second front axle 116 is coupled to the other of the front wheels 16. The first and second front axles 114, 116 may include any axle arrangement for transmitting torque from the side gears 124, 126 to the front wheels 16 and for receiving torque when the front wheels 16 are driven by the rear wheels 18 in two wheel drive.

[0034] The transfer pinion 118 is coupled to the propeller shaft 120 for rotation therewith. In one example, the transfer pinion 118 is a bevel gear including a plurality of bevel gear teeth that are coupled to, engage with, or drive a front differential ring gear 122. The transfer pinion 118 is driven by the propeller shaft 120. The propeller shaft 120 interconnects the rear drive system 104 with the front drive system 102. The propeller shaft 120 is any shaft capable of transmitting torque between the rear drive system 104 and the front drive system 102. The propeller shaft 120 includes the transfer pinion 118 at a first end and includes a transfer pinion 150 at a second end opposite the first end. In one example, the transfer pinion 150 includes a plurality of bevel gear teeth that are coupled to, engage with, or drive the rear drive system 104.

[0035] refer to Figure 2 , the rear drive system 104 includes a planetary gear set 160, a second or rear drive shaft 162, a second or rear differential system 164, a pair of second or rear axles or a first rear axle 166 and a second rear axle 168. The motor 48, the planetary gear set 160 and the rear drive shaft 162 are axisymmetrical about the axis A1. In one example, the planetary gear set 160 includes a sun gear 170, a plurality of planetary gears 172, a planet carrier 174, a ring gear 176 and a second or rear brake 178. The sun gear 170 includes a central hole that is coupled around the output shaft 56 of the motor 48 so that the sun gear 170 is driven by the output shaft 56. For example, the sun gear 170 is coupled to the output shaft 56 via swaging. The sun gear 170 is a helical gear having a plurality of helical gear teeth.

[0036] The planet gears 172 are coupled to, engaged with, or driven by the sun gear 170. The planet gears 172 are each coupled to, engaged with, or driven by a ring gear 176. In one example, the planetary gear set 160 includes four planet gears 172, however, the number of planet gears 172 may vary. The planet gears 172 are each spur gears having a plurality of spur gear teeth. Each planet gear 172 also defines a central hole and is coupled to a planet carrier 174 via the central hole.

[0037] The planet carrier 174 is coupled to each planet gear 172 and is also coupled to the rear drive shaft 162. In one example, the planet carrier 174 includes a carrier portion 180 and a carrier shaft 182. The carrier portion 180 includes a pair of spaced-apart annular flanges 184. The flanges 184 are axially interconnected by segments or bridges spaced apart around the perimeter of the flanges 184 to define a plurality of gear receiving openings 186. Each flange 184 defines a plurality of holes 188, wherein each hole 188 of each flange 184 is coaxially aligned with a corresponding one of the gear receiving openings 186. A corresponding one of the planet gears 172 is coupled to a corresponding one of the gear receiving openings 186 such that the hole 188 is coaxially aligned with the center hole of the corresponding planet gear 172. A pin 190 may be swaged into one of the holes 188 and extend into the center hole of the planet gear 172 to couple the corresponding planet gear 172 to the planet carrier 174.

[0038] The carrier shaft 182 extends axially from the carrier portion 180. The carrier shaft 182 is integrally formed with the carrier portion 180 at a first end 192 opposite the second end 194. A central bore extends through the carrier shaft 182 from the first end 192 to the second end 194. At the second end 194, the carrier shaft 182 includes a coupling flange 196. The coupling flange 196 extends axially from the second end 194 and is received within a counterbore 198 of the rear drive shaft 162 to couple the rear drive shaft 162 to the carrier shaft 182. In one example, the coupling flange 196 is coupled to the counterbore 198 of the rear drive shaft 162 via swaging, however, other techniques may be employed. Bearings 200, such as ball bearings, may be used to support the carrier shaft 182 and the rear drive shaft 162 for rotation.

[0039] The ring gear 176 is positioned around the planet gears 172. The ring gear 176 defines an inner bore 202, which includes a plurality of helical gear teeth. The ring gear 176 is coupled to, engaged with, or driven by the planet gears 172, and generally rotates in a direction opposite to the direction of rotation of the planet gears 172. In this example, the ring gear 176 also includes an annular bracket 204. The annular bracket 204 is substantially hollow and includes a first end 206 opposite to a second end 208. A bearing 209 (such as a ball bearing) can be used to support the annular bracket 204 for rotation. The first end 206 includes an annular coupling flange 210. The annular coupling flange 210 extends radially outward from the first end 206 and is coupled to the inner bore 202 of the ring gear 176 near the plurality of gear teeth. The annular coupling flange 210 is coupled to the ring gear 176 so that the annular bracket 204 rotates with the ring gear 176 at substantially the same speed as the ring gear 176. The second end 208 is coupled to the drive gear 212. In one example, the ratio of the pitch diameter of the ring gear 176 to the pitch diameter of the sun gear 170 is about 5 to about 2. The difference in gear ratios between the ring gear 176 and the sun gear 170 results in the rear differential system 164 receiving more torque than the front differential gear set 110. Regardless of the ratio of the ring gear 176 to the sun gear 170, the difference between the effective ratios of the ring gear 176 and the annular carrier 204 results in greater rear torque. The difference in effective ratios also enables the step size between the two-wheel drive and all-wheel drive ratios to be less than 2 to 1, such as about 1.7, which limits the inertial energy involved in switching between two-wheel drive and all-wheel drive, thereby improving the efficiency of the all-wheel drive system 100.

[0040] The drive gear 212 includes a central hole that is coupled around the outer circumference of the second end 208, for example, via swaging. The drive gear 212 is driven by the ring gear 176. The drive gear 212 is a bevel gear and includes a plurality of bevel gear teeth defined around the outer periphery of the drive gear. The drive gear 212 is coupled to, engages with, or drives the transfer pinion 150. Typically, the drive gear 212 and the transfer pinion 150 are arranged at approximately a 90 degree angle relative to each other, or include a right angle drive.

[0041] The rear brake 178 is coupled to or fixed to the inner hole 220 defined in the motor housing 60 to surround the ring gear 176. The rear brake 178 includes any suitable brake, and in one example is an electronic brake. In one example, the rear brake 178 communicates with the controller 34, for example, via a communication bus, and is activated in response to one or more control signals from the controller 34. When activated, the rear brake 178 is configured to apply torque to the ring gear 176 to inhibit the rotation of the ring gear 176. In other words, the rear brake 178 is configured to apply a braking force to inhibit the rotation of the ring gear 176, so that the ring gear 176 remains stationary and the torque is not transmitted to the drive shaft 120. It should be noted that the rear brake 178 may include a plate clutch, a band clutch, a dog clutch, etc.

[0042] The rear drive shaft 162 is coupled to the planet carrier 174 for rotation with the planet carrier 174. The rear drive shaft 162 includes a central bore and defines a counterbore 198 at a first end 230. A second end 232 is opposite the first end 230. The second end 232 includes a collar 234. The collar 234 is sized to receive a bearing 236 that supports the second end 232 of the rear drive shaft 162 for rotation. Between the first end 230 and the second end 232, the rear drive shaft 162 defines a gear 238. The gear 238 is integrally formed on the rear drive shaft 162 as a plurality of gear teeth. In this example, the plurality of gear teeth of the gear 238 are substantially spur gear teeth, but the plurality of gear teeth may also be helical. The gear 238 is coupled to, engaged with, or drives the rear differential system 164.

[0043] The rear differential system 164 transfers torque from the motor 48 to the rear wheels 18. In one example, the rear differential system 164 includes a rear differential ring gear 240, a pair of rear side gears 242, 244, and a plurality of rear star gears 246. The rear differential ring gear 240 is a helical gear having a plurality of helical gear teeth defined around an outer circumference 240a of the rear differential ring gear 240. The rear differential ring gear 240 is coupled to, engaged with, or driven by a gear 238 defined on the rear drive shaft 162. Typically, the rear side gears 242, 244 and the rear star gears 246 are mounted for rotation within a differential housing 248.

[0044] In one example, the rear differential system 164 includes four rear spider gears 246 that are spaced approximately 90 degrees apart and are coupled to rotate within a differential housing 248. Each rear spider gear 246 is a bevel gear and includes a plurality of bevel gear teeth. Each rear spider gear 246 is coupled to, engages with, or drives a rear side gear 242, 244. The rear side gears 242, 244 are each coupled to a differential housing 248. The rear side gears 242, 244 are each a bevel gear having a plurality of bevel gear teeth. The rear side gear 242 is coupled to the first rear wheel axle 166 to drive the first rear wheel axle 166, and thus drive one of the rear wheels 18. The rear side gear 244 is coupled to the second rear wheel axle 168 to drive the second rear wheel axle 168, and thus drive another of the rear wheels 18.

[0045] The first rear axle 166 is coupled to one of the rear wheels 18, and the second rear axle 168 is coupled to the other of the rear wheels 18. The first rear axle 166 and the second rear axle 168 may include any axle arrangement for transmitting torque from the rear side gears 242, 244 to the rear wheels 18. The first rear axle 166 and the second rear axle 168 each extend along an axis A2 that is substantially parallel to the axis A1 of the motor 48. By arranging the motor 48 along the axis A1 that is substantially parallel to the axis A2, the rear drive system 104 has improved efficiency because a right angle gearing is not required to transmit torque to the rear axles 166, 168.

[0046] The first rear axle 166 and the second rear axle 168 can be supported for rotation by bearings 250, 252. The bearings 250, 252 can include ball bearings and can be coupled to an outer housing 254 associated with the rear drive system 104. The outer housing 254 can be coupled to the motor housing 60 and cooperate with the motor housing 60 to substantially enclose the motor 48 and a portion of the rear drive system 104. Typically, the axis A2 of the first rear axle 166 and the second rear axle 168 is spaced apart from the axis A1 of the motor 48 by a distance D, which reduces the packaging associated with the rear drive system 104. In one example, the distance D is about 125 millimeters (mm) to about 135 millimeters (mm).

[0047] refer to Figure 1 and Figure 2, when the vehicle 10 is assembled and the front drive system 102 is coupled to the rear drive system 104 via the drive shaft 120, in two-wheel drive, the controller 34 outputs one or more control signals to the rear brake 178 to activate and lock the position of the ring gear 176 relative to the motor housing 60. The controller 34 can output one or more control signals to the control valve 138 to discharge the hydraulic fluid from the hydraulic actuator 136 to the hydraulic fluid source 142. In the absence of hydraulic fluid acting on the hydraulic actuator 136, the front clutch 112 is in the second disconnected state due to the spring force of the spring 140. The motor 48 receives power from the power source 50 to rotate, for example, based on one or more control signals from the controller 34. As the rotor 52 rotates, the output shaft 56 rotates. The rotation of the output shaft 56 drives the sun gear 170. The rotation of the sun gear 170 drives the planetary gears 172, thereby driving the carrier shaft 182, which is coupled to the carrier portion 180 holding the planetary gears 172. The rotation of the carrier shaft 182 in turn drives the rear drive shaft 162. The rotation of the gear 238 formed on the rear drive shaft 162 drives the rear differential ring gear 240. The rotation of the rear differential ring gear 240 in turn drives the rear star gear 246. The rotation of the rear star gear 246 drives the rear side gears 242, 244. The rotation of the rear side gears 242, 244 drives the first rear wheel axle 166 and the second rear wheel axle 168, respectively, to drive the rear wheels 18 to propel the vehicle 10. With the rear brake 178 activated, the ring gear 176 does not rotate, and no torque is transmitted to the propeller shaft 120. With the front clutch 112 in the second disconnected state, the front wheels 16 are able to rotate when the vehicle 10 is propelled by the rear wheels 18.

[0048] In all-wheel drive, the rear brake 178 is deactivated to enable the ring gear 176 to rotate relative to the motor housing 60. The controller 34 outputs one or more control signals to the control valve 138 to supply hydraulic fluid to the hydraulic actuator 136 to move the front clutch 112 to the first connection state. In the first connection state, the front differential ring gear 122 is engaged with the differential housing 129 to drive the planetary gear 128. The motor 48 receives power from the power source 50 to rotate, for example, based on one or more control signals from the controller 34. As the rotor 52 rotates, the output shaft 56 rotates. The rotation of the output shaft 56 drives the sun gear 170. The rotation of the sun gear 170 drives the planetary gears 172, thereby driving the carrier shaft 182, which is coupled to the carrier portion 180 holding the planetary gears 172. The rotation of the carrier shaft 182 in turn drives the rear drive shaft 162. The rotation of the gear 238 formed on the rear drive shaft 162 drives the rear differential ring gear 240. The rotation of the rear differential ring gear 240 in turn drives the rear star gear 246. The rotation of the rear star gear 246 drives the rear side gears 242, 244. The rotation of the rear side gears 242, 244 drives the first rear axle 166 and the second rear axle 168 respectively to drive the rear wheels 18 to propel the vehicle 10.

[0049] The rotation of the planetary gears 172 also drives the ring gear 176. The rotation of the ring gear 176 rotates the annular carrier 204, which in turn drives the drive gear 212. The rotation of the drive gear 212 drives the transfer pinion 150. The rotation of the transfer pinion 150 in turn rotates the propeller shaft 120 and the transfer pinion 118. The rotation of the transfer pinion 118 drives the front differential ring gear 122. The rotation of the front differential ring gear 122 drives the star gear 128, and the rotation of the star gear 128 drives the side gears 124, 126. The rotation of the side gears 124, 126 drives the first front wheel axle 114 and the second front wheel axle 116, respectively, to drive the front wheels 16 to propel the vehicle 10.

[0050] It should be noted that in other embodiments, the rear drive system 104 and the propeller shaft 120 may be configured differently to transfer torque to the front drive system 102. For example, referring to Figure 3 , showing the Figure 1 The vehicle 10 is used together with a propeller shaft 302 and a rear drive system 304 to transfer torque to Figure 1 The front drive system 102. Since the propeller shaft 302 and the rear drive system 304 include the reference Figure 1 and Figure 2 The components of the propeller shaft 120 and the rear drive system 104 discussed are the same or similar components, and thus the same reference numerals will be used to identify the same or similar components.

[0051] In one example, the transfer pinion 118 ( Figure 1 ) is coupled to the transmission shaft 302 to rotate with the transmission shaft 302. The transfer pinion 118 is driven by the transmission shaft 302. The transmission shaft 302 interconnects the rear drive system 304 with the front drive system 102. The transmission shaft 302 is any shaft capable of transmitting torque between the rear drive system 304 and the front drive system 102. The transmission shaft 302 includes the transfer pinion 118 at a first end, and includes a transfer shaft 306 and a rear clutch 308 at a second end opposite to the first end. In one example, the transfer shaft 306 includes a first shaft end 310 opposite to a second shaft end 312. The first shaft end 310 is coupled to the rear clutch 308, and the second shaft end 312 defines a bevel gear 314. The bevel gear 314 has a plurality of bevel gear teeth, which is coupled to the rear drive system 304, engaged with the rear drive system 304, or driven by the rear drive system 304.

[0052] The rear clutch 308 couples or connects the transfer shaft 306 with the drive shaft 302. In one example, the rear clutch 308 can be configured to include an intermediate shaft 316 that is received within the second end of the drive shaft 302 and coupled to the second end of the drive shaft 302, for example, via swaging. The use of the intermediate shaft 316 makes maintenance and assembly of the drive shaft 302 easier. The rear clutch 308 is coupled to the intermediate shaft 316 and the transfer shaft 306. The rear clutch 308 is connected to the hydraulic fluid source 142 ( Figure 1 ) fluidly connected, and a control valve 307 (similar to the control valve 138) can also be used to control the flow of hydraulic fluid to the rear clutch 308. Generally, the control valve 307 is a two-way valve that is fluidly coupled to the hydraulic fluid source 142 and the rear clutch 308. The control valve 307 communicates with the controller 34 via a communication bus and responds to one or more control signals from the controller 34 to enable hydraulic fluid to flow from the hydraulic fluid source 142 to the rear clutch 308 or to enable hydraulic fluid to flow from the rear clutch 308 to the hydraulic fluid source 142. In one example, the rear clutch 308 is not limited to a hydraulic dog clutch that responds to hydraulic fluid from the hydraulic fluid source 142 to connect the transfer shaft 306 with the intermediate shaft 316 in a first state. In the first state, the transfer shaft 306 is connected to the intermediate shaft 316 via the rear clutch 308, so that the transfer shaft 306 rotates together with the intermediate shaft 316 or drives the intermediate shaft 316 to transmit torque to the front drive system 102 ( Figure 1 ). When the rear clutch 308 is disengaged in the second state, allowing hydraulic fluid to flow from the rear clutch 308 to the hydraulic fluid source 142, the transfer shaft 306 rotates independently of the intermediate shaft 316. In the second state, the rear clutch 308 inhibits torque from being transferred from the rear drive system 304 to the front drive system 102 ( Figure 1 ).

[0053] The rear drive system 304 includes a gear set 360, a rear drive shaft 362, a rear differential system 164, a first rear axle 166, and a second rear axle 168. It should be noted that Figure 1 and Figure 2 The motor 48 can be connected with Figure 3 The embodiment of the present invention can be used together, but the output shaft 56 of the motor 48 can be modified. In this regard, in Figure 3 In the example of, the motor 48 includes an output shaft 56'. The output shaft 56' includes a gear 350 that is integrally formed or defined on the output shaft 56'. The motor 48 is axisymmetrical about the axis A1, and the gear set 360 and the rear drive shaft 362 are axisymmetrical about the axis A3. The axis A3 is offset from the axes A1, A2 and is substantially parallel to the axes A1, A2. The axis A3 is substantially perpendicular to the longitudinal axis L of the vehicle 10. In one example, the gear set 360 includes a first gear 370 and a second gear 372. The first gear 370 includes a center hole that is coupled around the rear drive shaft 362 so that the first gear 370 is arranged substantially perpendicular to the axis A3. For example, the first gear 370 is coupled to the rear drive shaft 362 via swaging. The first gear 370 is a helical gear having a plurality of helical gear teeth defined around an outer periphery 370a of the first gear 370. The first gear 370 is coupled to, engaged with, or driven by the gear 350 of the output shaft 56 ′ such that the first gear 370 is driven by the output shaft 56 ′.

[0054] The second gear 372 includes a central hole coupled around the rear drive shaft 362. For example, the second gear 372 is coupled to the rear drive shaft 362 via swaging. The second gear 372 is a bevel gear having a plurality of bevel gear teeth defined around an outer periphery 372a of the second gear 372. The second gear 372 is coupled to, engages with, or drives the bevel gear 314, such that the second gear 372 drives the transfer shaft 306.

[0055] The rear drive shaft 362 is coupled to the first gear 370 and the second gear 372. In one example, the rear drive shaft 362 is a solid cylindrical shaft with a first shaft end 376 opposite to a second shaft end 378. The first gear 370 is coupled near the first shaft end 376, and the second gear 372 is coupled near the first shaft end 376 so as to be positioned directly adjacent to or in close proximity to the first gear 370. A bearing 377 (such as a ball bearing) is coupled at the first shaft end 376 and supports the rear drive shaft 362 for rotation. Gear 238 is integrally formed or defined between the second gear 372 and the second shaft end 378 and has a plurality of helical gear teeth. Gear 238 is coupled to, engaged with, or drives the rear differential system 164. The second shaft end 378 includes a groove portion 380. The groove portion 380 is sized to receive a bearing 382 that supports the second shaft end 378 of the rear drive shaft 362 for rotation. The second shaft end 378 may also be integrally formed with or define a gear 384 having a plurality of helical gear teeth. The plurality of gear teeth of the gear 384 may be coupled to or engaged with a parking gear 386.

[0056] The rear differential system 164 transfers torque from the motor 48 to the rear wheels 18. In one example, the rear differential system 164 includes a rear differential ring gear 240, a pair of rear side gears 242, 244, and a plurality of rear spider gears 246. The rear side gears 242, 244 and the rear spider gears 246 are mounted for rotation within a differential housing 248. Each rear spider gear 246 is coupled to, engages with, or drives a rear side gear 242, 244. The rear side gears 242 are coupled to the first rear wheel axle 166 to drive the first rear wheel axle 166, and thus drive one of the rear wheels 18. The rear side gears 244 are coupled to the second rear wheel axle 168 to drive the second rear wheel axle 168, and thus drive another of the rear wheels 18. The first rear axle 166 and the second rear axle 168 each extend along an axis A2 that is substantially parallel to the axis A1 of the motor 48. By arranging the motor 48 along the axis A1 that is substantially parallel to the axis A2, the rear drive system 304 has improved efficiency because a right-angle gearing is not required to transfer torque to the rear axles 166, 168.

[0057] refer to Figure 1 and Figure 3, when the vehicle 10 is assembled and the front drive system 102 is coupled to the rear drive system 304 via the propeller shaft 302, in two-wheel drive, the controller 34 can output one or more control signals to the control valve 138 to discharge the hydraulic fluid from the hydraulic actuator 136 to the hydraulic fluid source 142. In the absence of hydraulic fluid acting on the hydraulic actuator 136, the front clutch 112 is in the second disconnected state due to the spring force of the spring 140. The controller 34 can output one or more control signals to the control valve 307 to discharge the hydraulic fluid from the rear clutch 308 to the hydraulic fluid source 142 to move the rear clutch 308 to the second state and disconnect the propeller shaft 302 from the rear drive shaft 362.

[0058] The motor 48 receives power from the power source 50 to rotate, for example, based on one or more control signals from the controller 34. As the rotor 52 rotates, the output shaft 56' rotates. The rotation of the output shaft 56' drives the first gear 370. The rotation of the first gear 370 drives the rear drive shaft 362. The rotation of the rear drive shaft 362 drives the second gear 372 coupled to the transfer shaft 306. When the transfer shaft 306 is disconnected from the drive shaft 302 via the rear clutch 308, the transfer shaft 306 rotates without transmitting torque to the front drive system 102. The rotation of the rear drive shaft 362 also drives the gear 238. The rotation of the gear 238 drives the rear differential ring gear 240. The rotation of the rear differential ring gear 240 in turn drives the rear star gear 246. The rotation of the rear star gear 246 drives the rear side gears 242, 244. Rotation of the rear gears 242, 244 drives the first and second rear axles 166, 168, respectively, to drive the rear wheels 18 to propel the vehicle 10. With the front clutch 112 in the second disconnected state, the front wheels 16 can rotate when the vehicle 10 is propelled by the rear wheels 18.

[0059] In all-wheel drive, the controller 34 outputs one or more control signals to the control valve 307 to supply hydraulic fluid to the rear clutch 308 to move the rear clutch 308 to connect the transfer shaft 306 to the intermediate shaft 316 in the first state. The controller 34 outputs one or more control signals to the control valve 138 to supply hydraulic fluid to the hydraulic actuator 136 to move the front clutch 112 to the first connection state. In the first connection state, the front differential ring gear 122 is engaged with the differential case 129 to drive the star gear 128. The motor 48 receives power from the power source 50 to rotate, for example, based on one or more control signals from the controller 34. As the rotor 52 rotates, the output shaft 56' rotates. The rotation of the output shaft 56' drives the first gear 370. The rotation of the first gear 370 drives the rear drive shaft 362. The rotation of the rear drive shaft 362 drives the gear 238. The rotation of the gear 238 drives the rear differential ring gear 240. The rotation of the rear differential ring gear 240 in turn drives the rear star gear 246. The rotation of the rear star gear 246 drives the rear side gears 242, 244. The rotation of the rear side gears 242, 244 drives the first rear axle 166 and the second rear axle 168 respectively to drive the rear wheels 18 to propel the vehicle 10.

[0060] The rotation of the rear drive shaft 362 also drives the second gear 372 coupled to the transfer shaft 306. With the transfer shaft 306 connected to the propeller shaft 302 via the rear clutch 308, the transfer shaft 306 drives the propeller shaft 302 to transfer torque to the front drive system 102. The rotation of the propeller shaft 302 drives the transfer pinion 118. The rotation of the transfer pinion 118 drives the front differential ring gear 122. The rotation of the front differential ring gear 122 drives the star gear 128, and the rotation of the star gear 128 drives the side gears 124, 126. The rotation of the side gears 124, 126 drives the first front wheel axle 114 and the second front wheel axle 116, respectively, to drive the front wheels 16 to propel the vehicle 10.

[0061] It should be noted that in other embodiments, the rear drive system 104 and the propeller shaft 120 may be configured differently to transfer torque to the front drive system 102. For example, referring to Figure 4 , showing the Figure 1 The vehicle 10 is used together with a propeller shaft 402 and a rear drive system 404 to transfer torque to Figure 1 The front drive system 102. Since the propeller shaft 402 and the rear drive system 404 include the reference Figure 1 and Figure 2 The components of the propeller shaft 120 and rear drive system 104 discussed above and Figure 3 The propeller shaft 302 and the components of the rear drive system 304 are the same or similar components, so the same reference numerals will be used to represent the same or similar components.

[0062] In one example, the transfer pinion 118 ( Figure 1 ) is coupled to the transmission shaft 402 to rotate with the transmission shaft 402. The transfer pinion 118 is driven by the transmission shaft 402. The transmission shaft 402 interconnects the rear drive system 404 with the front drive system 102. The transmission shaft 402 is any shaft capable of transmitting torque between the rear drive system 404 and the front drive system 102. The transmission shaft 402 includes the transfer pinion 118 at a first end, and includes a transfer shaft 306 and a rear clutch 408 at a second end opposite to the first end. The first shaft end 310 is coupled to the rear clutch 408, and the second shaft end 312 defines a bevel gear 314. The bevel gear 314 has a plurality of bevel gear teeth, which is coupled to the rear drive system 404, engaged with the rear drive system 404, or driven by the rear drive system 304.

[0063] The rear clutch 408 couples or connects the transfer shaft 306 with the drive shaft 402. In one example, the rear clutch 408 can be configured to include an intermediate shaft 416 that is received within the second end of the drive shaft 402 and coupled to the second end of the drive shaft 302, for example, via swaging. The use of the intermediate shaft 416 makes maintenance and assembly of the drive shaft 402 easier. The rear clutch 408 is coupled to the intermediate shaft 416 and the transfer shaft 306. The rear clutch 408 is connected to the hydraulic fluid source 142 ( Figure 1 ) fluidly connected, and the control valve 407 can also be used to control the flow of hydraulic fluid to the rear clutch 408. Typically, the control valve 407 is a two-way valve that is fluidly coupled to the hydraulic fluid source 142 and the rear clutch 408. The control valve 407 communicates with the controller 34 via a communication bus and responds to one or more control signals from the controller 34 to enable hydraulic fluid to flow from the hydraulic fluid source 142 to the rear clutch 408 or to enable hydraulic fluid to flow from the rear clutch 408 to the hydraulic fluid source 142. In one example, the rear clutch 408 is not limited to a hydraulic plate-type clutch that responds to hydraulic fluid from the hydraulic fluid source 142 to connect the transfer shaft 306 with the intermediate shaft 416 in a first state. In the first state, the transfer shaft 306 is connected to the intermediate shaft 416 via the rear clutch 408, so that the transfer shaft 306 rotates together with the intermediate shaft 416 or drives the intermediate shaft 316 to transmit torque to the front drive system 102 ( Figure 1 ). When the rear clutch 408 is disengaged in the second state, allowing hydraulic fluid to flow from the rear clutch 408 to the hydraulic fluid source 142, the transfer shaft 306 rotates independently of the intermediate shaft 416. In the second state, the rear clutch 408 inhibits torque from being transferred from the rear drive system 404 to the front drive system 102 ( Figure 1 ).

[0064] The rear drive system 404 includes a gear set 460, a rear drive shaft 462, a rear differential system 164, a first rear axle 166, and a second rear axle 168. It should be noted that Figure 1 and Figure 2 The motor 48 can be connected with Figure 4 , but the output shaft 56 of the motor 48 can be modified. In this regard, the motor 48 includes an output shaft 56'. The motor 48 is axisymmetrical about the axis A1, and the gear set 460 and the rear drive shaft 462 are axisymmetrical about the axis A3. The axis A3 is offset from the axes A1, A2 and is substantially parallel to the axes A1, A2. The axis A3 is substantially perpendicular to the longitudinal axis L of the vehicle 10. In one example, the gear set 460 includes a first gear 370. The first gear 370 includes a central hole coupled around the rear drive shaft 462. For example, the first gear 370 is coupled to the rear drive shaft 462 via swaging. The first gear 370 is coupled to the gear 350 of the output shaft 56', engaged with the gear 350 of the output shaft 56', or driven by the gear 350 of the output shaft 56', so that the first gear 370 is driven by the output shaft 56'.

[0065] The rear drive shaft 462 is coupled to and driven by the first gear 370. In one example, the rear drive shaft 462 is a solid cylindrical shaft having a first shaft end 476 opposite a second shaft end 478. The first gear 370 is coupled near the first shaft end 476. A bearing 477, such as a ball bearing, is coupled at the first shaft end 476 and supports the rear drive shaft 462 for rotation. The first shaft end 476 may also include a counterbore 480 that receives a pin 482 to assist in coupling the bearing 477 to the first shaft end 476. The gear 238 is integrally formed or defined between the first gear 370 and the second shaft end 478. The gear 238 is coupled to, engages with, or drives the rear differential system 164. The second shaft end 478 includes a recessed portion 485 and a second counterbore 485. The recessed portion 484 is sized to receive a bearing 486 that supports the second shaft end 478 of the rear drive shaft 462 for rotation. The second shaft end 478 may also be integrally formed with or define a gear 384 having a plurality of helical gear teeth. The plurality of gear teeth of the gear 384 are coupled to or engaged with the parking gear 386. The second counterbore 485 receives a portion of the second rear drive shaft 488.

[0066] When the rear clutch 408 is in the first state, the second rear drive shaft 488 transfers torque from the rear drive shaft 462 to the transfer shaft 306. The second rear drive shaft 488 includes a first end 490 opposite to a second end 492. The first end 490 is received in the second counterbore 485 to couple the second rear drive shaft 488 to rotate with the rear drive shaft 462. The second end 492 is coupled to a sleeve 494 that supports the rotation of the second rear drive shaft 488 for rotation. A sleeve 496 is positioned between the first end 490 and the second end 492 and has an inner hole around the second rear drive shaft 488. The sleeve 496 is coupled to the second rear drive shaft 488 to rotate with the second rear drive shaft 488 at substantially the same speed as the second rear drive shaft 488. The sleeve 496 integrally forms or defines a gear 498 around the outer periphery of the sleeve 496 with a gear 498 near the first end of the sleeve 496, the gear including a plurality of helical gear teeth. Gear 498 is coupled to, engages with, or drives bevel gear 314 of transfer shaft 306 to transfer torque to front drive system 102 ( Figure 1 ).

[0067] The rear differential system 164 transfers torque from the motor 48 to the rear wheels 18. In one example, the rear differential system 164 includes a rear differential ring gear 240, a pair of rear side gears 242, 244, and a plurality of rear spider gears 246. The rear side gears 242, 244 and the rear spider gears 246 are mounted for rotation within a differential housing 248. Each rear spider gear 246 is coupled to, engages with, or drives a rear side gear 242, 244. The rear side gears 242 are coupled to the first rear wheel axle 166 to drive the first rear wheel axle 166, and thus drive one of the rear wheels 18. The rear side gears 244 are coupled to the second rear wheel axle 168 to drive the second rear wheel axle 168, and thus drive another of the rear wheels 18. The first rear axle 166 and the second rear axle 168 each extend along an axis A2 that is substantially parallel to the axis A1 of the motor 48. By arranging the motor 48 along the axis A1 that is substantially parallel to the axis A2, the rear drive system 304 has improved efficiency because a right-angle gearing is not required to transfer torque to the rear axles 166, 168.

[0068] refer to Figure 1 and Figure 4, when the vehicle 10 is assembled and the front drive system 102 is coupled to the rear drive system 404 via the propeller shaft 402, in two-wheel drive, the controller 34 can output one or more control signals to the control valve 138 to discharge the hydraulic fluid from the hydraulic actuator 136 to the hydraulic fluid source 142. In the absence of hydraulic fluid acting on the hydraulic actuator 136, the front clutch 112 is in the second disconnected state due to the spring force of the spring 140. The controller 34 can output one or more control signals to the control valve 407 to discharge the hydraulic fluid from the rear clutch 408 to the hydraulic fluid source 142 to move the rear clutch 408 to the second state and disconnect the propeller shaft 402 from the rear drive shaft 462.

[0069] The motor 48 receives power from the power source 50 to rotate, for example, based on one or more control signals from the controller 34. As the rotor 52 rotates, the output shaft 56' rotates. The rotation of the output shaft 56' drives the first gear 370. The rotation of the first gear 370 drives the rear drive shaft 462. The rotation of the rear drive shaft 462 drives the gear 238 and the second rear drive shaft 488. With the transfer shaft 306 disconnected from the transmission shaft 302 via the rear clutch 408, the rotation of the second rear drive shaft 488 drives the transfer shaft 306 without transmitting torque to the front drive system 102. The rotation of the gear 238 drives the rear differential ring gear 240. The rotation of the rear differential ring gear 240 in turn drives the rear star gear 246. The rotation of the rear star gear 246 drives the rear side gears 242, 244. The rotation of the rear side gears 242, 244 drives the first rear wheel shaft 166 and the second rear wheel shaft 168, respectively, to drive the rear wheels 18 to propel the vehicle 10. With the front clutch 112 in the second disengaged state, the front wheels 16 are able to rotate when the vehicle 10 is propelled by the rear wheels 18 .

[0070] In all-wheel drive, the controller 34 outputs one or more control signals to the control valve 407 to supply hydraulic fluid to the rear clutch 408 to move the rear clutch 408 to connect the transfer shaft 306 to the intermediate shaft 416. The controller 34 outputs one or more control signals to the control valve 138 to supply hydraulic fluid to the hydraulic actuator 136 to move the front clutch 112 to the first connection state. In the first connection state, the front differential ring gear 122 is engaged with the differential case 129 to drive the star gear 128. The motor 48 receives power from the power source 50 to rotate, for example, based on one or more control signals from the controller 34. As the rotor 52 rotates, the output shaft 56' rotates. The rotation of the output shaft 56' drives the first gear 370. The rotation of the first gear 370 drives the rear drive shaft 462. The rotation of the rear drive shaft 462 drives the gear 238 and the second rear drive shaft 488. The rotation of the gear 238 drives the rear differential ring gear 240. The rotation of the rear differential ring gear 240 in turn drives the rear star gear 246. The rotation of the rear star gear 246 drives the rear side gears 242, 244. The rotation of the rear side gears 242, 244 drives the first rear axle 166 and the second rear axle 168 respectively to drive the rear wheels 18 to propel the vehicle 10.

[0071] The rotation of the rear drive shaft 362 also drives the second rear drive shaft 488, which is coupled to the transfer shaft 306 via the gear 498 of the sleeve 496. With the transfer shaft 306 connected to the propeller shaft 402 via the rear clutch 408, the transfer shaft 306 drives the propeller shaft 402 to transfer torque to the front drive system 102. The rotation of the propeller shaft 402 drives the transfer pinion 118. The rotation of the transfer pinion 118 drives the front differential ring gear 122. The rotation of the front differential ring gear 122 drives the star gear 128, and the rotation of the star gear 128 drives the side gears 124, 126. The rotation of the side gears 124, 126 drives the first front wheel axle 114 and the second front wheel axle 116, respectively, to drive the front wheels 16 to propel the vehicle 10.

[0072] Thus, the front drive system 102 and the rear drive system 104, 304, 404 enable the vehicle 10 to operate in both two-wheel drive and all-wheel drive. In two-wheel drive, the rear drive system 104, 304, 404 has improved efficiency because the motor 48 and the rear differential system 164 are coupled together along substantially parallel axes A1, A2, A3, respectively. In other words, since the motor 48, the rear drive shaft 162, 362, 462 and the rear differential system 164 are arranged along substantially parallel axes, right-angle drive is not required in two-wheel drive, which improves the efficiency of torque transmission from the motor 48 to the rear drive shaft 162, 362, 462 and the rear differential system 164. Improved torque transmission can extend the driving range of the vehicle 10, or can enable the capacity of the battery associated with the power source 50 to be reduced. Typically, right-angle drive is about 2% to 3% less efficient than a gear arrangement on parallel shafts. Furthermore, the arrangement of the rear drive shaft 162 and rear differential system 164 provides improved packaging as the distance D between the axes A1, A2 is reduced. Furthermore, the use of the front clutch 112 enables the front wheels 16 to rotate freely while the propeller shaft 120, 302, 402 is inhibited from rotating. It should also be noted that the bevel gears described herein as having bevel gear teeth may also have spiral cutting teeth or hypoid cutting teeth if desired.

[0073] The combination of the front drive system 102 and the rear drive system 104, 304, 404 also allows the vehicle 10 to operate in all-wheel drive at a first ratio between the output shaft 56 of the motor 48 and the driven wheels 18 and 16, and in two-wheel drive at a second ratio between the output shaft 56 of the motor 48 and the driven wheels 18. The first ratio is about 1.7 times the second ratio, or the step size between the two ratios is about 1.7. In this example, the ratio of the ring gear 176 of the planetary gear set 160 to the sun gear 170 is about 2 to about 5, and in one example is about 4.3. The ratio of the rear differential system 164 to the sun gear 170 is about 2.3. The final drive ratio in all-wheel drive is about 22.1, and the final drive ratio in two-wheel drive is about 12.2. The lower final drive ratio for two-wheel drive is advantageous because it enables the rear wheels 18 to be driven more efficiently by the motor 48, which also improves the mileage of the vehicle 10.

[0074] Thus, the all-wheel drive system 100 provides the vehicle 10 with all-wheel drive having sufficient torque to reach the traction limit of all wheels 16, 18 for traveling at lower vehicle speeds, and efficient parallel axis two-wheel drive having sufficient torque to reach the traction limit of those two wheels for traveling at higher vehicle speeds. In addition, the minimal amount of gearing provided by the front drive system 102 and the rear drive system 104 improves the efficiency of the front drive system 102 and the rear drive system 104, which increases the mileage of the vehicle 10. In addition, a single switching operation using the rear brake 178 and the front clutch 112 affects the change from all-wheel drive to two-wheel drive. If the front clutch 112 is a lockable overrunning clutch, the switching operation is easy and user-friendly to perform during forward driving by "lifting" the overrunning clutch to switch from the first ratio of all-wheel drive to the second ratio of two-wheel drive, and "dropping" the overrunning clutch to switch from the second ratio of two-wheel drive to the first ratio of all-wheel drive, with the front clutch 112 in its second disconnected state.

[0075] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that there are a large number of variations. It should also be understood that the exemplary embodiment or multiple exemplary embodiments are merely examples and are not intended to limit the scope, applicability or configuration of the present disclosure in any way. On the contrary, the foregoing detailed description will provide a convenient roadmap for implementing the exemplary embodiment or multiple exemplary embodiments for those skilled in the art. It should be understood that various changes may be made to the functions and arrangements of the elements without departing from the scope of the present disclosure as set forth in the attached claims and their legal equivalents.

Claims

1. An all-wheel drive system for a vehicle having a longitudinal axis, comprising: an electric motor configured to generate torque, the electric motor having an output shaft extending along a first axis, the first axis being substantially perpendicular to the longitudinal axis; a first drive system comprising a first clutch and a first differential system, the first differential system being configured to be coupled to a second drive system and to transfer the torque to a first wheel of the vehicle in a first state of the first clutch; as well as The second drive system includes a second drive shaft and a second differential system, wherein the second drive shaft is coupled to the output shaft and is configured to transfer the torque to the second differential system, and the second differential system is configured to transfer the torque to a second wheel of the vehicle, and the second differential system extends along a second axis substantially parallel to the first axis.

2. The all-wheel drive system according to claim 1, wherein: The second drive shaft is coupled to the output shaft via a planetary gear set, and the second drive shaft extends along the first axis.

3. The all-wheel drive system according to claim 2, wherein: The planetary gear set includes a sun gear coupled to the output shaft, a plurality of planet gears coupled to a planet carrier, and a ring gear, and the planet carrier is coupled to the second transfer shaft.

4. The all-wheel drive system according to claim 3, wherein: The ring gear is coupled to an annular carrier and a brake, and the brake is configured to lock the ring gear relative to a motor housing associated with the electric motor.

5. The all-wheel drive system according to claim 4, wherein: The annular carrier includes a bevel gear configured to be coupled to a first transfer pinion of a drive shaft, and the drive shaft is configured to couple the second drive system to the first drive system.

6. The all-wheel drive system according to claim 1, wherein: The second drive shaft extends along a third axis that is parallel to the first axis and the second axis, and the output shaft is coupled to the second drive shaft via a gear that is arranged substantially perpendicular to the third axis.

7. The all-wheel drive system according to claim 6, wherein: The second drive shaft is configured to be coupled to the first drive system via a second clutch.

8. The all-wheel drive system according to claim 1, wherein: The second drive shaft defines a gear that is coupled to a ring gear of the second differential system.

9. The all-wheel drive system according to claim 1, wherein: The first differential system includes a first differential ring gear and a differential housing, the differential housing including a plurality of star gears configured to drive a pair of side gears, each side gear being coupled to a corresponding first axle, the first clutch being coupled to the first differential ring gear and configured to connect the first differential ring gear with the differential housing in the first state, and in a second state, the first clutch being configured to disconnect the first differential ring gear from the differential housing.

10. A vehicle comprising: The all-wheel drive system of claim 1, wherein the first drive system is a front drive system and the first wheels are front wheels of the vehicle, and the second drive system is a rear drive system and the second wheels are rear wheels of the vehicle.

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