Patent Description:
An axle assembly having an electric motor module is disclosed in <CIT>. <CIT> discloses, in the opinion of the examining division of the European Patent Office, an axle assembly falling within the wording of the pre-characterizing portion of claim <NUM>.

An axle assembly is provided as set out in claim <NUM>.

The axle assembly <NUM> may be provided with a motor vehicle like a car, truck, bus, farm equipment, mining equipment, military transport or weaponry vehicle, or cargo loading equipment for land, air, or marine vessels. One or more axle assemblies may be provided with the vehicle.

The axle assembly <NUM> may provide torque to one or more traction wheel assemblies that may include a tire mounted on a wheel. In at least one configuration such as is shown in <FIG> and <FIG>, the axle assembly <NUM> comprises a housing assembly <NUM>, an electric motor module <NUM>, and a countershaft transmission module <NUM>. The axle assembly <NUM> may also comprise a rotor shaft <NUM>, a drive pinion <NUM>, a countershaft transmission module <NUM>, a drop gear set <NUM>, a differential assembly <NUM>, and at least one wheel end assembly <NUM>.

Referring to <FIG>, the housing assembly <NUM> may facilitate mounting of the axle assembly <NUM> to the vehicle. In addition, the housing assembly <NUM> may receive various components of the axle assembly <NUM>. For example, the housing assembly <NUM> may receive and support the electric motor module <NUM>, the rotor shaft <NUM>, the drive pinion <NUM>, the countershaft transmission module <NUM>, the drop gear set <NUM>, the differential assembly <NUM>, or combinations thereof. In at least one configuration, the housing assembly <NUM> comprises an axle housing <NUM> that comprises a drop gear housing portion <NUM>, a center portion <NUM>, and one or more arm portions <NUM>. The axle housing <NUM> may be made of any suitable material, such as a metal or metal alloy (e.g., steel, ductile iron).

Referring primarily to <FIG>, the drop gear housing portion <NUM> may be disposed at an end of the axle housing <NUM>. The drop gear housing portion <NUM> may protrude from the center portion <NUM> and may be integrally formed with the center portion <NUM> such that the drop gear housing portion <NUM> and the center portion <NUM> are a single one-piece component. Such a configuration may eliminate a connection interface between the drop gear housing portion <NUM> and the center portion <NUM>, such as a bolted joint, and may eliminate seals and leak paths between the drop gear housing portion <NUM> and the center portion <NUM>. In at least one configuration, the drop gear housing portion <NUM> comprises a first mounting flange <NUM>, and may comprise a connecting wall <NUM>, a plurality of ribs <NUM>, a ramp portion <NUM>, a first divider wall <NUM>, and a second divider wall <NUM>.

Referring primarily to <FIG>, <FIG>, <FIG> and <FIG>, the first mounting flange <NUM> facilitates mounting of the electric motor module <NUM> to the axle housing <NUM>. The first mounting flange <NUM> may be disposed at an end of the drop gear housing portion <NUM> that may be disposed opposite the center portion <NUM>. In at least one configuration, the first mounting flange <NUM> may extend in an outward direction that may extend away from a first axis <NUM> about which a rotor of the electric motor module <NUM> may rotate. The first mounting flange <NUM> may include a plurality of holes that may receive fasteners such as bolts that may couple the electric motor module <NUM> to the first mounting flange <NUM>. As is best shown in <FIG>, the first mounting flange <NUM> may define a first opening <NUM>.

Referring primarily to <FIG> and <FIG>, the connecting wall <NUM> may extend from the first mounting flange <NUM> to the center portion <NUM>. For example, the connecting wall <NUM> may extend from the first mounting flange <NUM> to an end wall of the center portion <NUM> as will be discussed in more detail below. In at least one configuration, the connecting wall <NUM> may extend substantially parallel to the first axis <NUM>, a countershaft axis <NUM>, or both. These axes will be discussed in more detail below. As is best shown in <FIG>, the connecting wall <NUM> may extend around a drop gear housing cavity <NUM> that may receive the drop gear set <NUM> as will be discussed in more detail below. The connecting wall <NUM> may be provided in various configurations. In at least one configuration such as is best shown in <FIG>, the connecting wall <NUM> may have a generally oval configuration that include a first arcuate portion <NUM>, a second arcuate portion <NUM>, a first lateral side <NUM>, and a second lateral side <NUM>.

The first arcuate portion <NUM> may extend along a curve or an arc from the first lateral side <NUM> to the second lateral side <NUM>. In at least one configuration, the first arcuate portion <NUM> may be radially disposed with respect to an axis, such as the first axis <NUM>.

The second arcuate portion <NUM> may be disposed opposite the first arcuate portion <NUM>. The second arcuate portion <NUM> may extend along a curve or an arc from the first lateral side <NUM> to the second lateral side <NUM>. In at least one configuration, the second arcuate portion <NUM> may be radially disposed with respect to an axis, such as the countershaft axis <NUM>.

The first lateral side <NUM> may extend from a first end of the first arcuate portion <NUM> to a first end of the second arcuate portion <NUM>. In at least one configuration, the first lateral side <NUM> may have a generally straight or linear configuration.

The second lateral side <NUM> may be disposed opposite the first lateral side <NUM>. The second lateral side <NUM> may extend from a second end of the first arcuate portion <NUM> to a second end of the second arcuate portion <NUM>. The second lateral side <NUM> may have a generally straight or linear configuration. In at least one configuration, the first lateral side <NUM> may be disposed parallel or substantially parallel to the second lateral side <NUM>.

Referring to <FIG> and <FIG>, a plurality of ribs <NUM> may be arranged around the drop gear housing portion <NUM>. The ribs <NUM> may help reinforce the housing assembly <NUM> to inhibit or reduce bending or flexing of the drop gear housing portion <NUM>, such as when the electric motor module <NUM> is mounted to the drop gear housing portion <NUM>. In at least one configuration, a rib <NUM> may be substantially flat and may extend in a generally linear or planar manner. Each rib <NUM> may extend from the first mounting flange <NUM> to an end wall of the center portion <NUM>. In addition, each rib <NUM> may extend outwardly from the connecting wall <NUM> or in a direction that may extend away from the inside of the drop gear housing portion <NUM>.

Referring to <FIG> and <FIG>, the ramp portion <NUM> may be disposed below the first axis <NUM>. The ramp portion <NUM> may extend in an axial direction from the connecting wall <NUM> toward the center portion <NUM>. In addition, the ramp portion <NUM> may extend in a downward direction from the connecting wall <NUM> toward the center portion <NUM> and may facilitate lubricant flow from the drop gear housing portion <NUM> to the center portion <NUM>. In at least one configuration, the ramp portion <NUM> may be bounded in a lateral direction by a first ramp side wall <NUM> and a second ramp side wall <NUM>. The first ramp side wall <NUM> and the second ramp side wall <NUM> may be disposed on opposite sides of the first axis <NUM>. In addition, the first ramp side wall <NUM> may be disposed parallel or substantially parallel to the second ramp side wall <NUM>.

Referring to <FIG>, the first divider wall <NUM> may be disposed proximate an end of the drop gear housing portion <NUM> and the first mounting flange <NUM>. For example, first divider wall <NUM> may extend from the connecting wall <NUM> toward or into the first opening <NUM>. In addition, the first divider wall <NUM> may be coplanar with the first mounting flange <NUM> and may extend downward from the second arcuate portion <NUM>.

Referring to <FIG>, the second divider wall <NUM> may be disposed inside the drop gear housing portion <NUM> of the axle housing <NUM>. The second divider wall <NUM> may extend from an interior surface of the connecting wall <NUM>. For example, the second divider wall <NUM> may extend downward from the second arcuate portion <NUM>. The second divider wall <NUM> may define a hole <NUM> that may extend around the countershaft axis <NUM>. The hole <NUM> may receive a first countershaft that may extend from the drop gear set <NUM> as will be discussed in more detail below. As is best shown in <FIG>, the drop gear set <NUM> may be axially positioned in the drop gear housing portion <NUM> between the first divider wall <NUM> and the second divider wall <NUM>.

Referring to <FIG> and <FIG>, the center portion <NUM> may be disposed proximate the center of the housing assembly <NUM>. The center portion <NUM> extends from the drop gear housing portion <NUM> and may at least partially define a cavity that may receive the differential assembly <NUM>. The center portion <NUM> may facilitate mounting of a differential carrier that supports the differential assembly <NUM>. A lower region of the center portion <NUM> may at least partially define a sump portion that may contain lubricant that may be splashed to lubricate internal components of the axle assembly <NUM>, such as the differential assembly <NUM> and associated bearings. The center portion <NUM> may also facilitate mounting of various external components. For instance, the center portion <NUM> may facilitate mounting of the electric motor module <NUM> and the countershaft transmission module <NUM> to the housing assembly <NUM>. In at least one configuration and as is best shown with reference to <FIG>, the center portion <NUM> defines a second mounting flange <NUM> and may include an end wall <NUM> and a ring <NUM>.

Referring to <FIG>, the second mounting flange <NUM> may be disposed opposite the first mounting flange <NUM>. The second mounting flange <NUM> facilitates mounting of the countershaft transmission module <NUM>, the differential assembly <NUM>, or both to the axle housing <NUM>. The second mounting flange <NUM> may be disposed at an end or side of the center portion <NUM> that may be disposed opposite the drop gear housing portion <NUM>. In at least one configuration, the second mounting flange <NUM> may extend continuously around the first axis <NUM>. The second mounting flange <NUM> may include a plurality of holes that may receive fasteners such as bolts that may couple a portion of the housing assembly <NUM> that may support the countershaft transmission module <NUM>, the differential assembly <NUM>, or both to the second mounting flange <NUM>. For instance, the differential carrier may be mounted to the second mounting flange <NUM>. As is best shown in <FIG>, the second mounting flange <NUM> may define a second opening <NUM>.

Referring primarily to <FIG> and <FIG>, the end wall <NUM> may be disposed opposite the second mounting flange <NUM>. The drop gear housing portion <NUM> may extend from the end wall <NUM>. For example, the connecting wall <NUM> may extend from the end wall <NUM> and the end wall <NUM> may extend outward from an end of the connecting wall <NUM> toward the arm portions <NUM>. In at least one configuration, the end wall <NUM> may be disposed parallel or substantially parallel to the first mounting flange <NUM>, the second mounting flange <NUM>, or both.

Referring to <FIG> and <FIG>, the ring <NUM> is disposed inside the center portion <NUM>. The ring <NUM> extends around the first axis <NUM> and extends from the end wall <NUM> toward the second mounting flange <NUM>. The ramp portion <NUM> may extend from the connecting wall <NUM> to the ring <NUM>.

Referring to <FIG>, one or more arm portions <NUM> may extend from the center portion <NUM>. For example, two arm portions <NUM> may extend in opposite directions from the center portion <NUM> and away from the differential assembly <NUM>. The arm portions <NUM> may have substantially similar configurations. For example, the arm portions <NUM> may each have a hollow configuration or tubular configuration that may extend around a corresponding axle shaft <NUM>, which is shown in phantom in <FIG>, and may help separate or isolate the axle shaft <NUM> from the surrounding environment. An arm portion <NUM> or a portion thereof may be integrally formed with the center portion <NUM>. Alternatively, an arm portion <NUM> may be separate from the center portion <NUM>. In such a configuration, each arm portion <NUM> may be attached to the center portion <NUM> in any suitable manner, such as by welding or with one or more fasteners. It is also contemplated that the arm portions <NUM> may be omitted.

Referring to <FIG> and <FIG>, the electric motor module <NUM> may provide torque to the differential assembly <NUM> via the rotor shaft <NUM>, the drop gear set <NUM>, the countershaft transmission module <NUM>, and the drive pinion <NUM>. In addition, the electric motor module <NUM> may be electrically connected to an electrical power source, such as a battery, capacitor, or the like. An inverter may electrically connect the electric motor module <NUM> and the electrical power source. The electric motor module <NUM> may have any suitable configuration. In at least one configuration, the electric motor module <NUM> may include an electric motor that has a stator <NUM> and a rotor <NUM>. In addition, the electric motor module <NUM> may have an electric motor housing <NUM>.

Referring to <FIG>, the stator <NUM> may be fixedly positioned with respect to the housing assembly <NUM> and the electric motor housing <NUM>. For example, the stator <NUM> may extend around a first axis <NUM> and may not rotate about the first axis <NUM>. The stator <NUM> may include windings that may be electrically connected to the electrical power source.

The rotor <NUM> may extend around the first axis <NUM> and may be received inside the stator <NUM>. The rotor <NUM> may be rotatable about the first axis <NUM> with respect to the stator <NUM>. For example, the rotor <NUM> may be spaced apart from the stator <NUM> and may include magnets or ferromagnetic material that may facilitate the generation of electrical current. The rotor <NUM> may be operatively connected to the countershaft transmission module <NUM> via the rotor shaft <NUM> and the drop gear set <NUM> as will be discussed in more detail below.

The electric motor housing <NUM> may receive the stator <NUM> and the rotor <NUM>. The electric motor housing <NUM> is mounted to the first mounting flange <NUM>. For instance, the electric motor housing <NUM> may contact the first mounting flange <NUM> and may be secured to the first mounting flange <NUM> with one or more fasteners. The electric motor housing <NUM> may include an opening <NUM> through which the rotor shaft <NUM> may extend.

The rotor shaft <NUM> may operatively connect the electric motor module <NUM> to the drop gear set <NUM>. For example, the rotor shaft <NUM> may extend from the rotor <NUM> or may be operatively connected to the rotor <NUM> such that the rotor <NUM> and the rotor shaft <NUM> may be rotatable together about the first axis <NUM>. The rotor shaft <NUM> may be fixedly coupled to the rotor <NUM> at or proximate a first end of the rotor shaft <NUM> and may be fixedly coupled to a gear of the drop gear set <NUM> proximate a second end that may be disposed opposite the first end. The rotor shaft <NUM> may extend through the opening <NUM> in the electric motor housing <NUM> and into the first opening <NUM> of the drop gear housing portion <NUM>. The rotor shaft <NUM> may be rotatably supported on the housing assembly <NUM> by one or more roller bearing assemblies. In the configuration shown in <FIG>, a pair of roller bearing assemblies are disposed in the opening <NUM> and may extend from the electric motor housing <NUM> to the rotor shaft <NUM>. The roller bearing assemblies may be positioned along the first axis <NUM> between the rotor <NUM> and a first drop gear of the drop gear set <NUM>. The roller bearing assembly may have any suitable configuration. For instance, the roller bearing assembly may include a plurality of rolling elements that may be disposed between an inner race and an outer race. The inner race may be mounted to the rotor shaft <NUM> and may extend around and may receive the rotor shaft <NUM>. The outer race may extend around the inner race and may be mounted to the electric motor housing <NUM>.

The drive pinion <NUM> may be at least partially received in the housing assembly <NUM>. The drive pinion <NUM> may be operatively connectable to the electric motor module <NUM> via the rotor shaft <NUM>, the drop gear set <NUM>, and the countershaft transmission module <NUM>. As such, the drive pinion <NUM> may help operatively connect the electric motor module <NUM> to components of the axle assembly <NUM> like the differential assembly <NUM>. The drive pinion <NUM> may extend along and may be rotatable about a drive pinion axis <NUM>. The drive pinion axis <NUM> may be disposed parallel or substantially parallel to the first axis <NUM>. In at least one configuration, the drive pinion axis <NUM> may be coaxially disposed with the first axis <NUM>. In at least one configuration, the drive pinion <NUM> may include a gear portion <NUM> and a shaft portion <NUM>.

The gear portion <NUM> may be disposed at or near an end of the drive pinion <NUM>. The gear portion <NUM> may have a plurality of teeth that may mate or mesh with corresponding teeth on a ring gear of the differential assembly <NUM> as will be discussed in more detail below. As such, the drive pinion <NUM> may provide torque from the electric motor module <NUM> to the ring gear.

The shaft portion <NUM> may extend along and may be rotatable about the drive pinion axis <NUM> with the gear portion <NUM>. The shaft portion <NUM> may be operatively connected to the countershaft transmission module <NUM> and may extend from the gear portion <NUM> in a direction that may extend away from the electric motor module <NUM>. The shaft portion <NUM> may be integrally formed with the gear portion <NUM> or may be provided as a separate component that may be fixedly coupled to the gear portion <NUM>.

The countershaft transmission module <NUM> may operatively connect the electric motor module <NUM> to the drive pinion <NUM>. The countershaft transmission module <NUM> may be spaced apart from the electric motor module <NUM> such that the differential assembly <NUM> may be positioned between the countershaft transmission module <NUM> and the electric motor module <NUM>. For instance, the differential assembly <NUM> may be positioned between the drop gear set <NUM> and the drive pinion <NUM> or between the drop gear set <NUM> and the countershaft transmission module <NUM>. In at least one configuration, the countershaft transmission module <NUM> may include a set of drive pinion gears <NUM>, a countershaft subassembly <NUM>, and a set of countershaft gears <NUM>.

The set of drive pinion gears <NUM> may include a plurality of gears. In the configuration shown, the set of drive pinion gears <NUM> includes a first gear <NUM>, a second gear <NUM>, and a third gear <NUM>; however, it is to be understood that a greater or lesser number of gears may be provided. The members of the set of drive pinion gears <NUM> may be selectively coupled to the drive pinion <NUM>, fixedly coupled to the drive pinion <NUM>, or at least one drive pinion gear may be selectively coupled to the drive pinion <NUM> and at least one drive pinion gear may be fixedly coupled to the drive pinion <NUM>. A member of the set of drive pinion gears <NUM> may be rotatable about the drive pinion axis <NUM> with the drive pinion <NUM> when that gear is coupled to the drive pinion <NUM>. Conversely, the drive pinion <NUM> may be rotatable about the drive pinion axis <NUM> with respect to a member of the set of drive pinion gears <NUM> that is decoupled from or not coupled to the drive pinion <NUM>. A member of the set of drive pinion gears <NUM> may be selectively coupled to the drive pinion <NUM> in any suitable manner, such as with a clutch as will be discussed in more detail below.

Referring to <FIG>, the first gear <NUM> may receive the shaft portion <NUM> of the drive pinion <NUM>. For example, the first gear <NUM> may have a through hole through which the shaft portion <NUM> may extend. The first gear <NUM> may extend around the drive pinion axis <NUM> and the shaft portion <NUM> and may have a plurality of teeth that may be arranged around and may face away from the drive pinion axis <NUM>. The teeth of the first gear <NUM> may contact and may mate or mesh with teeth of a first countershaft gear that may be provided with the set of countershaft gears <NUM> as will be discussed in more detail below. In at least one configuration, the first gear <NUM> may be axially positioned along the drive pinion axis <NUM> such that the first gear <NUM> is positioned closer to the electric motor module <NUM> and the differential assembly <NUM> than some or all of the other members of the set of drive pinion gears <NUM>.

The second gear <NUM> may receive the shaft portion <NUM> of the drive pinion <NUM>. For example, the second gear <NUM> may have a through hole through which the shaft portion <NUM> may extend. The second gear <NUM> may extend around the drive pinion axis <NUM> and the shaft portion <NUM> and may have a plurality of teeth that may be arranged around and may face away from the drive pinion axis <NUM>. The teeth of the second gear <NUM> may contact and may mate or mesh with teeth of a second countershaft gear that may be provided with the set of countershaft gears <NUM> as will be discussed in more detail below. The second gear <NUM> may have a different diameter than the first gear <NUM> and the third gear <NUM>. For example, the second gear <NUM> may have a larger diameter than the first gear <NUM> and a smaller diameter than the third gear <NUM>. In at least one configuration, the second gear <NUM> may be axially positioned along the drive pinion axis <NUM> between the first gear <NUM> and the third gear <NUM>.

The third gear <NUM> may receive the shaft portion <NUM> of the drive pinion <NUM>. For example, the third gear <NUM> may have a through hole through which the shaft portion <NUM> may extend. The third gear <NUM> may extend around the drive pinion axis <NUM> and the shaft portion <NUM> and may have a plurality of teeth that may be arranged around and may face away from the drive pinion axis <NUM>. The teeth of the third gear <NUM> may contact and may mate or mesh with teeth of a third countershaft gear that may be provided with the set of countershaft gears <NUM> as will be discussed in more detail below. The third gear <NUM> may have a different diameter than the first gear <NUM> and the second gear <NUM>. For example, the third gear <NUM> may have a larger diameter than the first gear <NUM> and the second gear <NUM>. In at least one configuration, the third gear <NUM> be axially positioned along the drive pinion axis <NUM> further from the electric motor module <NUM> and the differential assembly <NUM> than the first gear <NUM> and the second gear <NUM>.

The countershaft subassembly <NUM> may be rotatable about a countershaft axis <NUM>. The countershaft axis <NUM> may be disposed parallel or substantially parallel to the first axis <NUM>, the drive pinion axis <NUM>, or both. The countershaft axis <NUM> may be offset from and may not be coaxially disposed with the first axis <NUM>, the drive pinion axis <NUM>, or both. In at least one configuration, the countershaft axis <NUM> may be disposed above the first axis <NUM>. The countershaft subassembly <NUM> may be rotatably supported on the housing assembly <NUM> by one or more roller bearing assemblies. In at least one configuration, the countershaft subassembly <NUM> may include a first countershaft <NUM>, a second countershaft <NUM>, and a coupling <NUM>.

The first countershaft <NUM> may be at least partially received in the axle housing <NUM> and may be rotatable about the countershaft axis <NUM>. The first countershaft <NUM> may extend through the second opening <NUM> of the center portion <NUM>. The first countershaft <NUM> may be rotatably supported by a first bearing <NUM> and a second bearing <NUM>. The first bearing <NUM> may extend from the first divider wall <NUM> of the drop gear housing portion <NUM>. The second bearing <NUM> may be disposed proximate the second divider wall <NUM> of the drop gear housing portion <NUM>. The drop gear set <NUM> may be axially positioned between the first bearing <NUM> and the second bearing <NUM>.

The second countershaft <NUM> may be partially or completely disposed outside of the axle housing <NUM>. For example, the second countershaft <NUM> may be disposed in the housing that receives the set of drive pinion gears <NUM>, the countershaft subassembly <NUM>, the set of countershaft gears <NUM>, or combinations thereof. The second countershaft <NUM> may support the set of countershaft gears <NUM>. In addition, the second countershaft <NUM> may be rotatably supported by bearings such that the set of countershaft gears <NUM> may be axially positioned between the bearings.

The coupling <NUM> may fixedly couple the first countershaft <NUM> to the second countershaft <NUM>. For example, the coupling <NUM> may receive an end of the first countershaft <NUM> and an end of the second countershaft <NUM>. The coupling may couple the first countershaft <NUM> and the second countershaft <NUM> in any suitable manner. For instance, the coupling <NUM> may receive the first countershaft <NUM>, the second countershaft <NUM>, or both with an interference fit, may be coupled to a countershaft with mating splines, may be coupled to a countershaft with one or more fasteners, or the like.

The set of countershaft gears <NUM> may be at least partially received in a portion of the housing assembly <NUM>. The set of countershaft gears <NUM> may include a plurality of gears. In the configurations shown, the set of countershaft gears <NUM> may include a first countershaft gear <NUM>, a second countershaft gear <NUM>, and a third countershaft gear <NUM>; however, it is contemplated that a greater number of gears or a lesser number of countershaft gears may be provided. Members of the set of countershaft gears <NUM> may be selectively coupled to the countershaft subassembly <NUM>, fixedly coupled to the countershaft subassembly <NUM>, or at least one countershaft gear may be selectively coupled to the countershaft subassembly <NUM> and at least one other countershaft gear may be fixedly coupled to the countershaft subassembly <NUM>. A member of the set of countershaft gears <NUM> may be rotatable about the countershaft axis <NUM> with the countershaft subassembly <NUM> when that gear is coupled to the countershaft subassembly <NUM>. Conversely, the countershaft subassembly <NUM> may be rotatable about the countershaft axis <NUM> with respect to a member of the set of countershaft gears <NUM> that is decoupled from or not coupled to the countershaft subassembly <NUM>. A member of the set of countershaft gears <NUM> may be selectively coupled to the countershaft subassembly <NUM> in any suitable manner, such as with a clutch as will be discussed in more detail below.

The first countershaft gear <NUM> may receive the countershaft subassembly <NUM>. For example, the first countershaft gear <NUM> may have a hole that may receive the countershaft subassembly <NUM>. The first countershaft gear <NUM> may extend around the countershaft axis <NUM> and may have a plurality of teeth that may be arranged around and may face away from the countershaft axis <NUM>. The teeth of the first countershaft gear <NUM> may contact and may mate or mesh with the teeth of the first gear <NUM>. In at least one configuration, the first countershaft gear <NUM> may be axially positioned along the countershaft axis <NUM> closer to the electric motor module <NUM> and the differential assembly <NUM> than the second countershaft gear <NUM> and the third countershaft gear <NUM>.

The second countershaft gear <NUM> may receive the countershaft subassembly <NUM>. For example, the second countershaft gear <NUM> may have a hole that may receive the countershaft subassembly <NUM> and may be fixedly coupled to the countershaft subassembly <NUM>. The second countershaft gear <NUM> may extend around the countershaft axis <NUM> and may have a plurality of teeth that may be arranged around and may face away from the countershaft axis <NUM>. The teeth of the second countershaft gear <NUM> may contact and may mate or mesh with the teeth of the second gear <NUM>. The second countershaft gear <NUM> may have a different diameter than the first countershaft gear <NUM> and the third countershaft gear <NUM>. In at least one configuration, the second countershaft gear <NUM> may be axially positioned along the countershaft axis <NUM> between the first countershaft gear <NUM> and the third countershaft gear <NUM>.

The third countershaft gear <NUM> may receive the countershaft subassembly <NUM>. For example, the third countershaft gear <NUM> may have a hole that may receive the countershaft subassembly <NUM> and may be fixedly coupled to the countershaft subassembly <NUM>. The third countershaft gear <NUM> may extend around the countershaft axis <NUM> and may have a plurality of teeth that may be arranged around and may face away from the countershaft axis <NUM>. The teeth of the third countershaft gear <NUM> may contact and may mate or mesh with the teeth of the third gear <NUM>. The third countershaft gear <NUM> may have a different diameter than the first countershaft gear <NUM> and the second countershaft gear <NUM>. In at least one configuration, the third countershaft gear <NUM> may be axially positioned along the countershaft axis <NUM> further away from the electric motor module <NUM> and the differential assembly <NUM> than the first countershaft gear <NUM> and the second countershaft gear <NUM>.

A bearing, such as a roller bearing, may optionally be provided to rotatably support a corresponding gear that is not fixedly coupled to a shaft. For instance, the bearing may be received in the hole of a gear and may receive a shaft portion <NUM> of the drive pinion <NUM> or the countershaft subassembly <NUM>.

The first gear <NUM> and the first countershaft gear <NUM> may provide a different gear ratio than the second gear <NUM> and the second countershaft gear <NUM> and may provide a different gear ratio than the third gear <NUM> and the third countershaft gear <NUM>. As a non-limiting example, the first gear <NUM> and the first countershaft gear <NUM> may provide a gear ratio of <NUM>:<NUM> or less, the second gear <NUM> and the second countershaft gear <NUM> may provide a gear ratio from <NUM>:<NUM> to <NUM>:<NUM>, and the third gear <NUM> and the third countershaft gear <NUM> may provide a gear ratio of <NUM>:<NUM> or more. For instance, the first countershaft gear <NUM> may have a larger diameter than the first gear <NUM>, the second countershaft gear <NUM>, and the third countershaft gear <NUM>. The second countershaft gear <NUM> may have a larger diameter than the third countershaft gear <NUM> and a smaller diameter or the same diameter as the second gear <NUM>. The third countershaft gear <NUM> may have a smaller diameter than the third gear <NUM>.

It is also contemplated that other gear configurations may be provided. As one example, the first gear <NUM> may have a larger diameter than the second gear <NUM> and the third gear <NUM>. As another example, gears or gear pairings may be arranged in different sequences along their respective axes. As another example, multiple meshing gear pairings or no gear pairings may provide "overdrive" gear ratios of less than <NUM>:<NUM>. As another example, multiple meshing gear pairings may provide gear ratios of greater than <NUM>:<NUM>. As such, gear ratios may be provided that are greater than <NUM>:<NUM>, less than <NUM>:<NUM>, equal (i.e., <NUM>:<NUM>), or combinations thereof.

The teeth of the gears may be of any suitable type. As a non-limiting example, the meshing teeth of the members of the set of drive pinion gears <NUM> and the members of the set of countershaft gears <NUM> may have a helical configuration.

The drop gear set <NUM> may be received in the drop gear housing portion <NUM> of the axle housing. In addition, the drop gear set <NUM> may be disposed on the same side of the differential assembly <NUM> as the electric motor module <NUM>. For instance, the drop gear set <NUM> may be positioned between the electric motor module <NUM> and the differential assembly <NUM>. The drop gear set <NUM> may include a plurality of gears. In the configuration shown, the drop gear set <NUM> may include a first drop gear <NUM> and a second drop gear <NUM>; however, it is contemplated that a greater number of gears may be provided. Members of the drop gear set <NUM> may be rotatable about different axes and may have the same diameters or different diameters. The drop gear set <NUM> may operatively connect the rotor <NUM> to the first countershaft <NUM>. In addition, the drop gear set <NUM> may be positioned between the first mounting flange <NUM> and the second mounting flange <NUM>.

The first drop gear <NUM> may be fixedly disposed on the rotor shaft <NUM> or fixedly mounted to the rotor shaft <NUM>. As such, the first drop gear <NUM> may rotate about the first axis <NUM> with the rotor shaft <NUM>. For example, the first drop gear <NUM> may have a hole that may receive the rotor shaft <NUM> and may be fixedly coupled to the rotor shaft <NUM>. The first drop gear <NUM> may extend around the first axis <NUM> and may have a plurality of teeth that may be arranged around and may face away from the first axis <NUM>.

The second drop gear <NUM> may be fixedly disposed on the countershaft subassembly <NUM>. For example, the second drop gear <NUM> may be fixedly mounted to or fixedly coupled to the first countershaft <NUM> of the countershaft subassembly <NUM>. As such, the second drop gear <NUM> may rotate about the countershaft axis <NUM> with the countershaft subassembly <NUM>. For example, the second drop gear <NUM> may have a hole that may receive the first countershaft <NUM> of the countershaft subassembly <NUM> and may be fixedly coupled to the first countershaft <NUM>. The second drop gear <NUM> may extend around the countershaft axis <NUM> and may have a plurality of teeth that may be arranged around and may face away from the countershaft axis <NUM>. The teeth of the first drop gear <NUM> may contact and may mate or mesh with the teeth of the second drop gear <NUM>.

The first drop gear <NUM> and the second drop gear <NUM> may provide gear reduction when provided with different diameters. For example, the first drop gear <NUM> may have a smaller diameter than the second drop gear <NUM> and may provide a gear reduction ratio greater than <NUM>:<NUM>. As a nonlimiting example, the first drop gear <NUM> and the second drop gear <NUM> may cooperate to provide a <NUM>:<NUM> gear reduction ratio. Such gear reduction may decrease the rotational speed of the countershaft subassembly <NUM> with respect to the rotational speed of the rotor shaft <NUM> and may increase the torque provided from the electric motor module <NUM> to the countershaft transmission module <NUM>.

The differential assembly <NUM> may be at least partially received in the center portion <NUM> of the housing assembly <NUM>. The differential assembly <NUM> may transmit torque to the vehicle traction wheel assemblies and permit the traction wheel assemblies to rotate at different velocities. For example, the differential assembly <NUM> may be operatively connected to the axle shafts <NUM>, which are shown in phantom in <FIG>, and may permit the axle shafts <NUM> to rotate at different rotational speeds about a second axis <NUM>. The second axis <NUM> may be disposed perpendicular or substantially perpendicular to the first axis <NUM>, the drive pinion axis <NUM>, the countershaft axis <NUM>, or combinations thereof. Moreover, the electric motor module <NUM> may be positioned on an opposite side of the second axis <NUM> from the drive pinion <NUM>, the countershaft transmission module <NUM>, or both. In at least one configuration, the differential assembly <NUM> may include a differential case <NUM> and a ring gear <NUM>.

Referring to <FIG>, the differential case <NUM> may be configured to receive components of the differential assembly <NUM>. In addition, the differential case <NUM> may be rotatable about the second axis <NUM>. For example, the differential case <NUM> may be rotatably supported by a pair of roller bearing assemblies, which in turn may be mounted to a portion of the housing assembly <NUM>, such as a differential carrier. The differential case <NUM> may at least partially define a cavity that may at least partially receive gears of the differential assembly <NUM>. For instance, the differential case <NUM> may receive a first and second differential gears that may be rotatable with first and second axle shafts, respectively, and one or more pinion gears that may mesh with the first and second differential gears in a manner known by those skilled in the art.

The ring gear <NUM> may be fixedly disposed on the differential case <NUM> or fixedly mounted to the differential case <NUM>. As such, the ring gear <NUM> may rotate about the second axis <NUM> with the differential case <NUM>. The ring gear <NUM> may extend around the second axis <NUM> and may have a set of ring gear teeth that may contact and mate or mesh with teeth of the gear portion <NUM> of the drive pinion <NUM>. As such, torque may be transmitted between the countershaft transmission module <NUM> and the differential assembly <NUM> via the meshing teeth of the drive pinion <NUM> and the ring gear <NUM>.

As is best shown with reference to <FIG>, the first axis <NUM> and the countershaft axis <NUM> may be disposed in a plane <NUM>. The second axis <NUM> may be disposed at an oblique angle with respect to the plane <NUM>.

Referring to <FIG>, a wheel end assembly <NUM> may be disposed at the end of an arm portion <NUM> of the axle housing <NUM>. A wheel end assembly <NUM> may facilitate mounting of a wheel to the axle assembly <NUM>. For instance, the wheel end assembly <NUM> may include a hub <NUM> that may be rotatable about an axis, such as the second axis <NUM>, and to which a wheel may be mounted.

A control system may control operation of the axle assembly <NUM>. The control system may include one or more electronic controllers, such as a microprocessor-based controller, that may monitor and/or control operation of various components of the axle assembly <NUM>, such as the electric motor module <NUM> and coupling and decoupling of the gears, such as by actuating a clutch.

A clutch may have any suitable configuration. The clutch may be configured as a disc clutch that may include friction discs that may be selectively engaged to couple a gear to a corresponding shaft. Alternatively, the clutch may be configured as a dog clutch or clutch collar that may receive, rotate with, and slide along a corresponding shaft to selectively couple and decouple one or more members of the set of drive pinion gears <NUM> to and from the drive pinion <NUM>, one or more members of the set of countershaft gears <NUM> to and from the countershaft subassembly <NUM>, or combinations thereof. For example, a clutch that is configured as a dog clutch or a clutch collar may have a through hole that may receive the shaft portion <NUM> of the drive pinion <NUM> and may rotate about the drive pinion axis <NUM> with the shaft portion <NUM>, or may have a through hole that may receive the countershaft subassembly <NUM> and may rotate about the countershaft axis <NUM> with the countershaft subassembly <NUM>. For instance, the clutch and the shaft it receives may have mating splines that inhibit rotation of the clutch with respect to the shaft while allowing the clutch to slide in an axial direction along an axis (e.g., the drive pinion axis <NUM> or the countershaft axis <NUM>) with respect to the shaft to engage or disengage a gear, such as member of the set of drive pinion gears <NUM> or a member of the set of countershaft gears <NUM>. Such a clutch may have a tooth or teeth that may be configured to selectively mate or mesh with corresponding teeth on a member of the set of drive pinion gears <NUM> or a member of the set of countershaft gears <NUM> to couple the gear to the drive pinion <NUM> or the countershaft subassembly <NUM>, respectively, such that the gear is rotatable about the drive pinion axis <NUM> with the drive pinion <NUM> or is rotatable about the countershaft axis <NUM> with the countershaft subassembly <NUM>. The tooth or teeth of the clutch may be configured as a face gear that may be disposed along a lateral side of the clutch or may be configured like a spline and may be received inside a hole of a member of the set of drive pinion gears <NUM> or a member of the set of countershaft gears <NUM>. Clutches will primarily be described below as having a dog clutch or clutch collar configuration; however, it is to be understood that a clutch may have a different configuration and may not be configured as a dog clutch or a clutch collar, that a different number of clutches may be provided, and that clutches may be associated with a single member of the set of drive pinion gears <NUM> or a single member of the set of countershaft gears <NUM> rather than multiple gears or vice versa.

Referring to <FIG>, in at least one configuration a first clutch <NUM> and a second clutch <NUM> may be provided. In <FIG>, the first clutch <NUM> may be axially positioned along the countershaft axis <NUM> between the first countershaft gear <NUM> and the second countershaft gear <NUM> while the second clutch <NUM> may be axially positioned along the between the second gear <NUM> and the third gear <NUM>; however, it is contemplated that the first clutch <NUM> may be axially positioned along the countershaft axis <NUM> between the first gear <NUM> and the second gear <NUM>, the second clutch <NUM> may be axially positioned between the second countershaft gear <NUM> and the third countershaft gear <NUM>, or combinations thereof. It is also contemplated that a single actuator may be provided to actuate multiple clutches, like the first clutch <NUM> and the second clutch <NUM>, that different actuators may actuate different clutches, or that a single clutch may be provided to couple and decouple the members of the set of drive pinion gears <NUM> to and from the drive pinion <NUM> or to couple and decouple members of the set of countershaft gears <NUM> to and from the countershaft subassembly <NUM>.

Torque may be transmitted between the drive pinion <NUM> and the countershaft subassembly <NUM> via the first gear <NUM> and the first countershaft gear <NUM> when the first gear <NUM> is coupled to the drive pinion <NUM> and the first countershaft gear <NUM> is coupled to the countershaft subassembly <NUM>. Torque may be transmitted between the drive pinion <NUM> and the countershaft subassembly <NUM> via the second gear <NUM> and the second countershaft gear <NUM> when the second gear <NUM> is coupled to the drive pinion <NUM> and the second countershaft gear <NUM> is coupled to the countershaft subassembly <NUM>. Torque may be transmitted between the drive pinion <NUM> and the countershaft subassembly <NUM> via the third gear <NUM> and third countershaft gear <NUM> when the third gear <NUM> is coupled to the drive pinion <NUM> and the third countershaft gear <NUM> is coupled to the countershaft subassembly <NUM>.

Claim 1:
An axle assembly (<NUM>) comprising:
an axle housing (<NUM>) that includes:
a drop gear housing portion (<NUM>);
a center portion (<NUM>) that extends from the drop gear housing portion (<NUM>); and
an arm portion (<NUM>) that extends from the center portion (<NUM>) and is configured to receive an axle shaft (<NUM>);
an electric motor module (<NUM>); and
a countershaft transmission module (<NUM>), characterized in that the drop gear housing portion (<NUM>) defines a first mounting flange (<NUM>), in that the center portion (<NUM>) defines a second mounting flange (<NUM>), in that the electric motor module (<NUM>) is mounted to the first mounting flange (<NUM>), in that the countershaft transmission module (<NUM>) is mounted to the second mounting flange (<NUM>), and in that a ring (<NUM>) is disposed inside the center portion (<NUM>) that extends around a first axis (<NUM>) and extends from an end wall (<NUM>) of the center portion (<NUM>) toward the second mounting flange (<NUM>).