FIELD OF THE DISCLOSURE

The present invention relates to vehicle axle assemblies, and more particularly, to an axle assembly for use with a low floor vehicle.

BACKGROUND

In order to aid ingress and egress, it is oftentimes ideal for a vehicle to have a floor that is as low as possible. Busses and people carriers, commonly called low floor vehicles, are examples of vehicles that benefit from a low floor height. By minimizing the floor height, a step at a door of the vehicle may be eliminated, which in turn allows passengers easier ingress and egress of vehicle passengers. Furthermore, elimination of steps is especially beneficial to disabled passengers, and passengers with strollers. Increasingly, manufacturers have turned to electric and hybrid propulsion systems for low floor vehicles for increased performance and efficiency. In order to have the floor of the vehicle as low as possible, the drivetrain components are relocated so as to reduce intrusions into the vehicle floor.

At least some known low floor vehicles include wheel assemblies driven by electric motor having the electric rotor connected directly to the axle shaft of the wheel assembly. Because these electric motors are connected directly to the axle shaft, the orientation of the electric motor reduces the amount of space available across the wheel assembly, thus reducing the floor space available for the low floor vehicle. Accordingly, a new axle assembly is required to increase the spacing between wheel assemblies and provide larger floor areas.

The present invention is aimed at one or more of the problems identified above.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an axle assembly for a low floor vehicle with increased performance and efficiency.

In one embodiment of the present invention, an axle assembly is provided. The axle assembly includes an axle housing and a drive unit for driving a wheel assembly. The drive unit includes an axle shaft, a wheel end assembly, an electric machine, and a transmission unit. The axle shaft extends along an axle centerline axis between a first axle end and a second axle end. The wheel end assembly is coupled to the first axle end. The electric machine is positioned within the axle housing and includes a rotor shaft, a drive pinion coupled to the rotor shaft, and an electric motor for rotating the rotor shaft. The rotor shaft extends along a rotor shaft centerline axis that is orientated parallel to the axle centerline axis. The transmission unit is positioned within the axle housing and is configured to transfer torque from the electric machine to the axle shaft. The transmission unit includes an output assembly and an offset gear reduction assembly. The output assembly is coupled to the second axle end such that a rotation of the output assembly rotates the axle shaft. The offset gear reduction assembly is coupled to the output assembly and the drive pinion of the electric machine for transferring torque from the electric machine to the output assembly.

In another embodiment of the present invention, an axle housing is provided. The axle housing is configured to be used with an axle assembly that includes a drive unit including an electric machine, a transmission unit, and an inverter assembly. The axle housing includes a first outer section, a second outer section, and a bridge section extending between the first outer section and the second outer section. The first outer section includes a gearbox including an inner surface that defines a cavity configured to receive the electric machine and the transmission unit therein. The bridge section includes a cradle assembly coupled to the gearbox. The cradle assembly includes an inner surface that defines a support chamber configured to receive the inverter assembly therein.

In yet another embodiment of the present invention, a vehicle is provided. The vehicle includes a vehicle frame and an axle assembly coupled to the vehicle frame. The axle assembly includes an axle housing, a first drive unit, and a second drive unit. The axle housing includes a bridge section extending between a first outer section and an opposite second outer section. The first outer section includes a first gearbox and the second outer section includes a second gearbox. The bridge section includes a cradle assembly that is coupled to the first gearbox and the second gearbox. The cradle assembly includes an inner surface that defines a support chamber within the cradle assembly. The first drive unit is adapted to be coupled to a first wheel assembly. The first drive unit includes a first electric machine, and a first transmission unit. The first electric machine is positioned within the first gearbox. The first electric machine includes a drive pinion that is coupled to a rotor shaft. The first transmission unit is positioned within the first gearbox and includes an output assembly and an offset gear reduction assembly that is coupled to the output assembly and the drive pinion of the first electric machine for transferring torque from the first electric machine to the output assembly. A first axle shaft is coupled to the output assembly and extends outwardly from an outer surface of the first gearbox. The second drive unit is adapted to be coupled to a second wheel assembly. The second drive unit includes a gear reduction and a second axle shaft that is oriented coaxially with the first axle shaft along an axle centerline axis. The gear reduction is positioned within the second gearbox. The second axle shaft extends outwardly from the second gearbox towards the second wheel assembly. An inverter assembly is positioned within the support chamber of the cradle assembly and is coupled to the first electric machine for providing electrical power to the first electric machine.

