US 8,523,738 B2Granted

Method of shifting a tandem drive axle having an inter-axle differential

AssigneeDana Heavy Vehicle Systems Group, LLC

InventorsTimothy J. Morscheck, Kenneth E. Cooper, James F. Ziech, Richard A. Nellums, Steven J. Wesolowski, Donald J. Remboski

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Abstract

A method of shifting a power distribution unit for a vehicle from a first operating state to a second operating state is provided. The method includes the step of adjusting a rotational speed of a portion of a second axle assembly using a clutching device to impart energy to a lubricant within the second axle assembly. A controller in communication with a power source of the vehicle adjusts an operating condition of the power source to facilitate moving the clutching device. The power distribution unit includes an inter-axle differential capable being placed in a locked condition by the clutching device and of accommodating a rotational difference between a first output gear and a second output gear with the inter-axle differential.

Claims44

Dependent claims

A method of shifting a power distribution unit for a vehicle from a first operating state to a second operating state, the method comprising the steps of:

drivingly engaging a first axle assembly with a first output of the power distribution unit;
drivingly engaging a second axle assembly with a second output of the power distribution unit;
drivingly engaging an input of the power distribution unit with an output of a power source, the power distribution unit including an inter-axle differential, the first output, the second output, and a first clutching device having a first position and a second position, the first clutching device in the first position locking the inter-axle differential, engaging the first output with the input of the power distribution unit, and disengaging the second output from the inter-axle differential, the first clutching device in the second position unlocking the inter-axle differential and engaging the first output and the second output with the inter-axle differential;
placing the first clutching device in one of the first position and the second position;
applying a rotational force to the input of the power distribution unit;
adjusting the rotational force transferred to the power distribution unit to facilitate moving the first clutching device;
moving the first clutching device from one of the first position and the second position to a third position, the first clutching device in the third position neither locking the inter-axle differential nor engaging the second output with the inter-axle differential;
adjusting a rotational speed of the input of the power distribution unit to facilitate moving the first clutching device from the third position;
moving the first clutching device from the third position to one of the first and second positions;
and
adjusting the rotational force transferred to the power distribution unit.

8 more elements

A method of shifting a power distribution unit for a vehicle from a first operating state to a second operating state, the method comprising the steps of:

drivingly engaging a first axle assembly with a first output of the power distribution unit;
drivingly engaging a second axle assembly with a second output of the power distribution unit;
drivingly engaging an input of the power distribution unit with an output of a power source, the power distribution unit including an inter-axle differential, the first output, the second output, and a first clutching device having a first position and a second position, the first clutching device in the first position locking the inter-axle differential, engaging the first output with the input of the power distribution unit, and disengaging the second output from the inter-axle differential, the first clutching device in the second position unlocking the inter-axle differential and engaging the first output and the second output with the inter-axle differential;
placing the first clutching device in the first position;
applying a rotational force to the input of the power distribution unit;
one of reducing and interrupting the rotational force transferred to the power distribution unit;
moving the first clutching device from the first position to a third position, the first clutching device in the third position unlocking the inter-axle differential;
adjusting a rotational speed of the input of the power distribution unit to facilitate moving the first clutching device from the third position;
adjusting a rotational speed of a first portion of the second axle assembly to a target speed, the target speed facilitating engagement between the first portion of the second axle assembly and a second portion of the second axle assembly;
moving the first clutching device from the third position to the second position;
and
one of increasing and resuming the rotational force transferred to the power distribution unit.

9 more elements

A method of shifting a power distribution unit for a vehicle from a first operating state to a second operating state, the method comprising the steps of:

providing a first axle assembly including a first pair of output axle shafts, a first differential drivingly engaged with the first pair of output axle shafts, and a first driving gear coupled to the first differential, the first axle assembly having a first gear ratio;
providing a second axle assembly including a second pair of output axle shafts, a second differential selectively drivingly engaged with the second pair of output axle shafts, a second driving gear coupled to the second differential, and an inter-axle shaft drivingly engaged with the second driving gear, the second axle assembly having a second gear ratio;
drivingly engaging an input of the power distribution unit with an output of a power source, the power distribution unit including an inter-axle differential, a first output drivingly engaged with the first driving gear, a second output drivingly engaged with the inter-axle shaft, and a first clutching device having a first position and a second position, the first clutching device in the first position locking the inter-axle differential, engaging the first output with the input of the power distribution unit, and disengaging the second output from the inter-axle differential, the first clutching device in the second position unlocking the inter-axle differential and engaging the first output and the second output with the inter-axle differential;
placing the first clutching device in the first position;
applying a rotational force to the input of the power distribution unit;
one of reducing and interrupting the rotational force transferred to the power distribution unit;
moving the first clutching device from the first position to a third position, the first clutching device in the third position neither locking the inter-axle differential nor engaging the second output with the inter-axle differential;
adjusting a rotational speed of the input of the power distribution unit to facilitate moving the first clutching device from the third position;
adjusting a rotational speed of the second output, the inter-axle shaft, the second driving gear, and the second differential to a target speed, the target speed facilitating engagement between the second differential and the second pair of output axle shafts;
moving the first clutching device from the third position to the second position, the first clutching device in the second position engaging the second output with the inter-axle shaft, the second driving gear, and the second differential;
one of increasing and resuming the rotational force transferred to the power distribution unit;
distributing the rotational force between the first output and the second output through the inter-axle differential;
and
accommodating a rotational difference of the first output and the second output caused by a difference between the first gear ratio and the second gear ratio with the inter-axle differential, wherein the accommodating of the rotational difference between the first output and the second output provides a cumulative gear ratio for the first axle assembly and the second axle assembly, the cumulative gear ratio intermediate the first gear ratio and the second gear ratio.

11 more elements

A method of shifting a power distribution unit for a vehicle from a first operating state to a second operating state, the method comprising the steps of:

drivingly engaging a first axle assembly with a first output of the power distribution unit;
drivingly engaging a second axle assembly with a second output of the power distribution unit, the second axle assembly including an axle clutch, the axle clutch selectively disengaging a portion of one of a second pair of output axle shafts from a remaining portion of the one of the second pair of output axle shafts
drivingly engaging an input of the power distribution unit with an output of a power source, the power distribution unit including an inter-axle differential, the first output, the second output, and a first clutching device having a first position and a second position, the first clutching device in the first position locking the inter-axle differential, engaging the first output with the input of the power distribution unit, and disengaging the second output from the inter-axle differential, the first clutching device in the second position unlocking the inter-axle differential and engaging the first output and the second output with the inter-axle differential;
placing the first clutching device in the first position;
applying a rotational force to the input of the power distribution unit;
adjusting the rotational force transferred to the power distribution unit to facilitate moving the first clutching device;
moving the first clutching device from the first position to a third position, the first clutching device in the third position neither locking the inter-axle differential nor engaging the second output with the inter-axle differential;
imparting energy to a lubricant disposed within the second axle assembly by selectively engaging the axle clutch;
adjusting a rotational speed of the input of the power distribution unit to facilitate moving the first clutching device from the third position;
moving the first clutching device from the third position to the second position;
and
adjusting the rotational force transferred to the power distribution unit.

9 more elements

Dependencies are inferred from the claim text.