US 2002/0152824 A1 · Control system for transfer case range shift

Abstract

In accordance with the present invention, a preferred method is disclosed for operating a transfer case synchronized range shift mechanism. The range shift mechanism can be selectively actuated for establishing a four-wheel high-range drive mode, a neutral mode, and a four-wheel low-range drive mode. The synchronized range shift mechanism is comprised of a first input gear system, a second input gear system, and an output gear system. The output gear system is comprised of a rotary output member that may be selectively engaged with either the first input gear system or the second input gear system, depending on which four-wheel-drive operating mode the vehicle operator selects. The range shift mechanism is further comprised of a synchronizing mechanism. The present invention discloses a novel method for controlling the speed of the range shift as a means for reducing the time it takes to perform the range shift.

Claims39

Dependent claims

A method for performing a synchronized gear shift of a gear system comprised of a first rotary input member, a second rotary input member, a rotary output member movable between a first position where it is coupled to the first rotary input member and a second position where it is coupled to the second rotary input member, and a synchronizing mechanism for synchronizing the rotational speed of the rotary output member with the rotational speed of the second rotary input member while the rotary output member moves from its first position toward its second position at a variable shift velocity, which steps comprise:

accelerating the rotary output member to a first shift velocity that is greater than a synchronization shift velocity, wherein the synchronization shift velocity corresponds to the shift velocity of the rotary output member during the period of time in which rotational speed synchronization between the second rotary input member and the rotary output member occurs;
decelerating the rotary output member to a second shift velocity that is less than or substantially equal to the synchronization shift velocity;
and
accelerating the rotary output member to a third shift velocity that is greater than the synchronization shift velocity.

1 more element

A method for performing a synchronized gear shift of a gear system comprised of a first rotary input member, a second rotary input member, a rotary output member movable from a first position where it is coupled to the first rotary input member to a second position where it is coupled to the second rotary input member, and a synchronizing mechanism for synchronizing the rotational speed of the rotary output member with the rotational speed of the second rotary input member while the rotary output member moves from its first position toward its second position at a variable shift velocity, which steps comprise:

accelerating the rotary output member over a first shift interval, from an initial shift velocity to a first shift velocity;
decelerating the rotary output member over a second shift interval, from the first shift velocity to a second shift velocity;
accelerating the rotary output member over a third shift interval, from the second shift velocity to a third shift velocity;
accelerating the rotary output member over a fourth shift interval, from the third shift velocity to a fourth shift velocity;
and
decelerating the rotary output member over a fifth shift interval, from the fourth shift velocity to a final shift velocity.

3 more elements

Dependencies are inferred from the claim text.

Control system for transfer case range shift

Life of this patent

Control system for transfer case range shift

Life of this patent

Abstract

Claims39