Shifting mechanism

Details Shifting mechanism Shifting mechanism

1999-05-07

2001-02-27

Estremsky, Sherry (Department: 3681)

Interrelated power delivery controls, including engine control

Transmission control

Transmission controlled by engine

C475S201000, C475S069000, C475S204000, C475S206000, C192S108000

Reexamination Certificate

active

06193629

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of power transmission in a driveline for an automotive vehicle. More particularly, it pertains to a shifting mechanism to drivably connect relatively rotating shafts in the driveline of a motor vehicle.
2. Description of the Prior Art
To drivably connect relatively rotating shafts, a mechanical synchronizer is commonly provided to synchronize the rotational speed of the shafts, an example of which is provided in U.S. Pat. No. 4,375,172. The device of the '172 patent is a relatively effective mechanism, but is produced at high cost and not able to engage over a wide speed variation.
The mechanism employed in the '172 patent includes a blocked resilient axial interconnection between a jaw clutch assembly and main shaft
23
to improve the range of engagement. As described with reference to FIGS. 8 and 9 of the '172 patent, a device according to the '172 patent provides a large amount of backlash 208 to ensure adequate initial penetration, or engagement 212 of the teeth. This excessive backlash is not desirable as it provides additional slop in the system.
It would be desirable to provide a non-blocked engagement device for engaging relatively rotating shafts.
SUMMARY OF THE INVENTION
The avoid the difficulties and high cost associated with developing and manufacturing transmissions having a large number of forward speed ratios, and in order to improve the cost and performance of a device for shifting, an improved shift mechanism is provided.
In a shifting mechanism housed in a case a first relatively rotating member rotates about an axis. A second relatively rotating member is selectively coupled and decoupled with the first member. The coupling has a first spline tooth with a first axial length, and a second spline tooth with a second axial length longer than the first spline tooth. The second spline tooth has an end having a frusto-conical shape. One of the first and second members has a plurality of third spline teeth for engagement with the spline teeth of the coupling. The third spline teeth have a complimentary frusto-conical shape. A selector is moveable for actuating the coupling to mutually connect and disconnect the members. A resilient connection is provided between the coupling and selector.
Such a shift device allows for shifting on-the-go despite the input and output shafts lacking fully synchronized rotational speeds. Such a shift device is useful in many devices, including two-speed axles, subtransmissions (such as secondary transmissions or two-speed gearboxes), 4WD shift mechanisms and power take-off units. The shift mechanism may be coordinated with a computer to synchronize the input and output speeds to improve the shift “feel”.
Such a mechanism is further improved using an electronic controller to adjust the input and output rotational speeds closer to synchronous, utilizing engine, transmission and ABS control features in conjunction with adaptive shift motor controls. A shift device according to the present invention thereafter completes the shift at substantially synchronous speeds preferably using a “snap-action” shift device.


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