Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-08-09
2001-09-11
Bonck, Rodney H (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C477S124000, C475S204000
Reexamination Certificate
active
06286379
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of power transmission in a driveline for an automotive vehicle. More particularly, it pertains to a method of shifting multi-speed axles 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 '072 patent is a relatively effective mechanism, but is produced at high cost and not able to engage over a wide speed variation.
It would be desirable to provide a non-blocked engagement device for engaging relatively rotating shafts.
Also, multi-speed axles are commonly used on vehicle drivelines to incorporate different final drive ratios. This allows, for example, a highway gear, for fuel economy, and a towing gear, for maximum vehicle pulling power. Multi-speed axles are typically manually operated and are found on heavy trucks, which have manual transmissions. The use of a manually operated multi-speed axle generally requires a relatively skilled driver with the ability to properly manipulate the accelerator pedal during shifts to synchronize engine speed to axle speed, which has a direct impact on shift smoothness and axle durability.
Currently, the disadvantages of using multi-speed axles, i.e. skilled drivers and manual transmissions, outweigh the advantages, i.e. improved fuel economy with maximum pulling power. With the increased consumer use of light trucks and sport utility vehicles, however, improved fuel economy combined with maximum pulling power and the use of an automatic transmission are very desirable. The need, therefore, is to develop a multi-speed axle capable of providing improved fuel economy and maximum pulling power for use by a typical driver with an automatic transmission.
SUMMARY OF THE INVENTION
To 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 shifting of multi-speed axles, improved shaft mechanisms and methods for shifting multi-speed axles are 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 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 the 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 mechanism 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” and durability.
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. Mechanisms and methods for shifting multi-speed axles according to the present invention thereafter completes the shift at substantially synchronous speeds preferably using a “snap-action” shift device with minimal driver intervention.
A preferred method of shifting a multi-speed axle in a vehicle in accordance with the present invention includes requesting a gear ratio change, synchronizing the speed of the input shaft to the axle with the speed of the output shaft, and then shifting the axle. The request can be made manually by the operator or automatically by the engine controller based upon vehicle load.
Additional advantages and features of the invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.
In order that the invention may be well understood, there will now be described some embodiments thereof, given by way of example reference being made to the accompanying drawings, in which:
REFERENCES:
patent: 4787491 (1988-11-01), Kato
patent: 4944197 (1990-07-01), Stine et al.
patent: 5099711 (1992-03-01), Langbo et al.
patent: 5335566 (1994-08-01), Genis et al.
patent: 5643129 (1997-07-01), Richardson
patent: 5802915 (1998-09-01), Organek et al.
patent: 5888165 (1999-03-01), Besler et al.
patent: 5970811 (1999-10-01), Imao et al.
Fodor Michael Glenn
Tanzer John H.
Yester John Loring
Bonck Rodney H
Ford Global Technologies Inc.
McKenzie Frank G.
Pang Roger
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