Reconfigurable power spindle

Details Reconfigurable power spindle Reconfigurable power spindle

2000-04-18

2001-10-30

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

Input from independent power sources

Intermeshing planet pinions in drive train

C074S66500G

Reexamination Certificate

active

06309319

ABSTRACT:

FIELD OF THE INVENTION
In general, the present invention relates to machine tool spindles having multiple power inputs and one output, and to gear train systems capable of accommodating multiple power sources driving a single output while allowing variable contribution of power from each power source, including an equal contribution of power.
BACKGROUND OF THE INVENTION
Generally, a machine tool spindle has a fixed power input from a motor and a fixed power output, limiting its use to a certain range of machining operations and loads. There are, however, applications in which a multiple input or a multiple output is desirable, and may be achieved by a differential or similar type of drive system. Differential drive systems are used in automotive applications to drive, from one input-torque shaft, multiple output shafts connected to wheels, such as in the case of four-wheel drive vehicles. Conversely, multiple input shafts may drive a single propeller shaft, such as in fixed wing aircraft, as described in U.S. Pat. No. 4,829,850. Another related application is the use of hybrid transmissions for vehicles, using two- or four-mode input-split electromechanical transmissions, as described in U.S. Pat. Nos. 5,551,078, 5,577,973, and 5,931,757 to Schmidt, the contents of which are incorporated herein by reference.
Many of the conventional multiple input or multiple output differential drive systems require a combination of 2
n
differentials to provide equal power contribution among the several inputs or outputs, respectively. Greater freedom may be achieved by combining multiple epicyclic gear mechanisms in series, or by combining epicyclic and bevel gear systems, as described in U.S. Pat. Nos. 5,423,726 and 5,435,790, which relate to differential drives with plural or N outputs, respectively. U.S. Pat. Nos. 5,423,726 and 5,435,790 are incorporated herein by reference.
The gear drive mechanisms of the prior art, including those mentioned, are not well-suited to situations in which it is required that the same power spindle performs different machining operations with different power requirements. Nor are existing systems efficient in terms of power use, conservation of resources and reduction of machine set-up time, or space-conservation.
In addition to these considerations, it would also be desirable for the spindle itself to have exactly the power required for any specific operation in a given range of operations, and to be able to modify quickly the power range. The traditional epicyclic gear train consists of a sun gear rotatable about a center axis, one set of planetary gears, an arm or carrier rotatable about the center axis and supporting the planetary gears, and a ring gear rotatable about the center axis. The planetary gears are engaged with the ring gear and the sun gear. This epicyclic gear train may be used for a two-input, one-output application, but the contribution of angular velocity or power between the two inputs cannot be equal. An equal contribution of power is traditionally achieved by employing an additional set of bevel gears at the price of significantly increasing the space requirements, as shown in FIG.
1
.
SUMMARY OF THE INVENTION
The subject invention is directed to a reconfigurable power spindle, which is capable of accommodating different power requirements in an efficient design that not only conserves time and equipment resources, but also reduces space requirements. Two or more power sources provide the inputs which can be distributed equally or unequally, as desired, by means of a novel epicyclic gear train (the component gear train). When two or more such component gear trains are arranged in series, so that the output of one is connected to the input of the next, the result is a gear train system with as many inputs as the number of the component gear trains, plus one. This design of the component gear train allows for equal power contribution from the input shafts to the gear train system.
The present invention achieves equal contribution between two inputs of a component gear train by utilizing two sets of planetary gears carried by an arm, so that the gears of first set are engaged with the sun and with the gears of the second set, which are in turn engaged with the ring gear. This dual planetary arrangement can be used to create a reconfigurable power spindle, i.e. a power spindle that can accommodate one or two inputs with a desirable contribution of power. Higher number of inputs can be easily achieved by connecting additional dual gear trains in series, in parallel or in combination to create a compound gear train system, which exhibits the required properties when the gear sizes are properly adjusted.


REFERENCES:
patent: 5055087 (1991-10-01), Koch
patent: 5316525 (1994-05-01), O'Keefe
patent: 5423726 (1995-06-01), Kota et al.
patent: 5435790 (1995-07-01), Kota et al.
patent: 5551078 (1996-08-01), Connell et al.
patent: 5577973 (1996-11-01), Schmidt
patent: 5931757 (1999-08-01), Schmidt
Kelly, Oliver K., General Motors Corporation. “Design of Planetary Gear Trains” from the SAE paper presented as the 5th L. Ray Buckendale Lecture. pp. 71-76.

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