Endless belt power transmission systems or components – Plural belts or plural output loads
Patent
1996-06-06
1998-05-12
Schoeppel, Roger J.
Endless belt power transmission systems or components
Plural belts or plural output loads
474148, 474205, F16H 1906
Patent
active
057498008
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a synchronous belt drive with a high multiplication ratio for transforming a rotary movement into a translation or rotary movement.
Synchronous belt drives with high multiplication ratios for linear units are known. Mounted on a slide, movable between a driving wheel and a return wheel, are at least two interconnected driven wheels which are secured against independent rotation and on which a toothed belt is pressed with snub pulleys. The differences of the numbers of teeth of the interconnected wheels effect slide travel.
An embodiment produced by the Mulco company has a driven wheel rotated by a top strand and a bottom strand at the same time. A second, smaller gear is connected with the driven wheel. Also one strand of the toothed belt engages the smaller gear.
Another embodiment produced by the CYBERTRON company has two driven wheels equal in size which are engaged with one strand each at the same time. A second gear is attached to each of the two driven wheels. These have a difference in the number of teeth and are interconnected by a second toothed belt so that they are secured against rotation.
A similar embodiment is disclosed in the JP-PS 61-149665. Toothed outer sides of a top strand and a bottom strand are pressed on one driven wheel each. Both driven wheels are connected with each other by a toothed belt so that they are secured against rotation. The wheels of this belt drive (each of them being secured together with the driven wheels) are different in diameter.
The difference in the number of teeth causes a linear movement, i.e., the driven wheels not only rotate but also move parallel to the top strand and the bottom strand. The highest multiplication ratio, and therefore the minimum linear speed, results at the minimum difference possible in the number of teeth.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a synchronous belt drive with a high multiplication ratio.
In accordance with the present invention a synchronous belt drive has a driving wheel, a driven wheel and a return wheel and two interconnected wheels secured against independent rotation. At least two rows of teeth with different pitches interconnected by a toothed belt. The rows of teeth with different pitches are each engaged with one of the wheels of the pair of wheels secured against rotation. The rows of teeth with different pitches can be achieved on the inner or outer side of a toothed belt with double toothing or on the inner or outer sides of two parallel toothed belts.
The drive multiplication ratio is based on the products of the numbers of teeth of the wheels, connected with each other so that they are secured against independent rotation, multiplied by the different pitches of the respective row of teeth engaged with them differing from each other at least slightly. The smaller the product difference is, the higher is the multiplication ratio. This product difference can be preferably accomplished by a difference in the number of teeth of the rows of teeth by at least one tooth for pairs of wheels which are equal and rows of teeth of equal length. In contrast to the drives with a high multiplication ratio having a small difference in the number of teeth of the wheels, such as the harmonic drive, the multiplication ratio is determined not only by the difference in the number of teeth, but also very considerably by the belt length at which this difference of the number of teeth is achieved. The longer the toothed belt is, the smaller is the difference of pitches for the same difference of the number of teeth. After all, very fine gradations and, therefore, high multiplication ratios may be achieved, even when the tooth moduli are high for reasons of resistance.
Toothed belts with double toothing and opposite-sense contact of the inner pair of gears also allow the transmission of high momenta without any essential constructional restrictions.
The drive can be used for linear drives as well as for transforming a rotary movement into
REFERENCES:
patent: 2309578 (1943-01-01), Drachman
patent: 5006096 (1991-04-01), Breher
patent: 5209705 (1993-05-01), Gregg
patent: 5382198 (1995-01-01), Janne
patent: 5421789 (1995-06-01), Gregg
Antriebstechnik, vol. 32, No. 2, Feb. 1993 pp. 33-36, XP000339270 R. Perneder "Verdrehsteife Roboterantriebe dank Polyurethan-Sychronriemen" see p. 36, paragraph 5; figure 9.
Nagel Thomas
Richard Ulf
Schoeppel Roger J.
Technische Universitaet Dresden
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