Endless belt power transmission systems or components – Friction drive pulley or guide roll – With particular belt
Patent
1995-12-19
1997-05-20
Schoeppel, Roger J.
Endless belt power transmission systems or components
Friction drive pulley or guide roll
With particular belt
474197, 474199, 474902, F16H 5540
Patent
active
056307691
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a tension roller, particularly for belt drives of the type made of a plastic material, a castable material or a material spray-coated with a plastic material for adjusting a tension in a belt drive, comprising a wheel having an inner ring and an outer ring connected to each other by axially oriented, circumferentially spaced ribs and by a central web, the wheel being rotatably mounted on a support element which bears by a running face against a belt.
STATE OF THE ART
It is possible to adjust a desired belt tension in a belt drive with the help of a tension roller. From DE 32 26 419 A1, a tension roller is known in which a wheel made of a plastic material is mounted on a support element by means of a rolling bearing. The wheel includes an inner ring which is arranged rotationally fast on an outer ring of the rolling bearing and is connected by a central web and by axially extending, circumferentially uniformly spaced ribs to an outer ring. A connection with the belt drive is established via a running face of the outer ring.
At certain speeds of rotation, the uniform spacing of the ribs can lead to a resonance accompanied by detrimental noise stimulation which is particularly undesired in modern vehicles and detracts from comfort.
OBJECT OF THE INVENTION
It is an object of the invention to create a tension roller with reduced running noises.
THE INVENTION
The tension roller of the invention made of a plastic material, a castable material or a material spray-coated with a plastic material for adjusting a tension in a belt drive, comprising a wheel having an inner ring and an outer ring connected to each other by axially oriented, circumferentially spaced ribs and by a central web, the wheel being rotatably mounted on a support element which bears by a running face against a belt, is characterized in that successive ribs (12, 32, 52) enclose different angles therebetween with reference to a central point of the wheel (7, 27, 47).
The invention provides that the successive ribs of the wheel enclose different angles therebetween with reference to a central point of the wheel. Compared to the hitherto generally used uniform rib spacing, the non-uniform spacing of the ribs effectively eliminates resonance formation and contributes in particular to meeting the requirement of noise optimization in belt drives of automobile engines.
Conditional upon their manufacturing process, the plastic wheels of tension rollers have certain circularity errors, i.e. the portions of the running face between the ribs comprise almost straight sections instead of the desired curvature, so that the belt is periodically tightened in the region of the ribs and slackened in the intermediate portions. This causes a stimulation of vibration of the belt guided on the running face of the plastic wheel, and at certain speeds of rotation, the vibrations are intensified in the case of uniformly spaced ribs into a resonance accompanied by noise stimulation.
Due to the non-uniform spacing of the ribs as provided by the invention, different distances are advantageously obtained on the running face so that no uniform excitation of the belt is possible and the running noise of the tension roller is not detrimentally increased. The advantageous minimum distance between two adjacent ribs is 0.5 degrees or more.
In one embodiment of the invention, the ribs are arranged with periodically recurring angular dimensions. It is possible, for example, to choose a rib arrangement in which a particular angular distance occurs after every five ribs. If this measure is implemented, a balancing of the tension roller required for high speeds of rotation can advantageously be dispensed with or at least simplified.
To avoid excessively large differences in rib spacing, recites a maximum difference of <5 mm for all distances between ribs in the region of the running face is provided.
Another embodiment provides for the arrangement of intermediate ribs in alternation with standard ribs. Intermediate ribs are advantageously suited for t
REFERENCES:
patent: 989779 (1911-04-01), Harris
patent: 3350950 (1967-11-01), Gandrud
patent: 4794998 (1989-01-01), Iwai et al.
Kampitsch Klaus
Schmidt Werner
INA Walzlager Schaeffler KG
Schoeppel Roger J.
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