Machine element or mechanism – Gearing – Rotary bodies
Patent
1993-10-06
1995-04-18
Herrmann, Allan D.
Machine element or mechanism
Gearing
Rotary bodies
475182, F16H 5517
Patent
active
054068630
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a toothed wheel or gear with a variable number of teeth.
Such gear mechanisms are known from German Published, Non-Examined Patent Applications DE-OS 21 62 074, DE-OS 18 06 571, from German Letters Patents DE-PS 854 301, 727 593, 142 329 and from French Letters Patents 1 114 218 and 1 295 478.
German Patent Publication DE-A-18 06 571 discloses a single-stage planetary gear, in which the drive chain acts as an internally-geared toothed wheel. This toothed wheel is formed by a drive chain, the length of which is adjustable. A transmission ratio of the planetary gear is changed by changing the length of the drive chain. It has been shown to be disadvantageous that the drive chain is guided only over a few radially adjustable guides distributed over the circumference, so that the gear ring greatly diverges from its ideal circular shape. Therefore this gear can only be used at low rpm and also with high noise output.
SUMMARY OF THE INVENTION
Based on this state of the art, it is an object of the present invention to provide a multistage shiftable gear which can also function at high rpm and with low operational noise.
To attain this object, the present invention provides that all links of the drive chain located in the reference circle are laterally guided at a concentric, radially changeable distance from the axis of rotation and that the drive chain is placed under pre-stress.
Because of the present invention providing support of each individual link of the drive chain located in the reference circle it is assured that the chain does not s ag between the individual supports, and instead takes on an ideal circular shape. In this way a continuously good meshing between the toothed wheel and the transfer member is assured, so that it is also possible to attain a high rpm and especially to keep operational noise low.
In addition, the auxiliary toothed wheel can be disposed in a space-saving manner at the shortest possible distance from the gear ring. A sturdy construction along with an optimally low structural weight is possible for this reason. Thus, the deflection of the drive chain into the magazine can take place in a space-saving manner and with the smallest deflection radius. During operation, the drive chain is supported on the deflection side in such a way that the last link is still completely located in the reference diameter. Therefore, an optimal transfer of force and optimally low operating noise is achieved. A gear change during operation and even under load is possible, however, the shifting operation can only be performed if the energy transfer member does not prevent it in a positively form-fitting manner. The gear of the present invention is suited in particular for use in a planetary gear wherein the toothed wheel does not turn.
Preferably, the last link of the drive chain which is still engaged is supported by the auxiliary toothed wheel, by means of which an optimum support of the drive chain ahead of the magazine is assured and no friction problems occur during transit into the magazine. It is also pointed out, that belts, straps and wheels can be used as transfer members, where in the case of belts and straps the force to be transferred is evenly spaced in an advantageous manner over the entire envelope arc.
The gear change is realized in a particularly simple structural manner if the links of the drive chain have lateral support surfaces which cooperate with two cones, the axial distance of which can be changed, wherein the axial distance change of the cones is correlated with a change in the reference diameter of the gear ring and a corresponding change of the gear ratio is connected therewith.
Guidance optimization can be achieved in that the shape of the support surfaces on both sides of the drive chain is represented by two planes inclined at an angle with respect to each other, so that all four planes, two per cone, are supported in the form of lines on the cones. The contact of the lines is maintained in every gear. Thi
REFERENCES:
patent: 2669885 (1954-02-01), Fedri
patent: 3051022 (1962-09-01), Way, Jr.
patent: 4497221 (1985-02-01), Koser
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