DE29517963U1 - gear - Google Patents

Description

Maag Gearbox AG m/shz-046-de

Hardstrasse 219 13 November 1995

CH-8023 Zurich

gear

The present invention relates to a gear with involute toothing, in particular for high-speed transmissions.

In high-speed gears, the gears move at speeds of up to 200 m/sec, i.e. at speeds comparable to those of airplanes. Air currents cause high wind and ventilation losses.

When the teeth engage, the air, which is usually mixed with a mist of small oil drops, is compressed quickly and strongly. This causes the so-called compression or crushing losses.

This circumstance is not taken into account in today’s tooth shapes, although the crushing losses are relatively significant compared to, for example, the friction losses.

The object of the present invention was to remedy these disadvantages.

This problem was solved in a gear according to the invention in that the tooth flanks of the teeth outside the active involute profile, both at the head and at the root, are designed to be aerodynamic, i.e. such that no sharp edges occur in these surfaces (as is usual today, especially at the transition of the flank into the outer surface of the head).

ft · «4· 4

By optimizing the tooth shape, especially in the head area, crushing or compression losses could be significantly reduced.

The size of the oil droplets is of crucial importance for the residual losses in gears running in a partial vacuum. Very small particles are quickly slowed down, do not condense and return to the gear mesh (squeezing losses). Larger droplets (10/e and above), on the other hand, can be deflected and condensed and drained away, for example, on collecting plates.

The surface and shape of the teeth influence the droplet formation, since the shape of the surface, the surface tension between oil and steel, the internal friction and the centrifugal forces determine the size of the droplets thrown away.

Thanks to the tooth flanks without discontinuous transitions (no edges) and, if necessary, the fine grinding of the tooth flanks also at the base and the head, it is prevented that the droplets that have formed split up again and thus maintain their optimal size of, for example, over }0xst .

The drawing shows a schematic example of an optimized tooth shape.

It can be seen from this that in particular the transition of the tooth flank 2 of a tooth 1 into the head outer surface 3 is now designed as a curved surface 4 instead of as previously an edge. The head outer surface 3 itself is also curved, so that a flow-optimized surface

surface contour is ensured (no abrupt tearing at the edge). A streamlined shape is also provided in the foot area 5.

In addition, the entire tooth flank, especially in the head and root area, is finely ground so that the optimized surface finish also helps to solve the problem.

Viewed in section, the head area presents itself with radii r and r, and the foot area with transition radii r» and a connecting line G.

Claims (3)

Protection claims 1. Gear with involute toothing, in particular for high-speed transmissions, characterized in that both at the head and at the foot of the teeth, the tooth flanks outside the active involute profile are designed in such a way that no sharp edges occur in these surfaces. 2. Gear according to claim 1, characterized in that the head and/or root surfaces of the teeth are machined by fine grinding. 3. Gear according to claim 1 or 2, characterized in that the transition between the tooth flank and the head outer surface is designed as a curved, in particular cylindrical surface, and that the head outer surface is also a curved surface.