DE2161666C3 - Orthogonal wheel gear - Google Patents

Description

40

In a known orthogonal wheel drive which is the starting point of the present invention (US-PS 16 94 028) can the tooth flanks of the worm, those of the vertical on the two Axes facing have any profile because these flanks are not involved in the power transmission take part. The gear has only one direction of rotation, and only the convex flanks of the worm are driving flanks.

The object of the present invention is, in contrast, in the course of z. B. from DT-PS 11 95 125 or 10 53 269 in general direction of technical development an orthogonal wheel drive to create high load capacity, which operated in a power-transmitting manner in both directions of rotation can be and whose two screw flanks are highly resilient. In addition, they should be as optimal as possible Engagement ratios and undercut conditions are realized as this in itself is also sought in US-PS 16 94 028.

Flank training is used to solve the task at hand proposed in accordance with the characterizing part of the patent claim specified at the beginning.

A tooth shape obtained according to the present proposal for the invention is per se from US Pat 36 276 known, but with a form milling cutter whose cutting edges have a corresponding convex-concave course. That training is there chosen in order to ensure that the teeth of the bevel gears produced make point contact with one another have, and aspects of the resilience of appropriately designed gear flanks are included not addressed.

In the wheel drive designed according to the invention, the angle cv ₂ of the profile of the screw turns facing the common vertical on the axes is very small at the tip, which has a beneficial effect on increasing the contact pressure resistance. In addition, the design according to the invention leads to reduced stress concentrations at the foot of the screw turns, since the transition of the concave flank into the screw base cylinder takes place more gradually and to an increased flexural strength of the thread root due to the greater thickness at this point. In this way, the load capacity of the transmission is higher when these flanks are used to transmit power.

In order to further explain the invention, an exemplary embodiment is given below with reference to FIG Drawings described. It shows

F i g. 1 an orthogonal wheel drive viewed in the direction of the worm wheel axis,

r i g. 2 a section through a turn of the cylindrical worm,

F i g. 3 a reduction gear built with the gear according to the invention.

The gear consists of the cylindrical worm 1, the axis of which is designated by 2, and of the worm wheel 3 with the axis 4. The worm wheel is designed as a face gear with the ring gear 5. The turns 6 of the worm 1 have the same height h over their entire length, ie both the tooth roots and the tooth tips lie on a cylinder 7 and 8, respectively.

Worm 1 and worm wheel 3 are arranged so that they are outside the plane, which through the axis 4 of the worm wheel 3 goes and is perpendicular to the axis 2 of the worm 1, are in engagement.

The flanks 9 of the windings 6, which face the perpendicular 10 on the two axes of the transmission are, d. H. the "front sides" have a concave profile, while those opposite them Flanks 11, d. H. the "backs" have a convex profile.

The profile curves of the turns 6 are continuous and non-broken curves of any shape, e.g. B. circular or elliptical arcs, parabolic or sinusoidal sections.

The center of curvature C _{1 of} the profile of the front side 9 at its point of intersection 12 with the generatrix of the central cylinder 13 of the turns 6 of the screw 1 is always outside of said cylinder 13, while the center of curvature C _{9 of} the profile of the rear side 11 is at its point of intersection 14 with it the generatrix of the central cylinder 13 of the turns 6 of the screw 1 is always located within said cylinder 13.

The tangent 15 placed on the profile of the front side 9 of the turns at point 12 forms with the Plane 16, which is perpendicular to the axis 2 of the screw 1, an angle <* ", which is in the area between 5 and 20 °, while the profile of the front 9 in its intersection 18 with the

Tooth head cylinder 8, the tangent 17 placed with the plane 16 forms an angle <x ₂ , which is in the range between 0 and 10 °.

The radius of curvature ^ _{1 of} the profile of the front side 9 is at point 12 equal to 0.5 to 2.0 of the diameter (I _{1 of} the central cylinder 13 of the screw 1.

The concave profile shape of the front side 9 of the windings 6 and the areas in which the angles Ot ₁ , α, and the radius O _{1 are} selected ensure increased contact pressure and flexural strength of the windings 6 and, consequently, increased load capacity of the transmission when these Front side of the turn comes into play.

The tangent 19 placed on the profile of the rear side 11 at point 14 forms an angle cv ₃ between 20 and 35 ° with the plane 16, which is perpendicular to the axis 2 of the screw 1, while the one on the profile of the rear side 11 at its intersection 21 with the outer cylinder 8 laid tangent 20 with the plane 16 forms an angle <x _i between 30 and 50 °. The radius of curvature ρ. Of the rear side 11 is equal to 0.5 to 1.5 3th diameter d _{x of} the central cylinder 13 of the screw 1 at point 14.

To ensure that the flanks of the turns 6 of the worm 1 are in engagement with them To achieve standing flanks of the teeth 22 of the worm wheel 3, the pitch / the windings 6 according to calculated using the following formula:

t =

InA

η 11: - ■

2R

/ 4 = distance between axes, ie the distance between the points of intersection O ₁ and O _{2 of} the common perpendicular 10 on the axis 2 of the worm 1 and on the axis 4 of the worm wheel 3 with the axes mentioned in mm;

η = number of turns of the worm 1;

/ = Ratio of the number of teeth 22

of the worm wheel 3 to the number of turns η of the worm 1, ie the transmission ratio of the gear;

Z ₁ and Z ₂ = distances from the plane that goes through the vertical 10 on the two axes and is perpendicular to the axis 2 of the screw 1, to the adjacent end face 23 or to the remote end face 24 of the engaged screw part in mm;

R - radius of the outer cylinder 8 of the screw 1 in mm.

The parameters of the teeth 22 of the ring gear 5

of the worm wheel 3 depend on the parameters of the worm 1 and the transmission as a whole. The The gear ratio of the transmission can be between 3 and 450.

F i g. 3 shows a specific application example of the transmission, specifically in a rear axle reduction gear of a passenger car.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Orthogonal gear drive with intersecting, mutually offset axes and with a constant, S curvilinear tooth flank profile, with a face gear as a worm gear and with a cylindrical worm with asymmetrical tooth flanks, whereby the tooth flanks of the worm that are facing away from the vertical on the two axes are convex Have profile that has a center of curvature within this cylinder at its intersection with the central cylinder of the screw, characterized in that the tooth flanks (9) of the screw (1) facing the perpendicular (10) on the two axes are concave Have a profile which at its intersection (12) with the central cylinder (13) of the screw has a center of curvature (C ₁ ) outside this cylinder, the tangent (15) to the concave profile of the flanks (9) at its intersection ( 12) with the middle cylinder (13) of the screw (1) with the plane (16) perpendicular to its axis (2) a Wi nkel (^ ₁ ) between 5 and 20 °, and the tangent (17) to the named profile at its intersection (18) with the outer cylinder (8) defined by the tooth tips with the named plane (16) forms an angle (a ₂ ) forms between 0 and 10 °, whereby the radius of curvature ^ ₁ ) of the said profile at the point of intersection (12) with the central cylinder (13) of the screw (1) is 0.5 to 2.0 times the diameter Id ₁ ) of the middle screw cylinder (13).