Prestressed shaft and hub connection having a perfect cone shape
View Patent ↗The invention relates to a shaft and hub connection ( 20 ) for transmitting torque, a common longitudinal axis (X-X) comprising the following components: a shaft ( 22 ) which rotates about the longitudinal axis (X-X) and comprises an entraining longitudinal section having an untrue outer contour ( 26 ), and a hub ( 24 ) that is coaxial to the shaft ( 22 ) and encloses the shaft ( 22 ) with its internal contour ( 28 ) at least in the area of the entraining longitudinal section. The invention is characterized in that the outer contour ( 26 ) of the entraining longitudinal section of the shaft ( 22 ) and the inner contour ( 28 ) of the hub ( 24 ) have the shape of a perfect cone to such a degree that, when the shaft ( 22 ) and the hub ( 24 ) are assembled, they automatically self-lock, thereby holding the shaft and hub connection ( 20 ) together. The connection also comprises connecting means which prestress the shaft ( 22 ) and the hub ( 24 ), when assembled, in the direction of the longitudinal axis (X-X).
1. A shaft/hub connection ( 20 ) for transmitting torque, comprising the following components having a common longitudinal axis (X-X):
a shaft ( 22 ), which can be rotated about the longitudinal axis (X-X), the shaft comprising an entraining longitudinal section having a polygonal or trochoidal outer contour ( 26 );
a hub ( 24 ), which is coaxial to the shaft ( 22 ) and which encloses the shaft ( 22 ) with a longitudinally extending end recess having a corresponding polygonal or trochoidal inner contour ( 28 ) at least in the area of the entraining longitudinal section; and
a connecting means that prestresses the shaft ( 22 ) and the hub ( 24 ) when in a joined state, towards the longitudinal axis (X-X);
wherein the outer contour ( 26 ) of the entraining longitudinal section of the shaft ( 22 ) and the inner contour ( 28 ) of the hub ( 24 ) have the shape of a perfect cone to such an extent that, when the shaft ( 22 ) and the hub ( 24 ) are joined, the shaft and the hub automatically frictionally self-lock, thereby holding the shaft/hub connection ( 20 ) together;
wherein the connecting means is formed by a prestressing ring ( 34 ), which encompasses ramps ( 30 ), which are respectively disposed on an outer side of the shaft ( 22 ) adjacent the entraining longitudinal section and on an outer side of the hub ( 24 ) adjacent the recess, and which revolves around the longitudinal axis (X-X) and thus holds the shaft/hub connection ( 20 ) under prestress;
wherein the prestressing ring ( 34 ) has a circumferential sidewall ( 38 ) and a plurality of circumferentially spaced side wall sections ( 40 ) that clampingly engage the ramps and deform elastically at the ramps ( 30 ) of the outer side of the shaft ( 22 ) and the outer side of the hub ( 24 ) when the prestressing ring is secured to the shaft and hub; and
wherein the axial length of the entraining longitudinal section is up to 40% of the average cone diameter of the cross section of the polygonal or trochoidal entraining longitudinal section.
2. The shaft/hub connection ( 20 ) according to claim 1 , wherein the outer contour ( 26 ) and the inner contour ( 28 ) has a polygonal shape.
3. The shaft/hub connection ( 20 ) according to claim 2 , wherein the outer contour ( 26 ) of the shaft ( 22 ) in the area of the entraining longitudinal section has an outer cone angle (A) of from 0.5° to 7°.
4. The shaft/hub connection ( 20 ) according to claim 3 , wherein the shaft ( 22 ) has a six-sided outer contour ( 26 ) and the hub ( 24 ) has a six-sided inner contour ( 28 ), wherein the relative eccentricity E amounts to between 3% and 5% and is computed according to the formula E=(D 0 −D i /D 0 −D i )×50, wherein D 0 is the outer diameter of the contour and D i is the inner diameter of the contour.
5. The shaft/hub connection according to claim 2 , wherein the polygonal contours can be determined by the following formulas:
x (γ)=( D m /2)×cos(γ)+ε×cos(( n− 1)×γ)
y (γ)=( D m /2)×sin(γ)−ε×sin(( n− 1)×γ),
wherein D m is the diameter of a circular disk having the same surface content as the polygon;
wherein γ is a continuous parameter 0° to 360°;
wherein n is the number of sides of the polygon;
wherein ε is the out-of-roundness of the polygon; and
x and y are coordinates.
6. The shaft/hub connection ( 20 ) according to claim 1 , wherein the ramps ( 30 ) each have a slope ( 32 ) approaching each other in the direction away from the shaft/hub connection ( 20 ) and cooperating with an inner side of side walls ( 38 ) of the prestressing ring ( 34 ).
7. The shaft/hub connection ( 20 ) according to claim 6 , wherein the slopes ( 32 ) of the ramps ( 30 ) include an angle of from 20° to 28° and wherein the side walls ( 38 ) include an angle of from 14° to 22°, in each case with a plumb line on the longitudinal axis (X-X).
8. The shaft/hub connection ( 20 ) according to claim 1 , wherein the prestressing ring ( 34 ) in its circumference has an ear ( 26 ) pointing outwards and having the shape of an omega, via which the diameter of the prestressing ring ( 34 ) can be reduced by pressing together the sides of the omega.
9. The shaft/hub connection ( 20 ) according to claim 1 , wherein the prestressing ring ( 34 ) is embodied so as to be balanced for rapidly rotating connections.
10. A shaft/hub connection ( 20 ) for transmitting torque and defining a common longitudinal axis (X-X), the shaft/hub connection comprising:
a shaft ( 22 ) which can be rotated about the longitudinal axis (X-X) of the shaft/hub connection, the shaft comprising an entraining longitudinal section having a polygonal or trochoidal outer contour ( 26 ), the shaft defining a ramp ( 30 ) disposed along an outer side of the shaft adjacent the entraining longitudinal section, the ramp extending around the longitudinal axis (X-X);
a hub ( 24 ) positioned coaxial to the shaft ( 22 ) and having a longitudinally extending end recess having a corresponding polygonal or trochoidal inner contour ( 28 ) that encloses at least a portion of the entraining longitudinal section of the shaft, the hub defining a ramp ( 30 ) disposed along an outer side of the hub adjacent the recess and extending around the longitudinal axis; and
a prestressing ring ( 34 ) having side walls ( 38 ), the ring surrounding the ramps of the shaft and hub, and applying a prestressing force against the shaft ( 22 ) and the hub ( 24 ) when connected, the prestressing ring ( 34 ) having a circumferential sidewall ( 38 ) and a plurality of circumferentially spaced side wall sections ( 40 ) that clampingly engage the ramps and deform elastically at the ramps ( 30 ) of the outer side of the shaft ( 22 ) and the outer side of the hub ( 24 ) when the prestressing ring is secured to the shaft and hub;
wherein the polygonal or trochoidal outer contour ( 26 ) of the entraining longitudinal section of the shaft ( 22 ) and the inner contour ( 28 ) of the hub ( 24 ) have the shape of a perfect cone such that the shaft ( 22 ) and the hub ( 24 ) automatically frictionally self-lock when joined, thereby holding the shaft/hub connection ( 20 ) together; and
wherein the axial length of the entraining longitudinal section of the shaft is up to 40% of the average cone diameter of a cross section of the polygonal or trochoidal entraining longitudinal section of the shaft.