Fixed-ratio planetary traction gear
The gear is used for driving pneumatic turbomachinery while providing insignificant impact of the tolerances on the performance parameters leading to extended service life. It comprises a sun shaft ( 1 ) supported and driven by at least three planet wheels ( 2 ) rotating around their axes, on each side of which in axial direction there is an identical radially-elastic flat frame ( 7 ) in the shape of a flat planar closed-contour element having at least three annular bearing slots ( 7.1 ) with a cylindrical hole accepting the respective bearings ( 4 ) of the planet wheels ( 2 ). The bearing slots ( 7.1 ) are equidistant from the center of the frame ( 7 ) and each two adjacent bearing slots ( 7.1 ) are connected to one another via a respective curvilinear bridge ( 7.2 ) whose inner bend, towards the center, has an ear formed thereon ( 7.4 ) accepting the respective support pillar ( 6 ) fixed to the rear housing ( 5 ).
1. Fixed-ratio planetary traction gear, comprising:
a rotating sun shaft whose axis of rotation coincides with the axis of an input shaft,
which is mounted on bearings into a housing,
where the sun shaft is supported and driven by at least three rotating around their own axes planet wheels encompassed by an outer ring axially fixed to the input shaft and installed by means of radial pre-stretch over the planet wheels,
which position the said outer ring in radial direction and are driven by it, while the planet wheels are mounted onto respective bearing slots and the said sun shaft is fixed axially by the contact with the planet wheels characterized by the fact that the housing comprises a rear housing ( 5 ) with support pillars ( 6 ) fixed to said rear housing and equal in number to the planet wheels ( 2 ),
where each support pillar ( 6 ) is located symmetrically between two adjacent planet wheels ( 2 ), with,
located on each side of the planet wheels ( 2 ) in the axial direction, an identical, radially-elastic flat frame ( 7 ),
which is movable in relation to the housing,
with the said frames ( 7 ) having respective bearing slots ( 7 . 1 ) to accept the bearings ( 4 ) of the planet wheels ( 2 ) and respective ears ( 7 . 4 ) to accept the support pillars ( 6 ).
2. Fixed-ratio planetary traction gear according to claim 1 , characterized by the fact that each elastic flat frame ( 7 ) is a flat, planar, closed-contour component with constant thickness, which comprises at least three annular bearing slots ( 7 . 1 ) with a cylindrical hole to accept the respective bearing ( 4 ) of the respective planet wheel ( 2 ), whereas the axes of the annular bearing slots ( 7 . 1 ) are parallel to the axis of the sun shaft ( 1 ) and the annular bearing slots ( 7 . 1 ) are equidistant from a center of the frame ( 7 ) and each two adjacent annular bearing slots ( 7 . 1 ) are connected to one another via a respective curvilinear bridge ( 7 . 2 ) whose inner bend, towards the center, has an ear formed thereon ( 7 . 4 ) to accept the respective support pillar ( 6 ), with the axes of the annular bearing slots ( 7 . 1 ) coinciding with axes of the respective planet wheels ( 2 ).
3. Fixed-ratio planetary traction gear according to claim 1 , characterized by the fact that in fully assembled state each elastic flat frame ( 7 ) is prestressed in radial direction by selection of the concentricity factor CF.
4. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that each ear ( 7 . 4 ) of the elastic flat frames ( 7 ) has the shape of a closed contour.
5. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that each ear ( 7 . 4 ) of the elastic flat frames ( 7 ) has the shape of a part of a closed contour.
6. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that the ears ( 7 . 4 ) are equidistant to each other.
7. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that a cylindrical hole in each of the ears ( 7 . 4 ) has at least one radial undercut ( 7 . 5 a , 7 . 5 b ).
8. Fixed-ratio planetary traction gear according to claim 7 , characterized by the fact that the radial undercut ( 7 . 5 a , 7 . 5 b ) is concave in relation to the cylindrical hole in the ears ( 7 . 4 ), has a curvilinear shape and is symmetrical to a line connecting the axis of the ear ( 7 . 4 ) and a center of the frame ( 7 ), and is limited by a respective segment angle a, ß.
9. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that a cylindrical hole of each of the ears ( 7 . 4 ) has an outer radial undercut ( 7 . 5 a ) and an inner radial undercut ( 7 . 5 b ).
10. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that a segment angle a is within the range of 10° to 90°, while a segment angle ß is within the range of 10° to 70°.
11. Fixed-ratio planetary traction gear according to claim 1 , characterized by the fact that the support pillars ( 6 ) have a shape of cylinders.
12. Fixed-ratio planetary traction gear according to claim 7 , characterized by the fact that the support pillars ( 6 ) have the shape of prisms.
13. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that a ratio of a radial stiffness of the outer ring ( 3 ) to the radial stiffness of the frame ( 7 ) is within the range of 5 to 100.
14. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that a eccentricity of the annular ear ( 7 . 4 ) in relation to the support pillar ( 6 ) is within the range of 0.1% to 3.0% of a pitch circle radius R1+R2 of the planet wheels ( 2 ).
15. Fixed-ratio planetary traction gear, according to claim 1 , characterized by the fact that a concentricity factor CF is within the range of −3% to +3% of a pitch circle radius R1+R2 of the planet wheels ( 2 ).