Rotary drive, in particular for vehicle doors

Rotary drive, particularly for vehicle doors, in which the piston motion of a piston-power cylinder-unit 5 is converted into a rotary motion by means of roller pairs 14 which engage into oblique slots 10, 11. The oblique slots are provided in cylinders 4, 6 arranged coaxially inside each other and one of the cylinders is connected to the power output shaft 7. The slots exhibit an axial direction at their ends. Herein the cover 2 of a pot-shaped housing 1, through which cover the power output shaft 7 passes, exhibits a collar 15 projecting outwards and embracing the power output shaft. The power output shaft 7 is provided with a cup-type seal 17 seated firmly upon it, whose surface contour 18 overlaps outwardly the collar 15 and which with its edge 19 rests tightly at the cover 2. The cover is provided with an axially oriented groove 20 on its side facing away from the collar, into which groove the edge of the pot-shaped housing 1 is tightly fitted.

The invention is directed to a rotary drive, in particular, for vehicle 
doors, in which the piston motion of a hydraulic or pneumatic piston-power 
cylinder-unit is converted into rotary motion of one of the cylinders 
connected with a power output shaft by means of roller pairs, which engage 
into inclined slots provided in cylinders arranged coaxially inside each 
other, wherein the slots transit into an axial direction at their end. 
The known rotary drives of this type exhibit the disadvantage that they 
often do not satisfy the exacting conditions to which they are exposed. 
Above all the leakage in the housing repeatedly occurs, principally in the 
region of the passage of the power output shaft, so that functional 
deficiencies arise. 
The aim of the invention is the creation of a rotary drive with a 
leak-proof housing, which, however, does not complicate the accessibility 
to the components of the drive. 
This aim is attained in the invention in that the cover of the pot-shaped 
housing, through which the power output shaft passes, exhibits a collar 
embracing the power output shaft, which collar projects outwards and in 
that the power output shaft is equipped with a cup-shaped seal firmly 
seated in an annular groove, whose surface contour overlaps the collar 
from the outside and rests tightly at the cover with its edge, wherein 
said cover is provided with an axially oriented annular groove at its side 
facing away from the collar, into which the edge of the pot-shaped housing 
is tightly fitted. 
The invention is further directed to the structural embodiment of the 
rotary drive.

A pot-shaped housing 1, FIG. 4, consisting of the parts 1a and 1b is sealed 
with the cover 2, which exhibits an attachment flange 3 for the rotary 
drive. An outer cylinder 4 is provided inside of the housing, which 
cylinder is rigidly connected with the cover 2 and with a piston-cylinder 
unit designated with 5 in its entirety. This unit can be laid out for 
hydraulic or pneumatic media. A second cylinder 6 is provided coaxially 
inside of the cylinder 4, which second cylinder transits into a power 
output shaft 7 passing through the cover 2. The inner cylinder is 
rotatably supported in the ball bearings 8, 9. 
Both cylinders exhibit slots 10 and 11, which extend obliquely to the axis 
of the drive and transit at their ends into an axial direction, as is 
shown in the FIGS. 2 and 3. 
A radially oriented axis 13 sits on the piston rod 12 of the piston 
cylinder unit 5 on which axis roller pairs 14 are rotatably supported on 
both sides. The rollers run in the slots 10 and 11. In case of an axial 
movement of the piston rod 12 the inner cylinder 6 and with it the power 
output shaft 7 is rotated relatively to the outer cylinder 4 and the door 
movement is effected in this manner. The construction of the rotary drive 
is known and therefore not a subject of the invention. 
For a tight termination of this drive a cover 2 is provided with a collar 
15 embracing the power output shaft 7, whose outer front face extends 
obliquely towards the cover edge, so that the liquid can be diverted 
towards the circumference. The power output shaft 7 is provided with an 
annular groove 16, into which a cup-shaped seal 17 is tightly fitted. The 
outer contour 18 of this seal overlaps the collar 15 and the seal edge 19 
rests tightly at the front face of the cover 2. Said cover exhibits at the 
opposite side an axially oriented groove 20, into which the edge of the 
housing 1 is tightly fitted. 
In this manner a completely satisfactory sealing is assured also in the 
course of exacting operation as tests have shown. In order to facilitate 
the accessibility of the individual components, the housing 1 is 
preferably divided along a plane which extends parallel to the piston rod 
12, as shown in FIG. 4. 
It is often desired that the condition of the rotary drive be indicated, 
principally the locking condition must be indicated. For this purpose it 
has been been the practice to provide an appropriate switch, which is 
acted upon in circumferential direction by the position of the axis 13 of 
the roller pairs 14. Since, however, the orientation of the slots 10 and 
11 approaches the axial direction in their end area, the scanning accuracy 
is low. In order to remove this discrepancy it is provided in the 
invention to scan the axial position of the axis 13. Since the motion of 
this axis 13 in the end section of the slots 10 and 11 in axial direction 
greatly exceeds the motion in circumferential direction, the accuracy of 
the scanning can thus be considerably improved. 
As is shown in FIG. 2 the switch 22 is provided at an arm 21, whose switch 
arm 23 carries a scanning roller 24, which cooperates with a disk 25 
seated upon the axis 13. In the position of the switch 22 depicted in the 
FIG. 1 the final position of the rotary drive is being scanned and thus 
the signal "door locked" is given. 
According to FIG. 3 the switch 22 is arranged to be offset at the arm 21 
and this arm is attached in an oblique manner, so that the scanning roller 
24 monitors the disk 25 in a movement segment of the axis 13, which is 
constituted by the transition of the slots 10, 11 into the axial 
direction. In this arrangement the switch 22 signals "reversing switched 
off". 
Thus a switch is provided according to the invention, whose scanner 
projects into a segment of the movement path of a portion of the axis 
carrying the roller pairs, which portion protrudes outwardly from the 
outer cylinder provided with the oblique slots, wherein said segment is at 
the termination of the movement path or at the transition into the axial 
segment of the oblique slots. 
The invention is not limited to the depicted embodiment form.