Angular transmission device

Abstract

The present invention concerns an angular transmission device comprising: An input shaft and an output shaft, An assembly arranged for coupling the input shaft with the output shaft so that the output shaft can be rotationally driven by the input shaft, the assembly comprising a rotary actuator and a linear mobile, the rotary actuator being coupled with the input shaft and moves the mobile in a translation motion relative to the actuator, the mobile being coupled with the output shaft so that the rotation of the input shaft drives the rotation of the output shaft; the assembly further comprises a flexible blade fixed to said mobile and looped around the output shaft, so that when the actuator moves the mobile, the flexible blade drives the rotation of the output shaft. The invention also comprises a method using said device.

Claims

1. Angle transmission device comprising: an input shaft rotating around a first rotation axis and an output shaft rotating around a second rotation axis, an assembly arranged to couple the input shaft with the output shaft so that the output shaft can be rotationally driven by the input shaft, said assembly allowing for the transformation of the rotation of the input shaft around said first rotation axis into the rotation of the output shaft around the second rotation axis; the assembly comprising a rotary actuator and a linear mobile, the rotary actuator being coupled with the input shaft and arranged for moving the linear mobile in a translation motion relative to the actuator, the linear mobile being coupled with the output shaft so that the rotation of the input shaft can drive the rotation of the output shaft; the device being characterized in that the assembly further comprises a flexible blade or a flexible cable fixed to said linear mobile and looped around the output shaft, so that when the actuator moves the linear mobile, the flexible blade or the flexible cable drives the rotation of the output shaft.

2. Device according to claim 1, wherein the rotary actuator comprises a ball screw and the mobile comprises a ball nut, the device comprising a plurality of balls circulating between the ball screw and the ball nut so that the balls transmit the torque between the ball screw to the ball nut to move the ball nut in a linear motion, and wherein the rotation of the input shaft drives the ball screw and generates the linear motion of the ball nut that drives the rotation of the output shaft.

3. Device according to claim 1, wherein the actuator comprises a lead screw and the linear mobile comprises at least a nut, the lead screw being coupled with said nut to move said nut in a linear motion relative to the lead screw, the rotation of the input shaft drives the lead screw and generates the linear motion of the nut that drives the rotation of the output shaft.

4. Device according to claim 1, wherein the linear mobile comprises at least a nut and a housing integral with said nut, the flexible blade or the flexible cable being fixed on said housing.

5. Device according to claim 1, wherein the rotary actuator comprises a rotary motor.

6. Device according to claim 1, wherein the flexible blade or the flexible cable comprises two ends and a loop, said loop being between said two ends, said ends being fixed to the linear mobile.

7. Device according to claim 1, wherein the device is arranged to be in contact or to have a gap between the flexible blade or the flexible cable and the linear mobile.

8. Device according to claim 1, wherein the flexible blade or the flexible cable is made of metal or polymer.

9. Device according to claim 1, wherein the input shaft and/or the output shaft is mounted on at least one ball bearing.

10. Device according to claim 1, wherein the flexible blade or the flexible cable allows the angular rotation of the output shaft between −1000° and 1000°.

11. Device according to claim 1, wherein the flexible blade or the flexible cable allows for the control of the angular position of the output shaft between a plurality of discreet indexed positions.

12. Device according to claim 1, wherein the flexible blade or the flexible cable allows for the control of the angular position of the output shaft on an operational range comprised between a first angular position and a second angular position.

13. Device according to claim 1, wherein the device is a reducer for reducing the torque and/or the speed between the input shaft and the output shaft.

14. Device according to claim 1, wherein the first rotation axis is perpendicular to the second rotation axis.

15. Method for transforming a rotation around a first axis into a rotation into a second axis, the method using a device according to claim 1.

16. Device according to claim 5, said rotary motor being a brushless motor, a stepper motor, a piezo motor, a voice coil or a DC motor.

17. Device according to claim 10, said angular rotation of the output shaft being between −180° and +180°.

18. Device according to claim 17, said angular rotation of the output shaft being between −30° and +30°.

19. Device according to claim 13, a reduction ratio of said reducer being comprised between 1:1 and 1:20000.

20. Device according to claim 19, a reduction ratio of said reducer being comprised between 1:1 and 1:2000.

21. Device according to claim 20, said reduction ratio being comprised between 1:1 and 1:200.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood with the aid of the description of embodiments given by way of examples and illustrated by the figures, in which:

(2) FIGS. 1 and 2 show overviews of angular transmission devices according to the prior art;

(3) FIGS. 3a,b illustrate the device according to a first embodiment;

(4) FIG. 4 illustrates a flexible blade for a device according to the invention;

(5) FIGS. 5a to 5c illustrate a device according to a second embodiment;

DETAILED DESCRIPTION OF POSSIBLE EMBODIMENTS OF THE INVENTION

(6) FIGS. 3 to 5 illustrate some embodiments of the present invention but the invention is not limited to the disclosed embodiments.

(7) FIG. 3a,b show a device 1 according to a first embodiment. In particular, FIG. 3a,b illustrate the functioning, i.e. the concept, of the angular transmission device 1 according to the invention.

(8) The device 1 comprises an input shaft 2 rotating around a first rotation axis A and an output shaft 3 rotating around a second rotation axis B. In the present embodiment, the first axis A is perpendicular to the second rotation axis B.

(9) The device further comprises an assembly 4 arranged to couple the input shaft 2 with the output shaft 3. The assembly 4 allows for the transformation of the rotation of the input shaft 2 around said first rotation axis A into the rotation of the output shaft 3 around the second rotation axis B.

(10) The assembly 4 comprises a rotary actuator 5 and a linear mobile 6 coupled to said rotary actuator 5. The rotation of the rotary actuator 5 drives the linear mobile 6 in a translation motion. The role of the assembly 4 is to ensure the transmission of the force, and torque between the input shaft 2 and the output shaft 3.

(11) In the present embodiment, the rotary actuator 5 is a ball screw 7 and the linear mobile 6 comprises two ball nuts 8 received in a housing 9, said nuts 8 being integral with said housing 9, so that when the screw 7 drives the nuts 8, the housing 9 moves accordingly.

(12) The screw 7 is coupled to the input shaft 2; and the housing 9 is coupled to the output shaft 3.

(13) Alternatively, the screw is a lead screw coupled to at least a corresponding nut (not represented in figures).

(14) The assembly 4 further comprises a coupling element for the transmission of the motion of the mobile 6 to the output shaft 3. In other words, in this example, the coupling element is the flexible blade 10 ensuring the transmission of the forces between the mobile 6 and the output shaft 3, and thus between the input shaft 2 and the output shaft 3. The flexible blade 10 is fixed to the housing 9 and looped around the output shaft 3.

(15) In FIG. 3a, the device 1 is in an initial position where the input shaft 2 and the output shaft 3 are immobile, i.e. motionless.

(16) In FIG. 3b, the screw 7 is rotating. The rotation of the screw 7 drives the nuts 8 and the housing 9 in a linear motion in a direction parallel to the first rotation axis of the axis of the ball screw 7. While the housing 9 moves in a translation motion, the flexible blade 10, looped around the output shaft 3, drives the rotation of the output shaft 3.

(17) FIG. 4 illustrates an embodiment of a flexible blade 100 that can be used in the claimed device 1, 201. The blade 100 is a strip made of 301 stainless steel. In the present embodiment, the strip has 6.5 mm width, 80 mm length, 0.1 mm thick but the invention is not limited to these dimensions. Advantageously, the dimensions are comprised: Between 0.5 and 1000 mm wide; Between 1 and 5000 mm long; Between 0.01 and 2 mm thick.

(18) The flexible blade 100 comprises a flexible ribbon 101 comprising an aperture 102 and a narrow portion 103. The narrow portion 103 is inserted into the aperture 102 to form a loop 104, said loop 104 being designed to circle or loop around the output shaft (not represented in FIG. 4). The ribbon 103 comprises two ends 105 each equipped with traversing holes 106 to fix said blade 100 onto the mobile. For instance, the blade 100 is screwed onto the mobile via the holes 106.

(19) FIGS. 5a-c show a device 201 according to a second embodiment. The device 201 comprises an input shaft 202 coupled to an output shaft 203 via an assembly 204. Advantageously, the device 201 reducer allows for a reduction ratio of 56 between the input shaft 201 and the output shaft 202.

(20) The device 201 comprises a rotatory actuator 205 and a linear mobile 206: The rotatory actuator 205 comprising a ball screw 207; The linear mobile 206 comprising two ball nuts 208 received and integral with a housing 209.

(21) The device 201 is received in a casing 210, for instance a polygonal casing as illustrated in FIG. 5. The casing 210 comprises an input face 211 and an output face 212: The input face 211 comprising an input window 213 for operating the input shaft 202; for instance for coupling the input shaft 202 to a rotary motor (not represented in the figures); The output face 212 comprising an output window 214 for operating the output shaft 212; for instance for coupling the output shaft 212 to an instrument and controlling the angular position of said instrument, for instance a solar panel, optical devices etc. (not represented in the figures);

(22) The ball screw 207 is mounted on two ball bearings 215. Preferably, the output shaft 203 is also mounted on ball bearing(s) (not represented in the figures).

(23) A flexible blade 216 is fixed to the housing 209. In the present example, the blade 216 is screwed onto the housing with four fixing screws 217 after having adjusted the preload force on the flexible blade using the preloading screws. Once the fixing screws have been tightened with a given torque and using thread lock adhesive, the preloading screws can be removed.

(24) In the present embodiment, the device 201 can adopt three configurations as illustrated in FIGS. 5a-c: An initial configuration P0 before the rotation of the input shaft 202, shown in FIG. 5a; A first configuration P1 after the rotation of the input shaft with an angle of −α (plus alpha), shown in FIG. 5b; A second configuration P2 after the rotation of the input shaft with an angle of −α (plus alpha) shown in FIG. 5c;

(25) The rotation of the input shaft with an angle of −α (plus alpha) moves the mobile in a linear translation so that the flexible blade drives the rotation of the output shaft with an angle of +β (plus beta).

(26) The rotation of the input shaft with an angle of −α (minus alpha) moves the mobile in a linear translation so that the flexible blade drives the rotation of the output shaft with an angle of −β (minus beta).

(27) In the present embodiment, the angular position of the output shaft 203 varies on an operational range between a first angular position −β (minus beta) and a second angular position +β (plus beta). The output shaft can adopt any angular position within the interval defined by the first angular position and the second angular position.

(28) In another embodiment (not illustrated), the device can also be configured to limit the angular positions of the output shaft to a plurality of discreet indexed positions X1, X2, Xn. For instance, the output shaft is either in a position X1 corresponding to an angle beta of X degree, or position X2 corresponding to an angle beta of X degree.