Device for the Angular Positioning of a Shaft

Abstract

The invention relates to a device for the angular positioning of a shaft, having a computerized command motion controller, two motors with servo drivers and a mechanism with screws and nuts and one crank arm functioning together to lock the positioning output shaft into a fixed position or to rotate it into any direction with zero backlash with variable speed and/or torque.

Claims

1. Device for the angular positioning of a shaft, comprising: a controller (1) a first and a second driving means controlled by the controller (1), the first driving means being capable to drive a first driving screw (6) and the second driving means being capable to drive a second driving screw (7) the first (6) and the second (7) driving screws having their respective longitudinal axes arranged at a 90 angle relative to each other a first support element (14) capable to shift in the direction of the longitudinal axis of the first driving screw (6) upon driving the first driving screw (6) by the first driving means a second support element (14) capable to shift in the direction of the longitudinal axis of the second driving screw (7) upon the driving of the second driving screw (7) by the second driving means characterized in that the device further comprises: a first straight rail guide (12) rigidly fixed on the first support element (14), and arranged at a 90 angle relative to the longitudinal axis of the first driving screw (6) and parallel to the longitudinal axis of the second driving screw (7) a second straight rail guide (13) rigidly fixed on the second support element (14), and arranged at a 90 angle relative to the longitudinal axis of the second driving screw (7), and parallel to the longitudinal axis of the first driving screw (6) a first block (10) mounted on the first straight rail guide (12) in such a manner that it allows a relative movement between the first block (10) and the first straight rail guide (12), along at least a portion of the first straight rail guide (12), upon driving the first (6) and/or the second driving screw (7) a second block (11) mounted on the second straight rail guide (13) in such a manner that it allows a relative movement between the second block (11) and the second straight rail guide (13), along at least a portion of the second straight rail guide (13), upon driving the first (6) and/or the second driving screw (7) a motion imparting assembly capable to move along a path resulting from the movement of the first (12) and/or second (13) straight rail guides a circular transfer disc (16) that is parallel to the first (6) and second (7) driving screws, and is also parallel to the first (12) and second (13) straight rail guides, and is provided with a third straight rail guide (21) arranged along the direction of a radius of the transfer disc (16) the transfer disc (16) being capable to rotate, upon the movement of the motion imparting assembly, along a rotation axis perpendicular on the transfer disc (16) and passing through the center of the transfer disc (16) a shaft (20) fixed to the transfer disc (16), such that the longitudinal axis of the shaft (20) and the rotation axis of the transfer disc (16) are the same.

2. Device according to claim 1, wherein: the longitudinal axis of the first (6) and second (7) driving screws lie in the same plane the first (14) and second (14) support elements have each a substantially plane surface on which is fixed the first straight rail guide (12) and the second straight rail guide (13), respectively a first end of the first support element (14) is connected to a first end of the second support element (14) in a connection zone the motion imparting assembly comprises: a pin (19) fixed, at one of its ends, to the connection zone of the first (14) and second (14) support elements and perpendicular on both first (12) and second (13) straight rail guides a bearing (19) inside which the pin (19) is at least partly accommodated, a carriage (24) rigidly fixed to the bearing (19) the carriage (24) being capable to slide along the third straight rail guide (21) that is fixed on the circular transfer disc (16).

3. Device according to claim 2, wherein the bearing (19) is a ball bearing, or a roller bearing or a needle bearing.

4. Device according to claim 2, wherein a second end of the first support element (14) is connected to a second end of the second support element (14) by means of a reinforcing element.

5. Device according to claim 4, wherein the reinforcing element has the shape of a circular arc, or a circular sector, or a bar, or a triangle.

6. Device according to claim 1, wherein: the longitudinal axis of the first (6) and second (7) driving screws lie in different planes the first (14) and second (14) support elements have each a substantially plane surface on which is fixed the first straight rail guide (12) and the second straight rail guide (13), respectively the motion imparting assembly comprises: a first bearing (19a) rigidly fixed to the first block (10) a second bearing (19b) rigidly fixed to the second block (11) a pin (19) perpendicular on both first (12) and second (13) straight rail guides at least partly ccommodated inside the first (19a) and second (19b) bearings a carriage (24) rigidly fixed to one end of the pin (19) the carriage (24) being capable to slide along the third straight rail guide (21) that is fixed on the circular transfer disc (16).

7. Device according to claim 1, wherein the first driving means comprises a first electrical motor (4) driven by a first servo driver (2) and the second driving means comprises a second electrical motor (5) driven by a second servo driver (3).

8. Device according to claim 1, further comprising: means (17) for generating analog electrical signals to be transmitted to the controller (1) and related to the angular position of the shaft (20); a rotary encoder (18) for generating digital signals to be transmitted to the controller (1) and related to the angular position of the shaft (20).

9. Device according to claim 8, wherein said means for generating analog electrical signals comprise three coils, the first and second coils being fixed in a crossing position at a 90 angle relative to each other and the third coil being capable to rotate together with the shaft (20) to generate a phase variation of electrical current related to the angular position of the shaft (20) into the first and second coils, all three coils having separate and opposed north-south poles.

10. Device according to claim 1, wherein the controller (1) is capable to run an interpolation algorithm to command the first servo driver (2) and the second servo driver (3).

11. Device according to claim 9, wherein an analogical electrical continuous signal, obtained through the variation of the phases of the electrical currents from said coils, is capable to command the first servo driver (2) and the second servo driver (3) in-phase or in phase-difference according to the position of the shaft (20) inside the four quadrants of its axis in such a manner to control the speed and direction of the rotation of the shaft (20).

12. Device according to claim 1, wherein the device is accommodated inside a housing (15).

13. Device according to claim 1, wherein the shaft (20) is fitted on a bearing fixed in the housing (15).

14. Positioning system provided with at least one device according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 is a perspective dimetric view of the first embodiment of the device according to the invention;

[0042] FIG. 2 is atop view of the positioning device shown in FIG. 1 in a specific angular position and generating high torque;

[0043] FIG. 3 is a top view of the positioning device shown in FIG. 1 in specific angular position and generating low torque;

[0044] FIG. 4 is a top view of the positioning device shown in FIG. 1 in specific angular position at 90 relative to FIG.2 and generating high torque;

[0045] FIG. 5 is a top view of the second embodiment of the device according to the invention;

[0046] FIG. 6 is a sectional view of the device shown in FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0047] According to a preferred embodiment of this invention, an angular positioning generator device, such as on a rotary table or rotary head having a range of motion around an axis is adaptable for use in connection with any number of components. Components may include angular positioning systems, CNC machine tools, CNC measurement machines, surveillance systems, such as cameras, and positioning and/or guidance systems, such as lasers. FIGS. 1-6 show various features on the preferred embodiment of the subject invention.

[0048] The positioning device is preferably accommodated inside a housing 15. The housing 15 is preferably constructed of structural materials that provide maximum torsional rigidity. In addition, the housing is preferably powder-coated and corrosion and weather resistant. In particular, the housing 15 is preferably capable of withstanding wet and otherwise corrosive environments; high (+80 C.) and/or low (30 C.) temperature environments; may operate in high humidity and/or any other possible environment suitable for the angular positioning device such as disclosed herein. The housing 15 may include one or more removable sidewalls (not figured due the specifics of each embodiment) which are removably attached to the housing 15 to facilitate access and/or maintenance to the mechanical internals, as described in detail below.

[0049] The device for the angular positioning of a shaft, as shown in FIGS. 1 and 5, comprises: [0050] a controller 1 [0051] a first and a second driving means controlled by the controller 1, the first driving means being capable to drive a first driving screw 6 and the second driving means being capable to drive a second driving screw 7 [0052] the first 6 and the second 7 driving screws having their respective longitudinal axes arranged at a 90 angle relative to each other [0053] a first support element 14 capable to shift in the direction of the longitudinal axis of the first driving screw 6 upon driving the first driving screw 6 by the first driving means [0054] a second support element 14 capable to shift in the direction of the longitudinal axis of the second driving screw 7 upon the driving of the second driving screw 7 by the second driving means [0055] a first straight rail guide 12 rigidly fixed on the first support element 14, and arranged at a 90 angle relative to the longitudinal axis of the first driving screw 6 and parallel to the longitudinal axis of the second driving screw 7 [0056] a second straight rail guide 13 rigidly fixed on the second support element 14, and arranged at a 90 angle relative to the longitudinal axis of the second driving screw 7, and parallel to the longitudinal axis of the first driving screw 6 [0057] a first block 10 mounted on the first straight rail guide 12 in such a manner that it allows a relative movement between the first block 10 and the first straight rail guide 12, along at least a portion of the first straight rail guide 12, upon driving the first 6 and/or the second driving screw 7 [0058] a second block 11 mounted on the second straight rail guide 13 in such a manner that it allows a relative movement between the second block 11 and the second straight rail guide 13, along at least a portion of the second straight rail guide 13, upon driving the first 6 and/or the second driving screw 7 [0059] a motion imparting assembly capable to move along a path resulting from the movement of the first 12 and/or second 13 straight rail guides [0060] a circular transfer disc 16 that is parallel to the first 6 and second 7 driving screws, and is also parallel to the first 12 and second 13 straight rail guides, and is provided with a third straight rail guide 21 arranged along the direction of a radius of the transfer disc 16 [0061] the transfer disc 16 being capable to rotate, upon the movement of the motion imparting assembly, along a rotation axis perpendicular on the transfer disc 16 and passing through the centre of the transfer disc 16 [0062] a shaft 20 fixed to the transfer disc 16, such that the longitudinal axis of the shaft 20 and the rotation axis of the transfer disc 16 are the same.

[0063] The device preferably further comprises linear rail guides 8 and 9 on adjacently sides of the housing. The purpose of said linear rail guides 8 and 9 is to maintain the straightness of the axes of the first 6 and second 7 driving screws and, in case the screws are relatively long, to prevent the whipping of the screws.

[0064] As shown in FIGS. 1-4, corresponding to the first embodiment of the device according to the invention: [0065] the longitudinal axis of the first 6 and second 7 driving screws lie in the same plane [0066] the first 14 and second 14 support elements have each a substantially plane surface on which is fixed the first straight rail guide 12 and the second straight rail guide 13, respectively [0067] a first end of the first support element 14 is connected to a first end of the second support element 14 in a connection zone [0068] the motion imparting assembly comprises: [0069] a pin 19 fixed, at one of its ends, to the connection zone of the first 14 and second 14 support elements and perpendicular on both first 12 and second 13 straight rail guides [0070] a bearing 19 inside which the pin 19 is at least partly accommodated, [0071] a carriage 24 rigidly fixed to the bearing 19 [0072] the carriage 24 being capable to slide along the third straight rail guide 21 that is fixed on the circular transfer disc 16.

[0073] The bearing 19 is a ball bearing, or a roller bearing or a needle bearing.

[0074] A second end of the first support element 14 is connected to a second end of the second support element 14 by means of a reinforcing element.

[0075] The reinforcing element has the shape of a circular arc but can also be a circular sector, or a bar, ora triangle.

[0076] As shown in FIGS. 5-6, corresponding to the second embodiment of the device according to the invention: [0077] the longitudinal axis of the first 6 and second 7 driving screws lie in different planes [0078] the first 14 and second 14 support elements have each a substantially plane surface on which is fixed the first straight rail guide 12 and the second straight rail guide 13, respectively [0079] the motion imparting assembly comprises: [0080] a first bearing 19a rigidly fixed to the first block 10 [0081] a second bearing 19b rigidly fixed to the second block 11 [0082] a pin 19 perpendicular on both first 12 and second 13 straight rail guides at least partly accommodated inside the first 19a and second 19b bearings [0083] a carriage 24 rigidly fixed to one end of the pin 19 [0084] the carriage 24 being capable to slide along the third straight rail guide 21 that is fixed on the circular transfer disc 16.

[0085] In all embodiments (but represented only in FIGS. 1-5), the first driving means comprises a first electrical motor 4 driven by a first servo driver 2 and the second driving means comprises a second electrical motor 5 driven by a second servo driver 3.

[0086] In all embodiments, the device further comprises means 17 for generating analog electrical signals to be transmitted to the controller 1 and related to the angular position of the shaft 20 and a rotary encoder 18 for generating digital signals to be transmitted to the controller 1 and related to the angular position of the shaft 20.

[0087] Said means for generating analog electrical signals comprise three coils, the first and second coils being fixed in a crossing position at a 90 angle relative to each other and the third coil being capable to rotate together with the shaft 20 to generate a phase variation of electrical current related to the angular position of the shaft 20 into the first and second coils, all three coils having separate and opposed north-south poles.

[0088] In all embodiments, the controller 1 is capable to run an interpolation algorithm to command the first servo driver 2 and the second servo driver 3.

[0089] An analogical electrical continuous signal, obtained through the variation of the phases of the electrical currents from said coils, is capable to command the first servo driver 2 and the second servo driver 3 in-phase or in phase-difference according to the position of the shaft 20 inside the four quadrants of its axis in such a manner to control the speed and direction of the rotation of the shaft 20.

[0090] The shaft 20 is fitted on a bearing fixed in the housing 15.

[0091] The torque of motors 4, 5 is transformed by the screws 6 and 7 in thrust by a ratio provided by the thread with a specific pitch and lead and are pulling and/or pushing at the same time both support elements 14, 14 accordingly.

[0092] The crank arm formed by the support elements 14, 14, the motion imparting assembly and the transfer disc 16 with an output shaft 20 transform again the amplified thrust into torque with a ratio between the length of the crank arm and the diameter of the output shaft.

[0093] Backlash is removed from the positioning device by the acting motors 4 and 5 on both axis of the device (i.e. longitudinal axis of the screws 6 and 7, respectively) relative to the support elements 14, 14 with the crank arm based on the motion imparting assembly leveraging the output shaft 20 and according to the dialed-in position generated by the interpolation algorithm acting as an interlocking of the two axis due to the mathematical inaccuracy of each point on the interpolated circle.

[0094] Some applications may require the precise angular positioning of a plurality of shafts, so in order to solve this issue one can imagine a system provided with a plurality of devices according to the invention.

[0095] While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the device according to this invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.