Device for detecting the twist angle of a shaft and/or a torque occurring on the shaft and methods for operating the device

Abstract

A device for detecting a twist angle (dw) and/or a torque (Md) of a shaft ( 10 ) occurring on the shaft ( 10 ) and methods for operating the device are proposed. The procedure is distinguished in that at least one first encoder (G 1 ) is associated with the shaft ( 10 ), which influences at least one coil parameter, at least one first inductive sensor (S 1 , S 1 sin, S 1 cos, S 1 a sin, S 1 a cos, S 1 b sin, S 1 b cos) is provided for scanning the first encoder (G 1 ), the at least one first encoder (G 1 ) is associated with at least a part of the circumference of the shaft ( 10 ), the at least one first encoder (G 1 ) has at least one track ( 18, 18 a, 18 b ) having at least one period ( 32, 32 a, 32 b, 32 — 1 a, 32 — 1 b ) per revolution of the shaft ( 10 ), and the at least one first inductive sensor (S 1 , S 1 sin, S 1 cos, S 1 a sin, S 1 a cos, S 1 b sin, S 1 b cos) provides a sensor signal (SW 1 , SW 1 sin, SW 1 cos, SW 1 a sin, SW 1 a cos, SW 1 b sin, SW 1 b cos), which reflects at least one measure for the rotational angle (w 1 ) of the shaft ( 10 ) within the period ( 32, 32 a, 32 b, 32 — 1 a, 32 — 1 b ), a second encoder (G 2 ), which is also associated with at least a part of the circumference of the shaft ( 10 ), and which also influences at least one coil parameter, is provided at a predefined spacing (L) to the first encoder (G 1 ), at least one inductive sensor (S 2 , S 2 sin, S 2 cos, S 2 a sin, S 2 a cos, S 2 b sin, S 2 b cos) is provided for scanning the at least one second encoder (G 2 ), the at least one second encoder (G 2 ) also has at least one track ( 19, 19 a, 19 b ) having at least one period ( 32 — 2 a, 32 — 2 b ) per revolution of the shaft ( 10 ), the second inductive sensor (S 2 , S 2 sin, S 2 cos, S 2 a sin, S 2 a cos, S 2 b sin, S 2 b cos) also provides a sensor signal (SW 2 , SW 2 sin, SW 2 cos, SW 2 a sin, SW 2 a cos, SW 2 b sin, SW 2 b cos), which reflects at least one measure for the rotational angle (w 2 ) of the shaft ( 10 ) within the period ( 32 — 2 a, 32 — 2 b ), and a difference ascertainment unit ( 22 ) is provided, which ascertains and provides the twist angle (dw) of the shaft ( 10 ) as an angle difference of the two rotational angles (w 1 , w 2 ) detected by the inductive sensors (S 1 , S 1 sin, S 1 cos, S 1 a sin, S 1 a cos, S 1 b sin, S 1 b cos, S 2 sin, S 2 cos, S 2 a sin, S 2 a cos, S 2 b sin, S 2 b cos). The procedures according to the invention allow, in addition to the ascertainment of the twist angle (w 1 , w 2 ) of the shaft ( 10 ), in particular the ascertainment of the torque (Md) occurring on the shaft ( 10 ) on the basis of an angle difference (w 2 −w 1 ), which corresponds to the twist angle (dw).

What is claimed is: 
     
         1 . A device for detecting a twist angle of a shaft and/or a torque occurring on the shaft, the device comprising:
 at least one first passive encoder associated with at least a part of the circumference of the shaft, influencing at least one first coil parameter, and having at least one first encoder track having at least one period per revolution of the shaft,   at least one first inductive sensor for scanning the at least one first passive encoder and providing a first sensor signal reflecting at least one measure for a first rotational angle of the shaft within the period,   at least one second passive encoder also associated with at least a part of the circumference of the shaft, influencing at least one second coil parameter, being provided at a predefined spacing to the at least one first passive encoder, and having at least one second encoder track having at least one period per revolution of the shaft,   at least one second inductive sensor for scanning the at least one second passive encoder and also providing a second sensor signal reflecting at least one measure for a second rotational angle of the shaft within the period, and   a difference ascertainment unit ascertaining and providing the twist angle of the shaft as an angle difference of the first rotational angle detected by the at least one first inductive sensor and the second rotational angle detected by the at least one second inductive sensor;   wherein the at least one first encoder track and/or the at least one second encoder track only contains a single period and winds in the form of a spiral at least partially around the shaft having a predefined pitch in the longitudinal direction of the shaft so that an unambiguous relationship is always provided between the first rotational angle of the shaft and the first sensor signal and/or between the second rotational angle of the shaft and the second sensor signal.   
     
     
         2 . The device according to  claim 1 , wherein the pitch of the spiral in the longitudinal direction of the shaft is at least approximately constant, so that an at least approximately linear relationship is provided between the first rotational angle of the shaft and the first sensor signal and between the second rotational angle of the shaft and the second sensor signal. 
     
     
         3 . The device according to  claim 2 , wherein the pitch is established such that at least one of the at least one first encoder track and the at least one second encoder track extends at least once completely around the shaft. 
     
     
         4 . A device for detecting a twist angle of a shaft and/or a torque occurring on the shaft, the device comprising:
 at least one first passive encoder associated with at least a part of the circumference of the shaft, influencing at least one first coil parameter, and having at least one first encoder track having at least one period per revolution of the shaft,   at least one first inductive sensor for scanning the at least one first passive encoder and providing a first sensor signal reflecting at least one measure for a first rotational angle of the shaft within the period,   at least one second passive encoder also associated with at least a part of the circumference of the shaft, influencing at least one second coil parameter, being provided at a predefined spacing to the at least one first passive encoder, and having at least one second encoder track having at least one period per revolution of the shaft,   at least one second inductive sensor for scanning the at least one second passive encoder and also providing a second sensor signal reflecting at least one measure for a second rotational angle of the shaft within the period, and   a difference ascertainment unit ascertaining and providing the twist angle of the shaft as an angle difference of the first rotational angle detected by the at least one first inductive sensor and the second rotational angle detected by the at least one second inductive sensor;   wherein the at least one first encoder track and/or the at least one second passive encoder track only contains one period and winds in the form of an ellipsoid at least partially around the shaft having a predefined pitch in the longitudinal direction of the shaft, so that an only sectionally unambiguous relationship is provided between the first rotational angle of the shaft and the first sensor signal and between the second rotational angle of the shaft and the second sensor signal.   
     
     
         5 . The device according to  claim 4 , wherein the at least one first encoder track and/or the at least one second encoder track completely encloses the shaft, so that a closed ellipsoid form is provided. 
     
     
         6 . The device according to  claim 1 , wherein the at least one first encoder track and/or the at least one second encoder track is implemented as a groove in the shaft. 
     
     
         7 . The device according to  claim 1 , wherein the at least one first encoder track and/or the at least one second encoder track is implemented as a web on the shaft. 
     
     
         8 . The device according to  claim 7 , wherein the web is implemented as a separate part for subsequent application to the shaft.