Screening system for magnetic rotary-encoder sensor system

Abstract

It is disclosed a screening system (72) for a magnetic rotary-encoder sensor system (22) in an environment (12) of a machine (16) including a magnetic noise field (14), wherein the rotary-encoder sensor system (22) comprises a magnetic sensor (24), a pole wheel (26), and preferably a pole-wheel carrier (32), wherein the pole wheel (26) comprises in a circumferential direction (U) a plurality of permanent magnets (28) of alternating magnetic polarity generating a useful field, wherein the pole-wheel carrier (32) is configured to be mounted in a rotationally-fixed manner to a rotating machine shaft (30) extending axially, rotational speed and/or angular position of which is to be determined by means of the rotary-encoder sensor system (22), wherein the magnetic sensor (24) is positioned, in a mounted state of the rotary-encoder sensor system (22) relative to the machine shaft (30), in a rotational plane (36) of the pole wheel (26), which can affect the noise field, and directly opposite to the pole wheel (26), wherein the screening system (72) comprises at least one magnetically conducting, preferably machine-fixed, deflection element (74) being formed and dimensioned such that in the mounted state a measuring volume (76), which is substantially free of the noise field, is established, to which the magnetic sensor (24) and such ones of the permanent magnets (28) are at least adjacent which are required for generating an evaluable useful field (38), when the noise field (14) is active.

1 . A screening system for a magnetic rotary-encoder sensor system in an environment of a machine including a magnetic noise field, wherein the rotary-encoder sensor system comprises a magnetic sensor, a pole wheel, and preferably a pole-wheel carrier, wherein the pole wheel comprises in a circumferential direction a plurality of permanent magnets of alternating magnetic polarity generating a useful field, wherein the pole-wheel carrier is configured to be mounted in a rotationally-fixed manner to a rotating machine shaft extending axially, rotational speed and/or angular position of which machine shaft is to be determined by means of the rotary-encoder sensor system, wherein the magnetic sensor is positioned, in a mounted state of the rotary-encoder sensor system relative to the machine shaft, in a rotational plane of the pole wheel, which can affect the noise field, and directly opposite to the pole wheel, wherein the screening system comprises;
 at least one magnetically conducting, deflection element being formed and dimensioned such that in the mounted state a measuring volume, which is substantially free of the noise field, is established, to which the magnetic sensor and such ones of the permanent magnets are at least adjacent which are required for generating an evaluable useful field, when the noise field is active;   wherein a first deflection element is longitudinally extending parallel to the machine shaft, and is arranged radially between the machine shaft and the pole wheel.   
     
     
         2 . The screening system of  claim 1 , wherein the at least one deflection element is arranged such that the at least one deflection element surrounds the measuring volume so that components of the noise field being arranged almost parallel to a measuring direction of the magnetic sensor are guided, by the at least one deflection element, around the measuring volume and so that a passage remains for the rotating pole wheel and the pole-wheel carrier. 
     
     
         3 . The screening system of  claim 1 , wherein a second deflection element is provided, which longitudinally extends parallel to the machine shaft, and wherein the second deflection element is arranged radially external to the pole wheel and the magnetic sensor. 
     
     
         4 . The screening system of  claim 3 , wherein further a third deflection element is provided, which extends substantially along the rotational plane. 
     
     
         5 . The screening system of  claim 4  further comprising the pole wheel and the pole-wheel carrier, which comprises an axial sleeve portion including a radial protruding collar portion, to which the permanent magnets are fixed radially, wherein the pole-wheel carrier is manufactured, at least in a region close to the machine-shaft, of a material which is magnetically non-conducting, and wherein the first deflection element is positioned between the pole wheel, the machine shaft, and the collar portion. 
     
     
         6 . The screening system of  4 , wherein further a fourth deflection element is provided extending parallel, axially distanced, and radially opposite to the third deflection element. 
     
     
         7 . The screening system of  claim 1 , wherein the at least one deflection element forms a casing of the magnetic sensor receiving the magnetic sensor and further surrounding, at least partially, the permanent magnets generating the useful field. 
     
     
         8 . The screening system of  claim 1 , wherein the machine is an electric machine, wherein the noise field is caused by at least one of an electromagnetically operated accessory being fixable to a machine shield in a machine-fixed manner and axially adjacent to the rotary-encoder sensor system in common with the magnetic sensor and by the electric machine. 
     
     
         9 . The screening system of  claim 1 , wherein the magnetic sensor is at least one of a Hall sensor or an xMR sensor. 
     
     
         10 . The screening system of  claim 1 , wherein the at least one deflection element extends in the circumferential direction at least along the permanent magnets required for generating the useful field which is evaluable by the magnetic sensor. 
     
     
         11 . The screening system of  claim 4 , wherein the third deflection element connects the first and second deflection elements. 
     
     
         12 . The screening system of  claim 6 , wherein the third and fourth deflection elements are dimensioned at least as large as a base area of the magnetic sensor, and wherein the fourth deflection element is connected to the second deflection element. 
     
     
         13 . The screening system of  claim 8 , wherein the machine shaft is manufactured of a magnetically conducting material.