Bearing equipped with magnetic encoder and sensor including aligned sensing elements

Abstract

The invention relates to a bearing provided with an annular means generating magnetic pulses and with a device for detecting these pulses, wherein the detection device comprises a plurality of aligned sensitive elements.

1 . A bearing provided with an annular means generating magnetic pulses and with a device for detecting these pulses, wherein the detection device comprises a plurality of aligned sensitive elements ( 5 ).  
     
     
         2 . The bearing as claimed in  claim 1 , wherein the sensitive elements are chosen from among the groups comprising Hall-effect probes, magnetoresistors, giant magnetoresistors.  
     
     
         3  The bearing as claimed in  claim 1  or  2 , wherein the sensitive elements are placed equidistantly from one another.  
     
     
         4 . The bearing as claimed in any one of  claims 1  to  3 , wherein the pulse generating means is an annular member which is made of a synthetic material laden with ferrite particles and is formed by a plurality of contiguous domains having reversed direction of magnetization of a given domain with respect to the two domains which are contiguous with it.  
     
     
         5 . The bearing as claimed in any one of  claims 1  to  4 , wherein the detection device comprises an even number 2N of sensitive elements.  
     
     
         6 . The bearing as claimed in  claim 5 , wherein the assembly of 2N sensitive elements is divided into two subassemblies ( 8 ,  9 ) of N elements, each sensitive element ( 5 ) of the first subassembly ( 8 ) being connected to a first adder ( 10 ), each sensitive element ( 5 ) of the second subassembly ( 9 ) being connected to a second adder ( 11 ), the two sums (S 1 , S 2 ) emanating from the first and second adders ( 10 ,  11 ) being connected to the input of a third adder ( 12 ), the output (S 1 ) of the first adder ( 10 ) and, via an inverter ( 13 ), the output (S 2 ) of the second adder ( 11 ) being connected to the input of a fourth adder ( 14 ), the signals SIN=S 1 +S 2  and COS=S 1 −S 2  emanating from the third ( 12 ) and fourth adders ( 14 ) being processed by a circuit so as to deduce the direction of rotation and/or the speed or rotation and/or the position of the pulse generating means with respect to the detection device.  
     
     
         7 . The bearing as claimed in  claim 6 , wherein the polar length (Lp) of the encoder is substantially equal to the product of the number (2N) of sensitive elements ( 5 ) times the distance (d) between sensitive elements, the signals SIN and COS then being in substantially perfect quadrature and of substantially like amplitude.  
     
     
         8 . The bearing as claimed in  claim 6 , wherein the polar length (Lp) of the encoder is less than the product of the number (2N) of sensitive elements ( 5 ) times the distance (d) between sensitive elements.  
     
     
         9 . The bearing as claimed in  claim 6 , wherein the polar length (Lp) of the encoder is greater than the product of the number (2N) of sensitive elements ( 5 ) times the distance (d) between sensitive elements.  
     
     
         10 . The bearing as claimed in  claim 9 , wherein, by programming, an even number (2M) of sensitive elements, less than the total number (2N) of these elements ( 5 ) is employed to form two subassemblies of M elements, each sensitive element ( 5 ) of the first subassembly being connected to a first adder, each sensitive element of the second subassembly being connected to a second adder, the two sums emanating from the first and second adders being connected to the input of a third adder, the output of the first adder and, via an inverter, the output of the second adder being connected to the input of a fourth adder, the signals emanating from the third and fourth adders being processed by a circuit so as to deduce the direction of rotation and/or the speed or rotation and/or the position of the pulse generating means with respect to the detection device, said signals being in substantially perfect quadrature.  
     
     
         11 . The bearing as claimed in  claim 10 , wherein the programming is carried out by EEPROM.  
     
     
         12 . The bearing as claimed in  claim 10 , wherein the programming is carried out by Zener Zapping.  
     
     
         13 . The bearing as claimed in  claim 8  or  9 , wherein an amplifier circuit is able to re-establish an identical amplitude for the signals emanating from the third and fourth adders.  
     
     
         14 . The bearing as claimed in one of  claims 1  to  13 , wherein the detection device comprises a number of sensitive elements ( 5 ) which is a multiple of four.  
     
     
         15 . The bearing as claimed in  claim 14 , wherein the assembly of 4P sensitive elements is divided into four subassemblies of P elements, 
 each sensitive element ( 5 ) of the first subassembly with P elements being connected to a first adder supplying a signal S 1 ;    each sensitive element ( 5 ) of the second subassembly with P elements being connected to a second adder supplying a signal S 2 ;    each sensitive element ( 5 ) of the third subassembly with P elements being connected to a third adder supplying a signal S′ 1 ;    each sensitive element ( 5 ) of the fourth subassembly with P elements being connected to a fourth adder supplying a signal S′ 2 ;    a circuit of adders and of inverters supplying two signals SIN and COS respectively equal to:    SIN=(S 1 −S 2 )−(S′ 1 −S′ 2 );    COS=(S 1 +S 2 )−(S′ 1 +S′ 2 );    these signals SIN and COS being devoid of magnetic offset.    
     
     
         16 . The bearing as claimed in  claim 15 , wherein the detection device comprises an interpolator increasing the resolution of these output signals.  
     
     
         17 . The bearing as claimed in any one of  claims 1  to  16 , wherein the sensitive elements are integrated on an ASIC type circuit support.  
     
     
         18 . The bearing as claimed in  claim 17 , wherein the detection device is incorporated within an ASIC type customized integrated circuit.  
     
     
         19 . The bearing as claimed in one of  claims 1  to  18 , wherein the pulse generating means is integrated into a preassembled assembly forming a seal.  
     
     
         20 . The bearing as claimed in  claim 19 , wherein the detection device is secured in a possibly removable manner to the fixed race.