DEVICE FOR MEASURING AND FOLLOWING THE DEGREE OF WEAR OF A FIRST ELEMENT HAVING PREDETERMINED MAGNETIC PROPERTIES IN SLIDING CONTACT WITH A SECOND ELEMENT

摘要

1537552 Detecting wear electrically SOC D'ETUDES DE MACHINES THERMIQUES 14 July 1976 [1 Oct 1975] 29195/76 Heading G1N The degree of wear of a first element in sliding contact with a second element is determined by measuring the variation in the reluctance of the first element as it slides past the second element. An inductive sensor 10 is positioned in bores 8, 9 of cylinder block 7 and liner 6 of an internal combustion engine 1 so as to have its end flush with the liner 6 so that during the reciprocating motion of the piston 2 all the piston rings 5a-e successively pass the sensor. The sensor output is connected via amplifying and filter stage 11 to CRT 12. With the piston 2 in its upper position sensor 10 supplies a constant level signal S1, then as the ring 5a passes in front of the sensor 10 a pulse I, is produced and similarly pulses I 2 , I 3 , I 4 , I 5 are generated as the remaining rings pass the sensor 10. Due to rings 5a, b, c being located in the steel head 3 of the piston whereas rings 5d, e are in the aluminium skirt 4 the level between the rings changes from S 1 to S 2 . The upper ring 5e is chromium plated on its outer surface in contact with liner 6 so that its permeability is lower than that of the other rings. Thus as the chromium of ring 5a wears away the reluctance of this ring increases in a greater proportion to that of the other rings and the output signal increases from I 5 to I' 5 to I" 5 as the wear increases. The sensors may be mounted in the cylinder on to the same level and in diametrically opposite relationship so that a deformation of the piston ring can be detected when there is no coincidence between the two pulses produced.