Patent ID: 8485497

Claim:
A hydraulic valve ( 20 ), comprising: a valve body ( 19 ); inner channels ( 22 ) within the valve body, the inner channels defining passages for fluid flow; at least a spool ( 21 ) present in the body, the spool movable axially in order to control the fluid flow in the inner channels ( 22 ); and at least a sensor ( 30 ) attached to said body ( 19 ), said sensor ( 30 ) movable with the spool ( 21 ) to i) sense a current position of the spool, and ii) give out a corresponding electrical signal indicating the current position of the spool, wherein said sensor ( 30 ) measures a linear displacement of the spool ( 21 ) by sensing an angle of magnetic field lines, wherein said sensor comprises: a tube assembly comprising at least i) a tube ( 8 ) resistant to oil pressure, the tube comprising a thread ( 8 A), the sensor mounted on the valve body by the thread so that the tube together with the valve body create a closed space where oil flows, the tube serving as a magnet housing, ii) a moving plunger ( 1 , 2 , 4 , 5 ) having an axis (AA), iii) a magnet carrier ( 5 ) with a permanent magnet ( 4 ) located in an inside of the magnet carrier, iv) a spring ( 6 ) placed internal to the tube ( 8 ) and acting against the magnet carrier ( 5 ), the spring keeping the plunger, with the magnet ( 4 ) inside the magnet carrier, in contact with the spool ( 21 ), v) an anti-spin device ( 3 ) cooperating with the moving plunger and preventing the moving plunger from rotating around the axis (AA); and a body assembly comprising at least i) a connector ( 9 , 10 , 12 ) for power supply and output signals, ii) a printed circuit board ( 11 ) with an integrated circuit serving as magnetic pickup ( 23 ), iii) a body ( 13 ) supporting the integrated circuit and the tube, iv) a tube and PC board holder ( 14 ) within the body, v) a non-magnetic body cover ( 16 ), and vi) a seal-lock nut ( 18 ) keeping the tube assembly mounted in the body assembly, wherein, said magnet moves along with the spool and creates a variation in a magnetic field during movement with the spool, and the integrated circuit measures a linear displacement of the spool ( 21 ) by sensing a variation in an angle of magnetic field lines of the magnetic field from the permanent magnetic and generates an output signal proportional to the movement of the spool ( 21 ).