1、Directional Servo Valves,SM4-10 SM4-12 SM4-15 SM4-20 SM4-40 SM4-60 New in 2007 SX4-10 thru 20,Servo Valve Features,Reliable flapper nozzle design 2 Stage operation w/ mechanical feedback Wide range of coils to meet competition Jeweled orifices Jeweled feedback eliminates spool rotation and “null gli

2、tch”. Flow ranges from 1 GPM to 40 GPM ( 1000 PSI.) Custom spools from over lap to under lap configurations Industry standard mounting patterns Filtered pilot stage flow External pilot capabilities Pressures to 5000 PSI Bandwidths up to 350 HZ “Intrinsically Safe” Capabilities,SERVO VALVE,SERVO VALV

3、E - BODY,Construction of the servo valve starts with the body.,Directional Servo Valves,SERVO VALVE SLEEVE,The body is fitted with a sleeve in order that the spool lands can be accurately matched to the sleeve ports.,SERVO VALVE - SPOOL,The body is fitted with a sleeve in order that the spool lands

4、can be accurately matched to the sleeve ports.,SERVO VALVE - PILOT FILTER,A filter for the pilot supply is also fitted in the main body.,SERVO VALVE - PILOT SUPPLY,The body end-caps are used to connect pilot oil from the filter to the pilot stage of the valve.,SERVO VALVE - NOZZLE BLOCK,SERVO VALVE

5、- PILOT NOZZLES,The pilot stage includes two nozzles .,SERVO VALVE - TORQUE MOTOR,. and a torque motor. Attached to the torque motor armature is a flapper plate which extends down through the two pilot nozzles and locates in a recess in the main spool.,SERVO VALVE,When the valve is de-energised, the

6、 flapper is centred relative to the two pilot nozzles so pressures on either end of the main spool are equal and the main spool is also centred.,SERVO VALVE,The torque motor is fitted with a permanent magnet frame surrounding the armature.,SERVO VALVE,Passing a current through the torque motor coils

7、 magentises the armature and causes it to tilt. The direction of the tilt is determined by the voltage polarity and the amount of tilt by the magnitude of the current.,SERVO VALVE,The tilting of the armature causes the flapper to move closer to one nozzle and further away from the opposite nozzle.,SERVO VALVE,. causing the main spool to move and flow to pass through the valve. As the main spool moves, the flapper is dragged back to the cen