Valves - Part B

Question 1

Proportional valves

Answer 1

• solenoid operated valve that proportionally controls movement of the spool with electrical inputs.
• adjusting electrical energy to meter the flow
• pay attention to the diagonal arrow and the flow symbol on the drawing
• metering notches to smoothly and accurately control flow

Question 2

Amplifiers

Answer 2

-dead band, gain, dither signal, ramp functions

Question 2

Dead Band

Answer 2

-boosts the signal to make the spool jump quickly across the overlap distance

Question 3

Gain

Answer 3

-the number of times that the output voltage is greater than the input voltage

Question 4

Dither Signal

Answer 4

-small, high frequency alternating current that is applied to the solenoid

Question 5

Ramp functions

Answer 5

-control how fast the voltage to the solenoid is increased and decreased

Question 6

Three amplifier systems

Answer 6

• open loop (sees if the actuator is responding)
• closed inner loop (position of spool)
• closed outer loop (knows where actuator is and can correct it - most efficient)

Question 7

Stacking valves

Answer 7

-have ports that have o-ring seats to seal the connections between one valve and the next

Question 8

Cartridge valves

Answer 8

• screw in (low flow, disposable)

- slip in (larger flow and can be repaired)

Question 9

Transducers

Answer 9

-pickups or sensors for servo valves that measure position, pressure or velocity

Question 10

Hysteresis

Answer 10

In servo valves-(inconsistent spool movement) expresses how accurately the spool moves compared to the input current

Question 11

Six devices for signal input to amplifier cards

Answer 11

• joystick
• potentiometer
• PLC
• tach generator
• pressure transducer
• temperature sensor