Topics Flow Control Valve Types Flow Coefficient Circuits Cushioned Cylinders Flow Dividers Flow Control Valve Specifications Flow Control Types MECH1300 Metering Controlling the flow rate ID: 705910
Download Presentation The PPT/PDF document "Hydraulic Flow Control MECH1300" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Hydraulic Flow Control
MECH1300
TopicsFlow Control Valve TypesFlow CoefficientCircuitsCushioned CylindersFlow DividersFlow Control Valve SpecificationsSlide2
Flow Control Types
MECH1300
Metering – Controlling the flow rateMeter In – IN to OUT is the controlled direction, OUT to IN is uncontrolled (Controls the flow IN)Meter Out – OUT to IN is the controlled direction, IN to OUT is uncontrolled (Controls the flow OUT)Slide3
Flow Control Types
MECH1300
Needle valve - An adjustable orifice that can be closed to reduce the flow rate. Referred to as metering valves Often used as a manual shut off Flow is controlled in one direction only
Referred to as Flow Control valves when they have an integral checkSlide4
Flow Control Types
MECH1300
Pressure Compensated valve – Automatically adjust the size of the orifice in response to changes in system pressure.Uses a spring loaded compensator spool that reduces the orifice size when upstream pressure increases
Temperature compensated valves – orifice decrease as temperature increasesSlide5
Flow Coefficient
MECH1300
Flow coefficient describes the exact relationship between pressure drop and flow rateSlide6
Flow Coefficient
MECH1300
EX: A valve with a
of 2.1
has a pressure drop of 35 psi. What must the flow rate be through the valve? Standard hydraulic oil is used,
Slide7
Flow Coefficient
MECH1300
EX: A valve with a
of 2.2
has a flow rate of 20gpm. What must the pressure drop be across the valve? Standard hydraulic oil is used,
A larger
equates to a smaller pressure drop at a given flow rate
Slide8
Metering Circuit
MECH1300
A cylinder has a 3in diameter bore and a 2in diameter rod. The pressure relief valve is set to 3000psi. If the meter-out flow control valve is closed completely, what will the pressure be in the rod end? Assume the piston diameter is the same as the bore diameter.Calculate the areas:
Calculate the force:
Calculate the pressure:
Slide9
Circuits
MECH1300
Pressure Intensification – Occurs in cylinders if the flow control valve is completely closed. The cylinder won’t move and pressure builds up. (happens with meter out fcv’s). A disadvantage of metering out.Tractive Loads – Loads that act in the direction of movement (meter out).
Resistive Loads - Loads that oppose the direction of motion (meter in). Bleed Off – An additional line is run through a flow control back to the tank. To slow down the actuator, some of the flow is bled off through this line.Slide10
Cushioned Cylinders
MECH1300
Used when it is desired to slow a cylinder down just before it reaches the end of its stroke.Helps prevent a clamp from doing damage to itself or a work piece.Slide11
Flow Dividers
MECH1300
Divide the flow from a pump into two or more streams of equal flow ratesBalanced Spool RotarySlide12
Flow Control Valve Specifications
MECH1300
What to look for: Max Pressure, Max Flow, Filtration level, Fluid type, Size, Mounting and porting