Electro-proportional flow control valve - normally open
This valve is a normally open electro-proportional throttle that is spring-biased open. Energizing the coil generates an closing force on the spool proportional to the command current, and this force is countered by the spring and flow forces. This force balance creates a metering orifice whose effective size is proportional to the current. The valve exhibits a large degree of self-compensation in the 1-to-2 direction and will provide proportional flow control in the 2-to-1 direction with the addition of an external compensator. Full reverse flow (2-to-1) with no command in the 2-to-1 direction is possible without a compensator under all conditions.
- Available in either a normally open or normally closed configuration with three different capacity ranges.
- Capable of operating with pressures up to 5000 psi (350 bar).
- Low leakage levels in the closed position.
- Coils are interchangeable with Sun's other full flow, solenoid-operated valves and can be mounted on the tube in either direction.
- This cartridge has several manual override choices, including no manual override. See Option Configuration.
- For optimum performance, an amplifier with current sensing and adjustable dither should be used. Dither should be adjustable between 100 - 250 Hz.
- On models equipped with the D or L control, the detent mechanism in the manual override is meant for temporary actuation. The D, E, L and T manual control assemblies have a mechanical life expectancy of approximately 7,000 cycles.
- The momentary/twist override option "E" allows the operator to shift the valve by twisting the manual override clockwise 90 degrees.
- Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.
|Capacity||7 gpm28 L/min.|
|Maximum Valve Leakage at 110 SUS (24 cSt)||6 in³/min.@3000 psi100 cc/min.@210 bar|
|Manual Override Force Requirement||5 lbs/1000 psi @ Port 133 N/100 bar @ Port 1|
|Manual Override Stroke||.10 in.2,5 mm|
|Solenoid Tube Diameter||.75 in.19 mm|
|Valve Hex Size||7/8 in.22,2 mm|
|Valve Installation Torque||30 - 35 lbf ft41 - 47 Nm|
|Model Weight (with coil)||1.10 lb0,50 kg|
|Seal kit - Cartridge||Buna: 990413007|
|Seal kit - Cartridge||Polyurethane: 990413002|
|Seal kit - Cartridge||Viton: 990413006|
|Seal and nut kit - Coil||Viton: 990770006|
|Hysteresis (with dither)||<4%<4%|
|Hysteresis with DC input||<8%<8%|
|Linearity (with dither)||<2%<2%|
|Repeatability (with dither)||<2%<2%|
|Recommended dither frequency||140 Hz140 Hz|
|Deadband, nominal (as a percentage of input)||25%25%|
The spring force in our flow controls equates to about 100 psi (7 bar). This is high enough to give the valves acceptable capacity (not really) and not too high for proper circuit operation. 100 psi (7 bar) is the spring force; at the upper end of the flow control's range, the drop through the valve will be as high as 250 psi (17 bar) before it starts modulating.
There are exactly 250 Sun drops in a cubic inch or 15 in a cc.
In a meter-in flow control circuit if the pump is set at 3000 psi and the load is 2000 psi the drop through the flow control is 1000 psi. In a meter-out circuit with the load at 2000 psi the drop through the flow control is 2000 psi.
We claim +/- 10%. We set to +/- 5% in production testing to allow for differences in customers' conditions. If you want accuracy, stay in the bottom 2/3rds of the range. Our 12 gpm (45 L/min.) flow controls are quite flat at 9 gpm (34 L/min.) and dead flat below 6 gpm (23 L/min.), until you get to the bottom of the range. Below about .25 gpm (1 L/min.), spool leakage and orifice conditions start to limit accuracy.
I am afraid not. Unless you are overflowing your current valve and correctly size ours, you are not likely to notice any improvement. Priority flow controls are not efficient devices. They are an easy way to get more than 1 source of oil from 1 pump but they can generate a lot of heat. Try to size your actuators so the pressures are similar on both the priority and the bypass circuits. If you can't do that, try to have the lower flow leg be the lower pressure. The pump pressure is determined by whichever leg is higher and if there is flow that is taking a pressure drop that is not doing work it is creating heat.
All flow is blocked, hence the term priority. The priority flow has to be satisfied.
The valve acts as a 2 port restrictive flow control.
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