Proportional valves that employ powerful, voice-coil valve technology are used in applications where higher flows from smaller valves are ideal. While the list is endless, a few of the activities in which you may need to use these particular valves are lifting, steering and suspension. For an improved operation, acting on these three tips may be in your favor.
Test for trapped airflow
Trapped airflow is a common problem for proportional valve systems. When it comes to pilot operated valves, it can take some time to get the air out. Some indicators of trapped airflow due to valve instability include pulsing, modulation or an unusual performance overall. Higher flows tend to help push out the trapped air behind the spool so if you can run yours at a higher flow, then it should perform well at lower flows.
Understand the best valve position
The position of your valve plays a big role in the operation. Be sure that the valve is not positioned at the high point of your system or in an upright orientation. This can trap the air. Keep the valve mounted horizontally so the tube is off to the side. An advantage to having the tube horizontal is that any G load acting on the valve will not tend to self-activate the valve. Some systems see about 3 to 5 G loads but can go as high as 10 G.
Ideally, the proportional valve is located below the oil reservoir with the tank port of the valve oriented upward. This keeps the oil in the valve when the system is shut down. On many systems, we have used a check valve in the tank line to help with this and have seen this help with stability in several cases.
Use the manufacturer’s recommended PWM frequency
For our proportional valves, we call out a specific PWM frequency for best results on these products. Some operators may not be following this and could be using IQAN or something similar. However, we do not have any test results for this type of system. Keep in mind that the dither frequency and amplitude are different from each manufacturer but drivers typically range anywhere from 1 kHz to 10 kHz.
To achieve the best possible operation, users should follow the manufacturer’s operational guidelines. Find out more about Parker's proportional valve offering from the Hydraulic Cartridge System Division.
Parker offers a wide range of proportional valves that employ a powerful voice-coil valve technology through its Hydraulic Cartridge Systems Division. Visit the website or consult your Hydraulic Cartridge System Division Catalog for more information.
Article contributed by Stephen Brunton, product manager, Hydraulic Cartridge Systems Division.
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