The pressure of controlling the fan speed!
To control speed of an actuator in hydraulics, one need to control the inlet flow. So, when you want to control the speed of a hydraulic motor driven fan, you need to control the inlet flow. Correct?!
But why do we control inlet pressure when we need to control the speed of a fan drive? In case of electric fans, why do we control torque? Strange! But true!
It’s a fan drive, so it has to work with air, i.e. Wind. When you are blowing air,
T ∝ ω2
T = C ω2
Where, T = Torque in N,
?????????????ω = fan speed in radian/sec,
??????????? C = A constant.
In electric drives, we control current to control torque. In hydraulic drives, we control pressure to control torque. So, we control inlet pressure to control speed of a hydraulic fan drive.
Why do we prefer pressure control over flow control to control speed? A hydraulic engineer would agree that it’s easy to control pressure.
Why is it easy to control pressure? When you control flow, it is dependent on load and temperature. To make it load independent, you add a pressure compensator. There isn’t much you can do about temperature in open loop controls. Whereas, in case of pressure control, you just control pressure ??.
HydraForce has best in class, proportional pressure control valves such as TS10-26 (increasing pressure with increasing current) and TS10-27(decreasing pressure with increasing current).
We offer an excellent plug in controller too!
Regional Manager @ FLSPL Voith (South India)
1 年Great explanation! Thank you