Post #1
This is simply flow regulation. Many applications utilize a comparatively expensive Proportional valve to vary the speed of a hydraulic cylinder after some form of trip-point. The trip-point could be time, a limit-switch signal, analog/digital feedback, etc.
In my particular case, I would, ideally prefer to upgrade all actuators to full servo control but the client can't justify the extra-cost.
Because manual adjustments on an otherwise fully-automatic machine drives me nuts, as part of my control-system retrofit, I'm gifting a few enhancements to the client.
Instead of simply driving an SSR output fully on or off, I will use a simple H-Bridge driver and vary the coil-current via PWM.
This simply results in variable spool displacement. One can demonstrate this by manually pushing the spool using something like a small hex key/wrench.
Manual flow controls to be removed or left fully open.
Providing programmable parameters on the HMI is a trivial task.
Craig
At no point have I suggested this as a substitute for a high-performance, zero-overlap servo-valve under PID control.Anyone ever PWMd the coils of a bang-bang valve? I tried it recently so that I could reduce machine setup-time by eliminating the manual flow controls.
This is simply flow regulation. Many applications utilize a comparatively expensive Proportional valve to vary the speed of a hydraulic cylinder after some form of trip-point. The trip-point could be time, a limit-switch signal, analog/digital feedback, etc.
In my particular case, I would, ideally prefer to upgrade all actuators to full servo control but the client can't justify the extra-cost.
Because manual adjustments on an otherwise fully-automatic machine drives me nuts, as part of my control-system retrofit, I'm gifting a few enhancements to the client.
Instead of simply driving an SSR output fully on or off, I will use a simple H-Bridge driver and vary the coil-current via PWM.
This simply results in variable spool displacement. One can demonstrate this by manually pushing the spool using something like a small hex key/wrench.
Manual flow controls to be removed or left fully open.
Providing programmable parameters on the HMI is a trivial task.
Craig