Our previous post discussed how advancements in technologies such as drives showcase certain trends in a rapidly evolving industry. Here, let’s take a look at trends in FieldBus-based pneumatic and piezo-actuated valve technologies.
A big trend is that of pneumatics evolving from traditional manual to FieldBus installations. In general, a FieldBus replaces point-to-point links between “field” devices such as sensors and actuators of a plant and their controllers (for instance, PLCs or CNCs) by a digital single link on which all the information is transmitted. FieldBus systems are increasingly favored because data transmission is done in a standard form suitable for factory communication.
This trend has arisen largely as a result of increased labor costs. Shipping a piece of equipment from place to place, often requires a significant amount of labor to first dismantle the machine. Traditional manual systems are hardwired. FieldBus systems, though, use only a few wires and power cords, making it much easier to remove the control panel of the whole working device and ship the machine.
Additionally, pneumatic component interfaces are increasingly standardized. Historically, most manufacturers used their own proprietary interfaces on their pneumatic products; but suppliers are now providing devices such as valves and cylinders that adhere to an ISO standard, so the products from different suppliers are interchangeable. Thus, OEMs are not locked into one manufacturer down the road and engineers can make changes quickly. Basically, standardization lets companies have flexibility in their supply chains.
Microfluidics involves small liquid valves, pneumatic or air valves, liquid pumps, or air or pneumatic pumps that control and pump fluids. The trend here is that microfluidic devices are increasingly moving towards piezo-actuated technology. An example is our PACE Hf proportional valve, typically used to supply certain blends of air and oxygen into ventilators, depending on the patient's vital signs.
In the past, feedback happened via a straight analog signal sent to the valve. A challenge was that precise control was needed to go from a proportion of a very low percentage, say 1 to 2 percent of oxygen, all the way to full saturation, or 100 percent oxygen. Previously, valve manufacturers accomplished this through a large solenoid coil with a strong spring. However, the coil was about the size of a soda can and generated a lot of heat.
Compared to older technologies, the PACE Hf valve’s piezo actuation provides the same amount of flow and actually improves controllability at the lower ranges of 1 percent oxygen-air mix. One version of the valve uses an analog signal which still comes from the main board on the ventilator. The other version is digital and requires additional software from the ventilator manufacturer to control the valve.
Also, the piezo actuator is only about the size of a package of chewing gum. The actuator provides a tremendous amount of travel, which means the small package can provide a lot of flow.
Piezo actuators use significantly less power than solenoids. This can be important when the ventilators are on battery power while a patient is being transferred to an ICU for recovery because it eliminates the concern that the device will potentially run out of power before the unit is plugged back into the wall.
At Parker’s Automation Group, we see our customers increasingly replacing solenoids with piezo actuators. Often one proportional valve can replace multiple solenoids, cutting costs for the equipment OEM as well as saving space.
Article contributed by Nic Copley, Vice President Technology and Innovation, Automation Group, Parker Hannifin Corp.
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