TechArchive

Original article date: April 1998

The piezoelectric multi-layer bender element in Asco Joucomatic’s latest solenoid valve comes from PI in Germany. Alan Quinn takes a look at what it has to offer.

Ceramic multilayer actuator (CMA) technology is the key to Asco Joucamatic’s piezoelectric solenoid valves, which gives response times down to 100um, a service life exceeding a billion cycles and extremely lower power consumption – 0.3mA at 24V (0.007W) and 0.9mA at 70V, the voltage range over which the product operates.

The new valves have no moving parts and embody a CMA element. CMA technology originates from Philips Components and combines piezoceramic and multi-layer technologies. However, according to Kevin Grimley, product specialist at UK distributor Lambda Photometrics, Philips has now ceased all piezoceramic production. The ceramic multi-layer bender element used on the valve is supplied by PI in Germany, one of the few companies in the world able to manufacture multi-layer piezo devices. The company tends to stop at supplying devices for OEM integration and does not get involved in building finished products, such as complete valve assemblies.

The element comprises a monolithic piezo-ceramic strip with integrated electrodes that are specially configured to that the element bends when a voltage is applied. The bending action is used to open or close one or more nozzles (on/off control) in a valve, or to govern proprotionally the flow of air to a pneumatic control system.

The operation of the piezo valves means that there are no inductive peaks when switching, so unlike conventional solenoid valves, no circuit protection is necessary. No holding current is required for the valves to maintain position, so heat generation is not a problem either.

The functionality and size of the piezo-elements means that one of the units may b employed where two conventional solenoids were required previously. In spite of their small size and weight, however, the large stroke of the piezo actuator ensures impressive flow in direct-acting valves with nominal orifice sizes of 0.6mm and 0.8mm.

The piezo valves are available in normally opn and normally closed 2/2 and 3/2 configurations. There are versions for simple on/off control, a 2/2 unit for more involved proportional control and an intrinsically safe variant, rated EEx ia 11c T6. All versions have the option of a manual impulse-type override.

The P-803 series of multilayer bender actuators available from Physik Instrumente (PI)

(*) Displacement and force measured with bender clamped at one end , free length = actual length less 8mm

• Asco Joucomatic
• 0990 226699
• Lambda Photometrics
• 01582 768232

April 1998