Selenoid Valve Hystory

Solenoid valves technology history

Solenoid valves have made remarkable progress over the last three decades. Manual shutoff has given way to automated shutdown systems. In-line mounted valves have lost their popularity to pad mounted valves. And, specialized actuator designs have moved to standardized designs in the presence of the European NAMUR standard. These are only a few of the many changes that have occurred to the solenoid valve, the workhorse of the chemical processor's valve system. The solenoid valve has made tremendous leaps in the chemical processing industry. Yet, at the same time, market conditions can dictate the need to continue enhancing solenoid valve technology.

Solenoid Valves Evolution

During the 1970s, the chemical industry primarily utilized linear control valves that employed a rising stem. Once automated, these valves required pipe-mounted solenoid valves. Solenoid valve designed initially for linear control valves were, at this point, playing double-duty because they were being used for quarter-turn ball valves as well.
The quarter-turn ball valve, with its suitability for automated packages, began to gain popularity in the 1980s. In time, actuator manufacturers began to develop their own flat plates. They embedded these flat plates into the actuator by using an interface that had a direct-coupled solenoid valve. This flat interface found its way in time to close coupling against a flat-style valve. Eventually, spool valves replaced the flat-style valve for this application.
However, because standardization was not widespread at the time, each actuator manufacturer tended to have a unique interface configuration. Consequently, solenoid valve manufacturers needed to design five to six different styles of valves to fit onto these various actuators. It was not until the 1990s that the valve industry instituted its own standardization for an interface with the solenoid valve.

Higher flow rate for solenoid valves

In the 1990s the German chemical industry developed the NAMUR standard, which standardized the actuator interface to the solenoid valve. Initially, the U.S. was slow to accept the European standard; however, by the mid-1990s all actuator manufacturers worldwide embraced it.
Today, a new European CEN standard promises to follow in NAMUR's footsteps. Referred to as CEN/TC69/WG1/SG10/0/ N023, the new standard is an extension of the VDI/VDE3845 requirements. Its significant difference from the original NAMUR standard is that it covers even higher flow rates. To date, few manufacturers have developed valves to conform to this new CEN standard. We can expect future solenoid valve designs to accommodate this product gap.

Sustainable design

The European standard RoHS focuses on improving the impact manufacturers in all industries have on the environment. As of July 1, 2006, legislation mandates that any product shipped to Europe has to meet the RoHS standard.
Briefly, RoHS restricts the use of six hazardous substances within electrical and electronic equipment. This includes any product with minimal levels of lead, mercury, cadmium, hexavalent chromium Cr, Polybrominated biphenyls, and polybrominated diphenyl ethers.
Solenoid valves typically have small amounts of some of these restricted substances. For example, hexavalent chromium Cr exists in the standard plating used for corrosion protection in the electrical industry. As a result, we expect that solenoid valves will likely require alternate plating compounds in the near future.
Historically, newly written standards have been the impetus for many innovations in valve design. As you will see in this article, design standards – from the present and in the future – will also lead to the development of new valve technologies in the years to come.

Magnesense valves history

Magnesense first engine solenoid valve became a platform for trying out a new development: a spring that would fit the geometry of a cylinder valve solenoid. The approach with other solenoids, then and to this day, relies on two large opposing compression springs, one of them set into the engine block. Each of these springs is quite a bit larger than an ordinary valve return spring, as needed to achieve the high centering force required to move a valve quickly between its fullopen
and full-closed positions.
We figured that if the valve return spring could go back to its original size while the remaining restoration force came from a compact push-pull spring fitting above the solenoid, then the cylinder head modifications could be reduced considerably. By
designing a spring capable of both compression and tension, we could operate the metal almost symmetrically about a neutral stress, allowing for considerably more energy storage per unit of spring mass. We settled on side-by-side helices, joined across the middle, as a way to fit the flat rectangular envelope needed to stack valve actuators up side-by-side at the
spacing needed in a multi-cylinder engine. We got Peterson Spring interested, and they agreed to bend some prototype springs for testing.
The big challenge was to capture the spring ends and middle in a way that would allow reversing push-pull forces without developing any slop and without chafing the spring metal at the clamp. We developed a clamp design in which a hard rubber sleeve would surround the spring wire and be clamped in high compression. Rubber gets torn apart by tension or an
alternation of tension and compression, but Magnesense studies of elastomer dynamics indicated that if the rubber were kept in compression at all times, and if the force transferred from the clamp to the wire were transmitted mostly differences in positive pressure rather than by shear forces, then the rubber would last indefinitely.