Transpermanent Magnetics Using Alternating Uniform Linear Stacks

Abstract

In this paper we apply recent developments in transpermanent magnetics to the problem of ultra-low-power valve control. Whereas the traditional approach to ultra-low-power valve control is based on latching mechanisms that turn off valves during inactive periods, in this paper we describe an approach that eliminates the need for latching mechanisms. Instead of latching mechanisms, the principles of transpermanent magnetics are employed to switch the states of permanent magnets; the use of permanent magnets instead of electromagnets eliminates power loads during inactive periods, thereby reducing power consumption to ultralow levels. The permanent magnets in a transpermanent magnet valve are configured in a stack. The relationships between the strength and number of permanent magnets in the stack and the stroke and resolution of the valve are developed. In this paper we show that the alternating uniform linear stack is well suited for digital process valves having a small number of states. Then in the paper we report on the design and testing of a laboratory prototype valve that uses an alternating uniform linear stack. The prototype valve had five states yielding a range of flow rates between 0 and 1.58m∕s with a resolution of 0.3m∕s. In this paper we find that transpermanent valves represent a promising valve technology for digital process valves.