Reduced-energy-consumption actuator

A flow-control system comprising:

• A) a valve operable between open and closed states;
• B) an actuator including an armature operatively connected to the valve and further including a coil operable by application of a coil drive thereto to conduct current and thereby tend to drive the armature to an end position, in which the armature holds the valve in one of said open and closed states, from a rest position, to which the armature is biased to return in the absence of coil current and thereby hold the valve in the other of said open and closed states;
• C) an endpoint detector that detects the armature's reaching the end position and responds thereto by generating a detector output indicative thereof;
• and
• D) a control circuit operable to begin applying coil drive to the coil at a first level and responsive (i) to the detector output indicative of the armature's reaching the end position to change the coil drive to a different level great enough to keep the armature from returning to the rest position and (ii) to the failure to receive the detector output indicative of the armature's reaching the end position within a predetermined drive duration after the control circuit begins application of coil drive to the coil to apply coil drive to the coil at a level higher than that at which it began application of coil drive to the coil.

For controlling a actuator including an armature and a coil operable by application of a coil drive thereto to conduct current and thereby tend to drive the armature to an end position from a rest position, to which the armature is biased to return in the absence of coil current, a method comprising:

• A) applying coil drive to the coil at a first level;
• B) determining whether the armature has reached the end position;
• C) if so, changing the coil drive to a level lower than the first level but great enough to keep the armature from returning to the rest position;
• and
• D) if not within a predetermined duration after application of coil drive to the coil to apply coil drive has begun, driving the coil at a level higher than that at which it began application of coil drive to the coil.

An actuator system comprising:

• A) an actuator including an armature and a coil operable by application of a coil drive thereto through first and second drive terminals to conduct current and thereby tend to drive the armature to an end position from a rest position, to which the armature is biased to return in the absence of coil current;
• B) a sound sensor so coupled to the actuator as to sense sound made by the armature in reaching the end position, the sound sensor generating at first and second sensor terminal a sensor output indicative of the sound that it senses, the second sensor terminal being the same as the second coil terminal;
• and
• C) a control circuit operable to begin applying coil drive to the coil at a first level and responsive to the sensor output's meeting a predetermined end-position-indicating criterion to change the coil drive to a different level great enough to keep the armature from returning to the rest position.