Solenoid Actuator

Abstract

A solenoid actuator is described. The solenoid actuator comprises an armature, pole piece(s), electromagnet coil(s) arranged, in response to energisation, to cause travel of the armature between first and second positions along a direction of travel, permanent magnet(s) positioned and orientated for latching the armature in at least the first position when the armature is in the first position and spring(s) arranged to bias the armature. The solenoid actuator can be operated to provide partial lift.

1 - 87 . (canceled) 
     
     
         88 . A fuel injector comprising a solenoid actuator comprising:
 an armature, pole piece(s), electromagnet coil(s) arranged, in response to energization, to cause travel of the armature between first and second positions along a direction of travel, and spring(s) arranged to bias the armature, wherein in the first position the fuel injector is closed and wherein quasi-static position of the armature is at least monotonic with the coil current over all or some of length of travel of the armature.   
     
     
         89 . The fuel injector of  claim 88 , configured such that the armature is stably positionable at more than one position between the first and second positions dependent upon current(s) through the electromagnet coil(s). 
     
     
         90 . The fuel injector of  claim 88 , wherein the solenoid actuator further comprises: a pintle which is disengageably coupled to the armature. 
     
     
         91 . The fuel injector of  claim 88 , wherein the solenoid actuator further comprises: a pintle which is fixed to the armature. 
     
     
         92 . The fuel injector of  claim 88 , configured as an inward-opening injector. 
     
     
         93 . The fuel injector of  claim 88 , configured as an outward-opening injector. 
     
     
         94 . The fuel injector of  claim 88 , wherein permanent magnet(s) are positioned and orientated for latching the armature in at least the first position. 
     
     
         95 . The fuel injector of  claim 88 , comprising:
 at least two linked armatures arranged in a stack along the direction of travel, wherein each armature comprises first and second opposite shaped faces and wherein the pole piece(s) include at least one correspondingly inversely-shaped face for seating the armature.   
     
     
         96 . The fuel injector of  claim 88 , wherein the armature comprises first and second opposite shaped faces and wherein the pole piece(s) include at least one correspondingly inversely-shaped face for seating the armature. 
     
     
         97 . The fuel injector of  claim 88 , wherein the spring(s) is (are) configured to provide sufficient force so as to prevent the armature from latching in second position. 
     
     
         98 . The fuel injector of  claim 88 , wherein the spring(s) includes: a fixed spring of fixed spring rate. 
     
     
         99 . The fuel injector of  claim 98 , wherein the fixed spring is chosen from one of a plurality of fixed springs having different spring rates. 
     
     
         100 . A set of fuel injectors according to  claim 99 , wherein each fuel injector has a respective actuator, wherein each actuator comprising substantially identical pole pieces, armatures, electromagnet coils and permanent magnets and wherein at least one actuator in the set comprises a fixed spring having a different spring rate to another actuator in the set. 
     
     
         101 . The fuel injector of  claim 88 , comprising: a plurality of stacked actuators comprising pole piece portions and armatures disposed within a tube. 
     
     
         102 . The fuel injector of  claim 88 , wherein the actuator comprises:
 flux-sensing loop(s) and/or coils(s) for measuring magnetic flux.   
     
     
         103 . The fuel injector of  claim 88 , wherein comprising: a pintle or needle. 
     
     
         104 . A system comprising:
 the fuel injector of  claim 88 ; and   a control unit operatively connected to the actuator.   
     
     
         105 . A device for controlling fluid flow comprising a solenoid actuator comprising an armature, pole piece(s), electromagnet coil(s) arranged, in response to energisation, to cause travel of the armature between first and second positions along a direction of travel, and spring(s) arranged to bias the armature, wherein in the first position the device is closed and wherein quasi-static position of the armature is at least monotonic with the coil current over all or some of length of travel of the armature.