Magnetic Latching Valve and Method of Control

Abstract

An example system includes a valve assembly having: (i) a plurality of ports including an inlet port, an outlet port, and a vent port, (ii) a solenoid coil having a cavity therein, (iii) an armature slidably accommodated in the cavity of the solenoid coil, (iv) a magnet fixedly disposed within the solenoid coil, wherein the magnet applies a magnetic force on the armature in a distal direction, and (v) a spring applying a biasing force on the armature in a proximal direction; and a controller sending a signal having a particular polarity to the solenoid coil such that the signal is applied to the solenoid coil for a particular period of time, and resending the signal periodically every particular time interval.

What is claimed is: 
     
         1 . A system comprising:
 a valve assembly comprising: (i) a plurality of ports including a first port and a second port, (ii) a solenoid coil, (iii) an armature, (iv) a magnet applying a magnetic force on the armature, and (v) a spring applying a biasing force on the armature; and   a controller configured to perform operations comprising:
 sending a signal to the solenoid coil such that the signal is applied to the solenoid coil for a particular period of time, thereby causing a solenoid force to be applied to the armature, wherein a combination of the biasing force of the spring and the solenoid force overcome the magnetic force, causing the armature to move axially to a particular position, thereby allowing fluid flow from the first port to the second port, and wherein when the armature is in the particular position, the magnetic force of the magnet is smaller than the biasing force, and the armature remains in the particular position upon removal of the signal, and 
 resending the signal periodically every particular time interval, wherein the particular time interval is greater than the particular period of time. 
   
     
     
         2 . The system of  claim 1 , wherein the valve assembly comprises a manifold, wherein the manifold includes the first port, wherein the solenoid coil is coupled to the manifold, and wherein the solenoid coil includes the second port. 
     
     
         3 . The system of  claim 2 , wherein the plurality of ports further comprise a third port, wherein when the armature is in the particular position, the armature blocks fluid flow from the third port to the first port, wherein the armature comprises a seal element made of a flexible material, such that when the armature is in the particular position, the seal element is compressed against an interior surface of the manifold and seals a channel that is fluidly coupled to the third port. 
     
     
         4 . The system of  claim 1 , wherein the valve assembly further comprises: a first pole piece and a second pole piece, wherein the first pole piece and the second pole piece are fixedly disposed within the solenoid coil, and wherein the magnet is interposed between the first pole piece and the second pole piece. 
     
     
         5 . The system of  claim 1 , wherein the spring is a conical spring having a largest-diameter coil resting against and interior surface of the solenoid coil and a smallest-diameter coil resting against a flange formed at an end of the armature. 
     
     
         6 . The system of  claim 1 , wherein the valve assembly further comprises a porous plug disposed at the second port and configured to allow flow of pressurized fluid therethrough in a direction from within the valve assembly to an external environment of the valve assembly. 
     
     
         7 . The system of  claim 1 , wherein the valve assembly comprises a third port, wherein the signal is a first signal having a first polarity, the particular period of time is a first period of time, the particular position is a first position, and the particular time interval is a first time interval, wherein the controller is configured to perform further operations comprising:
 receiving a request to change a commanded state of the valve assembly;   responsively, sending a second signal having a second polarity, opposite the first polarity, to the solenoid coil such that the second signal is applied to the solenoid coil for a second period of time, thereby causing a respective solenoid force to be applied to the armature, wherein a combination of the magnetic force and the respective solenoid force overcome the biasing force of the spring, causing the armature to move axially to a second position, thereby allowing fluid flow from the third port to the first port, and wherein when the armature is in the second position, the magnetic force of the magnet is greater than the biasing force of the spring, and the armature remains in the second position upon removal of the second signal; and   resending the second signal periodically every second time interval, wherein the second time interval is greater than the second period of time.   
     
     
         8 . The system of  claim 7 , wherein the second time interval is equal to the first time interval, and wherein the second period of time is equal to the first period of time. 
     
     
         9 . The system of  claim 7 , wherein the valve assembly further comprises: (i) a first pole piece having a channel therein, and (ii) a second pole piece having a respective channel therein, wherein the first pole piece and the second pole piece are fixedly disposed within the solenoid coil, wherein the magnet is interposed between the first pole piece and the second pole piece, and wherein the magnet is ring-shaped and comprises a hole that is aligned with the channel and the respective channel. 
     
     
         10 . The system of  claim 9 , wherein the magnet is axially-magnetized such that a north pole of the magnet is oriented toward the second pole piece. 
     
     
         11 . The system of  claim 9 , wherein the hole of the magnet, the channel of the first pole piece, and the respective channel of the second pole piece form a fluid passage that fluidly couples an airgap formed between the armature and the first pole piece to a gap that separates the second pole piece from a porous plug disposed at the second port, wherein when the armature is in the first position, fluid from the first port flows to the airgap, then through the fluid passage and the porous plug at the second port to an external environment of the valve assembly. 
     
     
         12 . The system of  claim 11 , wherein the armature comprises one or more ridges that allow fluid flow from the first port to the airgap. 
     
     
         13 . The system of  claim 11 , wherein the armature comprises a seal element made of a flexible material, such that when the armature is in the second position, the seal element is compressed against the first pole piece and seals the channel of the first pole piece, thereby blocking the fluid passage. 
     
     
         14 . A method comprising:
 receiving a request to operate a valve assembly in a commanded state, wherein the valve assembly comprises: (i) a plurality of ports including an first port and a second port, (ii) a solenoid coil, (iii) an armature, (iv) a magnet applying a magnetic force on the armature, and (v) a spring applying a biasing force on the armature;   responsively, sending a signal to the solenoid coil such that the signal is applied to the solenoid coil for a particular period of time, thereby causing a solenoid force to be applied to the armature, wherein a combination of magnetic force and the solenoid force overcome the biasing force of the spring, causing the armature to move axially to a particular position, thereby allowing fluid flow from the first port to the second port, and wherein when the armature is in the particular position, the magnetic force of the magnet is greater than the biasing force, and the armature remains in the particular position upon removal of the signal; and   resending the signal periodically every particular time interval, wherein the particular time interval is greater than the particular period of time.   
     
     
         15 . The method of  claim 14 , wherein the valve assembly comprises a third port, wherein the request is a first request, the commanded state is a first commanded state, the signal is a first signal having a first polarity, the particular period of time is a first period of time, the particular position is a first position, and the particular time interval is a first time interval, and wherein the method further comprises:
 receiving a second request to operate the valve assembly in a second commanded state;   responsively, sending a second signal having a second polarity, opposite the first polarity, to the solenoid coil such that the second signal is applied to the solenoid coil for a second period of time, thereby causing a respective solenoid force to be applied to the armature, wherein a combination of the biasing force of the spring and the solenoid force overcome the magnetic force of the magnet, causing the armature to move axially to a second position, thereby allowing fluid flow from the second port to the third port, while blocking fluid flow from the first port to the second port, and wherein when the armature is in the second position, the magnetic force of the magnet is smaller than the biasing force, and the armature remains in the second position upon removal of the second signal; and   resending the second signal periodically every second time interval, wherein the second time interval is greater than the second period of time.   
     
     
         16 . The method of  claim 15 , wherein the second time interval is equal to the first time interval, and wherein the second period of time is equal to the first period of time. 
     
     
         17 . The method of  claim 15 , wherein the valve assembly further comprises: (i) a first pole piece having a channel therein, and (ii) a second pole piece having a respective channel therein, wherein the first pole piece and the second pole piece are fixedly disposed within the solenoid coil, wherein the magnet is interposed between the first pole piece and the second pole piece, and wherein the magnet is ring-shaped and comprises a hole that is aligned with the channel and the respective channel. 
     
     
         18 . The method of  claim 17 , wherein the hole of the magnet, the channel of the first pole piece, and the respective channel of the second pole piece form a fluid passage that fluidly couples an airgap formed between the armature and the first pole piece when the armature is in the second position to a gap that separates the second pole piece from a porous plug disposed at the third port, wherein when the armature is in the second position, fluid from the second port flows through the fluid passage and the porous plug at the third port to an external environment of the valve assembly. 
     
     
         19 . The method of  claim 18 , wherein the valve assembly comprises a manifold, wherein the manifold includes the first port and the second port, wherein the solenoid coil is coupled to the manifold, and wherein the solenoid coil includes the third port, wherein the armature comprises (i) a first seal element made of a flexible material such that when the armature is in the first position, the first seal element is compressed against the first pole piece and seals the channel of the first pole piece, thereby blocking the fluid passage, and (ii) a second seal element made of the flexible material such that when the armature is in the second position, the second seal element is compressed against an interior surface of the manifold and seals a channel that is fluidly coupled to the first port. 
     
     
         20 . The method of  claim 14 , wherein the spring is a conical spring having a largest-diameter coil resting against and interior surface of the solenoid coil and a smallest-diameter coil resting against a flange formed at an end of the armature, such that as the armature moves to the particular position, the conical spring is compressed.