Solenoid cassette pump with servo controlled volume detection

A pump arrangement comprising:

• a) a selectively removable cassette comprising:
• a housing
• a movable member associated with said housing in manner to define a variable volume chamber;
• an inlet valve disposed in said housing so as to selectively permit fluid to flow into the chamber;
• an outlet valve disposed in said housing so as to selectively permit fluid to flow out of the chamber, and
• b) a solenoid which is separate from said cassette and operatively connected with said movable member for actuating the movable member in a manner to sequentially induct fluid into and discharge fluid from the variable volume chamber;
• said solenoid comprising an armature;
• means for sensing the position of the armature;
• and means for determining, based on the sensed armature position, the composition of a fluid being pumped through the variable volume chamber.

A pump arrangement comprising:

• a) a selectively removable cassette comprising:
• a housing
• a movable member associated with said housing in a manner to define a variable volume chamber;
• an inlet valve disposed in said housing so as to selectively permit fluid to flow into the chamber;
• an outlet valve disposed in said housing so as to selectively permit fluid to flow out of the chamber, and
• b) a solenoid which is separate from said cassette and operatively connected with said movable member that actuates the movable member in a manner to sequentially induct fluid into and discharge fluid from the variable volume chamber;
• said solenoid including an armature which is supported within a housing by a flat spring member which comprises:
• an outer member,
• an inner member;
• and
• two curved connection portions which extend in first and second essentially opposed directions and which are each connected with the outer member at one end and with the inner member at the other.

A pump arrangement comprising:

• a) a selectively removable cassette comprising:
• a housing
• a movable member associated with said housing in a manner to define a variable volume chamber;
• an inlet valve disposed in said housing so as to selectively permit fluid to flow into the chamber;
• an outlet valve disposed in said housing so as to selectively permit fluid to flow out of the chamber, and
• b) a solenoid which is separate from said cassette and operatively connected with said movable member that actuates the movable member in a manner to sequentially induct fluid into and discharge fluid from the variable volume chamber;
• said solenoid having an armature which is supported within a housing by first and second flat spring members, the first flat spring being connected to the armature proximate a first end thereof and the second flat spring member being connected to the armature proximate a second end thereof, the first and second flat springs being operative to guide the armature so that it reciprocates back and forth along a predetermined axis, each of said first and second flat springs comprising:
• an outer member;
• an inner member;
• and
• two curved connection portions which extend in first and second essentially opposed directions and which are each connected with the outer member at one end and with the inner member at the other.