Volumetric pump with replaceable reservoir assembly
First Claim
1. A volumetric pump, comprising:
- a reservoir;
a piston with a central longitudinal axis of displacement, the piston being disposed within the reservoir such that displacement of the piston along its central axis causes a change in the volume of the reservoir;
a piston follower affixed to the piston, the piston follower displaying a threaded drive surface that substantially defines a longitudinal section of a cylindrical surface of revolution about an axis substantially parallel to the axis of piston displacement; and
an axially non-displaceable drive screw with an axis of rotation substantially parallel to the axis of piston displacement, the drive screw being short in comparison to the displacement of the piston and the threads of the drive screw being removably engaged with the threaded drive surface of the piston follower, such that rotation of the drive screw translates into linear displacement of the piston along its axis of displacement.
1 Assignment
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Accused Products
Abstract
An infusion pump has a removable reservoir including a piston and drive member. The drive member is an internally threaded elongated portion of the piston. A motor rotates a short drive screw, which engages the threads of the drive member to displace the piston in the reservoir. In one embodiment the piston is attached to the drive member by a severable central stem which breaks away to allow engagement with the drive screw. With the stem severed, the piston cannot be retracted, or the reservoir refilled. Other safety features are shown for locking the displaced piston in the reservoir. A digital metering system has a safety circuit to prevent dangerous failure modes of the rotation sensor and motor drive systems.
235 Citations
15 Claims
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1. A volumetric pump, comprising:
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a reservoir; a piston with a central longitudinal axis of displacement, the piston being disposed within the reservoir such that displacement of the piston along its central axis causes a change in the volume of the reservoir; a piston follower affixed to the piston, the piston follower displaying a threaded drive surface that substantially defines a longitudinal section of a cylindrical surface of revolution about an axis substantially parallel to the axis of piston displacement; and an axially non-displaceable drive screw with an axis of rotation substantially parallel to the axis of piston displacement, the drive screw being short in comparison to the displacement of the piston and the threads of the drive screw being removably engaged with the threaded drive surface of the piston follower, such that rotation of the drive screw translates into linear displacement of the piston along its axis of displacement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A reservoir assembly, for removable engagement with a motor assembly so as to form a volumetric pump, the reservoir assembly comprising:
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a reservoir; a piston with a central longitudinal axis of displacement, the piston being disposed within the reservoir such that displacement of the piston along its central axis causes a change in the volume of the reservoir; a piston follower, affixed to the piston, having a threaded drive surface that substantially defines a longitudinal portion of a surface of revolution about an axis substantially parallel with the axis of piston displacement, for linearly displacing the piston along its axis of displacement when the drive surface is engaged against an axially non-displaceable drive screw with an axis of rotation substantially parallel to the axis of piston displacement, such that rotation of the drive screw translates into linear displacement of the piston along its axis of displacement. - View Dependent Claims (10, 11, 12, 13)
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14. A volumetric pump, comprising:
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a reservoir; a piston with a central longitudinal axis of displacement, the piston being disposed within the reservoir such that displacement of the piston along its central axis causes a change in the volume of the reservoir; a piston follower affixed to the piston, the piston follower displaying a threaded drive surface that substantially defines a longitudinal section of a cylindrical surface of revolution about an axis substantially parallel to the axis of piston displacement; and an axially non-displaceable drive screw with an axis of rotation substantially parallel to the axis of piston displacement, the drive screw being short in comparison to the displacement of the piston and removably engaged against the threaded drive surface of the piston follower, such that rotation of the drive screw translates into linear displacement of the piston along its axis of displacement; and a motor for driving the drive screw, wherein a substantial portion of the motor and the drive screw are contained within a surface of revolution defined by the drive surface. - View Dependent Claims (15)
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Specification