Peristaltic pump
A peristaltic pump system including an arcuate pressing surface, a force element that applies an occluding force towards the pressing surface, a drive mechanism that drives the force element, a diaphragm disposed between the pressing surface and the force element that defines a pump cavity, an actuator strip disposed between the diaphragm and the force element that receives the occluding force, deflects to deform the diaphragm, and occludes the pump cavity, a support structure that retains the actuator and diaphragm positions relative to the pressing surface, and a restitution mechanism that recovers the open pump cavity configuration.
1. A peristaltic pump system comprising:
a planetary rotor sub-system, including:
a rotor;
a ring defining a pressing surface along an inner bearing surface, the pressing surface defining a groove along a circumferential section, wherein the groove has a substantially well-shaped cross section; and
a planetary roller element, driven by relative motion between the pressing surface and the rotor, wherein the roller element rolls along the pressing surface and applies an occluding force against the pressing surface;
an occlusion sub-system including:
a diaphragm that seals a groove opening, defining a deformable volume in conjunction with the groove, wherein the deformable volume is operable between:
an open configuration, wherein the deformable volume is unoccluded; and
an occluded configuration, wherein the deformable volume is occluded;
an actuator strip, disposed between the roller element and the diaphragm, that biases the deformable volume to recover the open configuration, the actuator strip having a butte-shaped cross-sectional profile with a narrow occluding surface, a wide bearing surface, and radiused side walls, wherein the occluding surface is coupled to the diaphragm along the longitudinal centerline of the diaphragm, and the bearing surface couples to the roller element; and
a support structure including:
a diaphragm restraint portion that clamps the diaphragm edges against the pressing surface of the ring; and
an actuator restraint portion , disposed along the longitudinal edges of the actuator strip bearing surface, that limits the deflection of the actuator strip away from the pressing surface;
wherein the actuator strip is held in tension against the actuator restraint portion to bias the deformable volume in an open configuration;
wherein the occlusion system is operable in three modes:
a rest mode, wherein the deformable volume achieves the open configuration;
an occluded mode, wherein the roller element applies the occluding force to a localized section of the actuator strip bearing surface, deflecting the actuator strip such that the occluding surface deforms the diaphragm, occluding the corresponding section of the deformable volume; and
a pressurized mode, wherein the pressure within the deformable volume is higher than ambient pressure, wherein the actuator restraint portion prevents actuator strip deflection, preventing diaphragm expansion, maintaining the volume of the deformable volume and maintaining the pressure within the deformable volume.
2. The system of claim 1 , wherein the pressing surface rotates and the angular position of the rotor of the planetary rotor sub-system is held substantially static.
3. The system of claim 1 , wherein the diaphragm is held in radial tension along the diaphragm thickness.
4. The system of claim 3 , wherein the diaphragm sheet is a circular band, wherein the diaphragm is radially stretched over a circular support structure to achieve radial tension.
5. The system of claim 1 , wherein the occlusion sub-system generates a suction force when shifting from occluded mode to rest mode.
6. A peristaltic pump system comprising:
an arcuate pressing surface;
a force element comprising a roller element that translates along the pressing surface and applies an occluding force towards the pressing surface;
a drive mechanism that facilitates force element translation, the drive mechanism comprising a planetary rotor system, wherein the roller element is a planetary roller and the pressing surface comprises a ring surface;
a diaphragm, disposed between the force element and the pressing surface, that defines a pump cavity, wherein the pump cavity is operable between an open configuration and an occluded configuration;
an actuator strip, disposed between the force element and the diaphragm, wherein the actuator strip is longitudinally aligned with the diaphragm, the actuator strip including:
an occluding surface that couples to the diaphragm and has a profile that minimizes diaphragm deformation stress; and
a bearing surface that receives the occluding force from the force element and transmits the occluding force to the occluding surface;
wherein the force element deforms successive localized segments of the actuator strip, which deform successive sections of the diaphragm to occlude the corresponding segments of a deformable volume;
a support structure including:
a diaphragm restraint portion that couples the longitudinal edge of diaphragm against the pressing surface of the ring; and
an actuator restraint portion, disposed along the longitudinal edges of the actuator strip bearing surface, that couples the actuator strip bearing surface to the pressing surface and limits the deflection of the actuator strip away from the pressing surface;
a restitution mechanism that recovers the open configuration of the pump cavity.
7. The system of claim 6 , wherein the width of a gap formed along each longitudinal edge between the actuator strip and a support structure is controlled.
8. The system of claim 6 , wherein rotation of the pressing surface drives roller element rotation.
9. The system of claim 6 , wherein the pressing surface further includes a groove along the longitudinal centerline of the pressing surface.
10. The system of claim 9 , wherein the pressing surface is concave.
11. The system of claim 9 , wherein the groove has a substantially butte-shaped profile.
12. The system of claim 9 , wherein the diaphragm substantially seals a groove opening to define the pump cavity.
13. The system of claim 12 , wherein the diaphragm is a flexible sheet of substantially uniform thickness.
14. The system of clam 13 , wherein the diaphragm is raised along the longitudinal centerline, such that the diaphragm has a substantially bell-shaped cross section.
15. The system of claim 9 , wherein the profile of the occluding surface compliments the body and edges of the groove.
16. The system of claim 6 , wherein the restitution mechanism disposes the actuator strip in radial tension toward the actuator restraint portion.
17. The system of claim 16 , wherein the actuator strip is stretched over the actuator restraint portion during assembly.
18. The system of claim 16 , wherein the actuator strip is coupled to the diaphragm, such that the actuator strip tension recovers the open configuration of the pump cavity.
19. The system of claim 6 , wherein the support structure clamps the diaphragm longitudinal edges to the pressing surface.
20. The system of claim 6 , wherein the actuator restraint portion includes a pair of flanges, disposed along the longitudinal edges of the bearing surface, that prevent actuator deflection past a predetermined distance away from the pressing surface.