Peristaltic pump
A peristaltic pump having at least first, second, and third stages is provided. The peristaltic pump includes a plunger, inlet and outlet valves, a spring, and an actuator. The plunger actuates toward and away from a tube, the inlet valve is upstream of the plunger, the outlet valve is downstream of the plunger, the spring biases the plunger toward the tube, and the actuator mechanically engages and disengages from the plunger. In the first stage, the inlet valve is opened and the plunger is actuated from the tube, in the second stage, the inlet valve is closed, the plunger is actuated toward the tube, and the actuator is mechanically disengaged from the plunger, and in the third stage, the outlet valve is opened. In the third stage or in a fourth stage, the actuator actuates the plunger toward the tube to discharge fluid downstream past the outlet valve.
1. A peristaltic pump for pumping fluid in a plurality of cycles where each cycle has at least a first stage and a second stage, the peristaltic pump comprising:
a biased plunger biased toward a tube;
a first valve upstream of the biased plunger;
a second valve downstream of the biased plunger; and
an actuator configured to engage and disengage from the biased plunger,
wherein:
in the first stage, the first valve is opened and the biased plunger is moved away from the tube by the actuator,
in the second stage, the first valve is closed, the biased plunger is moved toward the tube, and the actuator is disengaged from the biased plunger, and
the actuator allows the biased plunger to move toward the tube to discharge fluid.
2. The peristaltic pump according to claim 1 , wherein in a third stage, the second valve is opened and the actuator causes the biased plunger to move toward the tube to discharge fluid downstream past the second valve.
3. The peristaltic pump according to claim 2 , wherein in each cycle of the peristaltic pump, the first stage occurs prior to the second stage and the second stage occurs prior to the third stage.
4. The peristaltic pump according to claim 2 , wherein in the first stage, the second valve is closed.
5. The peristaltic pump according to claim 2 , wherein the actuator, a spring, and the biased plunger are configured to discharge the spring when the actuator disengages from the biased plunger.
6. The peristaltic pump according to claim 2 , wherein the actuator is configured to disengage from the biased plunger to thereby discharge a spring to bias the biased plunger against the tube.
7. The peristaltic pump according to claim 2 , wherein movement of the actuator does not correspond to movement of the biased plunger when the actuator disengages from the biased plunger.
8. The peristaltic pump according to claim 2 , wherein the actuator is configured to engage the biased plunger to lift the biased plunger away from the tube and disengage the biased plunger to allow a spring to generate a force from the biased plunger against the tube.
9. The peristaltic pump according to claim 2 , wherein the peristaltic pump is configured such that a force of the biased plunger applied to the tube by the biased plunger is produced by a spring and not the actuator.
10. The peristaltic pump according to claim 1 , wherein in the first stage, the second valve is closed.
11. The peristaltic pump according to claim 1 , wherein the actuator includes a cam and the biased plunger is coupled to a cam follower configured to follow the cam.
12. The peristaltic pump according to claim 1 , wherein the actuator includes a cam and the biased plunger is coupled to a cam follower configured to follow the cam.
13. The peristaltic pump according to claim 12 , wherein when the actuator engages with the biased plunger, the cam follower follows the cam.
14. The peristaltic pump according to claim 12 , wherein when the actuator engages with the biased plunger, the cam follower and the cam are in physical contact with each other.
15. The peristaltic pump according to claim 12 , wherein when the actuator is disengaged with the biased plunger, the cam follower does not follow the cam.
16. The peristaltic pump according to claim 12 , wherein when the actuator is disengaged with the biased plunger, the cam follower and the cam are not in physical contact with each other.
17. The peristaltic pump according to claim 1 , wherein the actuator, a spring, and the biased plunger are configured to discharge the spring when the actuator disengages from the biased plunger.
18. The peristaltic pump according to claim 1 , wherein the actuator is configured to disengage from the biased plunger to thereby discharge a spring to bias the biased plunger against the tube.
19. The peristaltic pump according to claim 1 , wherein movement of the actuator does not correspond to movement of the biased plunger when the actuator disengages from the biased plunger.
20. The peristaltic pump according to claim 1 , wherein the actuator is configured to engage the biased plunger to lift the biased plunger away from the tube and disengage the biased plunger to allow a spring to generate a force from the biased plunger against the tube.
21. The peristaltic pump according to claim 1 , wherein the peristaltic pump is configured such that a force of the biased plunger applied to the tube by the biased plunger is produced by a spring and not the actuator.
22. A peristaltic pump according to claim 1 , for pumping fluid in the plurality of cycles where each cycle has the first stage, the second stage, a third stage, and a fourth stage,
wherein:
in the third stage, the actuator is engaged with the biased plunger, the actuator moves the biased plunger away from the tube, and the second valve is opened, and
in the fourth stage, the actuator moves the biased plunger toward the tube to discharge fluid downstream past the second valve.
23. The peristaltic pump according to claim 22 , wherein in the first stage, the second valve is closed.
24. The peristaltic pump according to claim 22 , wherein the actuator includes a cam and the biased plunger is coupled to a cam follower configured to follow the cam.
25. The peristaltic pump according to claim 24 , wherein when the actuator engages with the biased plunger, the cam follower follows the cam.
26. The peristaltic pump according to claim 24 , wherein when the actuator engages with the biased plunger, the cam follower and the cam are in physical contact with each other.
27. The peristaltic pump according to claim 24 , wherein when the actuator is disengaged with the biased plunger, the cam follower does not follow the cam.
28. The peristaltic pump according to claim 24 , wherein when the actuator is disengaged with the biased plunger, the cam follower and the cam are not in physical contact with each other.
29. The peristaltic pump according to claim 22 , wherein in each cycle of the peristaltic pump, the first stage occurs prior to the second stage, the second stage occurs prior to the third stage, and the third stage occurs prior to the fourth stage.
30. The peristaltic pump according to claim 22 , wherein the actuator, a spring, and the biased plunger are configured to charge the spring when the actuator moves the biased plunger away from the tube.
31. The peristaltic pump according to claim 22 , wherein the actuator, a spring, and the biased plunger are configured to discharge the spring when the actuator disengages from the biased plunger.
32. The peristaltic pump according to claim 22 , wherein the actuator is configured to disengage from the biased plunger to thereby discharge a spring to bias the biased plunger against the tube.
33. The peristaltic pump according to claim 22 , wherein movement of the actuator does not correspond to movement of the biased plunger when the actuator disengages from the biased plunger.
34. The peristaltic pump according to claim 22 , wherein the actuator is configured to engage the biased plunger to lift the biased plunger away from the tube and disengage the biased plunger to allow a spring to generate a force from the biased plunger against the tube.
35. The peristaltic pump according to claim 22 , wherein the peristaltic pump is configured such that a force of the biased plunger applied to the tube by the biased plunger is produced by a spring and not the actuator.
36. A method for pumping fluid using a peristaltic pump, the method comprising:
biasing a plunger of the peristaltic pump toward a tube;
opening a first valve of the peristaltic pump in a first stage;
moving the plunger of the peristaltic pump away from the tube in the first stage;
closing the first valve of the peristaltic pump in a second stage;
moving the plunger of the peristaltic pump toward the tube in the second stage;
disengaging an actuator of the peristaltic pump from the plunger of the peristaltic pump in the second stage; and
moving the plunger of the peristaltic pump toward the tube to discharge fluid.