Peristaltic pump with roller pinch valve control

1. In a pump having a rotary portion which compels the movement of a fluid by peristaltic compression of resilient tubing containing the fluid, a roller assembly comprising the following:

a rotor having at least one roller mounted in the rotary portion of the pump for contact with the resilient tubing, the at least one roller having a range of rotation in contact with the tubing during pump operation; and

a rotor control mechanism adapted and constructed to stop the rotor such that the at least one roller is stopped at a single, predetermined location on the tubing when the pump operation is stopped.

2. A roller assembly in accordance with claim 1 , wherein the at least one roller comprises two rollers.

3. A roller assembly in accordance with claim 2 , wherein the rollers are spaced apart circumferentially such that the rollers trap a consistent quantity of fluid between them during operation of the pump.

4. A roller assembly in accordance with claim 2 , wherein the rotor control mechanism is adapted and constructed to cause one of the rollers to stop at a bottom position thereof.

5. A roller assembly in accordance with claim 4 , wherein the rotor control mechanism comprises a stop-pin and stop bar arrangement.

6. A roller assembly in accordance with claim 2 , further comprising a flow control mechanism adapted and constructed to compensate for localized tubing collapse at the rotor stop position.

7. A roller assembly in accordance with claim 1 , wherein the rotor control mechanism comprises a slip clutch on which the rollers are mounted.

8. In a pump having a rotary portion which compels the movement of a fluid by peristaltic compression of resilient tubing containing the fluid, a roller assembly comprising the following:

a rotor having a pair of rollers mounted at circumferentially spaced-apart positions in the rotary portion of the pump for contact with the resilient tubing, the rollers having a range of rotation in contact with the tubing during pump operation; and

a rotor control mechanism adapted and constructed to stop the rotor so that one of the rollers of the pair of rollers is stopped at a single, predetermined location on the tubing when the pump operation is stopped.

9. A roller assembly in accordance with claim 8 , wherein the rollers are mounted 180° from one another.

10. A roller assembly in accordance with claim 9 , further comprising a pump occlusion spaced from the rollers such that the rollers trap a consistent quantity of fluid between them during operation of the pump.

11. A roller assembly in accordance with claim 9 , wherein the rotor control mechanism is adapted and constructed to cause one of the rollers to stop at a bottom position thereof.

12. A roller assembly in accordance with claim 11 , wherein the rotor control mechanism comprises a stop-pin and stop bar arrangement.

13. A roller assembly in accordance with claim 9 , further comprising a flow control mechanism adapted and constructed to compensate for localized tubing collapse at the roller stop position.

14. A roller assembly in accordance with claim 8 , wherein the rotor control mechanism comprises a slip clutch on which the rollers are mounted.

15. A method for operating a pump having a rotary portion which compels the movement of a fluid by peristaltic compression of resilient tubing containing the fluid comprising the following:

mounting a rotor having at least one roller in the rotary portion of the pump for contact with the resilient tubing, the at least one roller having a range of rotation in contact with the tubing during pump operation;

operating the pump by rotating the rotor; and

stopping the rotor by using a rotor control mechanism to stop the rotor so that the at least one roller is stopped at a single, predetermined location on the tubing when the pump operation is stopped.

16. A method in accordance with claim 15 , wherein mounting comprises mounting a rotor having two rollers.

17. A method in accordance with claim 16 , wherein mounting comprises mounting the rotor so that the rollers are spaced apart circumferentially, thereby trapping a consistent quantity of fluid between the rollers during operation of the pump.

18. A method in accordance with claim 16 , wherein stopping comprises using the rotor control mechanism to stop the rotor so one of the rollers is stopped at a bottom position thereof.

19. A method in accordance with claim 16 , further comprising compensating for localized tubing collapse at the roller stop position via a flow control mechanism.

20. A method in accordance with claim 15 , further comprising mounting the rollers on a slip clutch.