Peristaltic pump

• US 6,106,249 A
• Filed: 02/26/1998
• Issued: 08/22/2000
• Est. Priority Date: 04/18/1997
• Status: Expired due to Term

• Current Assignee: Nestec SA (Nestle SA)
• Original Assignee: Nestec SA (Nestle SA)
• Inventors: Barak, Swi
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): ROBINSON, DANIEL LEON
• Application Number:
  US09/030,988
• Time in Patent Office: 908 Days
• Field of Search: 417/477.4, 417/18, 417/465, 417/466, 417/474, 417/471, 128/DIG. 12
• US Class Current: 417/474
• CPC Class Codes: A61M 5/14228 with linear peristaltic action, i.e. comprising at least three pressurising members or a helical member
• CPC Class Codes: F04B 2201/1201 Rotational speed of the axis
• CPC Class Codes: F04B 2201/12041 Angular position
• CPC Class Codes: F04B 2205/503 of gas in a liquid flow, e.g. gas bubbles
• CPC Class Codes: F04B 2207/01 Load in general
• CPC Class Codes: F04B 43/082 the tubular flexible member being pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the axes of the tubular member and each having its own driving mechanism
• CPC Class Codes: F04B 43/088 with two or more tubular flexible members in series F04B43/1133 takes precedence
• CPC Class Codes: F04B 49/106 Responsive to pumped volume

Abstract

A peristaltic pump for propelling liquid through a flexible tube segment. The pump has a cam shaft which carries a plurality of cams each having a driving surface. The driving surfaces of adjacent cams are spaced at an angle to each other about the cam shaft. The pump also has a plurality of cam followers which are each reciprocal in a common direction perpendicular to the axis of the cam shaft. Each cam follower has a cam surface riding on the driving surface of a cam and a tube engaging surface for engaging the flexible tube segment. At least one of the cam followers is a restriction cam follower of which the tube engaging surface engages the flexible tube segment for a longer period than that of the other cam followers. The pump also has a motor for rotating the cam shaft whereby the cams cause the cam followers to each engage and occlude the flexible tube segment to form a propagating depression wave in the flexible tube segment for propelling liquid. The restriction cam followers prevent back flow of the liquid.

Claims

1. A peristaltic pump for propelling liquid through a flexible tube segment, the pump comprising:

a cam shaft carrying a plurality of cams each having a driving surface, the driving surfaces of adjacent cams being spaced at an angle to each other about the cam shaft;

a plurality of cam followers which are each reciprocal in a common direction perpendicular to the axis of the cam shaft, each cam follower having a cam surface riding on the driving surface of a cam and a tube engaging surface for engaging the flexible tube segment, at least one of the cam followers being a restriction cam follower of which the tube engaging surface engages the flexible tube segment for a longer period than that of the other cam followers; and

a motor for rotating the cam shaft whereby the cams cause the cam followers to each engage and occlude the flexible tube segment to form a propagating depression wave in the flexible tube segment for propelling liquid;

the restriction cam followers preventing back flow of the liquid.

2. A pump according to claim 1 in which the tube engaging surfaces of the restriction cam followers extend further from the cams than the tube engaging surfaces of the other cam followers.

3. A pump according to claim 2 in which the tube engaging surfaces of the restriction cam followers have a planar tube engaging surface while the other cam followers have a concave tube engaging surface.

4. A pump according to claim 1 in which a restriction cam follower is mounted as a terminal cam follower.

5. A pump according to claim 4 in which the restriction cam follower is mounted as the terminal cam follower in a forward pumping direction of the pump.

6. A pump according to claim 5 in which the terminal cam follower retracts to open the flexible tube segment only when a rear terminal cam follower is fully extended.

7. A pump according to claim 1 further comprising sensor means for determining the direction and speed of rotation of the cam shaft.

8. A pump according to claim 7 in which the sensor means comprises:

a disc which rotates in accordance with the cam shaft, the disc having a plurality of substantially identical apertures through it equally spaced about its axis; and

a pair of sensors mounted adjacent the disc in alignment with the apertures, the sensors being able to determine at any point in time whether both sensors are aligned with the same aperture, one sensor is aligned with an aperture but the other is not;

or both sensors are not aligned with an aperture, monitoring of the changes in alignment of the sensors with the apertures enabling the direction and speed of rotation of the disc to be computed.

9. A pump according to claim 1 in which each cam is aligned at an angle of 30°

with respect to its adjacent cams.

10. A pump according to claim 1 further comprising a housing having a chamber through which the tube segment extends and into which the cam followers reciprocally extend, the chamber having a removable wall element which retains the tube segment between it and the tube engaging surfaces of the cam followers.

11. A peristaltic pump for propelling liquid through a flexible tube segment, the pump comprising:

a cam shaft carrying a plurality of cams each having a driving surface, the driving surfaces of adjacent cams being spaced at an angle to each other about the cam shaft;

a plurality of cam followers which are each reciprocal in a common direction perpendicular to the axis of the cam shaft, each cam follower having a cam surface riding on the driving surface of a cam and a tube engaging surface for engaging the flexible tube segment, at least one of the cam followers being a restriction cam follower of which the tube engaging surface extends further from the cams than the tube engaging surfaces of the other cam followers for engaging the flexible tube segment for a longer period than that of the other cam followers; and

a motor for rotating the cam shaft whereby the cams cause the cam followers to each engage and occlude the flexible tube segment to form a propagating depression wave in the flexible tube segment for propelling liquid;

the restriction cam followers preventing back flow of the liquid.

12. A pump according to claim 11 further comprising sensor means for determining the direction and speed of rotation of the cam shaft.

13. A pump according to claim 12 in which the sensor means comprises:

a disc which rotates in accordance with the cam shaft, the disc having a plurality of substantially identical apertures through it equally spaced about its axis; and

a pair of sensors mounted adjacent the disc in alignment with the apertures, the sensors being able to determine at any point in time whether both sensors are aligned with the same aperture, one sensor is aligned with an aperture but the other is not;

or both sensors are not aligned with an aperture;

monitoring of the changes in alignment of the sensors with the apertures enabling the direction and speed of rotation of the disc to be computed.

14. A pump according to claim 11 in which a restriction cam follower is mounted as a terminal cam follower.

15. A pump according to claim 14 in which the restriction cam follower is mounted as the terminal cam follower in a forward pumping direction of the pump.

16. A peristaltic pump for propelling liquid through a flexible tube segment, the pump comprising:

a cam shaft carrying a plurality of cams each having a driving surface, the driving surfaces of adjacent cams being spaced at an angle to each other about the cam shaft;

a plurality of cam followers which are each reciprocal in a common direction perpendicular to the axis of the cam shaft, each cam follower having a cam surface riding on the driving surface of a can and a tube engaging surface for engaging the flexible tube segment, at least one of the cam followers being a restriction cam follower of which the tube engaging surface engages the flexible tube segment for a longer period than that of the other cam followers;

sensor means for determining the direction and speed of rotation of the cam shaft; and

a motor for rotating the cam shaft whereby the cams cause the cam followers to each engage and occlude the flexible tube segment to form a propagating depression wave in the flexible tube segment for propelling liquid;

the restriction cam followers preventing back flow of the liquid.

17. A pump according to claim 16 in which the sensor means comprises:

a disc which rotates in accordance with the cam shaft, the disc having a plurality of substantially identical apertures through it equally spaced about its axis; and

a pair of sensors mounted adjacent the disc in alignment with the apertures, the sensors being able to determine at any point in time whether both sensors are aligned with the same aperture, one sensor is aligned with an aperture but the other is not;

or both sensors are not aligned with an aperture, monitoring of the changes in alignment of the sensors with the apertures enabling the direction and speed of rotation of the disc to be computed.

18. A pump according to claim 16 in which the tube engaging surfaces of the restriction cam followers extend further from the cams than the tube engaging surfaces of the other cam followers.

19. A pump according to claim 16 in which a restriction cam follower is mounted as a terminal cam follower.

20. A pump according to claim 19 in which the restriction cam follower is mounted as the terminal cam follower in a forward pumping direction of the pump.