Linear peristaltic pump

• US 6,213,739 B1
• Filed: 07/09/1999
• Issued: 04/10/2001
• Est. Priority Date: 01/17/1997
• Status: Expired due to Term

• Current Assignee: Niagara Pump Corporation
• Original Assignee: Niagara Pump Corporation
• Inventors: Phallen, Iver J., Vogt, Douglas N.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): CAMPBELL, THOR S
• Application Number:
  US09/341,443
• Time in Patent Office: 641 Days
• Field of Search: 417/474, 417/478, 417/475, 417/479, 417/476, 417/477.1, 417/477.3, 417/477.9, 604/153, 604/151
• US Class Current: 417/478
• 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 13/02 of two or more fluids at the same time
• CPC Class Codes: F04B 2201/0201 Position of the piston
• CPC Class Codes: F04B 2201/0206 Length of piston stroke
• CPC Class Codes: F04B 2201/0601 Opening times
• CPC Class Codes: F04B 2203/1001 Opening time of the valves
• CPC Class Codes: F04B 2205/09 Flow through the pump
• CPC Class Codes: F04B 43/0072 of tubular flexible members
• CPC Class Codes: F04B 43/1133 with fluid-actuated pump inlet or outlet valves; with two or more pumping chambers in series
• CPC Class Codes: F04B 43/1136 with two or more pumping chambers in parallel
• CPC Class Codes: F04B 49/065 and making use of computers

Abstract

A liquid pumping apparatus for pumping liquids, more specifically a linear peristaltic pump apparatus. The apparatus consists of a high durometer compressible elastomeric liquid flow tube (12), an infeed valve assembly (26), an outfeed valve assembly (38), an extensible and retractable actuator anvil (34) having a round surface which engages the flow tube (12) at all times, an opposed anvil (24.1) having a round surface in engagement with the flow tube at all times, the flow tube being held between the anvils (34, 24.1) in a slightly compressed state when the anvil (34) is retracted, and a control assembly (100) for causing the movable anvil to be sequentially extended and retracted to cause flow within the flow tube (12) from the infeed valve assembly (26) to the outfeed valve assembly (38). With this apparatus the lumen of the flow tube (12) to the sides of the anvils is not completely reduced to zero volume during displacement compression whereby gas embolisms do not erupt or explode when discharged. Two principal embodiments are disclosed, one having infeed and outfeed check valves which oclude the flow tube, and the other having check valves.

Claims

1. A linear peristaltic pump apparatus for pumping liquids comprising:

a pump housing (22);

a high durometer compressible elastomeric liquid flow tube (12) carried by the housing (22);

an infeed valve assembly (26);

an outfeed valve assembly (38);

a discrete extensible and retractable displacement actuating assembly (36) including a movable actuator anvil (34) having a round surface which engages the flow tube (12) at all times;

a spaced apart top anvil (24.1) mounted in a location directly opposite from the actuator anvil (34), the top anvil (24.1) having a round surface in engagement with the flow tube at all times, the flow tube being held between the movable actuating anvil and the top anvil in a slightly compressed state when the actuating assembly is retracted, and the lumen of the flow tube not being completely reduced to zero volume during displacement compression whereby gas embolisms do not erupt or explode when discharged; and

control means (100) for sequentially extending and retracting the actuating assembly (36) to cause flow within the flow tube (12) from a location adjacent the infeed valve assembly (26) to a location adjacent the outfeed valve assembly (38).

2. The linear peristaltic pump apparatus as set forth in claim 1 wherein the infeed valve assembly (26) and the outfeed valve assembly (38) are discrete infeed and outfeed extensible and retractable actuating assemblies, each including a movable actuator anvil (34) having a round surface which engages the flow tube (12) at all times, each of the infeed and outfeed valve assemblies further including a spaced apart top anvil (24.1) mounted in a location directly opposite from the associated actuator anvil (34), each of the top anvils (24.1) having a round surface in engagement with the flow tube at all times, the flow tube being held between the movable actuating anvils (34) and the top anvils (24.1) in a slightly compressed state when the actuating assemblies are retracted.

6. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the pump housing (22) has spaced apart sides (22.2, 22.3), the distance between the sides being adequate to assure no contact between the flow tube (12) and sides (22.2, 22.3) when the flow tube (112) is fully compressed to occlusion.

7. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the liquid flow tube (12) consists of a thick walled, multi-layer, laminated, compound reinforced, high pressure rated construction.

8. The linear peristaltic pump apparatus as set forth in any on of claims 1, 3, or 5 wherein the flow tube (12) is fitted with pressure rings (52) such that they contain the tube that they surround, thus limiting pressure mediated radial distension or swelling of the pump tube during high pressure pumping, such enhanced containment advantageously increasing the volumetric displacement of the pump with each complete pumping sequence.

9. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the pump housing is U-shaped.

10. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the round surface of each of the actuator anvils (34) has the same effective diameter as each of the round shaped top anvils (24.1).

11. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein each actuator assembly includes a pneumatic cylinder (28).

12. The linear peristaltic pump as set forth in claim 11 wherein each pneumatic cylinder assembly has a pneumatic port (29) for receiving compressed gas, and further characterized by the provision of an electrically operated pneumatic solenoid valve (30, 60) closely coupled to the pneumatic port for the purpose of reducing the volume of compressed gas required to operate each actuator, thus increasing actuator speed and pump speed, reducing gas consumption required to operate the pump assembly and allowing the use of smaller pneumatic solenoid valves.

13. The linear peristaltic pump apparatus as set forth in claim 11 further characterized by the provision of a regulator (33) to vary the pressure to the actuators, whereby the cycle time may be varied.

14. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 further characterized by the provision of an external flow meter capable of measuring the displacement of the pump apparatus.

45. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the control means can be selected to operate in one of the two primary liquid flow operating modes, the first mode being termed metering mode and the second being termed dosing mode;

wherein the metering mode allows the pump to establish and maintain a defined volumetric flow rate, and wherein the dosing mode allows the pump to deliver a defined volume of liquid with a high degree of repeatability.

46. The linear peristaltic pump apparatus as set forth in claim 45 wherein the control means (100) includes a variable potentiometer (110) which may be used to adjust the last pump cycle when volumetrically dosing.

47. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the control means includes a microcontroller (102), and further characterized by the provision of an external flow meter (128), the output of which is interconnected with the microcontroller in order to control the flow output from the pump.

48. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the control means (100) produces an electronic output firing pulse, which firing pulse is selected to initiate at any desired point in the pump sequence, and which pulse may be used to simultaneously actuate two or more similar pumps, thus allowing concurrent metering of one or more liquids which allows the batching or blending of liquids in any desired ratio or proportion, or allowing concurrent dosing or one or more liquids, or allowing cascaded dosing, or allowing two or more pumps of this invention to be operated in series as in pressure boost pumping, or in parallel with the outputs combined into a single flow and wherein the flow pulsations are progressively reduced.

49. The linear peristaltic pump apparatus as set forth in any one of claims 1, 3, or 5 wherein the control means (100) is provided with multiple presettable digital counters to allow the control means to provide self-contained dose volume capability where each counter can be set to a different count in order to provide different dose volumes under separate and discrete start inputs.

50. The linear peristaltic pump apparatus as set forth in claim 49 wherein at least on presettable digital counter is provided for the express purpose of counting reverse pumping cycles.

51. The linear peristaltic pump apparatus as set forth in either claim 1, 3, or 5 wherein the control means (100) is provided with multiple presettable digital counters and with multiple start inputs in order to allow it to be operated by signals from multiple discrete locations, wherein each start input can address a different preset digital counter.

52. The linear peristaltic pump as set forth in claim 51 in which the electronic controller is provided with valve driver outputs for initiating drive signals to remote shut-off valves at the point of pump output flow termination or at the point of dispense, said signals directly reflecting the on/off status of the pump.

53. The linear peristaltic pump as set forth in claim 52 wherein each valve driver output signal is associated with a particular dose counter and a particular start input, thus allowing start inputs at different locations to address different flow termination points.

54. The linear peristaltic pump apparatus as set forth in either claim 1, 3 or 5 wherein the control means includes a microcontroller (102) and an input signal terminal which can indicate to the microcontroller that the supply of liquid to the pump is low, and where the input signal can cause the controller to reconnect the pump to an alternate supply of liquid.

55. The linear peristaltic pump apparatus as set forth in either claim 1, 3 or 5 further characterized by the provision of start means associated with the control means, the control means assuring that no new start input is allowed until the last cycle step in the pump sequence is complete, and further assuring that once a pump cycle is initiated by a start input, the loss or change in state of the start input cannot stop or interrupt the completion of the pump sequence, and further assuring that a control stop input can be implemented only at the completion of the pump sequence.

56. The linear peristaltic pump apparatus as set forth in either claim 1, 3 or 5 wherein the control means includes a pump start input circuit, a control stop input circuit, a run/count output signal circuit which allows external verification of pump status and external counting of pump cycles, and a fault signal output.

57. The linear peristaltic pump apparatus as set forth in claim 1, 3 or 5 wherein the control means provides for diagnostic outputs which can be serially encoded or discrete, consisting of outputs for excess back pressure, excess system pressure, loss of liquid supply, operable or inoperable status, cycle count, and maintenance interval.

58. The linear peristaltic pump apparatus as set forth in either claim 1, 3 or 5 wherein a linear incremental encoder (58) is fitted to at least one of the displacement actuator assemblies, wherein the control means (100) includes a microcontroller (102), the control means being capable of making automatic sequence changes as a function of adjustment of actuator pressure or force without manual recalibration or alteration such that correct sequence motion relationship required among actuators for correct pumping action is maintained.

59. The linear peristaltic pump apparatus as set forth in either claim 1, 3 or 5 wherein the control means causes the infeed valve actuator assembly and all displacement actuator assemblies to be retracted to their unoccluded positions at the completion of operating cycles, thus greatly reducing the duration of occlusion and minimizing compression set and tube rebound fatigue.

60. The linear peristaltic pump apparatus as set forth in claim 59 wherein the control means is further provided with an alternative operating mode which will cause all actuator assemblies to be retracted when unrestricted flow through the flow tube (12) is desired.

3. A linear peristaltic pump apparatus for pumping liquids comprising:

a pump housing (22);

a high durometer compressible elastomeric liquid flow tube (12) carried by the housing (22);

at least three discrete extensible and retractable actuating assemblies carried by the housing, including one occlusive infeed valve actuator assembly (26), one or more displacement actuator assemblies (36), and one occlusive outfeed valve actuator assembly (38), each actuating assembly including a movable actuator anvil (34) having a round surface which engages the flow tube (12) at all times;

spaced apart top anvils (24.1), each mounted in a location directly opposite from the corresponding actuator anvil (34) and having a round surface in engagement with the flow tube at all times, the flow tube being held between the movable actuator anvils and the top anvils in a slightly compressed state when the actuating assemblies are retracted; and

control means (100) for sequentially extending and retracting the actuating assemblies (26, 36, 38) to cause flow within the flow tube (12) from a location adjacent the infeed valve actuator assembly (26) to a location adjacent the outfeed valve actuator assembly (38),

whereby the apparatus can pump highly particulated or non-homogeneous liquids and slurries effectively because of the dual symmetrical anvil design which serves to provide an efficient mechanism to move solids sway from the occlusion contact areas of the pump elements such that large solids are not trapped at the occlusion points of the pump elements and the large inclusions pass through the pump essential undamaged.

4. The linear peristaltic pump apparatus as set forth in claim 3 wherein each of the actuators is a linear actuator.

15. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the occlusive infeed valve actuator assembly (26) is capable of applying more force than either the occlusive outfeed valve actuator assembly (38) or the one or more displacement actuator assemblies (36) to allow the pump apparatus to operate at relatively higher pumping pressure than can be achieved with all actuating assemblies having the same force capability.

16. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein each actuator assembly includes a pneumatic cylinder assembly, the diameter of the piston within the pneumatic cylinder assembly of the occlusive infeed valve actuator assembly being greater than the diameter of the pistons within the other pneumatic cylinder assemblies, whereby a constant force ratio is established between the occlusive infeed valve assembly and the other actuating assemblies when the same pressure is applied to each pneumatic cylinder assembly.

17. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein each of the actuator anvils (34) is formed of bar stock, circular in cross section.

18. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein each of the actuators is a pneumatic cylinder assembly having a cylinder (28) and an operating rod (32) extending out of the cylinder, each of the actuator anvils (34) being mounted on an end of an operating rod remote from the associated cylinder, wherein the cover plate is a serpentine rigid sheet stock element, wherein the housing has spaced apart apertured side walls, and wherein the cover plate mounting means is a plurality of pull pins (50), one for each of the top anvils, the pull pins passing through the apertures in the side walls, each pull pin (50) being located at the center of a force line applied by each actuating assembly along the centerline of the operating rod thus creating an extremely rigid assembly capable of withstanding very high compressive forces.

19. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein each of the actuators is a pneumatic cylinder assembly having a cylinder (28) provided with a movable piston, an operating rod (32) extending out of the cylinder, each of the actuator anvils (34) being mounted on an end of an operating rod remote from the associated piston, the area of each of the pistons being greater than the area of the each of the actuator anvils which contact the flow tube during occlusion to achieve force multiplication, and wherein the flow tube (12) is fitted with pressure rings (52) such that they contain the tube that they surround, thus allowing high rebound forces to be generated by the pump tube after compression, these high rebound forces generating a high suction priming force adequate to overcome the high flow resistance and suction drag associated with priming viscous liquids.

20. The linear peristaltic pump apparatus as set forth in either claim 4 or 5 wherein each of the linear actuators is a pneumatic cylinder assembly, further characterized by the provision of a linear incremental encoder (58) fitted to at least one of the displacement actuator assemblies, wherein the control means (100) includes a microcontroller (102), and wherein the control means may operate the pump in a metering mode of a given flow rate per minute in response to signals received by the microcontroller from the linear encoder.

21. The linear peristaltic pump apparatus as set forth in either claim 4 or 5 wherein each of the linear actuators is a pneumatic cylinder assembly, further characterized by the provision of a linear incremental encoder (58) and end of travel encoders (35.1, 35.2) fitted to at least one of the pneumatic cylinder assemblies, and wherein the control means (100) includes a microcontroller (102), the control means being capable of operating the pump apparatus in a dose mode wherein a defined volume of liquid is pumped with a high degree of repeatability.

22. The linear peristaltic pump apparatus as set forth in claim 21 wherein the linear incremental encoder is mounted on the pneumatic cylinder assembly for a displacement actuator assembly, and the end of travel encoders are mounted on the pneumatic cylinder assemblies for the infeed and outfeed valve actuator assemblies.

23. The linear peristaltic pump apparatus as set forth in either claim 4 or 5 wherein each of the linear actuators is a pneumatic cylinder assembly having a cylinder (28) and an operating rod (32) extending out of the cylinder, each of the actuator anvils (34) being mounted on an end of an operating rod remote from the associated cylinder.

24. The linear peristaltic pump apparatus as set forth in claim 23 wherein the of the pump housing has spaced apart sides (22.2, 22.3), wherein each of the actuator anvils (34) is formed of bar stock, circular in cross section and having a length slightly less than the distance between the sides, the spaced apart sides (22.2, 22.3) preventing rotation of the anvils (34) about the operating rods (32).

25. The linear peristaltic pump apparatus as set forth in claim 23 wherein a piston is mounted in each of the cylinders, the area of each of the pistons being greater than the area of the each of the actuator anvils which contact the flow tube during occlusion to achieve force multiplication.

26. The linear peristaltic pump apparatus as set forth in claim 23 wherein a piston is mounted in each of the cylinders, the maximum stroke of the piston being greater than the movement required to occlude the flow tube.

27. The linear peristaltic pump apparatus as set forth in claim 23 wherein the rebound or opening force of the pump tube is sufficient to return each operating rod to its retracted position, even when a vacuum is being applied to the inlet end of the pump tube.

28. The linear peristaltic pump apparatus as set forth in claim 23 further characterized by the provision of a mechanical stroke limiting stop (59) to limit return movement of the actuator anvil, thereby reducing to some desired degree the volume displacement capability of the pump.

29. The linear peristaltic pump apparatus as set forth in claim 23 further characterized by the provision of a pressure supply valve (60) and an exhaust valve (62) associated with each of the one or more displacement actuator assemblies, each of the supply valves and exhaust valves being a 2-way normally closed solenoid valve, and further characterized by the control means including timer means, whereby the pressure supply valve is opened for a defined time as determined by the pump electronic controller, and then closed, this resulting in movement of the pump displacement actuator over a defined distance, the actuator remaining at some intermediate displaced distance of extension for a holding time during which time the outfeed valve is closed completing a displacement cycle of the pump in which a reduced volumetric displacement is achieved, and whereafter the pressure exhaust valve is opened, allowing the displacement actuator to return to its fully open position;

and wherein this method of flow rate control is easily varied and linearized electronically and is repeatable and operable over a broad range of flow within the capability of the pump and where the flow rate is stable over extended periods of time and the pressure and viscosity capabilities of the pump are preserved; and

wherein as flow rate is reduced, pump cycle frequency increases of may be electronically adjusted to be held steady at the full displacement cycle rate.

30. The linear peristaltic pump apparatus as set forth in claim 29 further characterized by the provision of full open and full closed encoding sensors (35.1, 35.2) mounted on the actuating assemblies for detecting the end of stroke of each actuating element, whereby the start is marked by the change in state of the full open sensor (35.1) signal thus allowing actual actuator motion to be determined, thus further improving the precision of this method of pump flow rate control.

31. The linear peristaltic pump apparatus as set forth in claim 29 further characterized by the provision of a linear incremental encoder (58) fitted to the pneumatic cylinder assembly to precisely define its desired displacement motion, thus providing a closed loop control of said motion to any intermediate location and thereby further improving the pump flow rate accuracy and stability of the method;

and wherein the use of an incremental encoder on the pump displacement actuator assures that the movement of the actuator continues until a prescribed position is reached regardless of any change in actuator velocity or force as a function of any external influence.

32. The linear peristaltic pump apparatus as set forth in claim 23 further characterized by the provision of a pressure supply valve (60) and an exhaust valve (62) associated with each of the one or more displacement actuator assemblies, each of the supply valves and exhaust valves being a 2-way normally closed solenoid valve, and further characterized by the displacement actuator including encoder means whereby the pressure supply valve is opened to allow movement of the pump displacement actuator to a defined location.

61. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the control means may control the infeed valve actuator assembly valve open time effectively increasing the priming time as a discrete and separately adjustable event in the pump cycle, thus allowing the priming lumen of the pump tube to completely fill with liquid, thus allowing the volumetric displacement of each pumping cycle to be maintained.

62. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the control means may detect and signal when the infeed valve actuator assembly valve open time becomes longer in time than desired, thus constituting an end to effective useful pump tube life or pump tube fatigue.

63. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the control means includes an internal timer, the open time of the infeed valve actuator assembly being adjusted by the timer to adjust the volumetric flow rate of a pump apparatus.

64. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the control means functions to allow the flow rate of the pump to be controlled by electronically altering the timing and thus the motion relationship between the one or more displacement actuator assemblies and the outfeed valve actuator assembly to effect a change in displaced pump volume per cycle, such that after the one or more displacement actuator assemblies has compressed, and before the outfeed valve actuator assembly has occluded, the one or more displacement actuator assemblies is allowed to partially return to an open condition, a portion of the volume previously expelled thus being drawn back into the lumen of the flow tube, the outfeed valve actuator assembly then being closed to occlusion;

wherein this method of flow rate adjustment is smoothly variable and repeatable and operable over a broad range of flow within the capability of the pump and where the discharge pressure capability of the pump is not impaired and the feed of liquid into the pump is not altered and the method is largely insensitive to variations in pump discharge pressure.

65. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein each of the control means will insure that all actuators begin and end the pumping sequence in the same position.

66. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the control means may vary the open time of the occlusive infeed valve actuator assembly to permit operation with liquids of varying viscosities.

67. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 wherein the control means may vary the close time of the occlusive outfeed valve actuator assembly to permit operation with a low back pressure setting and a high back pressure setting.

68. The linear peristaltic pump apparatus as set forth in either claim 3 or 5 having more than one displacement actuator assembly in order to increase the liquid flow rate per pump cycle without a reduction of pump discharge pressure capability and without a significant increase in pump cycle time.

69. The linear peristaltic pump as set forth in claim 68 wherein the displacement actuator assembly nearest the infeed valve actuator assembly can move a distance sufficient to occlude the flow tube (12), the other displacement actuator assemblies not being able to move a distance sufficient to occlude the flow tube thus allowing simultaneous compressive actuation of all displacement actuator assemblies in the pump apparatus without the possibility to trap or block the displaced flow of any of the displacement actuator assemblies.

70. The linear peristaltic pump as set forth in claim 68 wherein all of the displacement actuator assemblies are not able to move a distance sufficient to occlude the flow tube thus allowing simultaneous compressive actuation of all displacement actuator assemblies in the pump apparatus without the possibility to trap or block the displaced flow of any of the displacement actuator assemblies.

71. The linear peristaltic pump apparatus as set forth in claim 68 wherein all displacement actuator assemblies are the same, whereby the displacement of the pump is altered by the addition of displacement actuator assemblies in a known and predictable manner and with no change in the pumps discharge pressure capability.

72. The linear peristaltic pump apparatus as set forth in claim 68 wherein the control means (100) is operated such that the displacement actuator assembly furthest from the occlusive outfeed valve actuator assembly is actuated first, with a time delay being imposed between this first displacement actuator assembly and the actuation of the next adjacent displacement actuator assembly, said delay being electronically determined by pump control electronics and of a duration less than the displacement actuator assembly occlusion travel time, and the same delay being interposed before the actuation of each successive displacement actuator assembly, such that each displacement actuator assembly closer to the occlusive outfeed valve actuator assembly cannot occlude ahead of the displacement actuator assembly immediately preceding it, thus assuring that no displaced flow can be cut off prior to sequential compression by each displacement actuator assembly.

73. The linear peristaltic pump apparatus as set forth in claim 68 wherein the control means (100) includes a microcontroller (102), the control means also including input means for inputting the number of displacement actuator assemblies in the pump apparatus or automatically detecting the number of displacement actuator assemblies, whereby the pump control sequence is altered to insert the required sequence actuation delay times.

74. The linear peristaltic pump apparatus as set forth in claim 73 wherein the input is automatic.

75. The linear peristaltic pump apparatus as set forth in claim 68 wherein each of the displacement actuator assemblies is provided with an end of travel sensor (35.1, 35.2).

76. The linear peristaltic pump assembly as set forth in claim 68 wherein the control means includes a microcontroller (102) and each of the actuators is provided with travel encoding sensors (35.1, 35.2) in such a way as to allow detection of the fully retracted and fully extended positions of each actuator element in the pump, such that the status of each encoding sensor is integrated into the microcontroller providing absolute and continuous control, diagnostics, and optimization of the pump apparatus.

77. The linear peristaltic pump assembly as set forth in claim 75 wherein the control means (100) senses the signals from the end of travel sensors to provide optimum adjustment, on a completely automatic basis, of the proper sequencing of multiple displacement actuator assemblies, such that the loss of signal from an open position end of travel sensor fitted to the displacement actuator assembly closest to the infeed valve actuator assembly causes the next displacement actuator assembly to begin motion, which, in turn, causes the next to sequence, thus allowing the time delay between actuations to be under directly sensed control and thus to be as minimal as possible.

78. The linear peristaltic pump apparatus as set forth in claim 68 wherein the control means (100) is operated to accommodate the pumping of large entrained solids within the flow tube by insuring that each displacement actuator assembly is allowed to complete pump tube occlusion before the next downstream displacement actuator assembly begins compressive movement, the sequence delay being established on a time basis in which case the delay is equal to or greater than the compress to occlusion time of the displacement actuator assemblies.

5. A linear peristaltic pump apparatus for pumping liquids comprising:

a rigid generally channel shaped pump housing (22);

a high durometer compressible elastomeric liquid flow tube (12) mounted within the channel shaped pump housing (22);

at least three discrete extensible and retractable actuating assemblies carried by the housing, including one occlusive infeed valve actuator assembly (26), one or more displacement actuator assemblies (36), and one occlusive outfeed valve actuator assembly (38), each actuating assembly including a linear actuator and a movable actuator anvil (34) having a round surface which engages the flow tube (12);

a cover plate (24) provided with spaced apart round shaped top anvils (24.1) such that when assembled to the housing (22) each top anvil (24.1) is in a location directly opposite from a corresponding actuator anvil (34);

cover plate mounting means (50) for assembling the cover plate (24) to the housing (22) with the top anvils (24.1) bearing against the flow tube (12) in such a manner that the flow tube is slightly compressed; and

control means (100) for sequentially extending and retracting the actuating assemblies (26, 36, 38) in such a manner as to cause flow within the flow tube (12) from a location adjacent the infeed valve actuator assembly (26) to a location adjacent the outfeed valve actuator assembly (38).

33. The linear peristaltic pump apparatus as set forth in claim 5 wherein the pump housing (22) has spaced apart sides (22.2, 22.3), the distance between the sides being adequate to assure no contact between the flow tube (12) and sides (22.2, 22.3) when the flow tube (12) is fully compressed to occlusion, and wherein the round surface of each of the actuator anvils (34) has the same effective diameter as each of the round shaped top anvils (24.1).

34. The linear peristaltic pump apparatus as set forth in claim 33 wherein the liquid flow tube (12) consists of a thick walled, multi-layer, laminated, compound reinforced, high pressure rated construction to allow relatively high pump feed and discharge pressures to be contained by the tube with minimal distortion, swelling or bulging or stretching of the pump tube, thus allowing comparatively high pressure operation of the pump.

35. The linear peristaltic pump apparatus as set forth in any one of claims 5, 33, or 34 wherein the cover plate (24) is a serpentine rigid sheet stock element.

36. The linear peristaltic pump apparatus as set forth in claim 35 wherein the cover plate is symmetrical.

38. The linear peristaltic pump apparatus as set forth in claim 35 wherein the housing has spaced apart apertured side walls, and wherein the cover plate mounting means is a plurality of pull pins (50), one for each of the top anvils, the pull pins passing through the apertures in the side walls, the foregoing assuring a simple and self evident procedure for assembly.

39. The linear peristaltic pump apparatus as set forth in claim 38 wherein a spacer (50.1 or 50.2) is inserted about each of the pull pins (50) so that the round shaped top anvils (24.1) are forced closer to the actuator anvils (34), thus establishing the desired and proper degree of symmetrical compression capture when a smaller diameter flow tube (12) is used.

40. The linear peristaltic pump apparatus as set forth in claim 5 wherein the liquid flow tube (12) consists of a thick walled, multi-layer, laminated, compound reinforced, high pressure rated construction, wherein the pump housing (22) has spaced apart sides (22.2, 22.3), the distance between the sides being adequate to assure no contact between the flow tube (12) and sides (22.2, 22.3) when the flow tube (112) is fully compressed to occlusion, wherein the round surface of each of the actuator anvils (34) has the same effective diameter as each of the round shaped top anvils (24.1), and wherein a piston is mounted in each of the cylinders, the area of each of the pistons being greater than the area of the each of the actuator anvils which contact the flow tube during occlusion, the foregoing allowing long term pump tube operating fatigue phenomenon such as progressive reduction in suction or priming capability or discharge pressure capability as the tube wears fatigues or compression sets to be nearly completely avoided.

41. The linear peristaltic pump apparatus as set forth in claim 5 wherein the housing has inlet and outlet end plates (40, 42), and wherein the flow tube (12) has a length just slightly less than the distance between the end plates.

42. The linear peristaltic pump apparatus as set forth in claim 41 wherein the inlet and outlet end plates are provided with slots (40.1, 42.1), and further characterized by the provision of pump hose fittings (14, 18) mounted within opposed ends of the flow tube (12), the pump hose fittings being captured by the slots in the end plates.

43. The linear peristaltic pump apparatus as set forth in claim 42 wherein the cover plate is provided with locking tongues (24.2, 24.3) for locking into position the pump hose fittings at each end of the flow tube (12).

44. The linear peristaltic pump apparatus as set forth in claim 5 further characterized by the provision of pump hose fittings (14, 18) mounted within opposed ends of the flow tube (12), each of the hose fittings having an internal shank with an end that terminates within the flow tube, the distance (dd) between the end of the internal shank of the hose fitting and the center line of its respective anvil pair being within the range of 1.20 to 2.0 times the internal diameter of the pump hose, this arrangement causing a faster restoration of the compressed pump hose when the adjacent actuating assembly is retracted.

37. The linear peristaltic pump apparatus as set forth in 35 wherein a unitized spacer (23) consisting of a single serpentine shaped piece is overlaid onto the original cover plate (24) and then assembled to the pump body (22) utilizing the cover plate mounting means (50) so that the round shaped top anvils (24.1) are forced closer to the actuator anvils (34), thus establishing the desired and proper degree of symmetrical compression capture when a smaller diameter tube is used.