PERISTALTIC PUMP

Abstract: A peristaltic pump for pumping fluids through a flexible tube (34) is described which has a quick release and engagement mechanism that permits easy and rapid removal or insertion of the flexible tube (34) into the device. The quick release and engagement mechanism of the invention consists of a shoe (19) mounted for vertical displacement on the body (19) of the pump. Upward movement of the shoe (19) engages the flexible tube (34) holding the fluid to be pumped and locks the tube against the roller assembly (31, 32, 33) containing an eccentrically mounted roller (16) which intermittently engages the tube (34) and forces fluid out of it. To disengage the flexible tube (34) from the pump, the shoe (19) is moved downward out of contact with the flexible tube (34).

Description: The present invention is directed to a peristaltic pump for pumping fluids having a unique, quick release mechanism for inserting or removing a flexible tube carrying the liquid which is being pumped. The invention is particularly useful in the medical arts for pumping biological fluids such as urine or therapeutic agents in liquid form. Peristaltic pumps for moving fluids through flexible tubing are known in the art and have found particular application in the medical sciences both for moving biological fluids and for administering therapeutic agents. Typically in such peristaltic pumps, a rotor is mounted eccentrically on a shaft so that rotation of the shaft causes the rotor to transcribe an orbital path in which it is intermittently brought into pressure contact with a flexible length of tubing to compress the tubing and thereby force liquid through the tubing. Pumps of this type are, for example, described in Patent number US-B-4,559,040 (Horres et al.) which shows a peristaltic pump having a segmented stator chamber and Patent numbers US-B-4,540,351 and US-B-4,631,007 (both Olson) describing peristaltic pumps which are provided with hinged jaws to permit insertion and removal of the flexible tube carrying the liquid being pumped. As exemplified by the prior art described above, one of the problems encountered with peristaltic pumps is the complexity of the mechanism for holding the flexible tubing in the pump against the rotating pressure member. While it is necessary during the pumping operation for the flexible tubing to be held securely in the pump against a rigid surface so that the orbiting rotor can compress the tubing and move the liquid along within it, it is also desirable to provide a mechanism which permits rapid and easy removal or insertion of the flexible tubing without requiring complex disassembly or reassembly procedures. This is a particularly important and critical feature when the peristaltic pumps are being employed as positive displacement pumps in a medical environment either for transporting or measuring biological fluids or to meter liquid therapeutic agents since the attending physician or his assistants are unlikely to have the time or attention to become involved in extensive manipulative procedures and must depend on metering and volumetric measurements from a positive displacement pump designed for this use. It is accordingly an object of the present invention to provide a peristaltic pump having a closure mechanism which permits quick and easy insertion and securing of a flexible tube carrying the liquid to be pumped. It is a further object of the present invention to provide a peristaltic pump having a release mechanism which permits quick and efficient removal of the flexible tube from the pump without requiring dismantling or disassembly of the pump structure. GB-A-2109474 discloses a peristaltic pump comprising a housing, a roller assembly mounted on the housing for engaging and compressing a flexible tube to continuously displace fluid through the flexible tube, and a shoe movably mounted on the housing adjacent the roller assembly. The shoe comprises a body defining an arcuate surface for contacting the flexible tube. The shoe is adapted for displacement in one direction to engage a portion of the flexible tube and hold it in engagement with the roller assembly, as well as displacement in the other assembly, as well as displacement in the other direction to disengage the flexible tube from the roller assembly and permit its removal from the pump. The pump further includes a cam member to displace the shoe. The present invention is characterised in that its shoe is adapted for displacement by a release mechanism comprising a cam shaft having a cam eccentrically mounted on one end, and the cam shaft passes through a slot in the pump housing to engage the shoe on its other end, with the cam acting against bearing surfaces of a cam journal formed in the pump housing when the cam shaft is turned, to cause displacement of the shaft and the shoe. There now follows a description of a specific embodiment of the invention, by way of example, with reference being made to the accompanying drawings in which: Figure 1 is an exploded perspective view showing the elements of the present invention; Figure 2 is a front plan view showing the pump of the invention opened to receive a length of flexible tubing; Figure 3 is a front plan view showing the pump of the invention opened with a length of flexible tubing inserted; Figure 4 is a front plan view showing the pump of the invention with a length of flexible tubing inserted and the pump closed and ready for operation; Figure 5 is an enlarged isolated plan view of the cam journal and associated bearing surfaces showing the cam eccentrically mounted on a shaft shown in phantom in the closed position; Figure 6 is an enlarged isolation plan view of the cam journal and associated bearing surfaces showing the cam eccentrically mounted on a shaft shown in phantom and partially rotated toward the open position; and Figure 7 is an enlarged isolated plan view of the cam journal and associated bearing surfaces showing the cam eccentrically mounted on a shaft shown in phantom and completely rotated in the open position. Directing attention to Figure 1 of the drawings, a pump housing 9 is shown to which an electric motor 29 and an associated gear mechanism 1 (which is well known in the art) are attached by means of flexible motor mounts 28 and associated mounting screws 2 which isolate both noise and vibration. A circular recessed cavity 40 is defined by the upper portion of pump body 9 to receive a roller housing 17. The roller housing comprises a pair of circular disks or plates 31 and 32 joined together by a shaft 33 of reduced diameter to define an annular slot 30. Rollers 16 are mounted eccentrically within the roller housing 17 by means of roller pin 13. Bearings 15 are mounted on pins 13 in the rollers 16 to facilitate revolution of the rollers within the housing and spacers 14 are mounted on pins 13 on each side of rollers 16 to space the rollers 16 in the annular slot 30 of roller housing 17. The roller housing 17 is attached to shaft 41 which pass through bearing 12 mounted in a throughgoing aperture of cavity 40 of the pump body 9. Additional spacers 11 are provided along with clip 10 to maintain the shaft and roller housing properly in alignment with the pump body 9. Rotary motion is imparted to the roller assembly 17 by means of the electric motor 29 to which the shaft 41 is coupled by flexible coupling 8. Mounted between the motor 29 and gear mechanism 1 is a switch and sensor mounting plate 3. The switch and sensor mount 3 holds rotation counting sensor assembly 4 which is attached to the sensor mount 3 by means of screw 5. The rotation counting sensor assembly 4 counts the rotation of the vane 7 which is attached to the coupling 8 by screw 6. The vane 7 is provided with appropriate marking indicia to register on the counting sensor 4 as the coupling and shaft are turned by the motor. The sensor-counter is of conventional design and may sense revolutions of the shaft either mechanically or optically. As will be seen by reference to Figures 2, 3 and 4 of the drawings, movement of fluid through the flexible tube 34 is imparted by rotation of the roller housing 17 which causes orbital revolution of the rollers 16 with intermittent engagement and compression of the flexible tubing containing the fluid against the shoe 19 in its closed position as shown in Figure 4. Returning to Figure 1 of the drawings, it will be seen that the shoe 19 is provided with a concave face which corresponds to the circular configuration of the roller housing 17 when the device is in the closed configuration shown in Figure 4. Pump housing 9 is provided with vertical slots 36 in mounting plate 42 to receive the projections 38 on the shoe 19 which permits vertical movement of the shoe 19 against the face of plate 42 of the pump housing. This vertical movement of the shoe 19 permits opening as shown in Figures 2 and 3 of the drawings and closing to engage the flexible tube with the rollers 16 and roller housing 17 as shown in Figure 4. Cam shaft 39 passes through the vertical slot 37 in plate 42 of the pump housing 9 to engage the shoe 19. A cam 24 is eccentrically mounted on the shaft 39, and the shaft 39 is turned along with the cam 24 by means of lever 20 which passes through a slot 35 in the bottom of the shoe 19 to threadably engage the shaft 39. Cam cover 25 is mounted on the pump body 9 by means of 3 screws 26. The cam cover 25 retains the cam 24 in the cam journal 43 which extends from the rear of plate 42. Ball plunger set screw 27 is used to lock the cam in closed position. As shown in Figures 5-7, the cam journal 43 comprises two bearing surfaces 44 and 45 which in connection with the cam 24 open and close the pump shoe 19. Movement of lever 20 rotates the cam 24 and cam shaft 39 causing vertical displacement of the cam shaft 39 within the slot 37 and corresponding vertical movement of shoe 19 whose projections 38 travel within the slots 36. Thus, by merely rotating the lever arm 20 with knob 21 through the slot 35 from either its position on the left to its position on the right the shoe 19 is caused to slide vertically downward to open the device for insertion or removal of the flexible tubing or slide vertically upward to lock the shoe against the roller housing 17 with the tubing compressed between the concave inner surface of the shoe 19 and roller 16 within the annular slot 30 of the roller housing. A safety switch 22 and safety switch set screw 23 are conveniently provided on the pump housing to signal the locking of the cam shaft in place and prevent inadvertent disengagement of the shoe and opening of the pump. In operation, once the flexible tube 34 containing a fluid to be pump is inserted between the concave surface of the shoe 19 and the roller housing 17, mouvement of the lever 20 from the open, right side position to the closed, left side position shown in Figure 4 raises the shoe 19 and brings tube 34 into pressure contact with rollers 16 between the shoe 19 and roller housing 17. As housing 17 is turned by the motor, the rollers 16 transcribe an orbital motion which intermittently brings rollers 16 into pressure contact with the tube 34 to positively displace liquid in the tube through the tube. The present invention, can of course be employed in a number of contexts but finds particular utility with regard to medical practice and the pumping of biological and therapeutic fluids. The present invention is particularly advantageous in its quick and easy manipulation to permit insertion or removal of the flexible tubing which carries the fluids being pumped. As can readily be ascertained from the drawings, the device of the invention can in fact be opened and closed with the use of only a single hand and does not require any disassembly or reassembly procedures. It will also be apparent that the present invention contemplates various modifications and variations which are considered to fall within the scope of the invention as defined in the claims presented herein.

Claims: 1. A peristaltic pump comprising a housing (9), a roller assembly (17) mounted on said housing (9) for engaging and compressing a flexible tube (34) to continuously displace fluid through the flexible tube, a shoe (19) movably mounted on the housing adjacent the roller assembly, said shoe comprising a body defining an arcuate surface for contacting said flexible tube, said shoe being adapted for displacement in one direction to engage a portion of said flexible tube and hold it in engagement with said roller assembly and displacement in the other direction to disengage said flexible tube from said roller assembly and permit its removal from said pump, and cam means to displace said shoe in said one direction and said other direction, characterised in that said cam means comprises a cam shaft (39) having a cam (24) eccentrically mounted on one end, and said cam shaft passes through a slot (37) in the pump housing to engage the shoe on its other end, and said cam acts against bearing surfaces (44, 45) of a cam journal (43) formed in the pump housing when the cam shaft is turned, to cause displacement of said shaft and said shoe in said one direction or said other direction. 2. A peristaltic pump in accordance with Claim 1 further comprising a lever (20) engaging the shaft (39) for turning the shaft. 3. A peristaltic pump in accordance with claim 2 further characterised in that said shoe (19) has a slot (35) therein through which said lever (20) passes. 4. A peristaltic pump in accordance with any of the preceding claims further characterised in that said roller assembly (17) comprises a pair of parallel circular plates (31 32) spaced apart on a connecting shank (33) to form an annular slot (30) for receiving a portion of said flexible tube, and at least three rollers (16) mounted between said plates. 5. A peristaltic pump in accordance with any of the preceding claims further comprising an electric motor (29) driving the pump.

Inventors: KAHLER, WILLIAM, LEVEEN, HARRY H.
Applicants: DEVICE SCIENCE, INC.
Application year: 1988
Main classification: A61M1
IPC codes: F04C5, F04B43, A61M5, A61M1