Peristaltic pump

Abstract

The peristaltic pump provided by the present disclosure includes a rotatable drive plate, a closed-loop channel, a fluid inlet disposed at a first position along the channel, a fluid outlet disposed at a second position along the channel at a distance from the first position, a flexible membrane extending between the fluid inlet and the fluid outlet and fluidly connecting the fluid inlet and the fluid outlet, and a first roller. A first portion of the channel extends between the fluid inlet and the fluid outlet, a second portion of the channel extends between the fluid outlet and the fluid inlet separately from the first portion of the channel, the flexible membrane defines a closed fluid path between the fluid inlet and the fluid outlet along the first portion of the channel, the first roller is constrainedly disposed between the channel and the drive plate such that rotation of the drive plate causes the first roller to move along the channel, and when passing along the flexible membrane, the first roller deflects the flexible membrane downward to contract the closed fluid path and send the fluid in the closed fluid path from the fluid inlet to the fluid outlet. Advantageously, according to the present invention, a planar peristaltic pump with the drive plate superimposed on the fluid path is provided, enabling top-down assembly of components along a single vertical axis.

Description

Technical Field

[0001] The present invention relates to a peristaltic pump.

Background Art

[0002] Peristaltic pumps are well known in the art. They are particularly useful in applications where contact with the liquid being transferred is a problem. A peristaltic pump applies pressure while moving along the outside of a conduit and does not contact the liquid being conveyed. Peristalsis is achieved by the volume of liquid being sequentially conveyed. As a result, a pumping action occurs, suction is generated at the inlet, and the liquid to be transferred is sucked in.

[0003] A typical peristaltic pump includes a rotating rotor or disk having a plurality of rollers spaced circumferentially. The liquid conduit is arranged to extend along the circumference of the rotating rotor or disk. As the rotor or disk rotates, the rollers move while pressing and engaging with the conduit in a "wipering" action, thereby reliably sending out the liquid captured in front of each roller. The rollers convey the liquid from the inlet of the pump to the outlet of the pump. The rollers disengage from the engagement with the conduit at the outlet and rotate from the outlet to the inlet to start a new pump cycle.

[0004] Peristaltic pumps are widely used, for example, in medical applications where the sterility of the liquid being transferred must be maintained. Furthermore, peristaltic pumps can be used for small amounts of liquid and are mechanically simple. Despite such advantages, the usefulness of peristaltic pumps may be limited by size constraints and ease of manufacture.

Summary of the Invention

[0005] The peristaltic pump provided by the present disclosure includes a rotatable drive plate, a closed-loop channel, a fluid inlet disposed at a first position along the channel, a fluid outlet disposed at a second position along the channel at a distance from the first position, a flexible membrane extending between the fluid inlet and the fluid outlet and fluidly connecting the fluid inlet and the fluid outlet, and a first roller. A first portion of the channel extends between the fluid inlet and the fluid outlet, a second portion of the channel extends between the fluid outlet and the fluid inlet separately from the first portion of the channel, the flexible membrane defines a closed fluid path between the fluid inlet and the fluid outlet along the first portion of the channel, and the first roller is constrainedly disposed between the channel and the drive plate such that when the drive plate rotates, the first roller traverses the channel. When the first roller passes along the flexible membrane, the flexible membrane is deflected downward to contract the closed fluid path, and the fluid in the closed fluid path is sent (transferred) from the fluid inlet to the fluid outlet. Advantageously, according to the present invention, a planar peristaltic pump with the drive plate overlapping the fluid path is provided, enabling top-down assembly by assembling components along a single vertical axis.

[0006] As used herein, "liquid" and "fluid" are interchangeable, and the present invention is intended to function in relation to incompressible fluids or liquids.

[0007] These and other features of the present invention will be better understood through the following description and consideration of the accompanying drawings.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Referring to the above drawings, a peristaltic pump is indicated by reference numeral 10. The peristaltic pump 10 generally includes a rotatable drive plate 12, a closed-loop channel (groove, path) 14, a flexible membrane 16, and at least one roller 18. The flexible membrane 16 fluidly connects a fluid inlet 20 disposed at a first position along the channel 14 and a fluid outlet 22 disposed at a second position along the channel 14 at a distance from the first position, and defines a closed fluid path (closed fluid path) 24 between the fluid inlet 20 and the fluid outlet 22. Due to the rotation of the drive plate 12, at least one roller 18 is captively disposed between the channel 14 and the drive plate 12 such that at least one roller 18 moves along the channel 14. When passing along the flexible membrane 16, this at least one roller 18 causes the flexible membrane 16 to deflect downward and contracts the closed fluid path 24, thereby pushing out the fluid in the closed fluid path 24 from the fluid inlet 20 to the fluid outlet 22.

[0010] The drive plate 12 is an annular body having a central opening 13 for receiving a drive shaft 26. As shown in FIG. 14, the peristaltic pump 10 may include a motor 28. The motor 28 is coupled to the drive shaft 26 to rotate the drive plate 12 about a rotation axis R. The motor 28 may be mounted on an upper portion of a motor support 30 disposed adjacent to the drive plate 12 on a base plate 32. Thus, the motor 28 may be of a cantilever type extending to the drive shaft 26. The drive shaft 26 may be coupled to the drive plate 12 by any known method for transmitting a rotational force. The drive shaft 26 includes one or more keys received in corresponding openings of the drive plate 12, or vice versa, or a combination thereof. Utilizing the key / openings arrangement, the motor 28 can be easily assembled to or removed from the drive plate 12 by inserting or withdrawing the drive shaft 26 into or from the central opening 13 of the drive plate 12.

[0011] The motor support portion 30 may include a cradle 34 for receiving the motor 28. Further, a shroud 36 for surrounding the motor 28 may be provided on the upper portion of the motor support portion 30. The shroud 36 may be provided with a plurality of retaining openings 38 formed to snap-engage with a retaining detent 40 disposed on the motor support portion 30. To provide additional fixation, at least one barrier 42 may be provided on the base plate 32 (including above the side of the drive plate 12 opposite to the motor support portion 30). The barrier 42 may include a retaining detent 40 that is snap-engaged by the retaining openings 38 of the shroud 36.

[0012] As shown in FIG. 3, when the motor 28 is removed, the drive plate 12 is exposed. As shown in FIGS. 14 - 15, the drive plate 12 has a first surface 44 facing the channel 14. Preferably, the channel 14 is a closed loop that generally exists within a single plane P, and the first surface 44 is generally parallel to the single plane P. At least one recess 45 for accommodating at least one roller 18 is formed in the first surface 44. The recesses 45 are provided one by one for each roller 18. As shown in FIGS. 14 - 15, when at least one roller 18 is disposed within the channel 14, due to the mutual engagement between the at least one roller 18 and the drive plate 12, the at least one roller 18 moves along the channel 14 as the drive plate 12 rotates. When the roller 18 is received in the recess 45, interference occurs between the drive plate 12 and the roller 18 due to the rotation of the drive plate 12, and as a result, the roller 18 moves.

[0013] Channel 14 is formed under drive plate 12 such that drive plate 12 covers channel 14. Channel 14 is preferably circular. The first face 44 of drive plate 12 preferably has a diameter sufficient to overlap (overlap) portions that face each other in the diametrical direction of channel 14. Thereby, good contact between at least one roller 18 and drive plate 12 is ensured while moving along the entire length of channel 14. When channel 14 is circular, at least one recess 45 may rotate about rotation axis R with a fixed radius that coincides with channel 14.

[0014] Furthermore, drive plate 12 is positioned to apply a downward pressure to at least one roller 18. Using this downward pressure, when at least one roller 18 moves along flexible membrane 16, at least one roller 18 compresses flexible membrane 16. When flexible membrane 16 is compressed, closed fluid path 24 contracts (narrows). This is utilized to capture and reliably deliver the liquid. The contraction occurs below the contact point between at least one roller 18 and flexible membrane 16 and moves along flexible membrane 16 with the movement of at least one roller 18.

[0015] Channel 14 may be formed in base plate 32. As shown in FIG. 7, fluid inlet 20 and fluid outlet 22 may extend through base plate 32, may be defined by base plate 32, and / or may be tubes that extend through base plate 32. Channel 14 includes two portions, namely, a first portion 14A that extends from fluid inlet 20 to fluid outlet 22 and a second portion 14B that extends from fluid outlet 22 to fluid inlet 20. The second portion 14B is separate (separated) from the first portion 14A. The first portion 14A and the second portion 14B may together cover the entire length of channel 14.

[0016] Channel 14 includes side walls 46. The side walls 46 have a shape that supports at least one roller 18 that rolls or slides along the side walls 46. For example, as shown in FIGS. 14-15, when at least one roller 18 is ball-shaped, the side walls 46 may be arc-shaped that match the radius of at least one roller 18. At least one roller 18 may be formed in other shapes, such as a barrel shape, a conical shape, or a block shape. The side walls 46 are formed to match the contour of at least one roller 18, whereby at least one roller 18 can roll or slide along the side walls 46.

[0017] The flexible membrane 16 fluidly connects the fluid inlet 20 and the fluid outlet 22 and defines a closed fluid path 24 between the fluid inlet 20 and the fluid outlet 22. The fluid inlet 20 and the fluid outlet 22 define openings that communicate with the closed fluid path 24 covered by the flexible membrane 16 as shown in FIG. 6. The liquid introduced from the fluid inlet 20 may be conveyed to the fluid outlet 22 through the closed fluid path 24 continuously covered by the flexible membrane 16 so as not to contact at least one roller 18.

[0018] The flexible membrane 16 may be formed of an elastomeric or polymeric material such as silicone (e.g., room temperature vulcanizing (RTV) silicone) or polyurethane. The flexible membrane 16 preferably has sufficient elasticity and shape memory to compress and contract the closed fluid path 24 and substantially recover its original shape (profile) after compression to reopen the closed fluid path 24. The elastomeric material may be selected based on a durometer to achieve the desired function. It has been found that a membrane with a durometer of 70 Shore A can be used in the present invention. The size, flow rate, and pressure requirements of the pump can also affect the selection of the durometer.

[0019] The flexible membrane 16 is fixed to a portion along the first portion 14A of the channel 14. The flexible membrane 16 may extend between the side walls 46 and define the bottom of the first portion 14A of the channel 14. When the channel 14 is formed in the base plate 32, the flexible membrane 16 may be fixed to the base plate 32 along the first portion 14A of the channel 14. The flexible membrane 16 may define a closed fluid path 24 with an adjacent portion of the base plate 32. The base plate 32 may be provided as a single plate or may be formed of a plurality of joined layers. As shown in FIG. 16, when formed of a plurality of layers, the upper layer 32A may be provided on and joined to the lower layer 32B. The lower channel 48 may be undercut into the upper layer 32A according to the profile of the channel 14. The lower layer 32B may have a ridge (protrusion) 50 formed to extend into the lower channel 48, and a trough (valley) 52 may be formed along the ridge 50. The trough 52 may define a closed fluid path 24 together with the flexible membrane 16. The flexible membrane 16 may be formed in a dome shape above the trough 52 and define a closed fluid path 24.

[0020] The upper layer 32A and the lower layer 32B may be manufactured separately. For assembly, the flexible membrane 16 may be arranged along the ridge 50 with the upper layer 32A attached to the lower layer 32B. With the ridge 50 received in the lower channel 48, an edge portion 54 of the flexible membrane 16 is captured between the upper layer 32A and the lower layer 32B, and the flexible membrane 16 is fixed to the channel 14. In the upper layer 32A, a retaining ridge 56 may be formed to press in the edge portion 54 of the flexible membrane 16, and the retention may be strengthened. The upper layer 32A and the lower layer 32B may be formed of a polymer material (e.g., a thermoplastic), and may be joined using any known technique such as adhesion or fusion.

[0021] When the base plate 32 is a single plate, the trough 52 may be formed as a depression extending below the side wall 46 of the first portion 14A of the channel 14. The flexible membrane 16 may be fixed to the side wall 46 (its lower edge) using any technique such as adhesion, fusion, etc.

[0022] As shown in FIG. 16, in order to define a gap into which the flexible membrane 16 can enter during compression between the flexible membrane 16 and the base plate 32, it is preferable to define a relief 58 around the flexible membrane 16. By shaping the profile of the flexible membrane 16, for example, by providing an inwardly curved portion 58A along the side wall 46 and / or by defining a gap 58B such that the edge portion 54 and the upper layer 32A do not come into complete contact, the relief 58 may be defined.

[0023] The second portion 14B of the channel 14 is formed outside the closed fluid path 24. The channel 14 may have a solid base 60 extending between the side walls 46. The solid base 60 is formed to match the shape of the corresponding at least one roller 18 and may extend continuously with the profile of the side walls 46. The solid base 60 may be formed on the base plate 32. The second portion 14B functions as a return path for returning at least one roller 18 from the fluid outlet 22 to the fluid inlet 20 in order to continuously repeat the pumping operation.

[0024] There may be a height difference between the first portion 14A and the second portion 14B of the channel 14, particularly due to the thickness of the flexible membrane 16. It is preferable to provide a transition portion 62 at the intersection between the first portion 14A and the second portion 14B to function as an inclined path that enables a smooth transition between the first portion 14A and the second portion 14B. For example, as shown in FIGS. 11 to 13, when the second portion 14B is lower than the first portion 14A, the transition portion 62 is inclined to smoothly connect the first portion 14A and the second portion 14B and has the same profile as the channel 14.

[0025] The drive plate 12 may be assembled when in use so as not to apply pressure to at least one roller 18 during storage. Compressing one or more distinct spots of the flexible membrane 16 for an extended period of time may inadvertently cause permanent distortion. When using the spring mount 64 and the spring 68, these may likewise be assembled when in use.

[0026] Furthermore, in order to compensate for any height differences between the first part 14A and the second part 14B, and / or to optimally generate a consistent downward pressure on at least one roller 18, as shown in FIGS. 14-15, the drive plate 12 may comprise a spring mount 64 fixable to the drive shaft 26 around the central opening 13. The drive plate 12 may also be formed to have a spring groove 66 formed around the central opening 13. A spring 68 (e.g., a coil spring) is disposed within the spring groove 66 and engages the spring mount 64 in a pressing manner. The spring 68 is preferably disposed in a compressed state within the spring groove 66 to pre-apply a compressive stress (prestress) to the drive plate 12 downwardly towards at least one roller 18. With this arrangement, the drive plate 12 can engage at least one roller 18 in a pressing manner according to the height difference between the first part 14A and the second part 14B of the channel 14, and most reliably ensures that a consistent pressure is applied to at least one roller 18 to properly compress the flexible membrane 16. The downward elongation (deformation) of the base plate 32 resulting from the biasing force of the spring 68 is restricted by contact with at least one roller 18.

[0027] Optionally, an annular cage 70 may be provided to provide further stability. The cage 70 is disposed between the drive plate 12 and the channel 14 around the central opening 13. The cage 70 has a lower surface 72 facing the channel 14 and an upper surface 74 facing away from the channel 14. At least one seat 76 for receiving at least one roller 18 is formed on the lower surface 72. An opening 78 may be formed on the upper surface 74 in alignment (in a straight line) with at least one seat 76. Thereby, with at least one roller 18 received in at least one seat 76, a part of at least one roller 18 can protrude from the upper surface 74. The part of at least one roller 18 protruding from the opening 78 may be received in the recess 45. Also, at least one roller 18 may protrude from the lower surface 72 and be received in the channel 14. The seats 76 and the corresponding openings 78 are provided for the respective rollers 18 and recesses 45.

[0028] The cage 70 is rotatable independently of the drive plate 12. More specifically, as described above, the drive plate 12 is coupled to the drive shaft 26 and rotates with the drive shaft 26. The cage 70 is not fixed to the drive plate 12, the channel 14, at least one roller 18, or the drive shaft 26. Thereby, the cage 70 can rotate with at least one roller 18 being driven. Further, the cage 70 may be adjusted by at least one roller 18 in accordance with a change in height between the first portion 14A and the second portion 14B of the channel 14. The drive plate 12 moves at least one roller 18 along the channel 14 without being affected by the cage 70. At least one roller 18 is constrained between the drive plate 12 and the channel 14 independently of the cage 70.

[0029] As will be understood by those skilled in the art, any number of rollers 18 can be utilized. As shown in the figures, in the present invention, three rollers 18 may be used. When using a plurality of rollers 18, these rollers 18 are preferably arranged at equal intervals around the channel 14. For example, the recesses 45 are preferably arranged at equal intervals around the first surface 44 of the drive plate 12. By arranging them at equal intervals, more uniform pumping can be obtained and the drive plate 12 can be supported more evenly (thereby avoiding eccentric loads).

[0030] Figures 18 to 20 show the operation of the peristaltic pump 10 using three rollers 18 labeled A, B, and C. At the position shown in Figure 18, assuming that roller A rotates clockwise, it enters the first portion 14A of the channel 14 and starts a pumping cycle across the inlet 20. When roller A enters the first portion 14A, the pumping cycle is started, and roller A compresses the flexible membrane 16 to contract the closed fluid path 24 as shown by the dashed line in Figure 16, confining a volume of liquid between roller A and roller C. Rollers A, B, and C each move along the flexible membrane 16 while contracting the closed fluid path 24 to convey the liquid from the fluid inlet 20 to the fluid outlet 22. Roller C is in the middle of the first portion 14A and conveys the liquid trapped between roller C and roller B towards the fluid outlet 22. As roller C moves while contracting the closed fluid path 24 from the fluid inlet 20, suction is generated at the fluid inlet 20 and liquid is drawn into the closed fluid path 24 from the fluid inlet 20. The liquid drawn in by the movement of roller C is further trapped between roller A and roller C while rotating clockwise. After roller B discharges the liquid that had been trapped between roller B and roller A from the fluid outlet 22, the state of roller B moving away from the fluid outlet 22 is shown. Roller B is trying to enter the second portion 14B of the channel 14 to return to the fluid inlet 20. At this position, roller B is preventing the discharge of the liquid trapped between roller C and roller B.

[0031] Figure 19 shows the state where rollers A, B, and C are rotated clockwise from the position shown in Figure 18. Here, roller A is currently completely within the first portion 14A, continuously contracting the closed fluid path 24 and transporting the liquid captured between roller B and roller A toward the fluid outlet 22. Roller A is also creating suction at the fluid inlet 20, drawing the liquid into the closed fluid path 24. Roller C continues to move the first portion 14A toward the outlet 22 and similarly continuously contracts the closed fluid path 24. At the position shown in Figure 19, when roller B passes through the fluid outlet 22, the closed fluid path 24 between roller C and the fluid outlet 22 is not obstructed, so the liquid is discharged from the fluid outlet 22 by the force of the movement of roller C. When the preceding roller enters the second portion 14B, discharge from the fluid outlet 22 becomes possible. From the position shown in Figure 19, roller C continues to send the liquid out to the fluid outlet 22 by getting closer to the fluid outlet 22. Roller B is in the middle of the second portion 14B and returns to the fluid inlet 20.

[0032] Figure 20 shows the state where rollers A, B, and C are further rotated clockwise from the position in Figure 18. Here, it is assumed that roller A is in the position of roller C in Figure 18, roller B is in the position of roller A in Figure 18, and roller C is in the position of roller B in Figure 18. Roller B starts a new pumping cycle by contracting the closed fluid path and capturing the liquid between roller B and roller A. Roller A continues to transport the liquid captured between roller A and roller C toward the fluid outlet 22. Roller C has discharged the entire amount of the captured liquid from the fluid outlet and completed the pumping cycle. Roller C enters the second portion 14B and returns to the fluid inlet 20 while blocking the fluid outlet 22 due to the liquid captured between roller A and roller C.

[0033] As will be understood by those skilled in the art, various liquids including liquid medications, solutions, or body fluids may be conveyed by the peristaltic pump 10. The peristaltic pump 10 is suitable for applications involving the conveyance of small and trace amounts of liquid.

[0034] The peristaltic pump 10 can be modified. For example, the flexible membrane 16 may be in the form of a tube. Thereby, the flexible membrane 16 can be arranged along the channel 14 to define a closed fluid path 24.

Claims

1. A rotatable drive plate, A closed-loop channel, A fluid inlet disposed at a first position along the channel, A fluid outlet disposed at a second position along the channel at a distance from the first position, A flexible membrane extending between the fluid inlet and the fluid outlet and fluidly connecting the fluid inlet and the fluid outlet, A first roller, Comprising, A first portion of the channel extends between the fluid inlet and the fluid outlet, A second portion of the channel extends between the fluid outlet and the fluid inlet separately from the first portion of the channel, The flexible membrane defines a closed fluid path between the fluid inlet and the fluid outlet along the first portion of the channel, The first roller is constrainedly disposed between the channel and the drive plate such that rotation of the drive plate causes the first roller to move along the channel, The first roller, when passing along the flexible membrane, deflects the flexible membrane downward to contract the closed fluid path and pump the fluid in the closed fluid path from the fluid inlet to the fluid outlet, a peristaltic pump.

2. The peristaltic pump according to claim 1, wherein the second portion of the channel does not overlap with any part of the closed fluid path.

3. The peristaltic pump according to claim 1, wherein the drive plate has a first surface facing the channel.

4. The peristaltic pump according to claim 3, wherein at least one recess for accommodating the first roller is formed on the first surface.

5. The peristaltic pump according to claim 3, wherein the first surface has a diameter sufficient to overlap with diametrically opposed portions of the channel.

6. The peristaltic pump according to claim 1, wherein the first roller is ball-shaped.

7. The peristaltic pump according to claim 1, wherein the first roller is barrel-shaped.

8. The peristaltic pump according to claim 1, wherein the first roller is block-shaped.

9. The peristaltic pump according to claim 1, wherein the first roller is conical-shaped.

10. Further comprising a second roller, The peristaltic pump according to claim 1, wherein the second roller is constrainedly disposed between the channel and the drive plate such that rotation of the drive plate causes the second roller to move along the channel.

11. The peristaltic pump according to claim 1, further comprising a motor for rotating the drive plate.

12. The peristaltic pump according to claim 1, wherein the flexible membrane is fixed to a portion along the channel.

13. The peristaltic pump according to claim 1, wherein the channel is disposed generally in a first plane, and the drive plate has a first surface generally parallel to the first plane.

14. The peristaltic pump according to claim 1, wherein the flexible membrane defines a closed fluid path with adjacent portions of the base plate.

15. The peristaltic pump further comprises an annular cage having a lower surface facing the channel and an upper surface facing away from the channel, wherein a first seat for receiving the first roller is formed on the lower surface, and a first opening is formed on the upper surface in alignment with the first seat such that a part of the first roller can protrude from the upper surface in a state where the first roller is received in the first seat. The peristaltic pump according to claim 1.

16. The drive plate has a first surface facing the upper surface, and a first recess for receiving a portion of the first roller protruding from the upper surface is formed on the first surface. The peristaltic pump according to claim 15.

17. The peristaltic pump according to claim 16, wherein the cage is rotatable independently of the drive plate.

18. A plurality of rollers are provided, wherein the plurality of rollers are constrainedly disposed between the channel and the drive plate such that rotation of the drive plate causes the plurality of rollers to move along the channel, and the plurality of rollers are equally spaced around the channel. The peristaltic pump according to claim 1.

19. The peristaltic pump according to claim 1, wherein the flexible membrane defines a tube.

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