ROTARY PERISTALTIC PUMP

Abstract: A rotary peristaltic pump comprises a rotor member (4) fitted in a stator member (5) and coupled to a motor (2) and having a cylindrical head section (6) housing a plurality of pump tube compressing idler rollers (7) equidistantly radially disposed around the head section, with their longitudinal axes parallel to the axis of the head section. The rollers are positioned in an annular recess (8) in the periphery of the head section, the root periphery of the recess being grooved (17) to accept each compressing idler roller such that a substantial part of each roller protrudes into the annular recess. The stator member (5) comprises a base section (9) and wall section (10) defining an axial opening (11) to accomodate the cylindrical head section and has pump tube entry ports (12, 13) in the wall (10) for tangential communication with the annular recess. Stator member (5) may slide along the rotor shaft (31) to facilitate service to the rotor elements and tube. Rotor member (4) may also include pump tube stabilising idler rollers in the annular recess and a magnetic element to facilitate pump control in conjunction with an electronic control circuit.

Description: This invention relates to rotary peristaltic pumps, suitable for miniaturisation, the pump of the invention having a high degree of efficiency and accuracy, making it particularly suitable for medical drugs administration For example, the pump of the invention is especially suitable for the infusion of insulin or other drugs into ambulant patients, and by reason of its preferred materia of construction as hereinafter described, the pump of the invention is also suitable for use in corrosive environmen However, such uses are merely illustrativeand non-limitati Previous constructions of rotary peristaltic pumps for medical drug administration have suffered from one or more disadvantages, namely, (a) excessive size and complex ity; (b) dependence upon very close tolerances in componen subject to wear or warping; (c) susceptibility to the pre¬ sence of dirt and corrosion; (d) inability to tolerate hig temperatures, e.g. sterilisation; (e) high frictional loss and power requirements; (f) excessive wear of pump-tubing; and (g) poorly reproducible delivery volumes or rates. Thus, previous rotary peristaltic pumps have been constructed with compression r.ollers held in a cage by bearing pins. The driving force is transmitted either via a cage which is mounted on the driving shaft (hereinafter referred to a rotary peristaltic pump "Type A")-, or via a central shaft or roller whose rotation is transmitted to the compression rollers by direct contact, so that the cag travels more slowly than the driving shaft (hereinafter referred to as rotary peristaltic "Type B") . Rotary peristaltic pump "Type A" requires rigid bear- iπg pins to secure the compression rollers to the cage and these bearings are susceptible to wear and seizing. Wear results in failure adequately to compress the tubing, resu ing in loss of accuracy and pump failure. Seizing results in erratic operation and excessive wear of pump tubing. Two modifications of rotary peristaltic pump "Type exist, which seek to overcome the problems occasioned by wear, namely, (1) omission of the outer race, which is identified as the 'Holter' pump, the tubing merely being stretched over the rollers, resulting in an extremely pulsatile flow with considerable flow reversal, moreover, the pump can only maintain constant mean flow rates at l inlet and outlet pressures, and (iii) spring mounting of the rollers or of a segment of the outer race, which is more satisfactory in operation but is complex and often bulky. Rotary peristaltic pump "Type B" is not dependent o a rigid cage and close tolerance bearing between the cag and the compression rollers. However, the cage generall requires a separate central bearing and this is very sen¬ sitive to the least unevenness in the roller from wear o the presence of dirt, which rapidly results in erratic operation, heavy wear and consequent pump failure, this problem being exacerbated by miniaturisation. The rotary peristaltic pump of the present invention avoids many of the above problems, in particular, by bein compact and eminently suitable for miniaturisation; by having very low power requirements; by being of consi era simpler construction and thus easy to manufacture; by bei less susceptible to failure through wear or seizing; by being capable of great accuracy, especially at low flow rates; and by not requiring lubrication due to selection of the materials of construction. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a rotary peristaltic pump adapted to be fitted with motor drive means and pump tubing for connection to a source of fluid, said pump comprising: a rotor member adapted for operative coupling to the moto drive means and having a circular head section housing a plurality of pump tubing-compressing idler rollers in approximately equidistant radially disposed positions for idle rotation axially parallel to the axis of rotation of the rotor member in the course of rotation of said rotor member, the circular head section having a circumferential recess defining a race compartment for said pump tubing- compressing idler rollers so that a substantial part of the circumferential face of each pump tubing-compressing idler roller protrudes into the race compartment; and a stator member having a base section and a wall section wi inner faces which define an axial opening for accommodating .the circular head section of the rotor member and having pu tubing entry and exit ports in the wall section for tangent ial communication with said race compartment- of the rotor member; said pump tubing being fitted to the pump by loading into t race compartment via said pump tubing entry port, then passing around the race compartment to exit therefrom via said pump tubing exit port, whereby the portion of the pump tubing in said race compartment is successively contacted b the protruding circumferential faces of the pump tubing- compressing idler rollers in the course of rotation of said rotor member and is thereby compressed between said inner face of the stator member wall section and said circum- ferential faces of the pump tubing-compressing idler rollers to effect peristaltic pumping of fluid in said pump tubing. Thus, in general, the rotary peristaltic pump of the invention comprises two main components: the stator member and the rotor member, together with a minimum of two idler rollers, preferably three idler rollers being employed for satisfactory peristaltic pumping. The idler rollers of the rotor member successively contact a portion of the pump tub¬ ing passing around the race compartment, which the pump tub¬ ing enters via said entry port in the stator member, for successive compression contact by the idler roller, then leaves via said exit channel in the stator member. OMPI V.'lrO Said circular head section of the rotor member may also house a plurality of pump tubing-stabilizing idler rollers in approximately equidistant radially disposed position in between the approximately equidistant radially disposed position of the pump tubing-compressing idler rollers for idle rotation axially parallel to the axis of rotation of the rotor member in the course of rotation of said rotor member, so that a non-substantial part of the circumferential face of each pump tubing-stabilizing idle roller protrudes into said race compartment whereby the portion of the pump tubing in said race compartment is successively contacted by the protruding circumferential faces of the pump tubing-stabilizing idler rollers in the course of rotation of said rotor member and is thereby frictionally restrained between said inner face of the stator member wall section and said circumferential faces of the pump tubing-stabilizing idler rollers to counter a tendency of the pump tubing to move within said race compartment. Said rotor member may be slideably fitted to said stator member so as to be displaceable axially of the stator member through a coaxial opening in said base section of the stator member for accommodating a drive shaft section of the rotor member, the length of said drive shaft section being such that the rotor member can be displaced axially of the stator member sufficiently to give access to the pump tubing-compressing idler rollers and the pump tubing-stabilizing idler rollers if utilized and the part of the pump tubing in said race compartment for inspection and/or adjustment and/or replacement of any of said idler rollers and the pump tubing. PREFERRED EMBODIMENTS OF THE INVENTION In a preferred embodiment of the rotary peristaltic pump according to the invention, said circular head sectio of the rotary member comprises an inner flange member and an outer flange member joined in spaced-apart relationship by an axial cylindrical mid-section so as to form said circumferential recess defining the race compartment, said inner flange member and outer flange member and axial cylindrical mid-section jointly housing said plurality of pump tubing-compressing idler rollers in approximatel equidistant radially disposed position so that the circu ferential faces of the pump tubing-compressing idler rollers bear into the circumferential face of said axial cylindrical mid-section. The circumferemtial face of said axial cylindrical mid-section may be arcuately recessed longitudinally corresponding to the number of pump tubing-compressing idler rollers and conforming with the diameter of each said pump tubing-compressing idler roller so that a non- substantial part of the circumferential face of each sai pump tubing-compressing roller bears against said axial cylindrical mid-section and a substantial part of the ci cumferential face of each said pump tubing-compressing roller protrudes into said race compartment. According to a first practical form of the preferre embodiment of the invention, said inner flange member and outer flange member may be integral with the axial cylin¬ drical mid-section, the inner flange member having approximately equidistant radially disposed recesses forming end-seating cavities for inner ends of said plur¬ ality of pump tubing-compressing idler rollers, the outer flange member having correspondingly approximately equi¬ distant radially disposed apertures forming end-bearing openings for outer ends of said plurality of pump tubing- compressing idler rollers, and an outer end plate removab connected to the outer flange member for retaining said plurality of pump tubing-compressing idler rollers in sai inner end-seating cavities and said outer end-bearing openings. The opposite ends of each pump tύbing-compress roller may be conically pointed, and corresponding bearin faces of said inner end-seating cavities and of said oute end plate may be flat. According to a second practical form of the preferre embodiment of the invention, said inner flange member is integral with the axial cylindrical mid-section and the o flange member is a disc member non-integral with the axial cylindrical mid-section, the inner flange member having approximately equidistant radially disposed recesses forming end-seating cavities for inner ends of said plurality of pump tubing-compressing idler roller the disc member having correspondingly approximately equidistant radially disposed recesses forming end-seati cavities for outer ends of said plurality of pump tubing compressing idler rollers, and said disc member being removably connected to said axial cylindrical mid-secti for retaining said plurality of pump tubing-compressing idler rollers in said inner end-seating cavities and sai outer end-seating cavities. The opposite ends of each pump tubing-compressing roller may be conically pointed corresponding bearing faces of said inner end-seating cavities and said outer end-seating cavities may be flat. In the case where the circular head section of the rotor member also houses a plurality of pump tubing- stabilizing idler rollers, the circumferential face of s axial cylindrical mid-section may be arcuate_jy recessed longitudinally corresponding to the number of pump tubin compressing idler rollers and conforming with the diamet of each said pump tubing-compressing idler roller so tha non-substantial part of the circumferential face of each said pump tubing-compressing roller bears against said axial cylindrical mid-section and a substantial part of circumferential face of each said pump tubing-compressin roller protrudes into said race compartment, and the circumferential face of said axial cylindrical mid-sectio may also be arcuately xecessed longitudinally correspondi the number of pump tubing-stabilizing idler rollers and conforming with the diameter of each said pump tubing- stabilizing roller so that a substantial part of the circumferential face of each said pump tubing-stabilizing roller bears against said axial cylindrical mid-section a a non-substantial part of the circumferential face of eac said pump tubing-stabilizing roller protrudes into said r compartment. In this case, it is preferred that the practical form of the invention is such that the inner flange me and the outer flange member are integral with the axial cylindrical mid-section, the inner flange member having approximately equidistant radially disposed recesses forming end-seating cavities for inner ends of said plu ality of pump tubing-compressing idler rollers and for inner ends of said plurality of pump tubing-stabilizing idler rollers, the outer flange member having correspo ingly approximately equidistant radially disposed apert forming end-bearing openings for outer ends of said plu ality of pump tubing-compressing idler rollers and for outer ends of said plurality of pump tubing-stabilizing idler rollers, and an outer end plate removably connect to the outer flange member for retaining said plurality of pump tubing-compressing idler rollers and pump tubin stabilizing idler rollers in said inner end-seating cavities and said outer end-bearing openings. The opposite ends of each pump tubing-stabilizing roller may be conically pointed, as may the opposite ends of each pump tubing-compressing roller and cor¬ responding bearing faces of said inner end-seating cavities and of said outer end plate may be flat. Also, the circumferential face of each pump tubing-stabilizin idler roller may have a concave contour substantially corresponding to the diameter of the pump tubing. Said circular head section of the rotor member may integral with a drive shaft section of the rotor member which is adapted to be removably fitted to said motor dr means. Alternatively, said circular head section may be non-integral with a drive shaft section of the rotor mem which is adapted to be removably connected to the circul head section and adapted to be removably fitted to said motor drive means. In the case where the circular head section is inte with a drive shaft section of the rotor member, -a magn may be incorporated in said drive shaft section for poεi ETRIX OMPI sensing in conjunction with means statically mounted for accurate metering and control of delivered volume, and for limitation of axial movement of said rotor member to prevent disassembly during replacement of pump tubing, and for axial and angular location of a motor drive means shaft into said drive shaft section of the rotor member. In the case where the circular head section is non- integral with a drive shaft section of the rotor member, a magnet may be incorporated in the drive shaft section for position-sensing in conjunction with means statically mounted for accurate metering and control of delivered volume, and for limitation of axial movement of the rotor to prevent disassembly during replacement of pump tubing. Said drive shaft section of the rotor member may comprise a torque transfer member removably connected to the circular head section of the rotor member and remov¬ ably fitted to a motor drive means shaft. The torque transfer member of said drive shaft section may be in the form of a cylinder having an axially disposed spindle and adapted for removable connection to said motor drive means shaft and for removable connection to said drive shaft section of the rotor member, said axially disposed spindle adapted to be inserted into a corresponding axially disposed cavity in the circular head section of the rotor member for removable connection of the torque transfer _ member to said circular head section. Both the rotor member and the idler rollers are conveniently fabricated from polytetra fluoroethylene (PTF resin, while the stator member is conveniently fabricated from either polyacyl or polycarbonate resin, as is the idl roller retaining outer end plate when so utilised. The pu tubing is usually fabricated from silicone rubber and may be moulded into a medical drug reservoir. In a pump assembled from a total of six components, that is, the stator member, the rotor member, three idler rollers, an an idler roller-retaining end plate, only the stator mem and the rotor member require accurate machining. The machining tolerances are generally such as to provide 5 a clearance between the stator member wall section and the periphery of the rotor member of 0.03mm + 0.02 mm. The idler rollers can be conveniently fabricated fr PTFE cylindrical rod, with their ends machined to 150 c so as to serve as end thrust bearings. They are a loose 10 in slightly oversize cavities drilled and/or milled in th circular head section of the rotor member. The idler rol ers are retained in the cavities by the closed ends of th cavities in the circular head section of the rotor member ' • - and in the outer end plate removably fixed to the outer 15 end of said circular head section or in the non-integral outer flange member of the circular head section. Since the circumferential faces of the idler rollers are in contact throughout their length with the arcuately recess axial cylindrical mid-section of the circular head sectio 20 a large low-load PTFE-PTFE bearing surface is provided through which is transmitted the thrust to compress the pump tubing. When three (3) pump tubing-compressing idler rollers are utilized, _ the cavities for said idler rollers are 25 spaced at 120 intervals radially from the axis of the rotor member, conveniently in such a manner that the dis¬ tance between the inner surface of each cavity and the ra compartment, minus the diameter of the idler roller, is 1. +0.05 x the thickness of the wall of the pump tubing. Thi 30 ensures positive occlusion of the pump tubing by the pump tubing-compressing idler rollers. When loaded into the pump of the invention, the pump tubing lies in the race compartment formed by said circum ferential recess in the circular head section of the roto 35 member and the inner face of the stator member wall secti for compressing by the pump tubing-compressing idler rolle against said inner face of the stator member wall section. (TR: OM Since the sliding friction of silicone rubber is high, while that of a PTFE-PTFE bearing is low, there is little tendency for the pump tubing to move in the race compartm in the case of relatively small diameter tubing for medic 5 drug infusion. Instead, the pump tubing-compressing idle rollers generally roll along the pump tubing as desired, however, in the case of larger diameter such tubing, it i advantageous to employ a plurality of pump tubing-stabil¬ izing idler rollers as indicated above. 10 Loading or unloading of the pump tubing can be effec ed by inserting the pump tubing into or removing the pump tubing from the stator member/rotor member assembly, respectively,by sliding the rotor member axially so that outer flange of the rotor member head section clears the Ϊ5 * race compartment by at least the diameter of the pump- tubing, thus exposing said circumferential recess and the idler rollers around which the pump-tubing has passed. Said stator member is not subject to any significant degree ofwear, since the thrust is substantially adsorbed b 20 the pump tubing, which is stationary. Similarly, provide there are at least three (3) pump tubing-compressing idle rollers, there is little load on the inner and outer flan member of the rotor member or the drive shaft section of the rotor member or the bearing surfaces of the stator •25 member, consequently there is little wear o friction. T only surfaces subject to frictional load are those of the bearing between the idler rollers and the rotor member, h ever, as these are fabricated from PTFE and the load is spread over a relativley large area, then deformation/fri 30 ion/wear are insignificant. The magnet which may be connected to the rotor membe drive shaft after assembly ofthepump, generally serves the threefold purpose of: (a) position sensing in conjunction with reed or Hall effect switches statically mounted, 5 for accurate metering and control of delivered volume; (b) limitation of axial movement of the rotor member to prev disassembly during change of pump tubing; and (c) axial and angular location of the shaft in the rotor member for connection to a drive motor gearbox assembly. An important feature of the rotary peristaltic pump according to the invention is that in contrast to such pumps of the prior art, the pump tubing-compressing roll 5 are not fixed to the rotor member by bearing pins but instead are idly housed in cavities suitably machined in the circular head section of the rotor member for the purpose. The difference in diameter between the idler rollers and their cavities in the rotor member, combined 10 with the elastic properties of the PTFE under compressiv load, allow both low friction and wear with adequate, co pression of pump tubing, despite comparatively wide mach ining tolerances. - . Another important feature of the pump- according to 15 the invention is the simplicity of the design, which is increased by the several functions performed by the rot and stator members, so that apart from the decreased need close machining tolerance, there is a considerable reduc in the number of components. Thus, in a three (3) pump 20 tubing-compressing idler roller pump accordi ng to the inve tion, the total number of components is six (6) and the number of accurate machining operations required is seven (7) , whereas for a corresponding "Type A" pump of the pri art, the minimum numbers are eight (8) and fifteen (15) , 25 respectively, whilst for a corresponding "Type B" pump of the prior art, the numbers are nine (9) and seventeen (17) respectively. PRACTICAL EMBODIMENT OF THE INVENTION The rotary peristaltic pump of the invention will no 30 be described with reference to the illustrations of Figs. 1-8 of the accompanying drawings, which depict several embodiments of a medical drug infusion pump for long-term treatment of ambulant patients, a magnet being fitted to rotor member drive shaft in such a manner as to provide 35 both an end-stop for rotor advancement and location of th motor drive shaft, as well as to actuate electronic con¬ trol circuitry. In said drawings: OMPI _ Fig. 1 is a perspective view of a pump assembly in operative relationship according to the present invention, in which the outer flange member is integral with the axial cylindrica mid-section of the rotor member circular hea section, according to the first practical form of the preferred embodiment as indicate above; Fig. 2 . is an exploded view of the components formin the pump assembly shown in Fig. 1, in non- operative relationship; Fig. 3 is an exploded view of the components of the rotor member circular head section, in which the outer flange member is a disc member non integral with the axial cylindrical mid-sect of the rotor member circular head section, a cording to the second practical form of the preferred embodiment as indicated above; Fig. 4 is an inverted plan view of the non-integral outer flange member depicted in the embodime of Fig. 3, principally showing the inner fac of the non-integral outer flange member with radially disposed recesses for receiving the conically pointed outer ends of the pump tubi compressing idler rollers; Fig. 5 is a cross-sectional view of the non-integral outer flange member taken at lines B-B of Fig Fig. 6 is a part cross-sectional/part elevational vi of the pump assemblyaccording to the embodime shown in Figs. 1 and 2, in operative relation Fig. 7 is a part cross-sectional/part elevational vi of the pump assemblyaccording to the embodime shown in Figs. 1 and 2, in non-operative rela ship, in which the rotor member is displaced axially for inspection/adjustment/removal/rep ment of the pump tubing and/or the pump tubin com ressin idler r Fig. 8 is a cross-sectional view taken at line C-C of Fig. 7, on a reduced scale? Fig. 9 is a part cross-sectional/part elevational view of the pump assembly, in operative relationship, in which the circular head section of the rotor member houses a plurality of pump tubing-stabilizing idler rollers as well as a plurality of pump tub¬ ing-compressing idler rollers, and also showing the drive shaft section of the rotor member with a torque transfer member in the form of a cylinder removably connected there to, the cylinder having an axially disposed spindle removably connected to the circular head section of the rotor member; Fig. 10 is a cross-sectional view taken at line D-D of Fig. 9; and Fig. 11 is a diagrammatic representation of an electronic circuit for the intermittent operation of electric motor drive means for the pump assembly of the invention. Referring to the drawings, the pump 1 of the invention which is adapted to be fitted with motor drive means 2 an pump tubing 3, comprises a rotor member 4 and a stator member 5. The rotor member 4 is operatively coupled to t motor drive means 2 and has a circular head section 6 hous a plurality of pump tubing-compressing idler rollers 7 in approximately equidistant radially disposed positions for idle rotation axially parallel to the axis of rotation of the rotor member 4 in the course of rotation of said rotor member. A circumferential recess 8 in the circular head section 6 defines a race compartment for the pump tubing- compressing idler rollers 7 so that a substantial part of the circumferential face of each pump tubing-compressing idler roller 7 protrudes into the race compartment. The stator member 5 has a base section 9 and a wall section 10 with inner faces which define an axial opening 11 for accommodating the circular head section 6 of the rotor member 4, and has pump tubing entry and exit ports 12, 13 in the wall section 10 for tangential communication with said race compartment of the rotor member 4. Figs. 1 to 8 of the drawings show the circular head section 6 of the rotor member 4 as comprising an inner flange member 14 and an outer flange member 15 joined in spaced-apart relationship by an axial cylindrical mid- section 16 so as to form said circumferential recess 8 defining the race compartment, said inner flange member 14 and outer flange member 15 and axial cylindrical mid- section 16 jointly housing said plurality of pump tubing compressing idler rollers 7 in approximately equidistan radially disposed positions so that the circumferential faces of the pump tubing-compressing idler rollers 7 bea into the circumferential face of said axial cylindrical mid-section 16. For this purpose, the circumferential face of said axial cylindrical mid-section 16 has arcuat longitudinal recesses 17 corresponding to the number of pump tubing-compressing idler rollers 7 and conforming with the diameter of each said pump tubing-compressing idler roller 7 so that a non-substantial part of the circumferential face of each said pump tubing-compressin roller 7 bears against said axial cylindrical mid-sectio 16 and a substantial part of the circumferential face of each said pump tubing-compressing roller 7 protrudes into said race compartment. Figs. 1, 2,6, 7, and 8 of the drawings show said first practical form of the preferred embodiment, in which the inner flange member 14 and the outer flange member 15 are integral with the axial cylindrical mid- section 16. The inner flange member 14 has approximat¬ ely equidistant radially disposed recesses forming end- seating cavities 18 for inner ends of said plurality of pump tubing-compressing idler rollers 7. The outer flang member 15 has correspondingly approximately equidistant radially disposed apertures forming end-bearing openings 19 for outer ends of said plurality of pump tubing- compressing idler rollers 7. An outer end plate 20 is removably connected to the outer flange member by a screw 21 for retaining said plurality of pump tubing-compressin idler rollers 7 in said inner end-seating cavities 18 and said outer end-bearing openings 19. The opposite ends of each pump tubing-compressing roller 7 have a conical poin 22, while the corresponding bearing faces of said inner end-seating cavities 18 and of the inner face of said out end plate 20 are flat. Figs. 3, 4 and 5 of the drawings show said second practical form of the preferred embodiment, in which the inner flange member 14 is integral with the axial cylind¬ rical mid-section 16 and the outer flange member 15 is a disc member non-integral with the axial cylindrical mid- section 16. The inner flange member 14 has approximately equidistant radially disposed recesses forming end-seatin cavities - 18 for inner ends of said plurality of pump tubi compressing idler rollers 7. Said disc member has corres¬ pondingly approximately equidistant radially disposed recesses forming end-seating cavities 23 for outer ends of said plurality of pump tubing-compressing idler rollers 7. Said disc member is removably connected to said axial cyli rical mid-section 16 by screw 24 for retaining said plural of pump tubing-compressing idler rollers 7 in the inner en seating cavities 18 and the outer end-seating cavities 23. The opposite ends of each pump tubing-compressing roller 7 have a conical point 22 while corresponding bearing faces of the inner end-seating cavities 18 and the outer end- seating cavities 23 are flat. Figs. 9 and 10 of the drawings show the circular head section 6 of the rotor member 4 also housing a plurality o pump tubing-stabilizing idler rollers 25 in approximately equidistant radially disposed positions in between the approximately equidistant radially disposed positions of • the pump tubing-compressing idler rollers 7 for idle rotation axially parallel to the axis of rotation of the rotor member in the course of rotation of said rotor member 4. A non-substantial part o ' f the circumferential face of each pump tubing-stabilizing idler roller 25 protrudes into said race compartment whereby the portion of the pump tubing 3 in said race compartment is success¬ ively contacted by the protruding circumferential faces o 5 the pump tubing-stabilizing idler rollers 25 in the course of rotation of said rotor member 4. The pump tubing 3 is thereby frictionally restrained between said inner face of the stator member wall section 10 and said circumferential faces of the pump tubing-stabilizing '10 idler rollers 25 to counter a tendency of the pump tubing 3 to move within said race compartment. The circumferenti face of each pump tubing-stabilizing idler roller 25 has a concave contour substantially corresponding to the diam of the pump tubing 3 to minimise ' distortion of the pump ' 15 tubing. In this case, in addition to the circumferential face of said axial cylindrical mid-section 16 having the arcuate longitudinal recesses 17 corresponding to the number of pump tubing-compressing idler rollers 7 and 20 conforming with the diameter of each said pump tubing- compressing idler roller 7 so that a non-substantial part of the circumferential face of each said pump tubing- compressing roller 7 bears against said axial cylindrical mid-section 16 and a substantial part of the circumferent 25 face of each said pump tubing-compressing roller 7 protrud into said race compartment, the circumferential face of said axial cylindrical mid-section 16 also has arcuate longitudinal recesses 26 corresponding to the number of pump tubing-stabilizing idler rollers 25 and conforming 30 with the diameter of each said pump tubing-stabilizing roller 25, so that a substantial part of the circum- ferential face of each pump tubing-stabilizing roller 25 bears against said axial cylindrical mid-section 16, and a non-substantial part of the circumferential face of eac 35 pump tubing-stabilizing roller 25 protrudes into said rac compartment. Also in this case, the inner flange member 14 has approximately equidistant radially disposed recess formin end-seating cavities 27 for inner ends of said plurality of pump tubing-stabilizing idler rollers 25. The outer flange member 15 is shown integral with the axial cylindrical mid-section 16 and has 5 correspondingly approximately equidistant radially disposed apertures forming end-bearing openings 28 for outer ends of said plurality of pump tubing-stabilizing idler rollers 25- The outer end plate 20, removably connected to the outer flange member 15 by the screw 29 10 retains said plurality of pump tubing-stabilizing idler rollers 25 and said pump tubing-compressing idler rolle in said inner end-seating cavities 27 and said outer end-bearing openings 28. The opposite endsof each pump tubing-stabilizing roller 25 has a conical point 22, -15 similar to the opposite ends of each pump tubing- compressing roller 7, the corresponding bearing faces of said inner end-seating cavities 27 and of said outer end plate 20 being flat. The rotor member 4 is sli ' deably fitted to the stato 0 member 5 so as to be displaceable axially of the stator member 5 through a coaxial opening 30 in said base sect 9 of the stator member 5 for accommodating a drive shaf section 31 of the rotor member 4. The length of said drive shaft section 31 is such that the rotor member 4 5 can be displaced axially of the stator member 5 sufficie ly to give access to the pump tubing-compressing idler rollers 7 and the pump tubing-stabilizing idler rollers if utilized, and the part of the pump tubing 3 in said ra compartment, for inspection and/or adjustment and/or re¬ placement of any of said idler rollers and the pump tubi In the practical form of pump assembly illustrated in Fi 1 to 8 of the drawings, the drive shaft section 31 of th rotor member 4 is integral with the circular head sectio 6 of the rotor member 4, while in the practical form of pump assembly illustrated in Figs. 9 and 10 of the draw¬ ings, the drive shaft section 31 of the rotor member 4 i non-integral with said circular head section, the drive shaft section 31 of the rotor member 4 being removably connected to the motor drive means 2 by motor drive means shaft 32, in both forms. In the practical form of pump assembly illustrated in Figs. 9 and 10/ the drive shaft section 31 of the rotor member 4 comprises a torque transfer member in the - form of a cylinder 33 removably connected to the motor dri means shaft 32. Cylinder 33 has an axially disposed spindle 34 adapted to be inserted into a corresponding axially disposed cavity 35 in the circular head section 6 of the rotor member 4 for removable connection of the torque transfer member to said circular head section 6 by screw 29, with screw 36 further removably fastening cylind 33 to drive shaft section 31 of the rotor member 4. In the practical form of pump assembly illustrated in Figs. 1 to 8, in which the circular head section 6 is integral with the drive shaft section 31 of the rotor member 4, a magnet 37 is incorporated in said drive shaft section 31 for position-sensing in conjunction with suit¬ able means statically mounted for accurate metering and control of delivered volume, and for limitation of axial movement of said rotor member 4 to prevent disassembly during replacement of pump tubing 3, and for axial and angular location of the motor drive means shaft 32 into sa drive shaft section 31 of the rotor member 4. In the practical form of pump assembly illustrated in Figs. 9 and 10, in which the circular head section 6 is non-integral with a drive shaft section 31 of the rotor member 4, the magnet 37 is incorporated in the torqu -transfer member or cylinder 33 connected to drive shaft section 31 for position-sensing in conjunction with suitab means statically mounted (eg. on stator member 5) for accu metering and control of delivered volume, and for limitat¬ ion of axial movement of the rotor to prevent disassembly during replacement of pump tubing. In this case, axial and angular location of the motor drive means shaft 32 in O ? relation to the drive shaft section 31 of the rotor mem 4 is effected by grub screw 38. Fig. 11 exemplifies electronic control circuitry f the pump of the invention, in consisting of a simple dr ing circuit for intermittent operation using standard C gate technology. In Fig. 11, A = NAND Gate: h of MM74C B = Inverter: 1/6 of MM74C04; C * = Positive Supply 10 Vo D = Earth; E = D.C. Motor: Faulhaber 1616E024S (with 16 900:1 gearbox) ; R ± = 820 K ohm; R 2 = 47 K ohm; R = 10 ohm; R = 10 K ohm; R 5 = 1 M ohm; ^ = 0.1 fd; C„ = 0.0 mfd; C 3 = 0.1 mfd; OSC = Oscillator; FD = MM 5369 Frequ Divider; FF = Flip-Flop; PA = Post Amplifier; and RS = Switch. This circuit causes the pump to deliver a bolus 0.01 - 0.05 ml., depending on tubing size, every 2 hours The current drawn is only a few microamperes between pul Construction of the individual components of a pump in accordance with the invention and the functions of th components can be described in .the following terms: Rotor Member - This component,which can be machined from block of PTFE, embodies several functional elements as follows, with particular reference to Figs. 1, 2, 6, 7 a 8 of the drawings: (i) the rotor shaft, which fits into the bearing element of the stator member in which it rotates, absorbing any radial force resulting from eithe misalignment of the motor drive shaft or from the assyme rical loading of the pump tubing-compressing idler rolle though this is largely absorbed by the outer faces of th flanges, the rotor shaft also permitting axial movement the bearing for change of pump tubing; (ii) flanges, whi result from the machining of the circumferential recess the pump tubing, with (a) inner faces restricting axial movement of the pump tubing in the circumferential reces and (b) a lower face which bears on the thrust bearing surface of the stator member, and (c) outer faces, which bear on the race compartment between the rotor and stato members, absorbing the radial force resulting from the assymetrical loading of the pump tubing-compressing idle rollers; (iii) idler roller cavities, which are cylindri OM with axes parallel to the axis of the rotor member, and are approximately 10% wider in diameter than the idler rollers, the radial distance "d" between the central surface of each cavity and the outer faces of the flang being given by the expression d= * 1.90 (r + w) , where "r" is the radius of roller and "w" is the wall thickness o the pump tubing; and (iv) an upper end face, which has the rotor end plate fixed thereto after insertion of th rollers in the roller cavities. Idler Rollers - These components can be cut from PTFE rod to the length of the cavities, and have their ends chamfered to conical points so as to reduce the contact area with the bottom of each cavity and the end plate, respectively. They rotate within their cavities by rol ing against the pump tubing, due to rotation of the roto member during operation of the pump, thereby to exert pressure ' on the pump tubing for peristaltic pumping of fluid therein. End Plate - This component is a thin disc of "Delrin" or PTFE, which is removably fixed to the upper end face of the rotor member to retain the idler rollers and to act as a thrust surface to prevent the rotor member advancing from the stator member during normal operation Stator Member - This component, which can be machined from a single block of "Delrin" polyacyl or from a singl block of polycarbonate, since both these materials are of adequate tensile strength to withstand the radial force exerted by the pump tubing-compressing idler rolle via the pump tubing (the idler rollers having sufficient sliding friction with respect to silicone rubber to prevent the pump tubing being drawn through the pump during operation) , embodies several functional elements follows: (i) a bearing into which fits the shaft of the rotor member, (ii) a race compartment which has the func tions of (a) a bearing in which the flanges run, and (b a surface against which the pump tubing is compressed by the pump tubing-compressing idler rollers; (iii) a thrus bearing which supports the lower face of the flanges; (i UR£ entry/exit ports which carry the pump tubing tangential into and out of the race compartment and are disposed a such an angle with respect to each other that as one pu tubing-compressing idler roller arrives at one side of the junction of the pump tubing entry port and the race compartment, the previous pump tubing-compressing idler roller departs from the other side, which action increa smoothness of operation, decreases peak power require¬ ments, and avoids any tendency for the rotor to jump ba wards or forwards when the power is switched off; and ( a thrust base which fits against a clip in the pump ca lightly holding the pump head assembly against a rounde protuberance of a pump enclosure case (not shown in the drawings) which bears against the centre of the end plat Assembly and operation of the pump of the inventio when utilized as a medical drug infusion pump, can be described as follows: Driving Mechanism - The shaft of the rotor member is mounted on the motor drive output shaft of a D.C. mico- motor/gearbox assembly with a reduction ratio of approx¬ imately 900:1. A typical current requirementis 7 milliamperes at 5 volts. This is conveniently supplied by a mercury battery via a suitable control circuit as described above A reed switch is also mounted on the gearbox casing in such a position that it is affected by the field of the--iaq.net as the magnet rotates with the shaft of the rotor member and so can detect movement of the shaft. Pump Tubing Loading - The pump head assembly is swung clear of the clip and protuberance in the pump enclosure case (not shown in the drawings) . The stator member is then pushed axially towards the motor until it is stoppe by the magnet. This exposes the circumferential recess in the rotor head section around which the pump tubing is passed. The ends of the tubing are pulled tightly down into the pump tubing entry/exit ports, and the stator member is at the same time drawn back, away from the motor. The pump assembly is then clipped back into the pump enclosure case. Should it be desired to shorte one end of the pump tubing, for example in order to bring the medical drug reservoir of a miniature reservoi pump tubing assembly up against the pump head, this can be achieved by gentle traction on the distal end of the pump tubing. Normal Operation - Each pump tubing-compressing idler roller passing the pump tubing entry port by the rotatio of the rotor member, compresses the pump tubing, thus occluding the lumen. As the rotor member continues to rotate, each pump tubing-compressing idler roller moves along the pump tubing, pushing the contents of the tubin ahead. By the time each pump tubing-compressing idler roller reaches the pump tubing exit port, the succeeding pump tubing-compressingidler roller has already occluded the. lumen behind it, so that liquid cannot escape back towards the inlet, and pumping continues. The version of pump illustrated in Figs. 1 to 8 is designed to work with a range of commercially available silicone rubber tubing giving flows of 0.01 - 0.05 ml. p revolution. The accuracy using the magnet and reed-swit sensor and Dow Corning medical grade silastic tubing is typically 2%. The flow is pulsatile, hence the relative positions of reed switch and magnet are adjusted so that the switc closes just before a pump tubing-compressing idler rolle arrives at the junction of said pump tubing inlet port a said race compartment. This ensures that in intermitten operation, blood is not sucked back into the tip of an intravascular cannula at the end of a pulse.

Claims: CLAIMS : 1. A rotary peristaltic pump adapted to be fitted wit motor drive means and pump tubing for connection to a sourc of fluid, said pump pomprising: a rotor member adapted for operative coupling to the motor drive means and having a circular head section housing a plurality of pump tubing-compressing idler rollers in approximately equidistant radially disposed positions for idle rotation axially parallel to the axis of rotation of the rotor member in the course of rotation of said rotor member, the circular head section having a circumferential recess defining a race compartment for said pump tubing- compressing idler rollers- so that a substantial part of the circumferential face of each pump tubing-compressing idler roller protrudes into the race compartment; and a stator member having a base section and a wall section with inner faces which define an axial opening for accommo¬ dating the circular head section of the rotor member and having pump tubing entry and exit ports in the wall section for tangential communication with said race compartment of the rotor member; said pump tubing being fitted to the pump by loading into the race compartment via said pump tubing entry port, then passing around the race compartment to exit therefrom via said pump tubing exit port, whereby the portion of the pump tubing in said race compartment is successively contacted by the protruding circumferential faces of the pump tubing- compressing idler rollers in the course of rotation of said rotor member and is thereby compressed between said inner face of the stator member wall section and said circumferent ial faces of the pump tubing-compressing idler rollers to effect peristaltic pumping of fluid in said pump tubing. 2. A rotary peristaltic pump according to claim 1 wherein said rotor member is slideably displaceable axially of the stator member through a coaxial opening in said base section of the stator member for accommodating a drive shaft section of the rotor member, the length of said drive shaft section being such that the rotor member can be dis placed axially of the stator member sufficiently to give access to the pump tubing-compressing idler roller and th part of the pump tubing in said race compartment for inspection and pump tubing adjustment and pump tubing replacement. 3. A rotary peristaltic pump according to claim 1 wherein the circular head section of the rotary member comprises an inner flange member and an outer flange memb joined in spaced-apart relationship by an axial cylindric mid-section so as to form said circumferential recess defining the race compartment, said inner flange member a outer flange member and axial cylindrical mid-section joi ly housing said plurality of pump tubing-compressing idle rollers in approximately equidistant radially disposed position so that the circumferential faces of the pump tubing-compressing idler rollers bear into the circumfere tial face of said axial cylindrical mid-section. 4. A rotary peristaltic pump according to claim 3 wherein the circumferential face of said axial cylindrica mid-section is arcuately recessed longitudinally correspo ing to the number of pump tubing-compressing idler roller - and conforming with the diameter of each said pump tubing compression idler roller so that a non-substantial part o the circumferential face of each said pump tubing-compres ing roller bears against said axial cylindrical mid-secti and a substantial part of the circumferential face of eac said pump tubing-compressing roller protrudes into said r compartment. 5. A rotary peristaltic pump according to claim 3 wherein the inner flange member and the outer flange memb are integral with the axial cylindrical mid-section, the inner flange member having approximately equidistant radi disposed recesses forming end-seating cavities for inner en of said plurality of pump tubing-compressing idler roller the outer flange member having correspondingly approximat equidistant radially disposed apertures forming end-beari openings for outer ends of said plurality of pump tubing compressing idler rollers, and an outer end plate remova connected to the outer flange member for retaining said plurality of pump tubing-compressing idler rollers in sa inner end-seating cavities and said outer end-bearing openings. 6. A rotary peristaltic pump according to claim 5 wherein the opposite ends of each pump tubing-compressin roller are conically pointed, and corresponding bearing faces of said inner end-seating cavities and of said out er end plate are flat. 7. A rotary peristaltic pump according to claim 3 wherein the inner flange member is integral with the axi cylindrical mid-section and the outer flange member is a disc member non-integral with the axial cylindrical mid- section, the inner flange member having approximately equ distant radially disposed recesses forming end-seating cavities for inner ends of said plurality of pump tubing- comprising idler rollers, the disc member having correspo ingly approximately equidistant radially disposed recesse forming end-seating cavities for outer ends of said plurality of pump tubing-compressing idler rollers, and said disc member being removably connected to said axial cylindrical mid-section for retaining said plurality of pump tubing-compressing idler rollers in said inner end- seating cavities and said outer end-seating cavities. 8. A rotary peristaltic joump according to claim 7 wherein the opposite ends of each pump tubing-compressing roller are conically pointed and corresponding bearing faces of said inner end-seating cavities and said outer end-seating cavities are flat. 9. A rotary peristaltic pump according to claim 1 wherein the circular head section of the rotor member als houses a plurality of pump tubing-stabilizing idler rolle in approximately equidistant radially disposed positions between the approximately equidistant radially disposed positionsof the pump tubing-compressing idler rollers for idle rotation axially parallel to the axis of rotation of the rotor member in the course of rotation of said rotor member, so that a non-substantial part of the circumferent face of each pump tubing-stabilizing idler roller protrude into said race compartment whereby the portion of the pump tubing in said race compartment is successively contacted by the protruding circumferential faces of the pump tubing stabilizing idler rollers in the course of rotation .of sai rotor member and is thereby frictionally restrained betwee said inner face of the stator member wall section and said circumferential faces of the pump tubing-stabilizing idler rollers to counter a tendency of the pump tubing to move within said race compartment. 10. A rotary peristaltic pump according to claim 9 wherein the circular head section of the rotary member comprises an inner flange member and an outer flange membe * joined in spaced-apart relationship by an axial cylindrica mid-section so as to form said circumferential recess defining the race compartment, said inner flange member an outer flange member and axial cylindrical mid-section join ly housing said plurality of pump tubing-compressing idler rollers in approximately equidistant radially disposed positions so that the circumferential faces of the pump tubing-compressing idler rollers bear into the circumferen tial face of said axial cylindrical mid-section. 11. A rotary peristaltic pump according to claim 10 wherein the circumferential face of said axial cylindrical mid-section is arcuately recessed longitudinally correspon to the number of pump tubing-compressing idler rollers and conforming with the diameter of each said pump tubing- compressing idler roller so that a non-substantial part of circumferential face of each said pump tubing-compressing roller bears against said axial cylindrical mid-section an substantial part of the circumferential face of each said tubing-compressing roller protrudes into said race compart and the circumferential face of said axial cylindrical mid section is also arcuately recessed longitudinally correspo ing to the number of pump tubing-stabilizing idler rollers and conforming with the diameter of each said pump tubing stabilizing roller so that a substantial part of the cir¬ cumferential face of each said pump tubing-stabilizing roller bears against said axial cylindrical mid-section and a non-substantial part of the circumferential face of each said pump tubing-stabilizing roller protrudes into said race compartment. 12. A rotary peristaltic pump according to claim 10 wherein the inner flange member and the outer flange membe are integral with the axial cylindrical mid-section, the inner flange member having approximately equidistant radia disposed recesses forming end-seating cavities for inner e of said plurality of pump tubing-compressing idler rollers and for inner ends of said plurality of pump tubing-stabil izing idler rollers, the outer flange member having corr¬ espondingly approximately equidistant radially disposed apertures forming end-^bearing openings for outer ends of said plurality of pump tubing-compressing idler rollers an for outer ends of said plurality of pump tubing-stabilizin idler rollers, and an outer end plate removably connected the outer flange member for retaining said plurality of pu tubing-compressing idler rollers and pump tubing-stabilizi idler rollers in said inner end-seating cavities and said outer end-bearing openings. 13. - A rotary peristaltic pump according to claim 12 wherein the opposite ends of each pump tubing-compressing roller and each pump tubing-stabilizing roller are conical pointed and corresponding bearing faces of said inner end- seating cavities and of said outer end plate are flat. 14. A rotary peristaltic pump according to claim 9 wherein the circumferential face of each pump tubing-stabi izing idler roller has a concave contour substantially corresponding to the diameter of the pump tubing. 15. A rotary peristaltic pump according to claim 1 wherein the circular head section of the rotor member is integral with a drive shaft section of the rotor member which is adapted to be removably fitted to said motor dri means. 16. A rotary peristaltic pump according to claim 15 wherein a magnet is incorporated in the drive shaft secti of the rotor member for position-sensing in conjunction with means statically mounted for accurate metering and control of delivered volume, and for limitation of axial movement of said rotor member to prevent disassembly during replacement of pump tubing, and for axial and angu location of a motor drive means shaft into said drive sha section of the rotor member. 17. A rotary peristaltic pump according to claim 1 wherein the circular head section is non-integral with a drive shaft section of the rotor member which is adapted to be removably connected to the circular head section an adapted to be removably fitted to said motor drive means. 18. A rotqry peristaltic pump according to claim 17 wherein a magnet is incorporated in the drive shaft secti of the rotor member for position-sensing in conjunction w means statically mounted for accurate metering and contro of delivered volume, and for limitation of axial movement of the rotor member to prevent disassembly during replace ment of pump tubing. 19. A rotary peristaltic pump according to claim 17 wherein the drive shaft section of the rotor member compr a torque transfer member removably connected to the circu head section of the rotor member andremovably fitted to a motor drive means shaft. 20. A rotary peristaltic pump according to claim 19 wherein the torque transfer member of said drive shaft se of the rotor member is in the form of a cylinder having a axially disposed spindle and adapted for removable connec to said motor drive means shaft and for removable connect to said drive shaft section of the rotor member, said axi disposed spindle adapted to be inserted into a correspond - O axially disposed cavity in the circular head section of the rotor member for removable connection of the torque transfer member to said circular head section.

Inventors: HACKMAN CHARLES HENRY, HACKMAN, CHARLES, HENRY
Applicants: HACKMAN CHARLES HENRY, HACKMAN, CHARLES, HENRY
Application year: 1982
Main classification: F04B43
IPC codes: F04B43