Linear peristaltic pump

Linear peristaltic pump for pumping a fluid through a flexible tube (13) comprises a rotatable central member (34) with a plurality of radially disposed planetary gears (51-53). An offset roller (61-63) is disposed on each of the planetary gears (51-53). The flexible tube (13) is inserted between a generally flat compression surface (40) and at least one of the plurality of rollers (61-63). Rotation of the central member (34) enables the plurality of rollers (61-63) to serially collapse the flexible tube (13) and to move in a substantially linear motion along the generally flat compression surface (40) for pumping the fluid through the flexible tube (13).

FIELD OF THE INVENTION

This invention relates to pumps and more particularly to an improved linear peristaltic pump

BACKGROUND OF THE INVENTION

The peristaltic pump was developed in the 1930′s by a medical student, who later became a noted heart surgeon. He recognized the need for a positive displacement pump which would negate cross contamination between the pump mechanism and sterile fluids. Progression of the art eventually led to three basic types of peristaltic pumps.

In a rotary peristaltic pump, fluid in a flexible tube is contained within a circular pump housing along in its internal circumferential area. A revolving series of rollers compresses and closes the tube, forcing the fluid ahead of the roller to be moved out of the pump exit and the tubing immediately following the roller to be returned to its normal expanded state (process called peristalsis), thereby drawing fluid into the pump through the pump inlet.

In a circular peristaltic pump, a single roller on an eccentric compresses the tubing through a full 360 degrees of rotation. This is accomplished by a roller with increased width contacting the slightly spiraled tubing within the pump housing.

Linear peristaltic pumps have typically used a series of sequential cam driven fingers to effect the peristaltic pumping action. Some variations to the linear peristaltic pump actions include systems which compress the tube between a flat platen and a series of belt mounted rollers which are successively driven along the platen. Another variation of a linear peristaltic pump attempts to utilize the traditional circular roller motion to achieve a linear pump. In this pump, a pair of shaft mounted rollers interacts with the tubing affixed to a spring loaded pivotal pump arm which moves under the influence of the rollers. As the rollers reach a position in which they are not occluding the tubing a fixed stop device occludes the tube, thereby preventing any back or forward flow until the next cycle of rollers contacts and occludes the tubing. The problem of combining the simplicity of the circular mechanism in a linear peristaltic pump has remained unanswered.

There have been many in the prior art who have attempted to solve these problems with varying degrees of success. None, however completely satisfies the requirements for a complete solution to the aforestated problem. The following U.S. patents are attempts of the prior art to solve this problem.

U.S. Pat. No. 2,446,618 to Stocks discloses pumps which are particularly suitable for use in moving sludges, slimes, and other fluids carrying a large amount of solids. The invention teaches a pump in which the pressure chamber is collapsed progressively, and continuously in the direction of he flow of the material being pumped.

U.S. Pat. No. 3,249,059 to Renn discloses a new and improved peristaltic pump. The invention teaches a new and improved means for supporting and guiding the planetary roller assembly which compresses the length of collapsible tubing.

U.S. Pat. No. 3,366,071 to Dutler discloses a peristaltic or tube squeezing pump of the planetary type, i.e. it has rollers without individual bearings and contacting a central driving member which preferably is circular. The rollers are arranged to roll on the tube and on a rolling face along different portions of their travel. In each roller the portion contacting the tube has a slightly greater diameter than the portion contacting the rolling surface so that a slight recoil movement of the tube contacting portion is produced while the roller is rolling on the rolling face.

U.S. Pat. No. 3,876,340 to Thomas discloses a peristaltic pipe in which there are several side-by-side flexible pumping tubes each having its own set of pumping rollers which are moved sequentially into a tube flattening position, along the tube for a predetermined length and then cut out of contact with the tube to perform the pumping action. Each tube has its own support against which it is pressed by the rollers and the support is resiliently yieldable in order to avoid placing excess flattening pressures on the tube. In a preferred case, each support is a spring loaded block which may be of resilient material, each set of rollers is carried on a rotatable spider, and the spiders are rotatable simultaneously.

U.S. Pat. No. 4,165,954 to Amos discloses a linear peristaltic pump. The pump includes a pivotal pump arm and a flexible tube secured thereto to inhibit longitudinal tube movement. A means for applying a force to such arm, such as a spring, is provided to cause the pump arm to pivot. A stop device is disposed in the path of travel of the pump arm so that the pump arm pivotal travel may be terminated as the pump arm comes to rest against such stop device. The flexible tube is disposed adjacent a surface of the pump arm and is pivotal therewith so that the flexible tube is pinched off between the pump arm surface and the stop device as the pump comes to rest against it. A rotatable roller assembly is provided having at least one roller mounted on a rotatable roller support. The roller intermittently contacts the flexible tube as the roller support is rotated causing a quantity of liquid to be peristaltically moved within the tube. The pump arm may have a concave surface to accommodate the flexible tube and the convex surface of the roller, if desired. The stop device may be adjustable so as to permit adjustment and change of the pivotal travel of the pump arm. The rotatable roller assembly may be caused to intermittently contact the flexible tube through the use of an electric clutch to which the roller assembly is rotatably responsive. The rotatable roller assembly causes the pump arm and flexible tube to pivot in a direction away from the stop device while the means for applying a force causes the pump arm and flexible tube to pivot in a direction towards the stop device.

U.S. Pat. No. 4,493,706 to Borsanyi et al. discloses a linear peristaltic pump, and a disposable cassette therefore, particularly suitable for the infusion of parenteral fluids. The pump includes a housing having a power-driven shaft and a series of small bearing assemblies having their inner members eccentrically mounted upon that shaft. A thin elastomeric membrane extends along the series of bearing assemblies for engagement with the outer members thereof along a first band or linear zone of contact lying in the same plane as the axis of the shaft. The disposable cassette is removably supported by the housing and takes the form of a rigid, planar, parametric frame having an opening across which is stretched a section of elastomeric tubing. Locators provided by the housing and frame orient the cassette with the axis of the tubing in the same plane as the first band of contact and the axis of the shaft, and a platen provided by the housing engages the section of elastomeric tubing that bridges the opening of the frame to urge that section into engagement with the opposite side of the membrane along a second band or linear zone of contact parallel with the first band of contact. The cassette may include tubular extensions and connectors for connecting opposite ends of the section of elastomeric tubing to a source of fluid and to a patient.

U.S. Pat. No. 4,715,435 to Foret discloses a method and apparatus for pumping and exchanging heat at an accelerated rate between two fluid streams. The apparatus comprises opposite peristaltic pumps moving a separate fluid on their respective side of a linear heat-conductive platen. Each pump consists of a flat elastomeric diaphragm clamped by its edges on the platen; the clamping squeeze displaces the elastomer and makes the diaphragm bulge. Closely spaced pins in combination with fixed cams, flatten and contract the bulge across to form a variable cross-section working chamber. Inlet and outlet are formed by the elastomer bulging into end block cavities leading to ports. In a typical operation, conveyed rollers depress the pins which in turn completely contract the bulge to sealing contact with the platen and forms shrinking volumetric chambers, wherein a gas or mixed-phase fluid is compressed progressively on one side of the platen; on the other side similar operation occurs but volumetric chambers circulate a non-compressible liquid. During operation, heat of compression is simultaneously rejected to the cooling liquid through the platen to achieve a near-isothermal process.

U.S. Pat. No. 4,921,477 to Davis discloses a surgical irrigation and aspiration system for aspirating fluid from a surgical site, such as the eye, including a surgical tool having irrigation and aspiration functions, and an irrigation fluid supply for providing irrigation fluid to the surgical tool. A peristaltic pump pumps aspiration fluid from the surgical site generally through and away from the surgical tool and through an aspiration flow line to a collection container. A dampening mechanism in the aspiration flow line before the pump dampens the oscillations of the aspiration fluid flow, caused by the inherent operation of the peristaltic pump, in the aspiration flow line, and thereby at the surgical site.

U.S. Pat. No. 5,044,902 to Malbec discloses a cartridge comprised of a housing which comprises, in the vicinity of each of its ends, a cylindrical raceway against which are capable of applying and rolling bevel gears which crush the flexible tube located between both raceways. The bevel gears are tubular and freely mounted inside the housing, within the concavity of the flexible tube, this housing comprising, at least on one side, a central opening with a diameter large enough to enable the driving of the bevel gears either directly from a rotary disc provided with planet gears capable of engaging into the tubular bevel gears or from a shaft internally engaged between the tubular bevel gears.

U.S. Pat. No. 5,054,947 to Frank, et al. discloses a self-contained power painting system in which a battery operated motor and pump are contained in a lid for a paint reservoir, and that entire unit is adapted to be carried on a user by a strap or belt. A paint applicator, such as a brush or roller, is connected to the pump by a flexible conduit and includes a switch activator at the applicator to permit the user to selectively control operation of the pump and to move about freely while painting without being encumbered by a relatively immobile paint reservoir or power source connection through extension cords.

U.S. Pat. No. 5,096,393 to Van Steendren, et al. discloses a peristaltic metering pump for dosing metered quantities of fluids along a plurality of flow lines. The pump comprises a set of rollers and a plurality of flexible liquid transfer tubes, the tubes being mounted on a tube mounting against which they are simultaneously compressed by the rollers. The rollers are drivingly connected to a motor, the rollers being mounted on a roller support. The motor is operable to drive the rollers so that they roll successively along the tubes and compress the tubes simultaneously against the tube mounting as they roll along the tubes. The roller support is biassed against a stop with the roller support being movable away from the stop against the bias by force exerted on at least one roller by the tubes.

U.S. Pat. No. 5,924,852 to Moubayed et al. discloses a peristaltic pump for pumping liquids through a resilient tube. In one embodiment, the pump includes a curved concave platen against which a resilient tube is placed. A multi lobed cam is positioned adjacent to the platen and tube. A plurality of pump fingers are mounted between tube and cam in a manner permitting radial movement of the pump fingers. As the cam rotates, the fingers are pressed toward the tube sequentially so as to pump liquid through the tube. The lobe end should press the tube sufficiently to occlude the tube and prevent back flow without over pressing and damaging the tube. A transverse pinch finger is provided on each pump finger, extending from the tube pressing face of each pump finger. At the tube occluding position, the pump finger nearly occludes the tube and the pinch finger completes occlusion without pressing the tube beyond the fully occluded position. A fixed or slidable spring pressed pinch finger may be used. In a second embodiment, the pump fingers also include pinch fingers and are moved toward and away from a planar platen by a plurality of cams mounted transversely on a rotatable shaft. The pinch fingers operate in the same manner as in the first embodiment.

U.S. Patent Application 2006/0228240 to Schroeder, et al. discloses a method and accompanying apparatus for dispensing product with a non-invasive linear peristaltic pump. The linear peristaltic pump includes a traction plate having a linear portion, a depressor and a driver. The depressor compresses the product tube between the linear portion and the depressor, such that an inner passage of the product tube is substantially sealed. The driver moves the depressor along the linear portion of the traction plate, such that the product tube located between the depressor and the linear portion is compressed along the linear portion. Product in an inner passage of the product tube is thereby moved or dispensed. Another embodiment may include depressors attached to belts, wherein successive depressors may be driven along the linear portion to dispense or move the product. A method for using a linear peristaltic pump and the use of a controller to dispense product is also provided.

U.S. Patent Application 2008/0319394 to Yodfat et al. discloses an infusion system, method and device for infusing therapeutic fluid into the body of a patient. The device includes a driving mechanism including a plurality of gears, wherein at least one gear is adjacent to another gear. The device includes a gear in the plurality of gears having plurality of teeth and at least another gear in the plurality of gears having a plurality of teeth. The plurality of teeth of another gear interact with the plurality of teeth of the gear. At least one tooth in the plurality of teeth of the gear is elastically deformable for causing at least one tooth to elastically deform upon meshing with a tooth in the plurality of teeth of another gear and further for causing reduction of noise associated with operation of the driving mechanism.

U.S. Patent Application 2009/0074597 to Baecke discloses a roller pump which comprises an abutment, at least one roller and a casing. A pump hose is squeezed between the roller and the abutment. A hinge connects the abutment and the casing pivotably, the axis of the hinge being parallel to the plane of the pump hose. The invention further relates to a roller pump which comprises a resilient roll member which is fixed to the abutment. The pump hose is pressed against the resilient roll member. The invention additionally relates to a roller pump which comprises two roller gears. Each roller gear being torque-proof connected to one of the two rollers. The two roller gears engage with another gear for ensuring zero relative velocity of the portion of the rollers squeezing the pump hose with respect to the squeezed portions of the pump hose. The invention finally relates to a roller pump which comprises a drive train for mechanically connecting a motor and the rollers. The drive train comprises a sliding hub for limiting the transmitted torque.

Although the aforementioned prior art have contributed to the development of the art of peristaltic pump, none of these prior art patents have solved the needs of this art.

Therefore, it is an object of the present invention to provide an improved linear peristaltic pump.

Another object of this invention is to provide an improved linear peristaltic pump utilizing a rotary driving mechanism.

Another object of this invention is to provide an improved apparatus that is simple for the operator to use.

Another object of this invention is to provide an improved apparatus that is easy to cost effectively produce.

The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.

SUMMARY OF THE INVENTION

A specific embodiment of the present invention is shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an improved linear peristaltic pump for pumping a fluid through a flexible tube. The improved linear peristaltic pump comprises a central member mounted for rotation about a central shaft. A plurality of planetary gear are mounted by a plurality of planetary gear shafts to the central member, respectively. A ring gear is disposed in a mesh engagement with each of the plurality of planetary gears. A roller is disposed on each of the planetary gears offset from the planetary gear shafts, respectively. A generally flat compression surface is located relative to the central axis for enabling the flexible tube to be inserted between the generally flat compression surface and at least one of the plurality of rollers. A motor effects relative rotation between the central member and the ring gear for enabling the plurality of rollers to serially collapse the flexible tube and to move in a substantially linear motion along the generally flat compression surface for pumping the fluid through the flexible tube.

In one example, the ring gear is an outer ring gear disposed outside of the plurality of planetary gears. In another example, the ring gear is an inner ring gear disposed inside of the plurality of planetary gears.

In a more specific embodiment of the invention, the plurality of planetary gears are radially mounted about a periphery of the central member. Each of the rollers is an idler roller. The motor rotates the central member relative to the ring gear and the ring gear is fixed relative to the motor. In one example, a motor drive connects the motor to the central shaft for rotating the central shaft and the central member mounted to the central shaft for rotation in accordance with the central shaft.

In one embodiment of the invention, the improved linear peristaltic pump includes a pivot for pivotably mounting the generally flat compression surface between an open position and a closed position. The open position enables insertion and removal of flexible tube between the generally flat compression surface and at least one of the plurality of rollers. The closed position causes engagement between the generally flat compression surface and at least one of the plurality of rollers.

In still another embodiment of the invention, the improved linear peristaltic pump includes a resilient member for accommodating minute non-linear motion of the plurality of rollers along the generally flat compression surface. In one example, the resilient member comprises a resilient spring for biasing the generally flat compression surface toward the central shaft. In another example, the resilient member comprises the flexible tube having a tube wall of sufficient thickness and sufficient resiliency for accommodating minute non-linear motion of the plurality of rollers along the generally flat compression surface.

Similar reference characters refer to similar parts throughout the several Figures of the drawings.

DETAILED DISCUSSION

FIGS. 1-5are various views of the linear peristaltic pump10of the present invention for pumping a fluid12through a flexible tube13. The flexible tube13extends between a first end14and a second end15. The flexible tube13has a flexible tube wall16defining a lumen17. Typically, the first end14of the flexible tube13is connected to a source of the fluid12for enabling the linear peristaltic pump10to discharge the fluid12from a second end15of the flexible tube13. Preferably, the flexible tube13is formed of a flexible polymeric material such as silicone or thermo plastics elastomor (TPE) or any other suitable flexible material.

The linear peristaltic pump10comprises a motor20having a motor shaft21connected to a motor drive22. A motor mounting24is connected to the motor drive22for mounting the motor20in an external device (not shown) such as a support frame, an external machine and the like. The motor drive22couples the motor20to a pump mechanism30.

Various types of motors20may be used with the present invention including direct current (DC) motors, stepping motors and the like. In the event a direct current (DC) motor is used, the motor drive22may include a reduction gear box. In the event a stepping motor is used, the motor drive22may include a direct drive between the stepping motor and the pump mechanism30. A pump closure31covers the pump mechanism30as shown inFIGS. 1-5.

FIG. 6is a sectional view along line6-6inFIG. 5illustrating the pump mechanism30. A compression surface40is enclosed by a compression surface cover44shown inFIGS. 1-5. The compression surface cover44is connected to the motor mounting24by pivots46and47. The compression surface cover44is moveable on the pivots46and47between an open and a closed position.FIGS. 1-5illustrate the compression surface cover44pivoted into a closed position.

FIGS. 7-10illustrate the compression surface cover44pivoted into an open position. The open position of the compression surface cover44enables the flexible tube13to be inserted and removed from the pump mechanism30without restriction. The closed position of the compression surface cover44engages the flexible tube13between the pump mechanism30compression surface40as shown inFIG. 6.

FIGS. 11-14are various views of the linear peristaltic pump10after removal of the pump closure31and the compression surface cover44. The pump mechanism30comprises a central member34mounted for rotation about a central shaft36. In this example, the central member34is fixed to the central shaft36with the central shaft36being connected through the motor drive22for rotation by the motor20.

A planetary gears system50comprises a plurality of planetary gears51-53mounted by a plurality of planetary gear shafts51S-53S to the central member, respectively. The plurality of planetary gears are mounted radially about a periphery of the central member34. The plurality of planetary gear shafts51S-53S defined gear teeth51T-53T.

Rollers61-63are disposed on the planetary gears51-53. Roller shaft61S-63S are secured to planetary gears51-53with the roller shaft61S-63S being offset from the planetary gear shafts51S-53S. Roller shaft61S-63S are affixed to the outer periphery of the planetary gears51-53to provide the offset of the roller shaft61S-63S from the planetary gear shafts51S-53S. The rollers61-63freely rotate on roller shafts61S-63S as idler rollers.

A ring gear70in a mesh engagement with the plurality of planetary gears51-53. In the embodiment, the ring gear70is shown as an outer ring gear70disposed about the plurality of planetary gears51-53and concentric with the central shaft36. The outer ring gear70is secured to the motor drive22by an outer ring gear mounting72. The outer ring gear70defines outer ring gear teeth70T. Each of the gear teeth51T-53T of the plurality of planetary gears51-53are in a mesh engagement with the outer ring gear teeth70T of the outer ring gear70.

FIG. 15is an isometric view of an example of dispensing system80incorporating the linear peristaltic pump10of the present invention. The dispensing system80includes a container82for containing the fluid12. A coupling84secures the first end14of the flexible tube13to the container82. A check valve86is affixed adjacent to the second end15of the flexible tube13. In this embodiment, the check valve86is integrally molded into the flexible tube13, but it should be understood that a separate and distinct check valve86may be affixed to the flexible tube13. In this example, the check valve86is shown as a duck bill check valve, although various other types of check valves may be used in the dispensing system80. The check valve86retains the fluid12within the container82and the flexible tube13under normal atmospheric conditions.

The compression surface cover44is shown pivoted on hinges46and47into the open position. The container82and the flexible tube13are positioned for introducing the flexible tube13between the compression surface40and the rollers61-63of the pump mechanism30. It should be understood by those skilled in the art, that the dispensing system80shown inFIG. 15is only a single example of possible uses of the present invention and that many other uses and dispensing systems80may be used with the linear peristaltic pump10of the present invention.

FIG. 16is an enlarged front view of a first embodiment of the linear peristaltic pump10with the pump closure31and the compression surface cover44removed for illustrative purposes. The linear peristaltic pump10is shown in a first rotational position. The compression surface cover44(not shown inFIG. 16) is pivoted on hinges46and47into the closed position whereat the flexible tube13engages one of the rollers61-63and the compression surface40.

In contrast to many of the peristaltic pumps of the prior art, the compression surface40has a generally flat or planar surface42while being used with the rotary pump mechanism30. The combination of the plurality of planetary gears51-53in combination with the offset rollers61-63provide a substantially linear of the rollers61-63along the generally flat or planar compression surface40. A resilient mechanism90is incorporated into the linear peristaltic pump10to compensate for minute non-linear motion of the plurality of rollers61-63along the flat or planar compression surface.

In this embodiment, the resilient mechanism90is shown as a spring92mounted between the compression surface cover44and the compression surface40. The spring92biases the compression surface40toward the central shaft36, Although, the spring92has been shown as a particular type of leaf spring, it should be understood that any other type resilient device may be use as will become evident with reference toFIGS. 23 and 24.

FIG. 16illustrates the first embodiment of the linear peristaltic pump10in a first rotational position. The fluid12is contained within the tube13and the container82by the check valve86. In the first rotational position, the roller61compresses the flexible tube13to separate the fluid12in the flexible tube13between a region adjacent to the first end14of the flexible tube13and a region adjacent to the second end15of the flexible tube13. Preferably, the roller61completely collapses the flexible tube13as shown inFIG. 16.

In this example, the outer ring gear70is fixed relative to the motor mounting24. The motor20rotates the central member34about the central shaft36in a counterclockwise direction. The central member34moves the plurality of planetary gears shafts51S-53S in a counterclockwise direction. Each of the plurality of planetary gears51-53is in mesh engagement with the fixed outer ring gear70. The counterclockwise rotation of the central member34results in a clockwise rotation of each of the plurality of planetary gears51-53.

FIG. 17is a view similar toFIG. 16with the linear peristaltic pump10in a second rotational position. The counterclockwise rotation of the central member34with the clockwise rotation of the planetary gear51in combination with the offset roller61results in a substantially linear movement of the roller61along the flat compression surface40.

FIG. 18is a view similar toFIG. 16with the linear peristaltic pump10in a third rotational position. The counterclockwise rotation of the central member34, the clockwise rotation of the planetary gear51moves the offset roller61in a substantially linear movement along the flat compression surface40.

FIG. 19is a view similar toFIG. 16with the linear peristaltic pump10in a fourth rotational position. The offset roller61moves in a substantially linear motion along the flat compression surface40. In this example, the resilient member90shown as the spring92resiliently mounts the flat compression surface40for accommodating for minute non-linear motion of the roller61along the flat compression surface40. The resilient spring92biases the flat compression surface40toward the central shaft36.

FIG. 20is a view similar toFIG. 16with the linear peristaltic pump10in a fifth rotational position. In the fifth rotational position, the roller62compresses the flexible tube13to separate the fluid12in the flexible tube13between a region adjacent to the first end14of the flexible tube13and a region adjacent to the second end15of the flexible tube13. Preferably, the roller62completely collapses the flexible tube13. The first roller61has been moved out of engagement with the flexible tube13.

FIG. 21is a view similar toFIG. 16with the linear peristaltic pump10in a sixth rotational position. The counterclockwise rotation of the central member34with the clockwise rotation of the planetary gear52in combination with the offset roller62results in a substantially linear movement of the roller62along the flat compression surface40. It should be appreciated by those skilled in the art that the motor20may rotate the outer ring gear70for moving the plurality of rollers61-63to serially collapse the flexible tube13and to move in a substantially linear motion along the generally flat compression surface40for pumping the fluid12through the flexible tube13.

FIG. 22is a sectional view of a second embodiment of the linear peristaltic pump10A of the present invention in a first rotational position. In this embodiment, the linear peristaltic pump10A comprises four planetary gears51-54carrying four offset rollers61-64. The roller61is shown completely collapses the flexible tube13.

FIG. 22Ais a view similar toFIG. 22with the linear peristaltic pump10A in a second rotational position. The counterclockwise rotation of the central member34with the clockwise rotation of the planetary gear51in combination with the offset roller61results in a substantially linear movement of the roller61along the flat compression surface40.

FIG. 22Bis a view similar toFIG. 22with the linear peristaltic pump10A in a third rotational position. In the third rotational position, the roller62compresses the flexible tube13whiles the roller61continues to compress the flexible tube13.

FIG. 22Cis a view similar toFIG. 22with the linear peristaltic pump10A in a fourth rotational position. The roller62moves in a substantially linear movement along the flat compression surface40. The first roller61has been moved out of engagement with the flexible tube13.

FIG. 22Dis a view similar toFIG. 22with the linear peristaltic pump10A in a fifth rotational position. The roller62continues to move in a substantially linear movement along the flat compression surface40.

FIG. 22Eis a view similar toFIG. 22with the linear peristaltic pump10A in a sixth rotational position. The roller62continues to move in a substantially linear movement along the flat compression surface40. The roller63is positioned to compresses the flexible tube13upon further rotation of the central member34.

FIG. 23is a sectional view similar toFIG. 16illustrating an alternative resilient member90B. In this example, the compression surface40B is substantially rigid. The resilient member90B comprises a flexible tube13B having a flexible tube wall16B of sufficient thickness and sufficient resiliency accommodating for minute non-linear motion of the plurality of rollers61-63along the flat compression surface40B.

FIG. 24is an enlarged view of a portion ofFIG. 23illustrating the relationship of the outer diameter18B of the flexible tube13B and the inner diameter19B of the lumen17B.

FIG. 25is a top view and sectional views of a third embodiment of the linear peristaltic pump10C of the present invention. In this embodiment, the linear peristaltic pump10C includes a fixed compression surface cover44C having an aperture48C for receiving the flexible tube13.

FIGS. 26 and 27are sectional view of the third embodiment of the linear peristaltic pump10C ofFIG. 25illustrating the inserting of the flexible tube13. The pumping mechanism30C comprises two planetary gears51and52carrying two offset rollers61and62. The planetary gears51and52are rotatably mounted to a central member34C. The central member of34C is freely rotatable about the central shaft36.

In this embodiment, the ring gear70C is an inner ring gear70C located between and in engagement with the two planetary gears51and52. The inner ring gear70C is secured to the central shaft36. Rotation of the central shaft36results in movement of the planetary gears51and52as shown inFIGS. 28-31.

FIG. 28is a view similar toFIG. 26with the flexible tube13fully inserted into the linear peristaltic pump10C. Since the linear peristaltic pump10C contains only to planetary gears51and52, the flexible tube13may be inserted through the aperture48C when the planetary gears51and52are disposed in the location shown inFIG. 28. The use of two planetary gears51and52eliminates the need for a pivotable compression surface cover44.

FIG. 29is a view similar toFIG. 28with the linear peristaltic pump in a second rotational position. The counterclockwise rotation of the central member34C with the clockwise rotation of the planetary gear51in combination with the offset roller61results in a substantially linear movement of the roller61along the flat compression surface40C.

FIG. 30is a view similar toFIG. 28with the linear peristaltic pump in a third rotational position.

FIG. 31is a view similar toFIG. 28with the linear peristaltic pump in a forth rotational position.

FIG. 32-34are enlarged views of an example of a check valve86suitable for use with the present invention in a closed position. The check valve86is shown as a duck bill check valve. Preferably, the duck bill check valve86is integrally formed with the flexible tube13.

FIG. 35is a view similar toFIG. 34with the check valve in an open position. The check valve86opens under the pressure of the linear peristaltic pump10to accurately control the volume of the fluid will dispense from the flexible tube13.

FIGS. 36 and 37are enlarged views of the flexible tubing13disposed between the compression surface40and an idler roller61. The resilient member90is in an uncompressed condition.

FIG. 38is a top view similar toFIG. 37illustrating the idler roller61collapsing the flexible tube13against the compression surface40. The resilient member90is in a partially compressed condition.

FIGS. 39 and 40are enlarged views of a large flexible tubing13L disposed between the compression surface40and an idler roller61. The resilient member90is in a partially compressed condition.

FIG. 41is a top view similar toFIG. 40illustrating the idler roller61collapsing the large flexible tube13L against the compression surface40. The resilient member90is in a more compressed condition. The resiliency of the resilient member90allows the improved linear peristaltic pump10of the present invention to be utilized with various sizes of flexible tubes with various sidewall thicknesses and form from various materials.