MODULAR FLUID PUMP WITH CARTRIDGE
A modular fluid pump including: a pump motor that provides a motor force, a sealed housing cartridge removably coupled to the pump motor, wherein the housing cartridge is interchangeable with a replacement housing cartridge, a frame enclosed in the housing cartridge and having a plurality of rollers arranged on the frame, a drive coupling means for transmitting the motor force from the pump motor to the frame thereby inducing rotation of the frame, and a fluid conduit, wrapped under tension around at least one of the plurality of rollers, that facilitates fluid flow from an inlet region of the fluid conduit to an outlet region of the fluid conduit. Rotation of the frame causes the plurality of rollers to compress the fluid conduit at subsequent intervals, thereby driving fluid to the outlet region with a peristaltic movement.
This application claims the benefit of U.S. Provisional Application No. 61/152,182, filed 12 Feb. 2009, which is incorporated in its entirety by this reference.
TECHNICAL FIELDThis invention relates generally to the fluid pump field, and more specifically to an improved modular fluid pump in the fluid pump field.
BACKGROUNDIn the medical field, blood pumps are commonly used to provide extracorporeal life support to patients lacking sufficient cardiac function. For example, patients with cardiac failure may require cardiac support long enough to sustain the patient until recovery, heart transplantation, or implantation of a permanent artificial cardiac device. As another example, a patient undergoing cardiac bypass surgery require external means of pumping blood throughout their circulatory system. One kind of pump often used in such extracorporeal life support systems is a roller pump. In a typical roller pump, rollers press against a piece of tubing that is wrapped around the rollers and backed by a rigid raceway to advance fluid through the tubing. Roller pumps typically draw blood from a patient or a venous reservoir of blood supplied by the patient. However, roller pumps typically provide no inherent means of preventing draining of the venous reservoir, and if left unattended, will drain the venous reservoir and continue to pump air to the patient, which may be dangerous for the patient. Furthermore, the tubing in a roller pump has a limited lifetime due to repeated stress during operation, and must periodically be replaced. However, optimal operation of a roller pump typically requires an experienced and skilled operator to carefully set settings on the pump, such as occlusion settings (effectively the maximum amount of compression exerted on the tubing) or tubing tension (wrapping the tubing around the rollers with the proper amount of tension) to optimize the performance of the pump and reduce harmful effects to the patient. Thus, there is a need in the fluid pump field to create an improved modular fluid pump. This invention provides such an improved modular fluid pump.
The following description of preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention.
1. Modular Fluid Pump SystemAs shown in
The pump motor 110 of the preferred embodiment functions to provide a motor force actuation for the plurality of rollers 140 on the frame 130. The pump motor 110 is preferably a direct drive, brushless DC motor with high torque at low RPM, which increases reliability and efficiency that may be lost in a speed reduction gearhead and reduces audible noise. A brushless DC motor also typically has a relatively low emission of electromagnetic radiation, which reduces the likelihood of the fluid pump interfering with other nearby medical and electronic devices. However, the pump motor may be a brushed DC motor, a stepper motor, a single or polyphase AC motor, or any suitable actuator, and may be coupled to a transmission such as a geartrain and/or pulley system to increase the torque output and/or direct the output in a particular orientation. The exact specifications of the pump motor 110 is preferably selected based on the desired application of the fluid pump; for example, in a fluid pump intended for pediatric patients, the pump motor 110 preferably has a smaller physical size and provides a lower torque output to satisfy a lower required torque. In some variations, the pump motor preferably is coupled to a motor housing 112. As shown in
The housing cartridge 120 of the preferred embodiment functions to enclose the pump head components and to removably couple with the pump motor 110 such that the housing cartridge 120 is interchangeable with a replacement housing cartridge. The housing cartridge 120 is preferably substantially airtight sealed and includes a port 122 that facilitates adjustment of the pressure within the housing cartridge. The pressure within the housing may be a fixed or variable subatmospheric or superatmospheric pressure. In one variation, the pressure control port 122 is a vacuum port that couples to a vacuum pump 180 and facilitates formation of a vacuum (i.e., negative pressure) within the housing cartridge. In another variation, the pressure control port 122 couples to a pump and facilitates a positive pressure within the housing cartridge. The housing cartridge 120 preferably further includes inlet and outlet conduit ports with mounted fittings, through which the fluid conduit 160 enters and exits, respectively, the housing cartridge. The housing cartridge 120 is preferably of unitary construction, which increases the robustness of the airtight seal. However, the housing cartridge may alternatively be composed of multiple separate pieces joined together by fasteners, epoxy, a welding process, and/or any suitable joining process. In this variation, the joints between the separate housing cartridge pieces are preferably sealed with a welding process, gasket, or sealant to make the housing cartridge 120 airtight sealed. Similar sealing processes are preferably used to seal the conduit ports, and any other openings in the housing cartridge. The sealing limits exposure of a user to the fluid within the tubing and the housing cartridge, by not requiring contact between the user and the fluid during removal of the housing cartridge from the fluid pump. The sealing also limits fluid that is potentially lost in a failure such as a tubing leak. As shown in
The frame 130 of the preferred embodiment functions to support a plurality of rollers 140 and provide the movement of a plurality of rollers 140 along a substantial length of the fluid conduit 160. The frame 130 is preferably enclosed in the housing cartridge 120 and is operatively coupled to the motor force of the pump motor no through the non-contact coupling means 150, such that the motor force induces rotation of the frame 130. The frame 130 preferably includes a plurality of rollers 140. As shown in
The drive coupling means 150 of the preferred embodiment functions to transmit the motor force to the frame 130, thereby inducing rotation of the frame during operation of the fluid pump. The drive coupling means 150 is preferably one of several variations. In a first variation, the drive coupling means is a non-contact coupling means. The non-contact coupling means preferably includes a magnetic coupler with a first mating portion 152 and a second mating portion 154 magnetically attracted to the first mating portion 152. The first mating portion 152 of the magnetic coupler is preferably connected to the rotor of the pump motor no, and the second mating portion 154 of the magnetic coupler is preferably connected to the frame 130. Because the first and second mating portions of the magnetic coupler are magnetically attracted, movement of the pump motor rotor is tracked by the frame, such that rotation and motor force of the pump motor is transmitted into rotation of the frame 130. Since the magnetic field of the magnetic coupling preferably passes through the material of the housing cartridge, the magnetic coupler allows the housing cartridge 120 to be self-contained without the need for additional mechanical drive coupling between the pump motor 110 and the frame 130 that would complicate the coupling between the pump motor 110 and housing cartridge 120. This simplifies the removable coupling between the housing cartridge and pump motor, in that the housing cartridge 120 is preferably interchangeable with a quick, drop-in replacement. The magnetic coupler preferably includes permanent magnets for reliable drive coupling. However, the magnetic coupler may alternatively include electromagnets that can be controlled to selectively provide the magnetic attraction forming the drive coupling, which may have certain advantages in some applications. For example, since removing electric current to an electromagnetic drive coupling removes the magnetic field, such selective decoupling of the frame 130 and pump motor no may be useful in quick shut-off situations, or to facilitate quick removal of the housing cartridge 120 for replacement of the housing cartridge.
The magnetic coupler is preferably one of several variations. In a first variation, as shown in
In a second variation, as shown in
In a third variation, the drive coupling means 150 is between the frame 130 and a manual actuator. In this variation, the manual actuator is a hand crank, a hand pump, or any suitable hand operable actuator that may be coupled to the frame to induce rotation of the frame.
Other embodiments may incorporate a combination of the variations of non-contact and contact coupling means. In any of these variations, as shown in
The fluid conduit 160 of the fluid pump functions to carry fluid flow through the fluid pump. As shown in
The fluid conduit 160 preferably operates in at least two modes: a filled mode 172 and a collapsed mode 174. As shown in
The fluid conduit 160 is preferably made of medical-grade polyurethane, and more preferably from a profile extrusion of thermoplastic polyurethane for durability and greater strength and toughness than other thermoset materials. However, the fluid conduit may be made of any suitable material. The extrusion is preferably shaped in a secondary heat biasing process that optimizes the filling characteristics of the pump. In this secondary process, the profile of the fluid conduit 160 is preferably formed to be as flat as possible, while maintaining two characteristics: (1) sharp interior corners that minimize wear and fatigue by allowing the fluid conduit 160 to completely flatten at the roller locations without inducing high cyclical bending stresses along the edges of the fluid conduit; and (2) maintaining additional material on the edges that increases durability of the fluid conduit 160. The fluid conduit 160 may be further treated to include an internal coating of heparin, an anticoagulant, to reduce the tendency of blood clots as blood passes through the fluid pump. The extrusion is preferably cut to length and wrapped around the plurality of rollers 140 in factory assembly of the housing cartridge 120. Fixtures are preferably used to obtain a consistent length of fluid conduit 160, and to ensure that uniform tension is applied as the fluid conduit is wrapped around the plurality of rollers 140. A polyurethane inlet tube 168 is preferably radiofrequency (RF) welded to the inlet region 162 of the fluid conduit and attached to a mounting fitting that is ultraviolet (UV) light bonded to the housing cartridge 120. Similarly, a polyurethane outlet tube 170 is preferably RF welded to the outlet region 166 of the fluid conduit and attached to a second mounting fitting that is UV bonded to the housing cartridge 120. As shown in
In one very specific example of the fluid pump intended for a pediatric patient weighing less than 25 kilograms, the fluid pump provides a blood flow rate of 0-2.5 liters/minute. The pump motor is approximately 5.3 inches in diameter, the frame is approximately 3.25 inches in diameter, and the combined depth of the housing cartridge and pump motor is preferably approximately 3.1 inches. The frame includes three rollers distributed at the vertices of an equilateral triangle. The fluid conduit has a priming volume of less than 25 milliliters, and has a ⅜″ diameter inlet tube 168 and a ¼″ diameter outlet tube welded to the fluid conduit.
The fluid pump may further include a controller that allows an operator to interact with, monitor, and control the fluid pump. The controller preferably includes a graphical user interface, a touch screen or buttons, an ultrasonic flow meter, a bubble detector, pressure sensors, a vacuum controller, and any suitable hardware. The controller preferably further includes an optical sensor located at the bottom end of the housing cartridge, which may be used to detect an obstruction such as pooling fluid levels in the bottom of the housing cartridge, which suggests a leakage in the fluid conduit. The controller preferably includes an audio and/or visual device to alert the user of the possible leak. The controller preferably also allows the user to define limits for triggering an alarm regarding various crucial characteristics of the fluid pump, such as flow rate and pressure.
2. Method of Supplying a Plurality of Housing CartridgesAs shown in
Step S210, which includes manufacturing a sealed housing cartridge, preferably includes the manufacturing steps described above, to form a rotating frame, a plurality of rollers arranged on the frame, and a fluid conduit wrapped around the plurality of rollers. The rotating frame preferably has a portion of a drive coupling that mates with another portion of the drive coupling connected to the pump motor.
Step S220, which includes tensioning the fluid conduit to a desired amount of tension, functions to tighten the fluid conduit around the rollers to a suitable tightness setting to limit the maximum amount of fluid pressure that, when the housing cartridge is coupled to the pump motor, limits the maximum amount of fluid pressure that can be generated in the fluid conduit. S220 preferably includes wrapping the fluid conduit around a fixture that ensures that uniform tension is applied as the fluid conduit is wrapped around the plurality of rollers.
Step S230, which includes positioning the plurality of rollers, functions to relieve tension in the fluid conduit to reduce creep that a fluid conduit continuously loaded in tension may experience over a long period of time such as during storage and/or shipping. Step S230 preferably positions the plurality of rollers such that the path length of the conduit around the rollers is minimized. Step S230 preferably includes rotating the frame, which preferably rotates the orientation of the plurality of rollers such that the path length of the fluid conduit around the rollers is minimized. For example, as shown in
Step S240, which includes setting the internal pressure of the housing cartridge to a desired pressure level S240, functions to limit the amount of suction that the fluid pump provides, when the housing cartridge is coupled to the pump motor. Through a pressure control port on the housing cartridge, the internal pressure is preferably set to a level that avoids cavitation and hemolysis of the patient and/or damage to downstream components of the fluid pump or other equipment. The internal pressure of the housing cartridge is preferably set to a vacuum, but may alternatively be set to a positive pressure. After setting the internal pressure of the housing cartridge, the pressure control port may be sealed or eliminated.
Step S250, which includes repeating steps S210-S240 for a plurality of housing cartridges preferably increases consistency between housing cartridges that are distributed, such that a fluid pump that is compatible with the distributed housing cartridges performs more reliably and consistently between interchanged housing cartridges.
Step 260, which includes distributing the plurality of housing cartridges, functions to provide a series of cartridges to a customer, such as a hospital. The series of cartridges are preferably provided in a case, such as a case of 24 cartridges, but may be provided in any suitable number or as a single cartridge on an as-needed basis.
As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.
Claims
1. A modular fluid pump comprising:
- a pump motor that provides a motor force;
- a housing cartridge removably coupled to the pump motor, wherein the housing cartridge is interchangeable with a replacement housing cartridge;
- a frame enclosed in the housing cartridge and having a plurality of rollers arranged on the frame;
- a non-contact drive coupling means for transmitting the motor force from the pump motor to the frame thereby inducing rotation of the frame; and
- a fluid conduit, wrapped under tension around at least one of the plurality of rollers, that facilitates fluid flow from an inlet region of the fluid conduit to an outlet region of the fluid conduit, wherein rotation of the frame causes the plurality of rollers to compress the fluid conduit at subsequent intervals, thereby driving fluid to the outlet region with a peristaltic movement.
2. The modular fluid pump of claim 1, wherein the housing is airtight sealed and includes a port that facilitates adjustment of the pressure within the housing cartridge.
3. The modular fluid pump of claim 1, wherein the non-contact drive coupling means includes a magnetic coupler.
4. The modular fluid pump of claim 3, wherein the magnetic coupler is a magnetic disc coupler including a first disc and a second disc magnetically attracted to the first disc, wherein the first disc is connected to the pump motor and the second disc is connected to the frame.
5. The modular fluid pump of claim 4, wherein at least one of the first and second discs of the magnetic disc coupler is enclosed in an airtight seal.
6. The modular fluid pump of claim 3, wherein the magnetic coupler is a magnetic coaxial coupler including a first portion and a second portion magnetically attracted to the first portion, wherein the first portion is connected to the pump motor and the second portion is connected to the frame.
7. The modular fluid pump of claim 6, wherein at least one of the first and second portions of the magnetic coaxial coupler is enclosed in an airtight seal.
8. The modular fluid pump of claim 1, wherein the pump motor is coupled to a motor housing having a mating surface that mates with the housing cartridge.
9. The modular fluid pump of claim 8, wherein the housing cartridge slides onto the mating surface of the motor housing.
10. The modular fluid pump of claim 1, wherein the fluid conduit operates in the following modes:
- a filled mode, wherein the cross section of at least a portion of the fluid conduit is expanded by the fluid and allows fluid flow toward the outlet region during rotation of the frame; and
- a collapsed mode, wherein the cross section of at least the inlet region is closed and prevents fluid flow toward the outlet region during rotation of the frame.
11. The modular fluid pump of claim 10, wherein fluid flow in the fluid conduit decreases in proportion to decreased filling pressure at the inlet region.
12. The modular fluid pump of claim 10, wherein the housing is airtight sealed and includes a vacuum port that facilitates formation of a vacuum within the housing.
13. A housing cartridge for a modular fluid pump system that includes a pump motor providing a motor force, the housing cartridge comprising:
- a frame enclosed in the housing cartridge;
- a plurality of rollers arranged on the frame;
- a second portion of a non-contact coupler connected to the frame, wherein the second portion of the non-contact drive coupler mates with a first portion of the non-contact drive coupler, such that the non-contact drive coupler transmits the motor force to the frame thereby inducing rotation of the frame; and
- a fluid conduit, wrapped under tension around at least one of the plurality of rollers, that facilitates fluid flow from an inlet region of the fluid conduit to an outlet region of the fluid conduit, wherein rotation of the frame causes the plurality of rollers to compress the fluid conduit at subsequent intervals, thereby driving fluid to the outlet region with a peristaltic movement;
- wherein the housing cartridge is interchangeable with a replacement housing cartridge in the modular fluid pump system.
14. The housing cartridge of claim 13, wherein the housing cartridge is airtight sealed and includes a pressure control port that facilitates adjustment of the pressure within the housing cartridge.
15. The housing cartridge of claim 15, wherein the non-contact drive coupler includes a disc that is connected to the frame and that is magnetically attracted to another disc connected to the pump motor.
16. The housing cartridge of claim 15, wherein the non-contact drive coupler includes a portion that is connected to the frame and that is magnetically attracted and co-axially aligned with another portion connected to the pump motor.
17. The modular fluid pump of claim 15, wherein the fluid conduit operates in the following modes:
- a filled mode, wherein the cross section of at least a portion of the fluid conduit is expanded by the fluid and allows fluid flow toward the outlet region during rotation of the frame; and
- a collapsed mode, wherein the cross section of at least the inlet region is closed and prevents fluid flow toward the outlet region during rotation of the frame.
18. A modular fluid pump comprising:
- a pump motor that provides a motor force;
- a housing cartridge removably coupled to the pump motor, wherein the housing cartridge is interchangeable with a replacement housing cartridge, wherein the housing cartridge is airtight sealed and includes a pressure control port adapted to facilitate adjustment of the pressure within the housing cartridge;
- a frame, enclosed in the housing cartridge and having a plurality of rollers arranged on the frame;
- a drive coupling means for transmitting the motor force from the pump motor to the frame thereby inducing rotation of the frame; and
- a fluid conduit, wrapped under tension around at least one of the plurality of rollers, that facilitates fluid flow from an inlet region of the fluid conduit to an outlet region of the fluid conduit, wherein the fluid conduit operates in the following modes: a filled mode, wherein the cross section of at least a portion of the fluid conduit is expanded by the fluid, wherein rotation of the frame causes the plurality of rollers to compress the fluid conduit at subsequent intervals, thereby driving the fluid to the outlet region with a peristaltic movement; and a collapsed mode, wherein the cross section of at least the inlet region is closed and prevents fluid flow towards the outlet region.
19. The fluid pump of claim 18, wherein the pressure control port is a vacuum port that facilitates formation of a vacuum.
20. The fluid pump of claim 18, wherein the drive coupling means includes a torque-limiting mechanism.
21. The fluid pump of claim 18, wherein the drive coupling means includes a magnetic disc coupler including a first disc and a second disc magnetically attracted to the first disc, wherein the first disc is coupled to the pump motor and the second disc is coupled to the frame.
22. The fluid pump of claim 18, wherein the drive coupling means includes a magnetic coaxial coupler including a first portion and a second portion magnetically attracted to the first portion, wherein the first portion is coupled to the pump motor and the second portion is coupled to the frame.
23. The fluid pump of claim 18, wherein the fluid conduit further operates in an occluded mode, wherein the pressure within the fluid conduit is greater than the pressure in the housing cartridge, wherein the fluid conduit is at least partially open at the point of contact with at least one of the plurality of rollers.
24. A method of supplying a housing cartridge, comprising:
- manufacturing a sealed housing cartridge including a rotating frame, a plurality of rollers arranged the frame, and a fluid conduit wrapped around the plurality of rollers;
- tensioning the fluid conduit to a desired amount of tension; and
- positioning the plurality of rollers to minimize the path length of the fluid conduit around the rollers, thereby removing at least a portion of tension in the fluid conduit.
25. The method of claim 24, wherein the step of positioning the plurality of rollers includes rotating the frame.
26. The method of claim 24, further comprising the step of setting the internal pressure of the housing cartridge to a desired pressure level.
27. The method of claim 26, wherein the step of setting the internal pressure of the housing cartridge includes forming a vacuum within the housing cartridge.
28. The method of claim 24, further comprising repeating all of the steps to create a series of housing cartridges and then distributing the series of housing cartridges.
Type: Application
Filed: Feb 12, 2010
Publication Date: Aug 19, 2010
Inventor: Daniel E. Mazur (Ann Arbor, MI)
Application Number: 12/705,359