Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2001-11-03
2003-08-19
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S478000, C604S153000
Reexamination Certificate
active
06607368
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a linear pump having a flexible, generally tubular bladder. The linear pump of the present invention is relatively simple and thus inexpensive to manufacture and maintain, yet has a surprisingly high pump efficiency. The pump may be used to pump a variety of fluids and may be used in various industrial, commercial, medical, astronautical, aeronautical, or military applications.
BACKGROUND OF THE INVENTION
Pumps have been used for centuries and various types of pumps have been devised, including positive displacement pumps, rotary pumps, vane pumps, centrifugal pumps, and the Archimedes screw pump. While many of these pumps are well suited for particular uses, pumps in general do not have a high efficiency and may not be well suited for special applications, such as pumping blood or pumping sewage wastewater. Many pumps cause damage to the blood components as these blood components make either direct contact or near contact with the surfaces of the pump. Such pumps may also tend to “shear” the non-neutonize blood fluid, which may further damage blood components. Ventricular assist pumps currently employ mechanisms to move blood that stresses the blood in some situations and are non-pulsatile.
When pumping blood, constant flow by conventional pumps may cause “pump-head” because of the sustained vasodilation which results in decreased oxygen and nutrients in the area close to the vascular wall. The alterations in the cellular components of the blood, typical with rotary and constant flow pumps, may be due to reactions with the vasodialated capillaries and the components of the blood reacting to this abnormal state. Ischemia may be present due to the decreased lumen secondary to an accumulation of platelets and/or the blood not pulsing enough to create turbulence and transfer the gases and nutrients. Memory loss and neurological deficits also may be due to the hemo-dynamics of fluid flow of blood, a non-Newtonian fluid under sustained pressure. The pulse flow preferably allows for a psychological pause in the short duration dilated phase and the contraction which contributes to the turbulence necessary to facilitate the movement of the blood components.
Various types of linear pumps have been devised, including linear pumps particularly intended for pumping blood. U.S. Pat. Nos. 5,676,162 and 5,879,375 disclose reciprocating pump and linear motor arrangements for pumping blood. The assembly includes a piston-valve that is placed at the inlet end of a hollow chamber. The valve leaflets may be in any arbitrary position. The pump module arrangement may occupy a space of no more than approximately 6 cm. in diameter and 7.5 cm. long. In a preferred embodiment, a quick connect locking system may be utilized, as shown in FIG. 3 of the '162 Patent. FIG. 11 of the '375 Patent illustrates the anatomical arrangement of a surgically implantable pump, with a reciprocating piston-valve. Other patents directed to implantable pumps and or linear pumps include U.S. Pat. Nos. 5,676,651, 5,693,091, 5,722,930, and 5,758,666.
Conventional pumps have long been used to pump a slurry consisting of a fluid and a solid or semi-solid material, as is common in sewage wastewater. Conventional wastewater pumps have significant problems due to pump plugging and abrasion, which increases repair and maintenance costs, and results in poor pump efficiency and/or short pump life.
U.S. patent application Ser. No. 09/747,832, filed Dec. 22, 2000, by Dr. Anthony Ross and Dr. Peter Guagliano, discloses a linear pump and method, including a housing enclosing a bladder engaged on each end to an end plate, thereby forming two chambers within the housing, one of which is within the bladder. Each end plate provides at least one inlet port and outlet port, which may also include check valves therein to control the direction of fluid flow through the pump housing. The pump may operate in a positive displacement manner by reciprocating one end plate toward and then away from the opposing end plate, thereby altering chamber volumes to cause a pumping action of the fluid. However, end plate movement within the housing may cause component friction and wear surfaces between the moving end plate and the housing. In addition, in some embodiments, inertial energy losses from moving the end plate may impede pump efficiency. The moving end plate may also contribute to pump noise and/or caviation, both of which may be key factors for silent propulsions systems, such as with submarines. In still other embodiments, problems may be experienced as the moving end plate reciprocates in an axial direction that is against the direction of fluid flow, such as when the moving end plate moves toward the opposing end plate, thereby potentially creating downstream back-flow or pressure reduction problems which may significantly reduce pump efficiency.
The disadvantages of the prior art are either overcome or are reduced by the present invention, and improved linear pumps and methods of pumping fluids are hereinafter disclosed which overcome many of the disadvantages of prior art pumps, including relatively high cost of manufacture and/or poor pump efficiency.
SUMMARY OF THE INVENTION
The present invention is directed to a versatile, reliable, and relatively low-maintenance linear pump. In one embodiment, the pump may be used for pumping blood through a living body and may include a pump housing having an inlet end cap and an outlet end cap in sealed engagement with the housing. A conforming bladder may be positioned within the housing, also secured to each end cap, thereby forming two chambers within the housing. An inner chamber may be formed within the bladder, while an outer chamber may be formed by the annular area external to the bladder and internal to the housing. Each chamber may be fluidly connected with at least one inlet port and at least one outlet port, with each port containing a check-valve to control fluid flow through the pump.
Each end plate may be axially fixed with respect to the position of the opposing end plate. The pump may include a plurality of ribs extending generally parallel with a central axis through the pump housing and circumferentially spaced interior or exterior of the bladder. Each rib is attached along a portion of its length to the bladder, and may be integral between bladder layers. Each rib may be engaged with a linear motor to cause the rib to extend or retract with respect to the linear motor. The ribs may be formed to flex or bow when moved with respect to the linear motor, such that the plurality of ribs may in concert act to apply lateral forces upon the bladder, thereby distorting the shape of the bladder with respect to a bladder resting shape. Depending upon the direction of flexion, such distortion may cause a constriction or an expansion of the bladder such that the volume of the inner bladder changes inversely with the volume of the outer chamber. To control the direction of flexion, the ribs may preferably be formed relatively slat-like, or oval shaped, such that a natural direction of flex or bending is achieved. A plurality of bladder extensions may each include an enlarged end for sliding within a slot in a respective rib.
After distorting the bladder in a first direction, the linear motor force may be relaxed or reversed to cause the ribs to allow the bladder to return to the resting shape, or to force the bladder into a second distorted shape. Such action may be cyclically repeated by the linear motor, ribs and bladder, thereby effecting a pumping action of fluid through the pump housing, at a desired pump or pulse rate. A power supply and a pump controller may be provided for controlling movement of the linear motors and movement of the ribs, thereby controlling the pump rate, volume, and pressure.
The pump may be used extra-corporeal as a single unit to move blood through the inner chamber and a lubricant/thermal fluid through the outer chamber to maintain a comfortable state for the patient treated. Another embodiment may uti
Guagliano Peter A.
Ross Anthony
Browning & Bushman P.C.
Freay Charles G.
Gray Michael K.
Helmreich Loren G.
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