WO1992021388A1

WO1992021388A1 - Pump

Info

Publication number: WO1992021388A1
Application number: PCT/BR1992/000007
Authority: WO
Inventors: Jarbas Jakson Dinkhuysen
Original assignee: Fundação Adib Jatene
Priority date: 1991-05-29
Filing date: 1992-05-29
Publication date: 1992-12-10
Also published as: BR9102221A

Abstract

The present invention refers to a pump particularly suitable for pumping blood and biological fluids, the innovative structural conception of which renders the pumping effected by flared rotors more efficient. The pump (1) comprises a housing (2) having a flared inner compartment, a base disc (9), an axial fluid inlet (3) adjacent the vertex of the inner compartment, and a tangential fluid outlet (4) at the base portion of the inner compartment. A flared rotor (5), coaxially arranged within the compartment, is driveable by an external motor and is rotatable about a support shaft (8) that is perpendicularly secured at the center of the base disc (9). According to the invention, a helical vane (6) is provided along a significant portion of the outer flared surface of the rotor (5).

Description

"POMP"

The present invention refers to an improved pump, particularly usable for pumping either blood or biological fluids of a living person or animal, to replace or assist the pumping functions of the human or animal heart in case of dis¬ ability thereof. This pump is also useful in non-biological applications, such as pumping water.

The closest pertinent prior art with respect to this invention is represented by the pump described in US Patent 3,647,324. Said pump comprises a plurality of hollow, conical or flared axially superimposed rotors enclosed in a substan¬ tially conical housing. Said rotors are magnetically coupled with an electric motor that drives them to rotate about their axis, at which time the blood flooding the housing will be forced to be displaced in a helical path, since the fluid layer that is in contact with the rotors tends to assume the speed thereof. It is noted that the fluid speed increases as the radial distance between the outer surface of the rotors and their axis of rotation increases. Such a pump is particularly suitable for pumping blood, since it produces minimum levels of shear and turbu¬ lence, eliminating therefore significant damage to the fluid and to its components. As a result, the pumped blood undergoes an extremely low level of hemolysis, which is the destruction o blood elements (erythrocytes, leucocytes and platelets) due to mechanical strain. The aforementioned impulsion concept en¬ ables one to construct a pump that virtually does not cause any cavitation, shearing, impacts or sudden changes in direc¬ tion of flow. One should bear in mind that the previously use roller pumps are "competent", that is to say, they have a con¬ stant output flow that is sometimes greater than that which the patient can receive at a given moment, whereas the above described pump is "incompetent", that is to say, its flow is reduced if the patient's absorption capacity is temporarily decreased.

However, this same impulsion concept is responsible for the main disadvantage of the latter pump, which is its low efficiency. US 3,647,324 mentions that the multiple rotors can be joined by spiral shaped connectors having an increasing amplitude, in order to enhance the efficiency of the pump. On the other hand, such connectors render the assembly of the pump expensive and complicated.

Thus, the main object of the present invention is to improve the above-described pump by increasing its efficiency, without compromising its main positive feature, namely the low level of mechanical aggression to the pumped fluid. This object is achieved through a pump particularly usable for pumping blood and biological fluids, comprising a housing having a flared inner compartment, a base disc, an ax¬ ial fluid inlet adjacent the vertex of said inner compartment, and a tangential fluid outlet at the base portion of said in- ner compartment; a flared rotor coaxially arranged within said compartment, said rotor being driveable by an external motor; and a support shaft, perpendicularly secured at the center of said base disc, about which said rotor turns; characterized in that a helical vane is provided along a significant portion of the outer flared surface of said rotor.

This invention will be better understood from the following description given by way of example, with reference to the accompanying drawings, in which:

- figure 1 is a longitudinal section view of a pump built in accordance with the present invention;

- figure 2 is a perspective view of the rotor of the pump illustrated in figure 1; and

- figure 3 is a schematic view of the rotors of a pump of the prior art. As shown in figure 1, a pump 1 embodying the present invention comprises fluid tight conical housing 2, preferably made of transparent plastic material, provided with an axial fluid inlet 3 at its vertex and a tangential fluid outlet 4 adjacent a base disc 9 that composes housing 2.

Housing 2 also contains a conical rotor 5, which is better illustrated in figure 2. Rotor 5 is provided with an outer helical vane 6, and is rotatably mounted, by means of bearings 7, on a perpendicular support shaft 8, which in turn is integral with or securely fixed to base disc 9.

The helical vane 6 is preferably integrally formed with rotor 5, and is preferably perpendicular to the outer surface of rotor 5 or to the support shaft 8.

Although the illustrated housing 2 and rotor 5 are conical, it should be noted that, for the purposes of this in¬ vention, such parts may have any flared shape.

An annular magnet 10 is arranged at the lower por¬ tion of rotor 5, adjacent base disc 9. Thus, pump 1 can be driven by an electric motor (not shown), the drive shaft of which is provided with an end disc made of a magnetic mate¬ rial, so that, when the motor is in operation, the end disc and magnet 10 will turn together due to the magnetic coupling existing therebetween. With the consequent rotation of rotor 5, the friction between the outer surface thereof and the ad- jacent layer of the fluid flooding housing 2 from inlet 3 and also the friction produced by helical vane 6 will cause dis¬ placement of the fluid in a helical path that terminates at outlet 4. As mentioned above, the speed at which the fluid flows will increase with the diameter of the flared or conical rotor 5.

Due to the rotating helical vane 6, pump 1 is capa¬ ble of transmitting the tangential speed of the outer surface of rotor 5 to the fluid much quic ier than the prior art pumps which rely only on the friction of the fluid with rotor 5. The efficiency of pump 1 will therefore be much greater than that of such prior art pumps.

Further, pump 1 is clearly distinguished from that of the prior art pump illustrated in figure 3, the spiral ele¬ ment 20 of which is arranged between two rotors 21a and 21b, as opposed to the pump of the present invention which uses a rotor 5 having a helical vane 6 preferably formed integrally along its outer surface. This structure simplifies the manu¬ facture and assembly of pump 1 and ensures that the fluid flow will be propelled and directed by the helical vane 6 along the entirety of the helical path leading to outlet 4.

On the other hand, pump 1 is characterized by an ex¬ tremely low level of physical aggression to the pumped fluid, for which reason it can advantageously be used for the extracorporeal pumping of blood. In this case, pump 1 is used preferably in a disposable manner. Besides, it should be noted that the levels of hemolysis (descruction of blood elements by physical aggression) caused by pump 1 are particularly low, when compared with the roller pumps presently used for this purpose.

In addition, as already mentioned, pump 1 stands out by being "incompetent", since it virtually stops propelling fluid when the fluid outlet is blocked for any reason. In this regard it can be seen that there is a certain distance between the outer edge of helical vane 6 and the inner wall of housing 2.

Enhancing this feature, it should be noted that there is a certain distance between the vertex of rotor 5 and inlet 3 of housing 2, and between the base edge of rotor 5 and the inner wall of the base portion of housing 2. Thus, a com¬ pression chamber 11 and a decompression chamber 12 are respec¬ tively provided adjacent inlet 3 and outlet 4, the function of which is to conform the operating pattern of pump 1 to possi¬ ble variations of inlet and outlet flows, which could result from a decrease of the patient's capacity of absorption.

Additionally, it should be pointed out that the gen¬ eral structural conception of pump 1 of the present invention, mainly with regard its operation, is quite similar to that of the pumps of the prior art that have flared rotors. As a con- sequence, pump 1 may be used with the same peripheral equip¬ ment used at present for driving the prior art pumps.

Finally, it should be noted that the above-described pump is nothing more than a preferred embodiment of the pres¬ ent invention, the true scope of which being defined by the accompanying claims.

Claims

1- A pump particularly usable for pumping blood and biological fluids, comprising:

- a housing (2) having a flared inner compartment, a base disc (9), an axial fluid inlet (3) adjacent a vertex of said inner compartment, and a tangential fluid outlet (4) at a base portion of said inner compartment;

- a flared rotor (5) having a flared outer surface, said rotor (5) being coaxially arranged within said compart- ment and driveable by an external motor; and

- a support shaft (8), perpendicularly secured at the center of said base disc (9), about which said rotor (5) turns;

- characterized in that a helical vane (6) is pro- vided along a significant portion of said flared outer surface of said rotor (5) .

2- A pump in accordance with claim 1, characterized in that said vane (6) is integral with said rotor (5).

3- A pump in accordance with claim 1 or 2, further characterized by comprising an annular magnet (10) secured to a base of said rotor (5), said rotor being magnetically associable with said external motor.

4- A pump in accordance with claim 3, characterized in that said rotor (5) is rotatably associated with said sup- port shaft (8) through bearings (7).

5- A pump in accordance with claim 4, characterized in that the distance between a vertex of said flared rotor (5) and the inlet (3) and the distance between an outer edge of said base of said rotor (5) and an inner wall of said base portion of said inner compartment are greater than the dis¬ tance between the outer edge of the vane (6) and the inner wall of said inner compartment, thereby defining compression (11) and decompression (12) chambers respectively adjacent said vertex and said base portion of said inner compartment. 6- A pump in accordance with claim 5, characterized in that said vane (6) is perpendicular to the outer surface of said rotor (5) .

7- A pump in accordance with claim 5, characterized in that said vane (6) is perpendicular to support shaft (8).

AMENDED CLAIMS

[received by the International Bureau on 4 November 1992 (04.11.92); original claims 1-7 replaced by amended claims 1-7 (2 pages)]

- a housing (2) having a substantially frusto- conical wall portion defining therewithin a frusto-conical pumping chamber region; an inlet wall portion contiguous with a smaller diameter end of said frusto-conical wall portion and defining a compression chamber region (11); a fluid inlet (3) in said inlet wall portion, located substantially coaxially with respect to said frusto-conical wall portion; an outlet wall portion contiguous with a larger diameter end of the frusto-conical wall portion and defining a decompression cham¬ ber region (12) and a tangential fluid outlet (4); and an end wall portion (9) closing said decompression chamber region; and a rotor (5) mounted for rotation within said pumping chamber region, said rotor comprising a conical body portion having a conicity corresponding to that of said frusto-conical wall portion and a spiral vane (6) around said conical body portion and having a spiral radially outer edge defining a conical envelope of the same said conicity inwardly spaced from said frusto-conical wall portion.

2- A pump in accordance with claim 1, in which said vane (6) is integrally formed with said conical body portion of said rotor (5).

3- A pump in accordance with claim 1 or 2, in which said end wall portion comprises a base disc (9) and said rotor rotates on a support shaft (8) supported by said base disc.

4- A pump in accordance with claim 3, in which said support shaft (8) is mounted in fixed relationship with said base disc (9) and said rotor is supported on, and for rotation with respect to said shaft (8).

5- A pump in accordance with claim 4, including an annular magnet (10) secured to a base of said rotor whereby said rotor is magnetically associable with an external motor.

6- A pump in accordance with any one of claims 3 to 5, in which rotor (5) is rotatably associated with said sup¬ port shaft (8) through bearings (7). 7- A pump in accordance with any one of the preced¬ ing claims, in which a compression chamber is defined in said compression chamber region (11) and a decompression chamber is defined in said decompression chamber region (12) due to the fact that the distance between said spiral radially outer edge of said vane (6) and said frusto-conical wall portion is smaller than both the distance between the vertex of said con¬ ical rotor body (5) and said fluid inlet (3) and the distance between the outer edge of the larger diameter end of said rotor and said outlet wall portion .

STATEMENT UNDER ARTICLE 19

Bearing in mind all the art cited in the search re¬ port and in particular US 3,156,190, new claim 1 defines the geometry of the pump housing more precisely and includes lim¬ itations (spacing between the rotor vane and the pump housing and the formation of compression and decompression chambers) to ensure that the pump it is "incompetent" and suitable to pump blood. The remaining claims deal with dependent and pre¬ ferred features. The pump as claimed combines the features of vaneless "incompetent" pumps, such as found in US 4,037,984, with "competent" vane pumps, such as US 3,156,190, to produce an "incompetent" pump of considerable efficiency.