DK171584B1 - displacement pump - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a displacement pump of the kind set forth in the preamble of claim 1.

Most displacement pumps - that is, pumps having a variable pump chamber comprising a movable displacement element - take in and deliver the liquid through ports that open to the chamber through a non-movable chamber wall. The inlet and outlet ports usually have one-way valves, such as ball check valves or flap valves. Due to limited space for these ports and the fact that the limiting factor for pump capacity is usually the piping to and from the pump and not in the pump itself, the inlet and outlet ports are relatively small. The small sizes of the gates limit the inlet and outlet flow rates, provide pulsed approach and exit and consume energy in the form of dynamic fluid friction and turbulence loss. The relatively small size of the inlet ports in most pumps also requires a relatively large pressure difference between the inlet and the pump chamber to ensure filling during the suction stroke.

The inventor of the present invention has done considerable work over several years on the development of blood pumps to replace or supplement the anatomical heart by pumping blood through the blood vessel system. Several properties of blood pumps that are not easy to meet are required. First, it is desirable for a mechanical blood pump to be able to suck blood substantially continuously, preferably with a minimum of pulsation. Second, a mechanical blood pump must have the ability to automatically adjust its discharge rate in relation to changes in the approach over a fairly large area. Third, as far as possible, a blood pump including the valves should be free of "dead compartments", compartments where there is little or no flow and where blood can be pooled and clumps formed; the blood must be kept moving through the pump at all times. Fourth, a blood pump should be sterile and free of toxic material when put into use, and should be persistent for as long as it is in use.

5

Mechanical blood pumps for temporary use, such as during heart surgery or to assist a damaged heart for a short while while healing, are increasingly being used.

The mechanical heart pumps currently in use only cater for 10 partially the recognized need. For example, they have little ability to automatically adjust to changes in the body's need for blood and instead need to be carefully monitored and controlled. Current mechanical blood pumping systems require a relatively large amount of the patient's blood to flow around the body, and an amount of blood similar to that flowing around the body, which is not desirable.

Lundbåck U.S. Patent No. 4,648,877 (March 10, 1987) discloses and discloses a blood pump which very effectively meets the above mentioned requirements. The pump of this patent has a supply chamber (atrium) and a pump chamber (ventriculus) connected to a short duct containing a one-way s valve. The chambers are made of a flexible, mostly non-stretchable material and can be made relatively inexpensively and thus can be replaced in case of use for various extracorporeal patients. A drive ring is driven in one direction to decrease the volume of the pumping chamber, that is, to pump blood from the pumping chamber and is moved in the opposite direction for sucking in blood in response to inflow of blood from the supplying chamber. The design of the pump according to the Lundbåck patent is such that there are no dead spaces where the flow is quiet and where the blood can collect and form solidified lumps. While flow restrictions are minimized, the pump has three relatively small ports, two of which have one-way valves.

The patent specification DE-C-875 142 discloses an air-pressure operated fuel pump comprising means defining a supply chamber for receiving the fluid to be pumped, means defining a variable volume pumping chamber, an access passage through the fluid being conducted from the supply chamber to the pump chamber, an outlet through which the fluid is discharged from the pump chamber, a displacement membrane connected to the pump chamber and movable in opposite directions so that the membrane moves through a variable displacement zone in the pump chamber to alternately increase and decrease the volume of the pump chamber; an inlet valve member for closing the inlet passage to block fluid return flow out of the pump chamber through the inlet passage. The supply chamber surrounds the pump chamber.

This pump, which is particularly suitable for introduction into a liquid body inside a reservoir or other vessel for emptying it, has a fixed volume supply chamber. As a result, the supply chamber contains a constant volume of the liquid to be pumped, so that the pumping chamber can only be filled as quickly as allowed by the inflow to the supply chamber.

Furthermore, all the fluid contained in the supply chamber and in any conduit through which the supply chamber is filled, must be accelerated and decelerated in each pump stroke.

Therefore, the pump known from DE-C-875 142 has all the limitations and disadvantages listed initially.

Brief Description of the Invention

The object of the present invention is to provide a throttle pump in which the pressure loss in the pump supply is minimized, thereby ensuring rapid flow to the pump chamber even with a low differential pressure over the access to the pump chamber while minimizing pulsation in the flow prior to the pump. , both when the inlet is closed (back pressure pulse) 35 and when it is open (induction pulse). In this connection, it is desirable to use one-way valves which are able to close reliably without having to be exposed and DK 171584 B1 4 without causing backflow, so that shocks resulting from backflow are avoided.

According to the invention, the object is achieved by arranging the displacement pump initially stated in the manner described in the characterizing part of claim 1.

According to the present invention, the supply chamber is disposed mainly adjacent to and substantially surrounds the displacement zone of the pump chamber, and the inlet passage is substantially the same as the supply chamber and opens against the pump chamber through an elongated slot-like opening in a restriction wall of the pump chamber adjacent to the displacement zone. whereby fluid can enter the pump chamber through the inlet passage substantially without pressure drop. Preferably, the pump chamber comprises a movable wall element which the displacer element can contact during the delivery stroke and which can exit contact with the displacer element during the suction stroke, such that the stroke volume of the pump is determined by the flow 20 of fluid through the inlet passage. It is usually advantageous to make the pump chamber substantially round (circular or oval) with a diameter substantially greater than the height.

In one embodiment of the invention, a wall of the pumping chamber which extends across the direction of movement of the displacement member is formed of a flexible material and is contacted and deflected by the displacement member through the displacement zone to decrease the volume of the chamber. A wall in the inlet passage may also be of flexible material and preferably be integral with the transverse wall of the pump chamber. One form of the inlet valve comprises a movable clamping valve element which contacts and moves the flexible wall at the inlet passage across to contact the opposite wall or with a flap valve, thereby closing the opening. Alternatively, the inlet valve may be a flap of flexible material connected to one of its edges to a wall of the inlet passage and with its other end free so that it responds to fluid flow and / or pressure by opening DK 171584 B1 5 at the suction stroke and closing of the pump chamber. at the pump stroke by contacting the second wall of the passage or by contacting a similar flexible flap attached to the second wall of the access passage.

In some embodiments, the pump chamber has a discharge in the form of a port, and a discharge valve in the discharge port uses the flexible pump chamber wall and a movable valve member which displaces the movable wall to contact the discharge port and thereby closes it. Other types of valves, such as flap valves, can be used at the exit of the pump chamber. It is also possible to completely omit the discharge valve.

Advantageously, the supply chamber, the inlet passage 15 and the pumping chamber are bounded by two flexible material blades supported by such rigid support members as are necessary to support the weight and resist forces due to pressure. The material sheets are preformed to determine the walls of the pump chamber, supply chamber, and inlet passage and are assembled so that they are 20 dense relative to one another along their outer circumference. The rigid supporting members determine the shapes at the maximum volume of the chamber and shape the inlet opening to the pump chamber.

The preferred annular and circular shapes of the supply chamber and pump chamber enable deflection of the flexible wall of the pump chamber with a minimum of wrinkles and allow uniform fluid flow radially into the pump chamber. With a outlet located axially opposite the displacement element, uniform flow is first ensured radially and then axially. In the circular form, the flow through the pump occurs at low turbulence levels but at relatively high speeds with no stationary areas.

Embodiments of the invention include embodiments having a second-stage variable volume chamber which receives fluid from the pump chamber during its delivery stroke. Part of the DK 171584 B1 6 fluid supplied by the pump chamber during its delivery layer passes through the second-stage chamber to a discharge passage, while the remainder is initiated during the second-stage suction stroke, which preferably operates in a counter phase relative to the pump chamber. In this way, fluid is discharged substantially continuously from the pump, that is, during both the suction and delivery stroke of the second stage, and pulsations in the discharge stream are reduced.

The preferred chamber element - preformed sheets of flexible material joined tightly to each other at their perimeter - can be manufactured at low cost and is easy to assemble into a support structure. Therefore, it is economically and practically advantageous for the chamber element to be a disposable component. For a better understanding of the invention, reference is made to the following description of exemplary embodiments, reference being made to the figures of the accompanying drawings.

Description of the Drawings 20

FIG. 1A-7A are schematic sectional views of seven configurations of one-stage pumps shown in the position below the suction stroke, FIG. 1B-7B are schematic sectional views of the respective embodiments of FIG. 1A-7A shown during the delivery stroke; FIG. 6C is a plan view of the chamber element of the embodiment of FIG. 6A and 6B; FIG. 7C is a schematic sectional view of the embodiment of FIG. 7A and 7B at the end of the suction stroke; FIG. 8A and 8B are schematic sections in a two-stage pump according to the invention during various working steps; FIG. 9A and 9B are sections as in FIG. 8A and 8B, showing a two-stage two-stage pump;

FIG. 10A and 10B are schematic sectional views of a further two-stage pump according to the invention during various 5 working steps, similar to the steps shown in FIG. 8A, 9A

8B, 9B and FIG. 10C is a plan view of the chamber element of the embodiment of FIG. 10A, 10B.

10

Corresponding parts in all designs are denoted by the same reference number followed by a hyphen (-) and a number after the hyphen corresponding to the figure number, which makes the whole number signifying the particular design.

15

Description of the embodiments.

In all of the embodiments shown in the drawings, the surfaces which come into contact with the liquid being pumped are surfaces of a disk-shaped, substantially circular or partially circular single-chamber element with an approach and outlet made of a flexible but within the essential non-stretchable material, such as polyethylene, polyurethane or another plastic film.

However, in other designs not described, some or all of these surfaces may be surfaces of stationary or movable pumping elements of, for example, metal, which are permanent parts of the pump. Also, the chamber element need not be circular.

30 As shown in FIG. 1A, 1B, the pump has a housing consisting of a fixed bottom member 10-1 and a movable or hinged cover member 11-1. The disc-shaped chamber member is designated 12-1 and is disposed between the base member and the cover member. At the perimeter, the chamber element 12-1 has an inlet connection 13-1 and on the center it has an upright axial outlet connection 14-1.

The element 12-1 has an annular supply chamber 15-1 into DK 171584 B1 8 which opens the access connection 13-1. Inside the supply chamber there is a pump chamber 16-1 which, along its limiting side wall, communicates with the supply chamber 15-1 through an inlet passage 17-1 in the form of an annular endless, slot-like opening between the opposing element walls. The pump chamber 16-1 communicates with the outlet connection 14-1 in the middle through an outlet passage 18-1 which is also formed by an endless annular gap.

The element 12-1 may be made of any flexible material which possesses the properties required by the pump in each particular case. Of course, the material must be compatible with the fluid to be pumped and be sufficiently flexible, durable and difficult to stretch to withstand the pressure and mechanical and, as the case may be, the thermal stresses it is subjected to.

The base element 10-1 of the housing carries various movable components on which the element 12-1 rests and which causes the pumping 20 by their repeated or cyclic movements. These components consist of a central valve outlet member 20-1 which serves to open and close the outlet passage 18-1 to allow flow between the pump chamber 16-1 and the outlet connection 14-1. The outlet valve element is movable vertically parallel to the central axis 21-1 of the pump, so that, by its upward movement, the opposite wall elements clamp against the cover element (11-1) of the pump, thereby closing the outlet passage 18-1, and allowing its element walls to down, in its downward movement, move apart to open the exit passage. The movement of the outlet valve element 30 is derived from an arm 22-1, which in turn is actuated by a cam or other suitable drive means (not shown) and an associated motor.

There is also a squeezing inlet valve member 23-1, which acts in a similar manner to the outlet valve member 22-1, for opening and closing the inlet passage 17-1. The supply valve element 23-1 is annular, and the up and down movement is derived from an arm 24-1, which in turn is activated synchronously with the arm 22-1 by a motor driven cam (not shown).

Between the valve elements 20-1 and 23-1 and opposite the pump chamber 5 16-1 there is an annular displacement element 25-1 which is moved vertically up and down by an arm 26-1 and a motor driven cam (not shown) in a similar manner to the valve elements and synchronously with these. The displacement element 25-1 serves, in its upward movement, to positively displace the lower pump chamber 10, thereby reducing the volume of the pump chamber 16-1 and, in its downward movement, to allow the pump chamber to expand as the liquid flows into the pump chamber.

In the embodiment of FIG. 1A and 1B there are also a pair of rollers 27-1, 15 located below and in contact with the supply chamber 15-1 of the element 12-1. During operation of the pump, these rollers, which may be more than two in number, run around the circumference of the supply chamber by means not shown to keep all the liquid in the supply chamber in constant motion. Such movement of the fluid may be necessary or advantageous in certain applications, for example when the fluid is blood.

During operation of the pump, the supply chamber 15-1 acts as a reservoir, the volume of which changes depending on the inflow 25 and which constantly receives liquid under relatively low pressure through the inlet connection 13-1. In the phase of the pump cycle shown in FIG. 1A, where the inlet passage 17-1 is open and the displacement element 25-1 moves downward or has just reached its lowest position, liquid from the supply chamber 15-1 enters the pump chamber 16-1 through the inlet passage 17-1. Filling of the pump chamber can take place very quickly because the access passage is very long, that is, has a very large extent along the circumference and can easily be opened over a relatively high height. In other words, the access passage can be easily opened and present a very large cross-sectional area for the flow. Because the supply chamber and the inlet passage surround most or all of the pump chamber circumference, and liquid enters radially from all directions, the filling length, that is, the distance the fluid must flow to fill the pump chamber, is also short and straight. , whereby the flow into the pump chamber can take place very quickly and with 5 literally no pressure drop. Pumps with annular chambers can have very high performance and yet have short filling times due to the large area of the access passage and the short filling length.

Filling of the pump chamber 16-1 is essentially "passive" - it takes place mainly under the action of hydrostatic pressure in the supply chamber 15-1 at the inlet passage 17-1, for no suction is produced in the pump chamber as a direct result of the displacement element 25-1 downward movement; the displacement element has no power transmitting connection with the element 12-1, which is effective in the direction of expansion of the pump chamber (downwards).

It is within the scope of the invention to exert an influence 20 on the filling by allowing the pressure in a gas body surrounding the pump chamber to vary in a particular way during the pump cycle. It is also possible to exert influence on the filling by subjecting the inlet or supply chamber to an external pressure.

25 As shown in FIG. 1b, the inlet passage 17-1 is then closed by an upward movement of the inlet valve member 13-1, and the outlet passage 18-1 is opened by a downward movement of the valve member 20-1.

Then, the displacement element 25-1 is moved upwardly to displace the lower wall of the pumping chamber, thereby permitting the liquid in the pumping chamber 16-1 through the outlet passage 18-1 and the outlet connection 14-1. During this time, the supply chamber 15-1 is refilled from the inlet connection 13-1. The exit passage 18-1 is then closed, the displacement element 25-1 is retracted downwards, and the inlet passage 17-1 is reopened so that another pump cycle 35 can be completed.

A characteristic of the pump described in the combination of DK 171584 B1 11 is the annular inlet passage 17-1, the annular outlet passage 18-1 and the short filling length, which allows a very fast filling of the pump chamber, even when the pressure on the inlet side is very low. and a very quick emptying of the pum-5 storage chamber. The pump can therefore pump a large volume of liquid per unit. time unit with small internal losses and as a result with very high efficiency. As long as the inflow to the pump does not exceed the flow rate corresponding to the product of maximum stroke volume and stroke rate, the pump, by virtue of its self-regulation, adjusts the volume pumped in each stroke to the inflow. Within a fairly large range of inlet velocities through the inlet connection 13-1, the pump receives a continuous flow free of pressure pulses and interruptions. If the inflow should exceed the flow rate corresponding to the aforementioned product, the pump speed or stroke speed may be increased. Due to the small internal losses, the impact velocity can be raised to high levels.

Another characteristic of the described pump as well as of the pumps which will be described, and which contributes to the rapid filling of the pump chamber 16-1, is that the supply chamber 15-1 is given a volume capacity which is sufficiently large - preferably substantially larger than the pump chamber 16-1, to ensure filling of the pump chamber 16-1 without any substantial replenishment of the supply chamber 15-1 being necessary during the filling of the pump chamber. Thus, all the liquid entering the pump chamber 16-1 during the pumping phase of the pumping cycle is immediately prepared close to the inlet passage 17-1 when the filling phase begins.

30

The element 12-1 is arranged in the pump housing 10-1 / 11-1 in such a way that the supply chamber 15-1 can be expanded and contracted within wide limits depending on the supply of liquid to the supply chamber and the flow of liquid from the supply chamber to the pump chamber, respectively. 16-1.

The embodiment of FIG. 2A and 2B differ from that of FIG.

DK 171584 B1 12 1A and IB only in that the rollers 27-1 are omitted and the supply chamber 15-2 is open to the atmosphere. Therefore, the pressure under which the filling of the pump chamber 16-2 takes place is determined by the level difference between the inlet passage 17-2 and the free liquid surface in the supply chamber.

In the embodiment of FIG. 3A and 3B, the supply chamber 15-3 is opened as in FIG. 2A and 2B. Counter or one-way flap or shutter-type valves 23-3 and 20-3 are arranged in the inlet passage 17-10 3 and the outlet passage 18-3 respectively. As a result, in the first two embodiments, the movable clamping valve members are replaced by portions of the housing member 10-3 which carry the chamber member and delimit the passages 17-3 and 18-3. Each valve 23-3, 20-3 is formed of a pair of annular, axially opposed 15 flaps of flexible material (e.g., of plastic), which may also be slightly elastic if the outer edges are sealed securely (for example, by heat welding) to the respective opposite wall elements in the access passage 17-3, which can be freely deformed, allowing them to be displaced up and down at their inner edges.

As fluid flows inwardly into the inlet passage or in the outlet passage, the flaps are spaced apart without noticeably resisting the flow of liquid, but as soon as there is a tendency for the fluid to flow in the opposite direction, the flaps close the passage to block the flow. Although the flaps are resilient, their elasticity is not so great as to be unable to withstand the occurring pressures, and therefore there is no danger of the flap turning in the wrong direction. When the working pressure of the pump is high, the flaps can be reinforced with a suitable material, such as fiberglass to prevent them from reversing.

The flaps may be designed so that, thanks to their elasticity, initial shape or otherwise, they contribute to accelerating the flow of liquid when opened. Furthermore, they may be somewhat biased toward open or closed position.

In a modified embodiment not shown, one or both of the valves may combine a clamping valve of the type shown in FIG. 1 and 2 with flaps. In this case, the clamping valve is arranged to only partially close the passage, leaving a flap valve to complete the closure.

As shown in FIG. 3A and 3A, the flap valves are formed by a flap element independent of the chamber element walls. However, the flaps may advantageously also be formed by a fold in the blade or the clamping material from which the element is made, the formation of this fold taking place during the manufacture of the chamber element. The latter design can be made by known techniques for producing elements and other plastic objects (vacuum forming and blow molding). The same design can also be used in the designs described below.

The embodiment shown in FIG. 4A and 4B are similar to FIG. 1A and 1B, except that the discharge valve is in the form of a counter or 20-way flap or lip type one-way valve 20-4 disposed in the outlet connection 14-4 and the displacement member 25-4 is disc-shaped or plate-shaped (mushroom-shaped). ). In this case, the pump chamber 16-4 is disc-shaped in planar projection and not annular as in the previous designs. Furthermore, the outlet passage 25-18-4 (Fig. 4B) is formed near the end of the pump stroke, which is somewhat different in shape and function from the previous designs.

The embodiment shown in FIG. 5A and 5B differ from that of FIG. 4A 30 and 4B, in that the rollers for moving the liquid in the supply chamber 15-5 are omitted, the inlet valve 23-5 consists of a single annular flap of flexible material which is attached along its outer edge to the lower element wall and movable to a position in sealing contact with the top 35 element wall under the influence of pressure within the pump chamber 16-5, leaving the valve in the outlet duct.

DK 171584 B1 14

It has been found that a valve which closes to block back flow in the outlet duct is not necessary in certain cases, namely when the pump is operating at high stroke rates. In such cases, the energy in the outgoing liquid is sufficient to allow filling of pump chamber 16-5 through the inlet passage 17-5, even though the pump chamber is open on the discharge side during the inlet.

FIG. 6A, 6B show a configuration similar to that of FIG.

10A, 5B except with respect to the location and design of the aisle passage 18-6, the outlet connection 14-6 and the associated outlet valve 20-6.

In this case, the outlet connection 14-6 is radial and is located in diametrically opposite relation to the inlet connection 13-6. Accordingly, it has its countercurrent side at the periphery of the pumping chamber 16-6 and, like the inlet connection, extends radially outward. As a result, some, but only part, of the element's circumference is not used for the supply chamber 15-6 and the supply passage 17-6, but the latter can still be very long.

In this embodiment, the outlet valve 20-6 is a flap or lip as in the case of the inlet valve 26-3 and, like the last one, it is connected to a wall of the outlet passage 18-6 located at the connection point between the pump chamber 16-6 and the supply chamber 15-6. (see Fig. 6C which is a plan view of the chamber element).

It may be advantageous in the embodiment shown in FIG. 6A, 6B, 6C to block or close the area of supply chamber 15-6 adjacent to the outlet connection. The wall of the supply chamber must then be designed so that no pockets are formed in which the liquid being pumped can stand still or be forced to undergo abrupt changes in flow direction to reach the outlet passage.

DK 171584 B1 15

The outlet connection 14-6 of the embodiment of FIG. 6A, 6B, 6C do not necessarily have to be in line with the access connection but can form a larger or smaller angle relative thereto. If desired, the two connections can even be placed side 5 side by side and substantially parallel. However, it is essential that the inlet passage 17-6 and its valve extend over the majority of the pump chamber perimeter.

FIG. 7A, 7B, 7C show a configuration in which a portion of the annular supply chamber 15-7 is arranged closer to the center of the element than the gap-like inlet passage 17-7. In this case, the drive mechanism of the displacement member 25-7 is a screw-spindle mechanism with ball bearings - not shown in detail if the spindle has a pivotal connection with the rotor 28-15 7 in an electric motor located in the bottom member 10-7 of the pump housing.

As can be seen from a comparison of FIG. 7A, 7B, 7C with each other, the movement of the displacement element 25-7 in this embodiment has a direct influence on the shape 20 and volume of the supply chamber. As the displacement element moves downward ("falls") see FIG. 7A, the volume of the supply chamber is reduced because the displacement element causes the supply chamber to collapse, see FIG. 7C. The liquid in the supply chamber then flows into the pump chamber 16-7 together with the liquid which enters the pump through the inlet connection 13-7. As the displacement element is driven upwards thereby reducing the volume of the pump chamber, see fig. 7B, the supply chamber is enlarged and at the same time the inlet valve 23-7 is closed. The liquid entering through the inlet connection is taken up in the supply chamber 30 and then flows, during the downward movement of the displacement element, into the pump chamber, as described.

The embodiment shown in FIG. 7A, 7B, 7C also have a discharge valve 20-7 which prevents backflow to the pump chamber 16-7 from the outlet connection 14-7. As shown in the figures, the outlet connection is parallel to and arranged diametrically opposite the access connection, but other positions and orientations may be conceivable.

The outlet valve 20-7 is an annular flap valve whose one circumferential edge is connected to the upper member 10-7 of the pump housing and the other free circumferential edge is provided with a bead ring 29-7. This padding reinforces the free flap edge and enters the valve closed position (Fig. 7C) in sealing contact with the inner wall of the upper element 11-7. As an alternative to the illustrated discharge valve configuration, a spring loaded, vertically movable valve member may be used which seals against an annular wall portion where the pump chamber enters the horizontal discharge connection.

The supply valve 23-7 of the embodiment shown in FIG. 7A, 7B, 7C is also an annular flap valve which is attached to the displacement member and thus moves with it. This arrangement results in an advantageous movement pattern for the fluid flowing from the supply chamber into the pump chamber, but it is within the scope of the invention to attach the flap 20 to the pump housing and align it so that its movable member interacts with the displacement member.

As in the other illustrated and described embodiments in which the inlet valve is a lip or flap valve, the inlet passage 17-7 opens and allows flow into the pump chamber with a very small pressure drop as soon as the pressure on the countercurrent side of the valve exceeds the pressure on the co-flow side quite a bit. Similarly, the inlet passage is immediately closed when the pressure in the pump chamber exceeds the pressure on the countercurrent side of the valve quite a bit. The rapid opening and closing of the flap valve can be attributed to the annular configuration and the resulting large surface area of the valve at which the pressure acts. For the same reason, the outlet valve 20-7 and thus the outlet passage 18-7 are closed immediately when the pressure in the outlet connection 14-7 exceeds the pressure in the pump chamber at the beginning of the suction stroke.

DK 171584 B1 17

FIG. Figs. 8A, 8B show a pump in which there are two displacement members 25-8A, 25-8B which operate in the opposite phase to decrease the volumes of different sections of the pump chamber at different times.

5

One displacement element 25-8A is similar to the displacement element shown in FIG. 4-6 and serves to decrease the volume of a central second stage section 16A-8A which corresponds to the pumping chamber of FIG. 4-6 and communicates with a central 10 exit connection 14-8.

The second displacement element 25-8B is annular and concentric with the first central element. This annular outer member serves to decrease the volume of a variable volume annular outer pump chamber section 16-8B which is concentric to the central second stage variable volume chamber 16-8A.

At its radially inner side, the outer pump chamber section 16-8B communicates with the central second stage section 16-8A by means of an annular passage 30-8, in which a one-way flap valve 31-8 is similar to the flap valve of FIG. . 3 and 5 are arranged to open and allow flow into the pump chamber section 16-8A. This passage constitutes both an access passage to the central pump chamber section 16-8A and a discharge passage for the outer pump chamber section 16-8B.

At its radially inner side, the outer pump chamber section 16-8B communicates with an annular supply chamber 30 15-8 which is similar to the supply chamber of FIG. 2 and 3, by means of an annular inlet passage 17-8 with a one-way flap valve 23-8, which opens and allows flow into the outer pump chamber section 16-8B, which is also similar to the flap valve 23-3 and 23-5 in FIG. . 3 and 5.

The two displacement elements 25-8A and 25-8B are substantially activated in the opposite phase by mechanisms similar to the mechanisms used to activate the displacement element and the clamp valve of FIG. 4. The maximum volumes of the pump chamber sections and the movements of the two displacement elements are selected such that the stroke volume of the outer pump chamber section 16-8B 5 is approximately twice the stroke volume of the central pump chamber section 16-8A.

FIG. 8A shows a phase of the pump operating cycle in which the outer displacement element 25-8B moves downwardly and the outer pump chamber section 16-8B is filled from the supply chamber through the inlet passage 17-8 without any noticeable pressure drop over it, while the central second stage displacement element 25 -8A moves upward to force the liquid out of the second stage chamber section 16-8A, holding the valve 31-8 closed in the closed position by the pressure in the central chamber section.

In the phase shown in FIG. 8B the conditions are reversed. The outer displacement member 25-8B moves upwardly to force fluid out of the outer pump chamber section 16-8B into the central and second stage chamber section 16-8A through the passage 30-8, whereas the central displacement member 25-8A moves downwardly. and allowing the central chamber section 16-8A to expand under the influence of the pressure exerted by the liquid on its walls.

The fluid volume pushed out of the outer pump chamber section during the upward movement of the outer displacement member is greater than the increase in volume in the central second chamber section. Accordingly, liquid will be discharged through the outlet compound 14-8 also during this phase (Fig. 8B) of the pump's duty cycle. While inflow to the pump chamber takes place only in the phase in which the outer chamber section expands, the discharge from the pump is substantially continuous, albeit with some pulsation.

35 The embodiment shown in FIG. 9A, 9B are similar in structure and function to that shown in FIG. 8A, 8B, except that the externally driven mechanical for positive activation of the inner displacement element 25-9A in the upward direction is replaced with an adjustable spring mechanism 26-9A which constantly forces this displacement element upwards. During the upward stroke of the outer displacement element 29-9A, the central second stage displacement element 25-9A is moved downwardly under the influence of the fluid pressure within the central second stage section 16-9A, thereby compressing the spring mechanism 26-9A as shown in FIG. 9A. During the downward movement of the outer displacement element 26-9B, the energy stored in the spring mechanism moves the central displacement element upwards, as shown in FIG. 9A.

FIG. 10A, 10B are sections similar to FIG. 8A, 8B and 9A, 9B in a further embodiment of a two-stage pump according to the invention; and FIGS. 10C is a plan view of the chamber element of this embodiment.

The pump shown in FIG. 10A, 10B, 10C contain two displacement members 25-10A and 25-10B which operate as described in connection with FIGS. 9A, 9B. Thus, the displacement element 25-10B communicates with an externally driven drive mechanism to positively or substantially positively activate it in the upward direction, while the displacement element 25-10A is in communication with an adjustable spring mechanism 26-10A which constantly forces it upwards .

25

The two displacement members 25-10A and 25-10B and the associated pump chamber sections 16-10A and 16-10B in the chamber element 12-10 are horizontally offset relative to each other and the inlet valve 23-10 and the valve 31-10 between the pump chamber sections are 30 flap valves. the valves 23-6 and 20-6 of FIG. 6A, 6B, 6C. As shown in FIG. 10C, the inlet connection 13-10 and the outlet connection 14-10 are further arranged side by side and substantially parallel.

Apart from the different flow pattern resulting from the horizontally positioned placement of the chamber sections, the pump of FIG. 10A, 10B, 10C in substantially the same manner as the pump of FIG. 9A, 9B.

In the embodiments illustrated and described above as examples, the pumping chamber 16 and the supplying chamber 15 of the chamber element are circular or shaped as a circular ring, and as is immediately apparent, the mechanical pumping components have a similar shape. This form is usually preferred taking into account both fluid flow and manufacturing views, but it is within the scope of the invention that the pump may have a different configuration, such as more or less oval or otherwise elongated. An elongated configuration may be used, especially in the case shown in FIG. 6A, 6B, 6C where the inlet and outlet are aligned.

15 In the designs shown in FIG. 8A, 8B and FIG. 9A, 9B, the central displacement members 25-8A, 25-9A may further be annular as are the outer displacement members 25-8B, 25-9B.

The open space within the central annular displacement member may then, for example, occupy a portion of the pump drive mechanism or be used for other purposes. If the drive mechanism for the two displacement members 25-8A and 25-8B of FIG. 8A, 8B in such cases are designed so that the elements can be activated together with a selected phase shift (for example, in the counter phase or push-pull manner), or individually (only one of the parts are activated) as desired, interesting possibilities are offered to vary the pump characteristics in terms of stroke volume and discharge flow characteristics.

In some cases, for example, when the pump is used as a blood pump, the displacement element may be suitably connected to the pump mechanism so that an elastic resilience of the displacement element relative to the pump mechanism is possible under the pressure of the pump chamber so that there is some "backlog" of the displacement element during the pressure or delivery stroke. The movement of the displacement element lost in the introduction due to "backlog" is "recovered" at the end of the pressure stroke and can be utilized to ensure that the liquid DK 171584 B1 21 is not stationary in the pump chamber, that is under the valve flap 31-8 in FIG. 6A, 6B. Such an arrangement can also be utilized to suppress any pressure waves that tend to occur at the end of the delivery stroke.

5

A pump of the type shown in FIG. 8A, 8B with two or more displacement elements and pump chamber sections, which are preferably annular, are also useful as a two-stage (multi-stage) compressor, especially for the purpose of compressing large amounts of air 10 to a relatively low pressure. A feature of compressors built in this way is that only a single valve is required between the steps, each valve acting both as a discharge valve for a radially outer or lower stage and as an inlet valve for a radially inner or higher stage. The other designs are also useful as compressors or air pumps (or for other gases), but in practice they are supposed to be best as liquid pumps.

As can be seen from the drawings, a feature of the pump according to the invention is that the liquid being pumped has a favorable flow pattern because it can pass through the pump without being subjected to abrupt changes in direction. Particularly advantageous in this regard are the designs of FIG. 1-6 and 8-10, where the height of the pump chamber is very small in relation to the diameter and the liquid therefore flows substantially horizontally up to the outlet connection. The generally low or flat shape of the pump chamber also allows a short stroke, which means the stroke rate can be high. In connection with the large flow cross-section that the inlet and outlet passage can have, this ensures a very low internal flow resistance in the pump.

In the embodiments of FIG. 5-10, the use of single flap valves which are connected to the lower wall 35 of the chamber element 12 and which can be moved upwardly in the liquid-pushing direction of the displacement element to a position in sealing contact with the upper wall, is advantageous in that the liquid flow which advances DK 171584 B1 22 is brought by the displacement element, sweeping towards the underside of the flap. The sweeping flow minimizes the danger of a portion of the fluid being pumped standing still under or behind the valve flaps. As a result, these designs are particularly suitable for pumping blood, since they meet the very important requirement that the blood pump be free of stagnant fluid areas.

In the designs by means of which examples 10 of the invention are given in the drawings, the displacement element and its drive mechanism are located below the pump chamber. This location is preferred in most cases, especially when, as in the embodiments shown, a separate easily replaceable chamber member of plastic film or plate constitutes the surfaces which the pumped fluid contacts during its passage through the pump. However, in some cases it may be preferred that the displacement element constitutes or acts on the overflow of the pump chamber and that the drive mechanism is located above the pump chamber. Furthermore, it is conceivable to have a common drive mechanism for two oppositely styled pumps stacked on top of each other and working in a counter phase. It is also possible to have two drive mechanisms for a single pump chamber, a drive mechanism on each side that works opposite.

25 The chamber 16-10A and the spring loaded displacement member 25-10A in the embodiment of FIG. 10A, 10B, 10C may be used in conjunction with the outlets of single stage pumps of other construction as a one-way valve and as a device for smoothing pulsed outflow from the pump. In the case of blood pumps 30, such an arrangement provides a one-way valve which is free of stagnant areas and an adaptive volume in the flow after the valve.

Claims (26)

A displacement pump comprising means defining a supply chamber (15) for receiving the fluid to be pumped, means (12) defining a variable volume pumping chamber (16), an inlet passage (17) through which the fluid is passed from the supply chamber (15) to the pump chamber (16), an outlet (14) through which the fluid is discharged from the pump chamber, a displacement element (25) which is in communication with the pump chamber 10 (16) and is movable in opposite directions along a predetermined voice. path so as to pass through a variable displacement zone in the pump chamber (16) to alternately increase and decrease the volume of the pump chamber (16), drive means (22) to move the displacement element (25) in at least one direction 15 to reduce the pump chamber ( 16) volume, and an inlet valve member (23) for closing the inlet passage (13) to block fluid return flow out of the pump chamber (16) through the inlet passage (17), characterized in that The reservoir (15) is a reservoir capable of receiving 20 variable volumes of fluid to be pumped and is disposed substantially adjacent to and substantially surrounding the displacement zone of the pump chamber (16), and the inlet passage (17) has substantially the same extent as the supply chamber (15) and opens towards the pump chamber (16) through an elongate slot-like opening in a restriction wall of the pump chamber (16), which is mainly adjacent to the displacement zone, whereby fluid can enter from the supply chamber (15) in the pump chamber (16) through the inlet passage (17) substantially without pressure drop. 30 Pump according to claim 1, characterized in that the pump chamber (16) comprises a movable wall element, which can be contacted by the displacement element (25) after the delivery stroke and released from the displacement element during the suction stroke, so that the stroke volume of the pump is determined by the supply of fluid from the supply chamber ( 15). DK 171584 B1 24 Pump according to claim 1 or 2, characterized in that the pump chamber (16) is substantially round. Pump according to any one of claims 1-3, characterized in that the dimensions of the pump chamber (16) across the direction of movement of the displacement element (25) are substantially larger than the dimensions in this direction of movement. Pump according to any one of claims 1-4, characterized in that the outlet (14) is located substantially in the middle of a transverse stationary wall in the pump chamber (16) opposite the displacement element (25). Pump according to any one of claims 1-5, characterized in that the supply chamber (13) is arranged to receive a continuous flow of fluid being pumped and to dispense at least a portion of its contents into the pump chamber (16) through the inlet passage (17) when the inlet valve member (23) is open while collecting a reservoir of fluid when the inlet valve member is closed. Pump according to claim 2, characterized in that the movable wall element in the pump chamber (16) is formed of a flexible material and is deformed and displaced by the displacement element (25) during at least part of the delivery stroke of the pump. Pump according to claim 7, characterized in that the movable wall element forms part of the limiting wall of the pump chamber (16) and defines a wall in the inlet passage (17), wherein the valve means comprises a clamping valve element (23-1, 23). -2) which contacts the laterally limiting wall portion and is movable to move this limiting wall portion across the aperture thereby closing the access passage, and drive means 35 (24-1, 24-2) to periodically move the clamp valve member across the aperture. DK 171584 B1 25 Pump according to claim 3, characterized in that the inlet valve means comprises a substantially annular flap (23) of flexible material attached along one edge to a wall in the inlet passage (17) and with the other edge free for movement to a open position to allow the flow of fluid into the pump chamber (16) and to a closed position in contact with the second wall of the inlet passage to stop backflow of fluid from the pump chamber through the inlet passage. 10 Pump according to claim 3, characterized in that the inlet valve means (23-3) comprises a first annular flap of flexible material attached along one edge to a wall in the access passage (17-3) and a second annular flap of flexible material attached along one edge to the other wall of the inlet passage, both flaps having the other edge free to move to an open position to allow inflow of fluid to the pump chamber (16-3) and to a closed position in contact with each other to stopping flow of fluid from the pump chamber (16-3) through the inlet passage (17-3). Pump according to any one of claims 1-10, characterized in that the supply chamber (15) and the pump chamber (16) are delimited by a first and a second wall element which are spaced apart, of which at least one wall element is formed of flexible material and comprises a first portion which can be contacted and displaced by the displacement member (25) to vary the volume of the pump chamber (16), and a second portion constituting a wall in the inlet passage (17). Pump according to claim 11, characterized in that the valve member comprises a clamping valve element which contacts the other part of one wall element, drive means for cyclically bringing the clamping valve element only part of the way across the inlet passage, and a flexible valve valve strip connected DK 171584 B1. 26 to the second wall of the inlet passage and with a free edge movable to contact the other part of one wall element in response to fluid pressure in the pump chamber. Pump according to claim 11, characterized in that the lateral restriction wall in the pump chamber (16) is mainly round and the supply chamber (15) is mainly annular and completely surrounds the pump housing. Pump according to claim 11, characterized in that both the supply chamber (13-1, 13-2, 13-3) and the pump chamber (16-1, 16-2, 16-3) are annular and that the outlet from the pump chamber is an annular aperture (18-1, 18-2, 18-3) located within an internal constriction of the pump chamber mainly at the side of the displacement zone. Pump according to claim 14, characterized by one of the actuating valves, which comprises a movable valve element (20-1, 20-2) which contacts a third part of the flexible wall element, and drive means (22-1, 22- 2) to move the valve member back and forth to displace this third portion of the flexible wall into and out of contact with an opposite edge of the aisle opening (18-1, 18-2) to open and close it. Pump according to claim 11, characterized in that it is the lower of the overlying and spaced-apart wall elements which are flexible and that the pump further contains means (10, 27) to support an additional part of the flexible wall element. , which further portion constitutes the lower wall of the supply chamber (15). Pump according to claim 16, characterized in that the means for supporting the further part of the flexible wall element comprise one or more rollers (27-1, 27-4) and means for rotating the rollers in a circuit path along the supply chamber (15 -1, 15-4) to continuously keep the fluid in the supply chamber moving. DK 171584 B1 27 Pump according to claim 16, characterized in that the means for supporting the further part of the lower wall element is a rigid stationary element (10). Pump according to any one of claims 1-18, characterized in that there is a discharge valve means (20) in the outlet (14). Pump according to any one of claims 1-19, 10, characterized by a second-stage variable volume chamber (16-8A, 16-9A, 16-10A) at the outlet (14-8, 14-9 , 14-10) from the pump chamber (16-8A, 16-9B, 16-10B) to receive fluid derived from the pump chamber, a one-way valve (31-8, 31-9, 31-10) in the outlet of the pump chamber for blocking fluid backflow from the second stage chamber into the pump chamber, a discharge passage leading from the second stage chamber, a second stage displacement element (25-8A, 25-9A, 25-10A) movable to alternately increase and decrease the volume of the second stage chamber. and drive means (26-8A, 26-9A, 26-10A) 20 for moving the second stage displacement element in at least one direction to decrease the volume of the second stage chamber. Pump according to claim 20, characterized in that the drive means comprises an external energy source. 25 Pump according to claim 20, characterized in that the drive for the second stage displacement element is a spring which stores energy as the volume of the second stage chamber is increased by the flow of fluid from the pump chamber and releases the stored energy when there is no inflow from the pump chamber to the second stage chamber. Pump according to any one of claims 20-22, characterized in that the stroke volume of the pump chamber (16-8B, 16-9B, 16-10B) is about twice the second-stage chamber (16-8A, 16-9A). 16-10A) stroke volume. DK 171584 B1 28 Pump according to any one of claims 20-23, characterized in that the pump chamber (16-8B, 16-9B) is mainly annular and the second stage chamber (16-8A, 16-9A) is mainly round and is located mainly at the side of and surrounded by the pump chamber. Pump according to any one of claims 20-24, characterized in that the supply chamber (15-10) is mainly annular, the pump chamber (16-10B) is substantially round, the outlet is a passage leading into it. substantially laterally from the pumping chamber, and the second stage chamber (16-10A) is substantially round and located adjacent to and close to the pumping chamber. Pump according to any one of claims 1-25, characterized in that the volume capacity of the supply chamber (15) is at least as large as the volume capacity of the pump chamber (16).