Pumps

This application is a continuation of U.S. application Ser. No. 18/560,367, filed on 10 Nov. 2023, which is a National Stage Application under 35 USC § 371 and claims the benefit of PCT Application No. PCT/EP2022/062908, filed on 12 May 2022, which claims priority to United Kingdom Patent Application No. 2106738.4, filed on 12 May 2021, all of which are hereby incorporated by reference in their entirety.

The invention relates to pumps.

It is known to provide a pump formed by a housing having an inlet and outlet for a fluid and containing a rotor provided with at least one surface recess that forms with the interior surface of the rotor a chamber that, on rotation of the rotor, conveys fluid from the inlet to the outlet. In order to prevent fluid passing from the outlet to the inlet, a flexible diaphragm is provided on or as part of the housing and is located between the inlet and the outlet. The diaphragm is urged into engagement with the rotor by a pressurising means, which can take many forms such as a block of resilient material, a resilient tube of material, a spring or hydraulic or pneumatic pressure. Pumps of this general kind are disclosed in International patent application number WO2006/027548. Since such pumps comprise a discrete number of chambers formed by recesses in the rotor surface conveying fluid from an inlet to an outlet, the resulting liquid flow tends to be pulsated, with periods of no flow and periods of high flow. This can be detrimental in some applications, for example, in administering medicine to a patient, where a pulsating flow can be uncomfortable. It is an object of the present invention to provide a pump with improved flow profile.

Attempts have been made to reduce pulsing of fluid flow in pumps such as the rotary infusion pump described in International patent application number WO2011/119464. This document discloses a pump having a housing containing a rotor, wherein the rotor includes a first ring of surfaces that form channels with the housing and a second ring of surfaces that form channels with the housing. The first and second rings being radially offset to dampen pulsing of the flow of fluid through the pump.

In addition, prior art pumps, such as that described in WO2006/027548, have limited design options for location of the inlet and outlet ports and the diameter, or cross-sectional area of these ports. It is another objective of the present invention to provide a pump with improved design flexibility.

Furthermore, it is important to be able to sterilise pumps in many applications, in order that they may be reused. It is an objective of the present invention to provide a pump which can be more easily sterilised.

It is an objective of preferred embodiments of the present invention to provide a rotary pump providing essentially continuous flow. Continuous flow as used herein is defined as a flow where there are no periods of no fluid flow. Continuous flow does not necessarily mean that there is a constant flow rate, there may be some variation in flow rate provided there is always a positive flow of fluid while the pump is operational and supplied with fluid.

Aspects of the invention described herein may be useful alone or in combination with another aspect described herein.

According to a first aspect of the present invention, there is provided a pump comprising, a first fluid port and a second fluid port, a housing having an interior surface defining a cavity in which a rotor is located, a rotor, being rotatably mounted within the housing and having a longitudinal axis of rotation, and comprising, a housing engaging surface area forming a sealing interference fit with the interior surface of the housing, and at least one surface recess that forms with said interior surface of the housing a fluid-conveying chamber that, on rotation of the rotor, conveys fluid from the first fluid port to the second fluid port, a resiliently deformable diaphragm providing part of the interior surface of the housing, the diaphragm comprising a rotor engaging surface and a rear surface opposite the rotor engaging surface, the rotor engaging surface of the diaphragm being urged into contact with the rotor by the action of a pressurising means acting on the rear surface of the diaphragm, a pair of flow channels being associated with the resiliently deformable diaphragm, the flow channels extending longitudinally from opposite ends of the rotor to overlie the surface recess of the rotor as the rotor rotates in use, the pair of flow channels comprising a first flow channel in fluid communication with the first fluid port and being closed to the second fluid port and a second flow channel being closed to the first fluid port and being in fluid communication with the second fluid port, with each flow channel being located at opposite sides of the diaphragm.

According to second aspect of the invention, there is provided a pump comprising, a first fluid port and a second fluid port, a housing having an interior surface defining a cavity in which a rotor is located, a rotor, being rotatably mounted within the housing and having a longitudinal axis of rotation, and comprising, a housing engaging surface area forming a sealing interference fit with the interior surface of the housing, and at least one surface recess that forms with said interior surface of the housing a fluid-conveying chamber that, on rotation of the rotor, conveys fluid from the first fluid port to the second fluid port, a resiliently deformable diaphragm providing part of the interior surface of the housing, the diaphragm comprising a rotor engaging surface and a rear surface opposite the rotor engaging surface, the rotor engaging surface of the diaphragm being urged into contact with the rotor by the action of a pressurising means acting on the rear surface of the diaphragm, a flow channel being associated with a leading edge of the resiliently deformable diaphragm, the flow channel extending longitudinally from one end of the rotor to overlie the surface recess of the rotor as the rotor rotates in use, the flow channel being in fluid communication with the first fluid port, and an aperture opening from the interior surface of the housing and being associated with the following edge of the resiliently deformable diaphragm and located to overlie the surface recess of the rotor as the rotor rotates in use, such that upon rotation of the rotor the second fluid port is in direct fluid flow communication with the fluid-conveying chamber via the aperture.

Suitably, in all aspects of the invention the housing comprises a resilient material, for example, polypropylene, polyethylene, thermoplastic polyurethane or rubber. The first fluid port and/or the second fluid port may extend from the housing. If the first fluid port and/or the second fluid port extend from the housing, the first and/or second fluid port are suitably moulded as a unit with the housing.

The rotor may be made from a rigid material such as stainless steel, polyether ether ketone (PEEK), HDPE or polycarbonate. The choice of material of the housing and rotor are interdependent and should be chosen such that they exhibit a low coefficient of friction at the contacting surfaces.

According to all aspects of the invention, the housing may comprise a single unit providing the interior surface defining the cavity in which the rotor is located, the first fluid port and the second fluid port and optionally the resiliently deformable diaphragm. Alternatively, the housing may provide the interior surface defining the cavity in which the rotor is located, and optionally the resiliently deformable diaphragm, and may be used with first and/or second separate end caps to close the cavity in which the rotor is located. In this embodiment, the first and/or second fluid port may be provided in the housing or in a separate end cap.

A pump according to all aspects of the present invention may comprise one resiliently deformable diaphragm.

Alternatively, a pump according to the first aspect of the present invention may comprise a plurality of resiliently deformable diaphragms. For example, a pump according to the first aspect of the present invention may comprise two resiliently deformable diaphragms. Alternatively, a pump according to the first aspect of the present invention may comprise three resiliently deformable diaphragms. If the pump comprises a plurality of resiliently deformable diaphragms, they are preferably equidistantly arranged about the circumference of the rotor.

In one embodiment of the first aspect of the present invention, the pump comprises two diaphragms, which are located on diametrically opposite sides of the rotor. In an alternative embodiment of the first aspect of the present invention, the pump comprises three diaphragms, which are equidistantly spaced about the circumference of the rotor.

In all aspects of the invention, the or each resiliently deformable diaphragm comprises sides, which sides are the edges of the diaphragm that extend from one end of the cavity in which the rotor is located to the other end of the cavity. In other words, the side edges are longitudinal edges of the diaphragm that extend essentially in the same direction of the longitudinal axis of rotation of the rotor. The sides of the diaphragm may be straight or curved. The or each diaphragm has a leading edge and a following edge, which are determined by the direction of rotation of the rotor in use.

In all aspects of the invention, the resiliently deformable diaphragm may be provided by a section of the housing manufactured to a sufficiently small thickness to have the required deformable resilience. For example, the resiliently deformable diaphragm is provided by a section of the housing that is no more than 1 mm, suitably no more than 0.5 mm and in some embodiments less than 0.1 mm thick. In this embodiment, the housing is preferably made from a resilient thermoplastic or thermoset material and the resiliently deformable diaphragm is unitary with the housing.

Alternatively, in all aspects of the invention the resiliently deformable diaphragm may comprise a section of resiliently deformable elastomeric material which is hermetically attached to or co-moulded with the housing. The separate diaphragm should be attached to the housing so as to create a continuous rotor engaging surface as the interior surface of the housing. If the resiliently deformable diaphragm is a separate elastomeric material, it suitably comprises a thermoplastic elastomer (TPE), or a thermoplastic polyurethane (TPU). If the diaphragm is provided by a separate resiliently deformable elastomeric material, the housing may comprise a resilient material, for example, polypropylene, polyethylene, thermoplastic polyurethane or rubber or the housing could be made of a rigid material.

In use, according to all aspects of the invention, the diaphragm or plurality of diaphragms is operable to prevent direct fluid communication between the first fluid port and the second fluid port, as a result of a fluid-tight contact between the rotor-engaging surface of the diaphragm and the rotor surface. Furthermore, the resiliently deformable nature of the one or plurality of diaphragms means that each diaphragm flexes with the contoured surface of the rotor, such that, in use, the one of more diaphragms are operable to ensure each fluid-conveying chamber is emptied as the rotor rotates.

In all aspects of the invention, the resiliently deformable diaphragm may comprise a rib on the rear surface. Alternatively, a rib may be provided on a spring means providing the pressurising means, arranged such that in use the rib acts on the rear surface of the diaphragm. Suitably, the rib extends along the full length of the diaphragm in a direction parallel to the longitudinal axis of rotation of the rotor.

In all aspects of the invention, any suitable pressurising means may be used to urge the rotor engaging surface of each diaphragm into contact with the rotor. The pressurising means may comprise a spring means acting on the rear surface of the resiliently deformable diaphragm. For example, a pressurising means may comprise a block or tube of resilient material, to which pressure may be applied to urge the spring means against the rear surface of the resiliently deformable diaphragm. Examples of suitable spring members are disclosed in International patent application number WO2013/117486. Alternatively, or in addition, the pressurising means may comprise a fluid applied to the rear surface of the resiliently deformable diaphragm. Examples of pumps comprising fluid applied to the rear surface of the resiliently deformable diaphragm are disclosed in International patent application numbers WO2010/122299 and WO 2014/135563.

In an embodiment of all aspects of the invention, a pump according to the invention may comprise a diaphragm chamber surrounding the rear surface of a resiliently deformable diaphragm.

In all aspects of the invention, the diaphragm chamber may be provided by walls extending from the housing and suitably a separate cap to close the chamber. Alternatively, the diaphragm chamber may comprise a separate unit that is attached to the housing. The diaphragm chamber suitably houses the pressurising means arranged to urge the resiliently deformable diaphragm against the rotor. Each diaphragm chamber may comprise either an open chamber or a closed chamber for locating the pressurising means. The closed chamber may be hermetically sealed.

In all aspects of the invention, the diaphragm chamber may be a closed chamber connected by a passage to the fluid flowing through the pump, such that fluid flowing through the pump provides the pressurising means. The passage providing fluid to the diaphragm chamber may comprise a one-way valve, allowing fluid to flow into the diaphragm chamber, but not out. This one-way valve arrangement allows for sustained pressure on the diaphragm even if the direction of flow of the pump is reversed.

Alternatively, in all aspects of the invention, the diaphragm chamber may be a closed chamber connected by a passage to a separate fluid source, which separate fluid source provides the pressurising means.

In all aspects of the invention, the second fluid port may extend from the diaphragm chamber. Furthermore, if the diaphragm comprises a separate cap to close the chamber, the second fluid port may extend from the cap.

In one embodiment a diaphragm chamber surrounds only one resiliently deformable diaphragm. If the pump comprises more than one diaphragm, an individual diaphragm chamber may surround the rear surface of each of the one or more resiliently deformable diaphragms.

In an alternative embodiment of the first aspect of the invention, comprising a plurality of resiliently deformable diaphragms, the diaphragm chambers may be inter-connected. The plurality of diaphragm chambers may be interconnected by providing a fluid channel between the chambers. This is particularly useful if the second fluid port of the pump extends from the diaphragm chamber and/or if fluid from the first or second chamber provides the pressurising means.

Suitably, in a pump according to the second aspect of the invention, the aperture is formed in the interior surface of the housing adjacent the following edge of the resiliently deformable diaphragm and located to overlie the surface recess of the rotor as the rotor rotates in use. Alternatively, in a pump according to the second aspect of the invention, the aperture is formed in the diaphragm, adjacent the following edge and located to overlie the surface recess of the rotor as the rotor rotates in use. In a further alternative, in a pump according to the second aspect of the invention, the aperture is formed partially in the diaphragm and partially in the interior surface of the housing across the following edge of the diaphragm and located to overlie the surface recess of the rotor as the rotor rotates in use.

The second fluid port is in fluid flow communication with the aperture. In embodiments of a pump according to the second aspect, the aperture may be provided by the second fluid port.

Suitably, in all aspects of the invention, each flow channel comprises a longitudinal channel with an open channel surface and is open at one end and closed at the other end. The open channel surface is coterminous with the surface of the rotor in use, and is in fluid flow communication with the surface of the rotor. Each flow channel may have the same width along the full length thereof. Alternatively, each flow channel, or one or both flow channel in each pair, may taper along the length thereof. If a flow channel is tapered it is suitably at its widest at the open end and at its narrowest at the closed end.

Preferably, in a pump according to the first aspect of the invention, the flow channels in a pair are substantially parallel to each other. If the pump comprises a plurality of pairs of flow channels, it is preferred that all of the flow channels are arranged substantially parallel to one another.

Suitably, in all aspects of the invention, the or each flow channel is linear and orientated to be substantially parallel to the axis of rotation of the rotor. Alternatively, in all aspects of the invention, the or each flow channel may be orientated helically about the longitudinal axis of rotation of the rotor. In the event that the pump comprises a plurality of flow channels, and they are oriented helically about the longitudinal axis of rotation of the rotor, the flow channels are preferably all parallel to one another.

In embodiments of a pump according to the first aspect of the invention, comprising a plurality of resiliently deformable diaphragms a pair of flow channels is associated with each resiliently deformable diaphragm. In embodiments of a pump according to the first aspect of the invention, comprising a plurality of resiliently deformable diaphragms and therefore a plurality of pairs of flow channels, the first and second flow channels are arranged alternately about the circumference of the rotor.

In all aspects of the invention the flow channels may be formed in the interior surface of the housing that defines the chamber in which the rotor is located. In one embodiment of all aspects of the invention, each flow channel or pair of flow channels is provided by recessed channels in the interior surface of the housing.

Alternatively, in all aspects of the invention each flow channel or pair of flow channels are formed in the rotor engaging surface of the diaphragm. In an embodiment of the invention, each flow channel or pair of flow channels is provided by recessed channels in the rotor engaging surface of the diaphragm.

In a preferred embodiment of all aspects of the invention, each flow channel is provided by a channel extending longitudinally along the length of the diaphragm, substantially parallel to the axis of rotation of the rotor, with one longitudinal edge of each channel being defined by the interior surface of the housing and the other longitudinal edge of each channel being defined by the diaphragm.

In the first aspect of the invention the flow channels are axially arranged substantially parallel to the longitudinal axis of rotation of the rotor and are preferably located at opposite side edges of the diaphragm.

The flow channels are formed in the interior surface of the housing defining the cavity in which the rotor is located and/or in the rotor engaging surface of the resiliently deformable diaphragm. In embodiments of the invention where there is more than one flow channel, the plurality of flow channels are circumferentially spaced about the cavity in which the rotor is located.

In all aspects of the invention, the flow channels extend from an end of the rotor to overlie the surface recess of the rotor, and thus the fluid-conveying chamber, as the rotor rotates. The flow channels may extend along substantially the full length of the fluid-conveying chamber formed by the surface recess on the rotor and the interior surface of the housing, providing in the first aspect of the invention, the first flow channel is closed to the second fluid port and the second flow channel is closed to the first fluid port, and provided in the second aspect of the invention, the flow channel is closed to the aperture and it thus not in direct fluid flow connection with the second fluid port.

In all aspects of the invention, each of the flow channels suitably extends along essentially the full length of the diaphragm, providing in the first aspect of the invention, the first flow channel is closed to the second fluid port and the second flow channel is closed to the first fluid port, and provided in the second aspect of the invention, the flow channel is closed to the aperture and it thus not in direct fluid flow connection with the second fluid port.

In a pump according to the first aspect of the invention, since each first flow channel is in fluid communication with the first fluid port and is closed to the second fluid port and each second flow channel is closed to the first fluid port and is in fluid communication with the second fluid port, each flow channel extends from one end of the rotor, but is closed at the other end before reaching the opposite end of the rotor.

In a pump according to the second aspect of the invention, the flow channel is in fluid communication with the first fluid port and is closed at the end of the recess distal the first fluid port such that the flow channel is closed to the aperture.

In a pump according to the first aspect of the invention, each flow channel in a pair is closed at opposite ends. Each of the first flow channels is closed to the second fluid port, such that it is not in direct fluid flow communication with the second fluid port, and each of the second flow channels is closed to the first fluid port, such that it is not in direct fluid flow communication with the first fluid port. In each pair of flow channels, the open end of the first flow channel is in direct fluid flow communication with the first fluid port and the open end of the second flow channel is in direct fluid flow communication with the second fluid port.

If a pump according to the first aspect of the invention comprises more than one pair of flow channels, then the open end of each of the first channels in all of the pairs of flow channels would be in direct fluid flow communication with the first fluid port and the open end of each of the second channels in all of the pairs of flow channels would be in direct fluid flow communication with the second fluid port. Furthermore, none of the second flow channels would be in direct fluid flow communication with the first fluid port and none of the first flow channels would be in direct fluid flow communication with the second fluid port.

In a preferred embodiment of the first aspect of the invention, the pump may comprise a first chamber, a second chamber or a first chamber and a second chamber. Suitably, the first chamber and the second chamber are formed between the interior surface of the housing and the rotor, and are located at opposite ends of the rotor. The first fluid port is suitably in fluid flow communication with the first chamber and the second chamber is suitably in fluid flow communication with the second fluid port. Suitably, the first channel of each pair of flow channels is in direct fluid flow communication with the first chamber, such that in use, fluid flows in through the first fluid port, into the first chamber and from there into the one or more first channels. Suitably, the second channels of each pair of flow channels are in direct fluid flow communication with the second chamber, such that in use, fluid flows from the one or more second channels, into the second chamber and then towards the second fluid port.

The presence of a first chamber advantageously means that a single first fluid port can supply multiple first flow channels. The presence of a second chamber advantageously means that multiple second flow channels can be combined into a single flow stream towards the second fluid port. Furthermore, the presence of a first and/or second chamber has the advantage of allowing greater flexibility of the location of the first fluid port and/or second fluid port on the pump.

The second chamber may be in fluid flow communication with a diaphragm chamber. Furthermore, the diaphragm chamber may be in fluid flow communication with the second fluid port. In this latter case, the fluid flows from the second chamber to the second fluid port via the diaphragm chamber. In an embodiment of the invention, the second chamber is connected to all of the diaphragm chambers.

In an embodiment of the first aspect of the present invention, the second chamber may be provided by a diaphragm chamber. The diaphragm chamber may comprise the second fluid port.