Infusion device comprising a wobbling device for acting onto a pump module

An infusion device (3) comprises a housing element (30) having a receptacle (301) for receiving a pump module (1), and a pump actuation mechanism (2) having a wobbling device (20) arranged on the housing element (30) and a drive shaft (21) being rotatable about a rotational axis (A). The wobbling device (20) is actuatable, by rotating the drive shaft (21) about the rotational axis (A), to perform a tumbling motion with respect to the receptacle (300) for acting onto the pump module (1) received in the receptacle (300) in order to pump a fluid through the pump module (1). Herein, the wobbling device (20) is displaceable along at least one direction (X, Y) transverse to the rotational axis (A) with respect to the receptacle (300). In this way an infusion device is provided which in an easy and cost-efficient manner allows for improving the positional accuracy of the pump module with respect to the wobbling device of the pump actuation mechanism upon arranging the pump module on the receptacle of the housing element.

The present application is a U.S. National Stage of PCT International Patent Application No. PCT/EP2016/058975, filed Apr. 22, 2016, which claims priority to EP Application No. 15305892, filed Jun. 11, 2015, both of which are hereby incorporated herein by reference:

DESCRIPTION

The invention relates to an infusion device according to the preamble of claim1.

An infusion device of this kind comprises a housing element having a receptacle for receiving a pump module and a pump actuation mechanism having a wobbling device arranged on the housing element and a drive shaft being rotatable about a rotational axis. The wobbling device is actuatable, by rotating the drive shaft about the rotational axis, to perform a tumbling motion about the rotational axis with respect to the receptacle for acting onto the pump module received in the receptacle in order to pump a fluid through the pump module.

An infusion device as generally concerned herein is for example described in US 2012/0207635 A1.

The infusion device is constituted as a peristaltic (volumetric) infusion pump. The pump module may, for example, have the shape of a disposable pump module which can be attached to the receptacle of the infusion device. By attaching the pump module to the receptacle it is brought into engagement with the wobbling device of the pump actuation mechanism such that, in operation of the infusion device, the wobbling device may act onto a flexible wall section of the pump module in order to locally depress it in a revolving fashion and in this way pump a fluid through a pump channel of the pump module. During operation the wobbling device hence depresses the flexible wall section at a depression location, wherein by actuating the wobbling device the depression location moves along the channel length of the pump channel and in this way peristaltically pumps a fluid through the pump channel.

For attaching the pump module to the infusion device it is inserted into the receptacle of the housing element such that the wobbling device of the pump actuation mechanism may act onto the pump module. The receptacle herein may for example be formed as a reception opening into which the pump module may be inserted such that, in an inserted state, it is held in the receptacle in a form locking manner. Since the wobbling device is arranged on the receptacle at a defined position, the pump module is brought into a defined spatial relation with the wobbling device when arranging the pump module in the receptacle. In this way, the wobbling device is for example brought into abutment with a flexible wall section in the shape of a membrane of the pump module such that it may peristaltically depress the flexible wall section in order to pump a fluid through a pump channel of the pump module during operation of the infusion device.

However, the pump module, the receptacle and the wobbling device may be subject to tolerances. The position of the pump module with respect to the wobbling device hence may deviate from an ideal, nominal position which the pump module should assume in order to achieve a pumping action with an accurate flow rate. If there is a lateral mismatch between the wobbling device and the pump module (transverse to the rotational axis of the drive shaft driving the wobbling device), this may affect the flow rate accuracy because the stroke volume (corresponding to the volume of fluid pumped through the pump channel of the pump module during one pump cycle) may differ from a reference, nominal stroke volume, causing the actual flow rate to differ from a desired, nominal flow rate.

There hence is a desire to be able to correct for a lateral mismatch in the position of the pump module with respect to the wobbling device in order to avoid a reduced flow rate accuracy.

It is an object of the instant invention to provide an infusion device which in an easy and cost-efficient manner allows for improving the positional accuracy of the pump module with respect to the wobbling device of the pump actuation mechanism upon arranging the pump module on the receptacle of the housing element.

This object is achieved by means of an infusion device comprising the features of claim1.

Accordingly, the wobbling device is displaceable along at least one direction transverse to the rotational axis with respect to the receptacle.

Because the wobbling device is displaceable in a direction transverse to the rotational axis with respect to the receptacle, lateral tolerances in the position in-between the wobbling device and the pump module may be corrected. When the pump module is attached to the housing element by placing it on the receptacle, the lateral position of the wobbling device may be adjusted with respect to the pump module such that the wobbling device may assume an optimum position with respect to the pump module for acting onto the pump module in order to pump a fluid through the pump module. Because the lateral position of the wobbling device with respect to the pump module can laterally be adjusted, inaccuracies in the stroke volume may be avoided or at least reduced and hence the flow rate accuracy of the infusion device may be improved.

Within the context of the instant text the displaceability of the wobbling device in a direction transverse to the rotational axis shall refer to a lateral change of position of the wobbling device as a whole, disregarding the tumbling motion of the wobbling device during operation of the infusion device. If the wobbling device is laterally mounted on the drive shaft, the lateral displaceability of the wobbling device will include a displaceability of the lateral position of the rotational axis with respect to the receptacle.

Because the wobbling device is displaceable along at least one direction transverse to the rotational axis, its lateral position with respect to the pump module is adjustable such that the wobbling device may assume an optimum lateral position with respect to the pump module during operation of the infusion device. In addition, the wobbling device beneficially is displaceable longitudinally along the rotational axis with respect to the receptacle, such that also the longitudinal position of the wobbling device is adjustable.

Herein, in one embodiment, the wobbling device is elastically pretensioned with respect to the housing element of the infusion device along the rotational axis in a direction pointing towards the receptacle, such that the wobbling device is brought into abutment with the pump module when placing the pump module in or on the receptacle. The abutment herein occurs under a pretension such that the wobbling device is tensioned towards for example a flexible wall section of the pump module. This may beneficially lead to a pre-loading of the flexible wall section of the pump volume in that in any case the wobbling device abuts the flexible wall section along the entire channel length. Herein, dependent on the position of the wobbling device the flexible wall section is only locally depressed such that the height of the pump channel at its depression location is reduced to a minimum and the pump channel is squeezed off at the depression location.

However, also at other locations along the pump channel the wobbling device abuts the flexible wall section such that the flexible wall section is preloaded along the entire channel length.

The wobbling device, in one embodiment, is mounted on the drive shaft via a first bearing such that the wobbling device is actuated to perform a tumbling motion when rotating the drive shaft. The wobbling device, during operation of the infusion device, performs a tumbling motion, but is not rotated about the rotational axis. The drive shaft, in contrast, is rotated about the rotational axis and acts onto the wobbling device such that the wobbling device tumbles about the rotational axis. For this to take place, the wobbling device is mounted on the drive shaft such that the drive shaft may be rotated with respect to the wobbling device. Because the bearing axis (corresponding to a tumbling axis) is at a skew angle with respect to the rotational axis, the wobbling device tumbles about the rotational axis upon rotating the drive shaft about its rotational axis.

The drive shaft in turn, in one embodiment, is mounted on a carrier element via a second bearing such that the drive shaft is rotatable with respect to the carrier element about the rotational axis. In that the carrier element is mounted on the housing element such that the carrier element is displaceable along at least one direction transverse to the rotational axis with respect to the housing element, the wobbling device mounted on the drive shaft is transversely displaceable with respect to the receptacle. The wobbling device hence, in this embodiment, is not displaceable with respect to the drive shaft, but the carrier element is displaceable together with the drive shaft and the wobbling device mounted on the drive shaft, such that a displacing of the carrier element in a direction transverse to the rotational axis leads to a displacement of the wobbling device with respect to the receptacle.

In principle, the carrier element may be mounted and connected to the housing element in different ways such that it is displaceable transversely to the rotational axis of the drive shaft. In one embodiment, the carrier element is connected to the housing element via an elastically deformable connection element, for example in the shape of a connection plate connecting the carrier element to the housing element. By means of the connection element the carrier element is held on the housing element, wherein the connection element may be deformed in order to displace the carrier element by at least some margin along a plane transverse to the rotational axis.

The displacement of the carrier element herein may beneficially occur against an elastic tensioning of the connection element. The displacing of the carrier element may take place dynamically upon placing the pump module in or on the receptacle for operation of the infusion device.

In one embodiment, the carrier element may be elastically pretensioned with respect to the housing element along the rotational axis. Via the elastic pretensioning of the carrier element, for example by means of a suitable spring element, hence the wobbling device is pretensioned towards the pump module for a suitable abutment with the pump module.

The wobbling device, in one embodiment, comprises a wobbling disc extending along a plane transverse to a tumbling axis, wherein the tumbling axis is arranged at a skew angle with respect to the rotational axis and tumbles about the rotational axis when the wobbling device is driven by the drive shaft. The wobbling disc may be mounted on the drive shaft by means of a suitable bearing, wherein the bearing axis (i.e. the axis about which the wobbling device is rotatable with respect to the drive shaft) corresponds to the tumbling axis and is arranged at a skew angle with respect to the rotational axis of the drive shaft. When driving the wobbling device by means of the drive shaft, the wobbling device remains rotationally fixed, but tumbles about the rotational axis of the drive shaft.

In order to act onto the pump module, a protrusion may be arranged on the wobbling device protruding from the wobbling device along the tumbling axis. Via the protrusion the wobbling device may act onto a flexible wall section of the pump module, for example a membrane confining the pump channel of the pump module for locally depressing the pump channel in a revolving fashion for peristaltically pumping a fluid through the pump channel.

The wobbling device, in one embodiment, may be constituted to self-align itself with respect to the pump module in a lateral direction with respect to the rotational axis of the drive shaft. The self-alignment for example may take place in that the wobbling device, when depressing the flexible wall section of the pump module, reaches into and engages with the pump channel formed in the pump module for example as a trench in a housing part of the pump module. Via the engagement, the wobbling device automatically is laterally aligned with respect to the pump module.

In one embodiment, the pump module comprises a housing part and a flexible wall section together forming a pump channel to which a fluid is to be pumped. The wobbling device herein is constituted to act onto the flexible wall section for locally depressing the flexible wall section, for example a membrane, in order to pump a fluid through the pump channel.

The pump channel advantageously is formed by a trench in the housing part of the pump module. The housing part may be made for example of a rigid plastic material. The flexible wall section in turn may for example be formed by a membrane attached to the housing part, or by a thin wall section having a sufficient elasticity and formed in one piece with the housing part, for example using a two-component molding technique.

The pump channel may for example extend along an arc of a circle, wherein the circle is not closed, but interrupted to separate an inlet at a first end of the pump channel from an outlet at a second end of the pump channel. The pump channel may for example extend along a plane transverse to the vertical direction. The pump channel hence is laid out in a horizontal plane, and the flexible wall section of the pump channel is depressed vertically to that horizontal plane in order to perform a peristaltic pump action on the pump channel.

Attached to the housing30is a door31which may be pivoted with respect to the housing30for accessing the front face300and the receptacle301arranged thereon. By pivoting the door31away from the front face300, the receptacle301may be accessed for inserting a pump module1into the receptacle301or for removing the pump module1from the receptacle301. During operation of the infusion device3, the door31is closed such that the pump module1is securely held in the receptacle301.

FIG. 2shows a schematic top view of a disposable pump module1which may be part of an infusion set to be attached to the infusion device3. The pump module1comprises a housing10having an inlet100and an outlet101. The inlet100and the outlet101may be connected to a suitable tubing forming an infusion line such that an upstream flow U may enter the pump module1at the inlet100and a downstream flow D may exit the pump module1through the outlet101.

Within the pump module1a flow path L is defined through which fluid may pass the pump module1. Along the flow path L, as viewed from the inlet100, a fluid flow first passes a pressure sensing location11, then through an end120A enters a pump channel121and exits the pump channel121through an end120B, and flows through another pressure sensing location13.

At the pressure sensing locations11,13thin, flexible wall sections on the housing10may be provided such that pressure sensors of the infusion device3are enabled to sense the pressure at the pressure sensing locations11,13on the flow path L.

In the embodiment of the pump module1according toFIG. 2, the pump channel121has the shape of an arch of a circle. The circle is not circumferentially closed such that the ends120A,120B of the pump channel121are separated from one another.

As visible fromFIG. 3A, 3BandFIG. 4A, 4B, the pump channel121is formed by a trench in a housing part103of the housing10of the pump module1. The pump channel121, towards the outside, is covered by a flexible wall section12in the shape of a membrane, which is held between the housing part103and another, top housing part102. The flexible wall section12may be glued or welded to the housing part103or may be held in-between the housing parts102,103in a clamping fashion. The flexible wall section12may alternatively be formed in one piece together with the housing parts102,130using for example a two-component molding technology.

Whereas the flexible wall section12is elastic such that it may locally be depressed in order to perform a pump action, the housing parts102,103are formed as rigid pieces for example from plastics.

FIG. 3A, 4AandFIG. 3B, 4Bshow the pump module1in interaction with different types of wobbling devices20of a pump actuation mechanism2. The wobbling devices20comprise a wobbling disc200and an arched projection201projecting from the wobbling disc200through an opening104in the top housing part102towards the flexible wall section12and, along the pump channel length, forming an arch similar in shape to the arch of the pump channel121.

In an operational state of the infusion device, as shown inFIGS. 4A and 4B, each wobbling device20is in abutment with a projecting rim122of the flexible wall section12of the pump module1. The wobbling device20herein is pretensioned towards the flexible wall section12. This leads to a preloading of the flexible wall section12, causing the wobbling device20to be in abutment with the flexible wall section12along the entire channel length of the pump channel121such that the flexible wall section12is preloaded along the channel length of the pump channel121.

By means of the wobbling device20fluid may be pumped through the pump channel121between the inlet100and the outlet101. The wobbling device20, during operation of the infusion device3, is driven to perform a wobbling action about a rotational axis A such that the wobbling device20, by means of its projection201, locally depresses the flexible wall section120at a depression location, the depression location revolving in a tumbling direction R about the rotational axis A along the channel length of the pump channel121. By the local depression of the flexible section120, the pump channel121is locally squeezed off, and by the revolving action of the wobbling device20fluid is peristaltically pumped through the pump channel121in the tumbling direction R.

The wobbling disk200of the wobbling device20extends along a plane perpendicular to a tumbling axis A′, which is arranged at a skew angle relative to the rotational axis A. During operation of the infusion device3, the wobbling disk200performs a tumbling motion T, and the tumbling axis A′ revolves about the rotational axis A, wherein the rotational position of the tumbling device20remains stationary.

The tumbling device20ofFIG. 3A, 4Aand the tumbling device ofFIG. 3B, 4Bdiffer in the shape of the projection201. The tumbling device20ofFIG. 3A, 4Acomprises a projection201having a rounded outer edge acting onto the rim122of the flexible wall section120. The projection201′ of the wobbling device20ofFIG. 3B, 4B, in contrast, is flat at its face pointing away from the wobbling disk200, and via its flat circumferential face acts onto the rim122of the flexible wall section120.

The embodiment of the wobbling device20ofFIG. 3A, 4Ais self-aligning in that it allows for a self-alignment of the lateral position of the wobbling device20with respect to the pump channel121formed in the pump module1. When the wobbling device20by means of its projection201engages with the pump channel121as shown inFIG. 4Aon the left, the wobbling device20will automatically find its position with respect to the pump module1such that an optimum depression of the flexible wall section120becomes possible.

The self-alignment of the wobble device20becomes possible when the wobble device20, by at least some margin, is laterally displaceable with respect to the pump module1, as will be described below with respect to the embodiment ofFIGS. 6 to 8.

In contrast to the embodiment ofFIG. 3A, 4A, the wobble device20of the embodiment ofFIG. 3B, 4Bis not self-aligning, because the flat face of the projection201′ does not cause a lateral alignment of the wobbling device20with respect to the pump module1as the projection201′, as visible fromFIG. 4B, does not engage with the pump channel121(i.e., it does not reach into the pump channel121).

The wobbling device20—in the embodiment ofFIG. 3A, 4AorFIG. 3B, 4B—is part of a pump actuation mechanism2, as it is shown inFIG. 5A.

The pump actuation mechanism2comprises a drive shaft21which is rotatably mounted about a rotational axis A on a carrier element22. The drive shaft21is driven by a drive device24in the shape of an electric motor, wherein a suitable gearing in-between the drive device24and the drive shaft21may be provided for driving the drive shaft21. The carrier element22is mounted on the housing30of the infusion device3in a pivotable fashion and for this is pivotable about a pivot axis P via an axis220.

By pivoting the carrier element22about the pivot axis P, the longitudinal position of the wobbling device20along the rotational axis A can be adapted. The carrier element22herein is pretensioned by means of a spring element23in the shape of a tension spring in a vertical direction Z towards a pump module1placed in the receptacle301on the front face300of the housing30. By means of the pre-tensioning, hence, the wobbling device20is brought into abutment with the flexible wall section12of the pump module1such that the flexible wall section12is elastically preloaded.

Because the distance between the pivot axis P and the rotational axis A is large, the wobbling device20is substantially displaceable along the vertical direction Z with respect to the pump module1. Because the axis220is stiff, the wobbling device20herein is not displaceable in a direction transverse to the rotation axis A with respect to the receptacle301on the front face300of the housing30.

An embodiment implementing the instant invention is shown inFIGS. 6 to 8. In this embodiment, the carrier element22is connected to the housing element30via a connection element25which is by at least some margin deformable such that the lateral position of the carrier element22is, to at least some degree, displaceable in a plane transverse to the rotational axis A, i.e. in a plane spanned by the horizontal directions X, Y.

The connection element25comprises a connection section250fixedly connected to the carrier element22and a connection section252fixedly connected to the housing element30. The connection sections250,252are integrally connected by means of elastic connecting webs251, which are bendable to allow for a lateral displacement of the carrier element22along bending directions B2, B2′ in the horizontal plane spanned by the horizontal directions X, Y, as shown inFIG. 8. In addition, the connection element25is bendable in a bending direction B1as shown inFIG. 6to allow for a vertical displacement of the wobbling device20along the vertical direction Z.

The position of the carrier element22hence is adjustable with two degrees of freedoms, namely by bending the connection element25in the bending direction B1as indicated inFIG. 6(to allow for a displacement of the wobbling device22along the vertical direction Z) and along the bending directions B2, B2′ as indicated inFIG. 8(to allow for a lateral displacement of the wobbling device20with respect to the vertical direction Z). The position of the wobbling device20with respect to the pump module, hence, is adjustable laterally within the plane of the front face300on which the receptacle301is arranged, namely along the plane spanned by the directions X, Y perpendicular to the vertical direction Z.

In particular, when the wobbling device20is self-aligning as in the embodiment ofFIG. 3A, 4A, the wobbling device20hence may find its optimum position with respect to the pump module1automatically when inserting the pump module1into the receptacle301. Once the wobbling device20by means of its projection201engages with the pump channel121, the carrier element22is laterally displaced by deforming the connection element25(by subjecting the connection element25to torsion). Tolerances in the pump module1and in the pump actuation mechanism2hence may be overcome, and an optimum engagement of the wobbling device20with the pump channel121of the pump module1may be achieved, leading to an increased flow rate accuracy during operation of the infusion device3.

FIG. 9shows the mounting of the wobbling device20on the drive shaft21and the mounting of the drive shaft21on the carrier element22. The wobbling device20is mounted on the drive shaft21by means of a first bearing203arranged between a pin202of the wobbling device20and a circumferential face of a bearing opening211provided in the drive shaft21. By means of the bearing203the wobbling device20is rotatable about the tumbling axis A′ with respect to the drive shaft21. The drive shaft21in turn is mounted via a bearing210on the carrier element22such that it is rotatable with respect to the carrier element22about the rotational axis A. When driving the drive shaft21via the drive device24, the drive shaft21is rotated about the rotational axis A relative to the carrier element22. This causes the bearing opening211to rotate about the rotational axis A such that the wobbling device20is forced into a tumbling motion T about the rotational axis A in that the tumbling axis A′ revolves about the rotational axis A. The wobbling device20herein remains rotationally fixed (and hence is not rotated), but performs a tumbling motion T and hence, in a revolving fashion, acts onto the flexible wall section12of the pump module1to peristaltically pump a fluid through the pump channel121.

Because the wobbling device20is mounted on the drive shaft21and the drive shaft21is mounted on the carrier element22, the wobbling device20is laterally displaced together with the carrier element22. Upon engaging of the projection201with the pump channel121, the lateral position of the wobbling device20hence is self-aligned with respect to the pump module1, causing a deformation of the connection element25and hence an adjustment of the lateral position of the carrier element22.

The idea underlying the invention is not limited to the embodiments described above, but may be implemented in an entirely different fashion.

In particular, the wobble device may have an entirely different shape. Likewise, the pump module may have a different structure and shape. Also, the structure and mechanics of the pump actuation mechanism may be implemented in a different fashion.

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