Patent Description:
An infusion device of this kind comprises a housing, a receptacle arranged on the housing for receiving a syringe, a syringe driver movable in a driving direction for acting onto a piston of a syringe received on the receptacle, and a drive mechanism for electromotively driving the pusher device along the driving direction, the drive mechanism comprising an electric drive motor and a rotatable drive element operatively coupled to the syringe driver to move the syringe driver along the driving direction.

<CIT> discloses an infusion device in the shape of a syringe pump which, for acting onto a piston of a syringe, comprises a syringe driver driven by a drive mechanism comprising a rotatable spindle. The rotatable spindle is coupled to an electric drive motor such that, by means of the electric drive motor, the spindle can be rotated in order to cause the syringe driver to be longitudinally moved along a driving direction to deliver a medical fluid from a syringe towards a patient. To establish a coupling in between the spindle and the syringe driver, herein, a clutch mechanism is provided which, in a clutched state, engages with the spindle such that in the clutched state the clutch device as a whole is longitudinally moved with respect to the spindle when the spindle rotates. The clutch device can be unclutched from the spindle such that a movement of the syringe driver is possible with respect to and independent of the spindle, for example during installation of a syringe on the infusion device or to exert a manual bolus. Documents <CIT> and <CIT> disclose features falling under the preamble of claim <NUM>.

There is a general desire to provide an infusion device implementing an alternative solution for a drive mechanism, in particular offering a simplification in construction and a possible reduction in costs.

It is an object of the instant invention to provide an infusion device having a drive mechanism which can be of simplified construction, yet providing a reliable and exact infusion operation for administering a medical fluid to a patient.

This object is achieved by means of an infusion device comprising the features of claim <NUM>.

Accordingly, the drive mechanism comprises a clutch device configured, in a coupled state, to couple the drive device to the drive element such that the drive device is operative to drive the drive element and, in an uncoupled state, to uncouple the drive device from the drive element.

The infusion device hence uses a drive mechanism comprising an electric drive motor and a rotatable drive element. The electric drive motor is coupled to the rotatable drive element by means of a clutch device, which may assume a coupled state in which an operative connection in between the electric drive motor and the rotatable drive element is established and an uncoupled state in which the operative connection in between the electric drive motor and the rotatable drive element is released. A force transfer in between the electric drive motor and the rotatable drive element hence takes place via the clutch device, wherein a force transfer in between the electric drive motor and the rotatable drive element may be interrupted by transferring the clutching device into its uncoupled state such that the drive element may be rotated freely and independently of the electric drive motor.

The clutch device for example may comprise a first clutch element and a second clutch element, wherein the first clutch element is operatively connected to the electric drive motor and the second clutch element is operatively connected to the drive element. In the coupled state of the clutch device the first clutch element and the second clutch element are in clutching connection with each other such that forces may be transferred in between the first clutch element and the second clutch element and the first clutch element and the second clutch element may be rotated together. In the uncoupled state, in contrast, a free movement of one clutch element with respect to the other clutch element is possible such that the rotatable drive element may be freely rotated with respect to the electric drive motor.

In the coupled state the clutch elements may for example be in frictional contact with each other such that the clutch elements are coupled to each other in a rotationally fixed manner. The clutch device herein may be electromagnetically driven such that the clutch elements may be brought into abutment with each other to transfer the clutch device to the coupled state or may be released from one another in order to transfer the clutch device into its uncoupled state.

In another embodiment the clutch elements are in positive-locking engagement in the coupled state, for example by means of a suitable toothing provided on the first clutch element and the second clutch element, and are released from one another in the unclutched state.

The clutch device may, alternatively, be implemented by a magnetic clutch device in which the clutch elements are operatively connected to each other by magnetic means, that is without frictionally contacting each other, in the coupled state.

In one embodiment, the electric drive motor comprises a drive shaft and a worm screw arranged on the drive shaft. During operation the electric drive motor drives the drive shaft to rotate, the worm screw herein for example engaging with a worm wheel such that by means of the worm screw the worm wheel is rotated. The worm wheel herein may be connected, by means of a shaft, to the first clutch element of the clutch device, such that the electric drive motor by means of the worm wheel acts onto the first clutch element of the clutch device.

The worm wheel together with the worm screw forms a gearing to connect the electric drive motor to the clutch device. In one embodiment, such gearing may be self-locking such that, in the coupled state of the clutch device, the drive mechanism is locked with respect to a movement of the syringe driver in case an external force is applied to the syringe driver. If external forces act onto the syringe driver when the clutch device is in its coupled state, hence, a movement of the syringe driver is prevented in that, due to the self-locking, the drive element cannot be rotated and hence the syringe driver is held in position by means of the drive element. An unintentional movement of the syringe driver due to external forces acting onto the syringe driver hence is effectively prevented. A driving of the drive element is possible, in the clutched state, only by means of the electric drive motor.

In one embodiment, the drive element is formed by a spindle having a screw thread. The drive element is rotatable about a longitudinal axis and, by means of the screw thread formed on the circumferential outside of the spindle, engages for example with a coupling element in the shape of a spindle nut connected to the syringe driver. The engagement of the spindle with the coupling element causes the coupling element to move longitudinally along the drive element when the drive element rotates about its longitudinal axis, a rotational movement of the spindle hence being translated into a longitudinal movement of the coupling element. By means of the longitudinal movement of the coupling element the syringe driver connected to the coupling element is moved, in particular for driving the piston of a syringe received on the receptacle of the infusion device such that a medical fluid is delivered from the syringe through an infusion line connected to the syringe.

The coupling of the syringe driver to the drive element in the shape of the spindle is, in one embodiment, non-releasable. In particular, the clutch device is functionally arranged prior to the spindle (when viewed from the electric drive motor), the clutch device hence serving to couple or uncouple the electric drive motor from the drive element in the shape of the spindle. Hence, when the clutch device is in the uncoupled state and the syringe driver is manually moved for example for installing a syringe on the infusion device, the longitudinal movement of the syringe driver is transferred to the drive element in the shape of the spindle, which correspondingly is rotated when moving the syringe driver.

In one embodiment, the infusion device comprises a control device for controlling the clutch device. The control device in particular may issue control commands to transfer the clutch device from its coupled to its uncoupled state and vice versa. In addition, the control device may be configured to control the electric drive motor and may be configured to evaluate sensing signals of sensor devices for controlling operation.

In one embodiment, the infusion device comprises an actuation device which is user actuatable for transferring the clutch device from one of the coupled state and the uncoupled state to the other of the coupled state and the uncoupled state. The actuation device may for example have the shape of a pushbutton (e.g. comprising a micro-switch), the actuation of the actuation device causing an electrical signal according to which the control device may control the clutch device to be transferred from one state to the other. Alternatively, the actuation device may have the shape of a mechanical device serving to mechanically transfer the clutch device from one state to the other.

In one embodiment, the actuation device, for example in the shape of a pushbutton, is arranged on the syringe driver such that a user may intuitively act onto the actuation device when manually acting onto the syringe driver. A user - who wishes to, for example in the course of installing a syringe on the infusion device, manually move the syringe driver towards the syringe such that the syringe driver is brought into abutment with the piston head of a piston of the syringe - may place one hand on the syringe driver and may actuate the actuation device such that the clutch device is transferred from the coupled state to the uncoupled state, hence allowing for a free manual movement of the syringe driver.

The clutch device, herein, in a rest state may assume the coupled state such that, when the actuation device is not actuated, the syringe driver is held in position, for example due to a self-locking of the drive mechanism or by an additional braking action of a brake device acting onto the drive element or onto another gear element of the drive mechanism. By actuating the actuation device the clutch device may be transferred from the coupled state to the uncoupled state such that the syringe driver is uncoupled from the electric drive motor and the drive chain of the drive mechanism hence is released, allowing for a free manual movement of the syringe driver independent of the electric drive motor.

In particular if the actuation device is implemented by means of a pushbutton, the actuation device may be configured, in case of an actuation, to produce an actuation signal in the shape of an electrical control signal, which may be provided to the control device and may be processed by the control device, causing the clutch device to be transferred from the coupled state to the uncoupled state. A user herein may have to keep actuating the actuation device, for example by pushing a corresponding pushbutton, in order for the clutch device to be maintained in the uncoupled state. Alternatively, a user may have to press the actuation device only once, upon which the clutch device is transferred from the coupled state to the uncoupled state and is maintained in the uncoupled state for a predetermined amount of time or until a particular event occurs. For example, the clutch device may be transferred back to the coupled state in case it is detected, by means of a sensor device, that a contact between the syringe driver and a piston head of a piston of a syringe is established, indicating that during installation a desired operative connection between the syringe driver and the syringe is established.

A sensor device for detecting a contact between the syringe driver and the piston of a syringe may be arranged for example on the syringe driver and may have the shape of a touch sensor, for example comprising a micro-switch or the like. A sensor device of this kind however may also be configured as a force sensor for measuring a force in between the syringe driver and the piston of a syringe, such sensor during operation of the infusion device providing force readings from which a pressure value in the syringe and in an infusion line connected to the syringe may be derived.

During installation, if by means of the sensor device it is detected that the syringe driver has been brought into contact with the piston of the syringe received on the receptacle of the infusion device, a sensor signal may be transmitted to the control device and may be processed by the control device to transfer the clutch device from its uncoupled state to the coupled state such that the drive mechanism is brought into an operative state for starting an infusion operation and, in particular, for effectively preventing an uncontrolled movement of the syringe driver and the piston of the syringe. In case a user wishes to provide a manual bolus, the user may (again) actuate the actuation device, causing the clutch device to be transferred from the coupled state to the uncoupled state such that a user may act onto the syringe driver for moving the piston of the syringe received on the receptacle of the infusion device, wherein after the manual bolus the clutch device is transferred back to its coupled state, for example after a predetermined time or after it is detected that a manual movement of the syringe driver has been terminated or after a calculated volume of infusion has been reached.

The idea underlying the invention shall subsequently be described in more detail with respect to the embodiments shown in the figures.

<FIG> shows an infusion device <NUM> in the shape of a syringe pump having a housing <NUM> and a receptacle <NUM> arranged on the housing <NUM> to receive a syringe <NUM> therein.

The syringe <NUM> comprises a cylindrical tube <NUM> which, when installing the syringe <NUM> on the infusion device <NUM>, contains a medical liquid, for example a medication or a solution for the parenteral feeding, to be infused to a patient. The cylindrical tube <NUM> is connected, via a connector <NUM>, to an infusion line <NUM> which may extend from the syringe <NUM> towards a patient for infusing the medical liquid to the patient.

For installing the syringe <NUM> on the receptacle <NUM> of the infusion device <NUM>, the cylindrical tube <NUM> of the syringe <NUM> is placed in the receptacle <NUM> and is mechanically connected to the housing <NUM> by means of a fixation device <NUM>. By means of the fixation device <NUM>, for example constituted by a releasable clamp element, the cylindrical tube <NUM> is secured within the receptacle <NUM> such that the cylindrical tube <NUM> is held in position on the receptacle <NUM>.

The syringe <NUM> comprises a piston <NUM> which, for delivering medical fluid contained in the cylindrical tube <NUM>, can be pushed into the cylindrical tube <NUM> in a driving direction P. For this, the infusion device <NUM> comprises a syringe driver <NUM> movably arranged within a guide device <NUM> and connected to a drive mechanism (which subsequently shall be described with relation to <FIG> and <FIG>) via a connecting rod <NUM>.

For operating the infusion device <NUM>, the syringe <NUM> is installed on the infusion device <NUM> and the syringe driver <NUM> is (e.g., manually) moved towards a piston head <NUM> of the piston <NUM> until the syringe driver <NUM> comes into abutment with the piston head <NUM>. For performing an infusion process the syringe driver <NUM> is then electrically moved in the driving direction P to move the piston <NUM> into the cylindrical tube <NUM> for delivering the medical fluid contained in the cylindrical tube <NUM> via the infusion line <NUM> towards the patient.

The syringe driver <NUM> is driven by a drive mechanism <NUM>, which, according to one embodiment, is schematically illustrated in <FIG>.

The drive mechanism <NUM> comprises a rotatable drive element <NUM> in the shape of a spindle, which is connected to the syringe driver <NUM> via a coupling element <NUM>. The drive element <NUM> in the shape of the spindle is rotatably mounted, about a longitudinal axis L, with respect to the housing <NUM> by means of bearings <NUM>, <NUM> and comprises an outer screw thread <NUM> by means of which the drive element <NUM> is in engagement with an internal screw thread <NUM> formed on the coupling element <NUM>, the coupling element <NUM> having the shape of a spindle nut being held rotationally fixed with respect to the housing <NUM>, but being longitudinally movable along the longitudinal axis L on the drive element <NUM>.

The drive mechanism <NUM> further comprises an electric drive motor <NUM> having a drive shaft <NUM> and a gear element <NUM> for example in the shape of a worm screw, as indicated in <FIG>, arranged thereon. By means of the gear element <NUM> the electric drive motor <NUM> is in operative connection with a gear element <NUM> in the shape of a worm wheel, as shown in <FIG>, the gear element <NUM> being, by means of a shaft <NUM>, connected to a clutch element <NUM> of a clutch device <NUM>.

The clutch device <NUM> comprises clutch elements <NUM>, <NUM>, which in a coupled state of the clutch device <NUM> are in a rotationally fixed connection with each other, for example by frictionally abutting each other. The clutch device <NUM> may be electromagnetically driven such that the clutch elements <NUM>, <NUM> are axially movable with respect to each other in order to transfer the clutch device <NUM> between its coupled state and the uncoupled state.

Whereas the clutch element <NUM> is associated with the gear element <NUM> on the side of the electric drive motor <NUM>, the clutch element <NUM>, by means of a shaft <NUM>, is connected to a gear element <NUM> in the shape of a tooth wheel, which acts onto a gear wheel <NUM> in the shape of a tooth wheel fixedly connected to the drive element <NUM>.

For operating the infusion device <NUM>, the clutch device <NUM> is in the coupled state. By operating the electric drive motor <NUM>, hence, a rotational movement of the drive shaft <NUM> may be transferred to the gear element <NUM> and the gear wheel <NUM>, by means of which the drive element <NUM> in the shape of the spindle is driven to rotate about its longitudinal axis L. Such rotation causes, due to the engagement of the coupling element <NUM> in the shape of the spindle nut with the outer screw thread <NUM> of the drive element <NUM>, the coupling element <NUM> to be longitudinally moved along the longitudinal axis L with respect to the drive element <NUM>, such that the syringe driver <NUM> fixedly connected to the coupling element <NUM> is moved along the guide <NUM> formed on the housing <NUM> of the infusion device <NUM>, as indicated in <FIG>.

The syringe driver <NUM> may be connected to the coupling element <NUM> by means of the connecting rod <NUM>, as shown in <FIG>.

During regular operation, hence, an electric drive motion of the electric drive motor <NUM> is transferred to the drive element <NUM> in the shape of the spindle and via the drive element <NUM> to the coupling element <NUM> and the syringe driver <NUM>, causing the syringe driver <NUM> to be longitudinally moved on the housing <NUM> for acting onto the piston <NUM> of a syringe <NUM> received on the receptacle <NUM> of the infusion device <NUM>.

The infusion device <NUM> comprises a control device <NUM>, as schematically indicated in <FIG>, serving to control the operation of the electric drive motor <NUM>. The control device <NUM> may in particular be configured to process signals of a sensor device <NUM> connected to the drive element <NUM> by means of a gear wheel <NUM>, such sensor device <NUM> being configured to detect a rotational position of the drive element <NUM>, such that by means of the signals of the sensor device <NUM> the actual position of the syringe driver <NUM> may be computed.

In addition, the control device <NUM> may be configured to control the clutch device <NUM> for transferring the clutch device <NUM> between its coupled state and the uncoupled state.

The drive mechanism <NUM> may have a self-locking configuration. Hence, if the clutch device <NUM> is in its coupled state the syringe driver <NUM> is held in position by means of the drive mechanism <NUM>, such that in particular external forces acting onto the syringe driver <NUM> may not cause an uncontrolled, lateral movement of the syringe driver <NUM> with respect to the housing <NUM>.

In addition, a detection device <NUM> in the shape of for example an optocoupler may be provided, the detection device <NUM> being configured to detect a position / movement of the gear element <NUM> in order to control the pumping flow rate.

For example for installing a syringe <NUM> on the receptacle <NUM> of the infusion device <NUM> it is desirable to allow a manual, free movement of the syringe driver <NUM>. For example for installation of a syringe <NUM>, thus, the clutch device <NUM> may be transferred to its uncoupled state, such that the drive chain in between the electric drive motor <NUM> and the drive element <NUM> is interrupted. In the uncoupled state of the clutch device <NUM> the syringe driver <NUM> may be freely moved independent of the electric drive motor <NUM> such that, for installing a syringe <NUM> on the receptacle <NUM> of the infusion device <NUM>, the syringe driver <NUM> may manually be approached towards the piston head <NUM> of the piston <NUM> of the syringe <NUM> until the syringe driver <NUM> is brought into abutment with the piston head <NUM> of the piston <NUM>.

If the clutch device <NUM> is in the uncoupled state, hence, a free manual movement of the syringe driver <NUM> is possible, independent of the electric drive motor <NUM>. The drive element <NUM> in the shape of the spindle herein is driven to rotate by means of the engagement with the coupling element <NUM>, the screw thread <NUM> of the drive element <NUM> and the screw thread <NUM> of the coupling element <NUM> having a (relatively large) thread pitch such that a longitudinal movement of the coupling element <NUM> causes a rotation of the drive element <NUM>.

As schematically indicated in <FIG>, an actuation device <NUM> for example in the shape of a pushbutton (e.g. having a micro-switch) may be arranged on the syringe driver <NUM>. A user may act onto the actuation device <NUM> in order to produce an electrical signal, which is transmitted to the control device <NUM> and is processed by means of the control device <NUM> in order to transfer the clutch device <NUM> from its coupled state to the uncoupled state. Hence, to allow a free manual movement of the syringe driver <NUM>, a user may act onto the actuation device <NUM>, upon which the control device <NUM> causes the clutch device <NUM> to be switched from the coupled state (which the clutch device <NUM> regularly assumes during rest) to the uncoupled state.

During installation, hence, a user may move the syringe driver <NUM> towards the piston head <NUM> of the piston <NUM> if the clutch device <NUM> is in the uncoupled state. In order to prevent an undesired bolus due to a force applied to the piston <NUM> during installation, once it is detected that the syringe driver <NUM> has been brought into abutment with the piston <NUM> the control device <NUM> causes the clutch device <NUM> to be automatically transferred back to the coupled state. For this, a sensor device <NUM> is arranged on the syringe driver <NUM>, the sensor device <NUM> being configured to detect a contact in between the syringe driver <NUM> and piston head <NUM> of the piston <NUM>. The sensor device <NUM> may for example have the shape of a touch sensor, for example having a micro-switch or the like. Alternatively, the sensor device <NUM> may be a force sensor configured to measure a force in between the syringe driver <NUM> and the piston head <NUM>.

Hence, once the syringe driver <NUM> has been approached towards the piston <NUM>, the clutch device <NUM> is transferred to the coupled state, hence locking the syringe driver <NUM> in its currently assumed position. Now, a fixation device <NUM> of the syringe driver <NUM> may be actuated for establishing a fixed connection in between the syringe driver <NUM> and the piston <NUM> of the syringe <NUM>, upon which regular infusion operation of the infusion device <NUM> may start.

If a user wishes to cause a manual bolus during an infusion operation, the user may again press on the actuation device <NUM>, causing the clutch device <NUM> to be transferred to the uncoupled state, upon which the user may move the syringe driver <NUM> and hence the piston <NUM> to apply the bolus. Once the bolus has been finished, the clutch device <NUM> is transferred back to its coupled state, for example after a predetermined time or after it is detected that the syringe driver <NUM> is no longer moved or after a calculated volume of infusion has been reached.

During rest, the clutch device <NUM> is in its coupled state. This ensures that, even in case of power failure, the syringe driver <NUM> is held in position, hence preventing an undesired free flow due to an uncontrolled movement of the syringe driver <NUM>.

For installing a syringe <NUM> on the receptacle <NUM> of the infusion device <NUM>, a user may have to manually move the syringe driver <NUM>, while the clutch device <NUM> is in the uncoupled state, for moving the syringe driver <NUM> opposite to the driving direction P for allowing placement of the syringe <NUM> on the receptacle <NUM> and for then moving the syringe driver <NUM> in the driving direction P towards the piston <NUM> to bring the syringe driver <NUM> into operative connection with the piston <NUM>.

Installation of a syringe <NUM> may alternatively take place in an automatic or at least semi-automatic mode.

In an automatic mode, the syringe driver <NUM> may electromotively be moved first opposite to the driving direction P for allowing placement of the syringe <NUM> on the receptacle <NUM> in order to then electromotively move the syringe driver <NUM> in the driving direction P to establish connection in between the syringe driver <NUM> and the piston <NUM>. In this case the clutch device <NUM> is in the coupled state, hence allowing an electromotive movement of the syringe driver <NUM> driven by the electric drive motor <NUM>.

In a semi-automatic mode a user may have to manually move the syringe driver <NUM> opposite the driving direction P, while the clutch device <NUM> is in the uncoupled state, to allow placement of the syringe <NUM> on the receptacle <NUM>. The approach of the syringe driver <NUM> towards the piston <NUM> of the syringe <NUM> then takes place by electromotively driving the syringe driver <NUM>, such that the operative connection in between the syringe driver <NUM> and the piston <NUM> is automatically established. In particular, motion of the syringe driver <NUM> towards the piston <NUM> may automatically stop once contact between the syringe driver <NUM> and the piston <NUM> has been established, upon which the syringe driver <NUM> is operatively fixed to the piston <NUM> by means of the fixation device <NUM>.

The fixation device <NUM> may be controlled by means of the control device <NUM>, the syringe driver <NUM> having for example an electromotive mechanism for moving the fixation device <NUM>. Fixation of the syringe driver <NUM> with respect to the piston <NUM> hence may take place automatically.

Infusion devices of the kind described herein may serve different purposes and may be constituted to receive syringes of different shape and different size. An infusion device of this kind may in particular not be limited to a particular type of syringe as it may be described herein.

A clutch device as described herein may be driven electromagnetically by moving clutch elements with respect to each other by means of electromagnetic forces. The clutch elements herein may for example frictionally abut in the coupled state, or may be locked with respect to each other in a positive locking manner.

Claim 1:
Infusion device (<NUM>) for administering a medical fluid to a patient, comprising:
- a housing (<NUM>),
- a receptacle (<NUM>) arranged on the housing (<NUM>) for receiving a syringe (<NUM>),
- a syringe driver (<NUM>) movable in a driving direction (P) for acting onto a piston (<NUM>) of a syringe (<NUM>) received on the receptacle (<NUM>), and
- a drive mechanism (<NUM>) for electromotively driving the syringe driver (<NUM>) along the driving direction (P), the drive mechanism (<NUM>) comprising an electric drive motor (<NUM>) and a rotatable drive element (<NUM>) operatively coupled to the syringe driver (<NUM>) for moving the syringe driver (<NUM>) along the driving direction (P),
,the drive mechanism (<NUM>) comprising a clutch device (<NUM>) configured, in a coupled state, to couple the drive device (<NUM>) to the drive element (<NUM>) such that the drive device (<NUM>) is operative to drive the drive element (<NUM>) and, in an uncoupled state, to uncouple the drive device (<NUM>) from the drive element (<NUM>),
the clutch device (<NUM>) comprising a first clutch element (<NUM>) operatively connected to the electric drive motor (<NUM>) and a second clutch element (<NUM>) operatively connected to the drive element (<NUM>), wherein the first clutch element (<NUM>) and the second clutch element (<NUM>) in the coupled state are in clutching connection with each other and in the uncoupled state are disconnected from each other such that the first clutch element (<NUM>) and the second clutch element (<NUM>) can be moved independent of each other, characterized in that in the coupled state the first clutch element (<NUM>) and the second clutch element (<NUM>) are in a rotationally fixed connection with each other by frictionally abutting each other.