Dispenser for taking up and dispensing volumes of fluid and a method for mounting and releasing a piston-cylinder unit from the dispenser

A dispenser for receiving and dispensing volumes of fluid, on which a piston/cylinder unit having a piston and a cylinder, can be fitted in a releasable manner by means of a movement running at least substantially in an axial direction of the dispenser. The dispenser has a piston actuator for moving the piston relative to the cylinder. The piston actuator is arranged in a movable manner in the dispenser and is driven by means of a drive. The dispenser has a locking element which is arranged in a movable manner in the dispenser and is driven by a further drive. Also disclosed is a system for receiving and dispensing volumes of fluid, to a method for fitting a piston/cylinder unit in a releasable manner on a dispenser, and to a method for releasing a piston/cylinder unit which has been fitted on a dispenser.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a dispenser for taking up and dispensing volumes of fluid on which a piston-cylinder unit having a piston and a cylinder can be releasably mounted by means of a movement at least substantially in an axial direction of the dispenser. The invention additionally relates to a system for taking up and dispensing volumes of fluid with such a dispenser, to a method for releasably mounting a piston-cylinder unit on such a dispenser, and to a method for releasing a piston-cylinder unit from such a dispenser.

Background of the Invention

The purpose of systems of the type under consideration is to take up a volume of fluid from a container and subsequently to dispense it into another, or several other containers. Such systems are used, in particular, for repeated dispensing, titrating, or pipetting, of liquids.

Such systems comprise a dispenser, and a piston-cylinder unit, realized as a replaceable part, which can be releasably mounted on the dispenser, in particular can be put into or inserted into the dispenser. Following one or more dispensing operations, the piston-cylinder unit can be released from the dispenser. Another, in particular different, piston-cylinder unit, can then be mounted on the dispenser.

Such systems may be realized as manual or motor-driven hand-held devices, on whose dispenser exactly one piston-cylinder unit can be mounted. There are also systems on whose dispenser a multiplicity of piston-cylinder units can be mounted simultaneously, such as, for example, in the case of an automatic pipetter.

Piston-cylinder units of the type under consideration may be realized, for example, as displacement units having attachable tips, or as syringes. They each have a cylinder, in particular having a straight hollow cylinder having a substantially circular cross section and an axial direction perpendicular thereto, and a piston that is displaceable in the cylinder, in the axial direction thereof. Depending on their type, piston-cylinder units have cross sections and/or lengths of differing sizes. For the purpose of identifying the respective type, they may have geometrically differing information carrier portions. Depending on the type, displacement of the piston in the cylinder may result in differing volumes of fluid being taken up into or dispensed from the cylinder or the tip attached therein. The displacement of the piston in the cylinder is a substantially linear movement in the axial direction of the cylinder.

Known from practice is a dispenser, for taking up and dispensing volumes of fluid, on which a piston-cylinder unit, having a piston and a cylinder, can be releasably mounted by means of a movement at least substantially in the axial direction of the dispenser. The known dispenser has a piston actuator for moving the piston relative to the cylinder. The piston actuator is arranged in a movable manner in the dispenser and driven by means of an electric motor. It is thus a motor-driven, electronic dispenser.

The known dispenser has a housing and a stop element, and is realized such that, when the piston-cylinder unit is being mounted on the dispenser, a fastening portion of the cylinder can abut on the stop element. The fastening portion of the cylinder is formed by a flange, i.e., by an annular widening of the cylinder, at one end of the cylinder.

The known dispenser additionally has a first fastening means for fixing the cylinder to the dispenser. The first fastening means has two cylinder gripping levers, and can be moved into a fixing position in which the first fastening means blocks a relative movement between the cylinder and the housing in the axial direction.

Furthermore, the known dispenser has a second fastening means for fixing the piston to the dispenser. The second fastening means has two piston gripping levers, and can be moved into a fixing position in which the piston is releasably connected to the piston actuator in such a manner that the piston can be moved relative to the cylinder, by means of the piston actuator, for the purpose of taking up and/or dispensing volumes of fluid.

During moving of the piston-cylinder unit in the direction of the stop element, relative to the housing of the dispenser, the first fastening means of the dispenser is moved by the flange of the cylinder out of the fixing position, such that the cylinder can be moved further toward the stop element. The cylinder gripping levers of the first fastening means in this case are forced radially outward by the flange of the cylinder. When the flange of the cylinder abuts on the stop element of the dispenser, the first fastening means of the dispenser engages, in particular by means of its cylinder gripping levers, behind the flange of the cylinder. The cylinder is thus held by positive engagement on the dispenser in the axial direction.

In addition, during moving of the piston-cylinder unit in the direction of the stop element, relative to the housing of the dispenser, the second fastening means is moved by the flange of the piston out of the fixing position, such that the piston can be moved further into the dispenser. In this case, the piston gripping levers of the second fastening means are forced radially outward by the flange of the piston. When the piston has been moved far enough into the dispenser, the second fastening means of the dispenser engages, in particular by means of its piston gripping levers, behind the flange of the piston. The piston is thus held by positive engagement on the dispenser in the axial direction. The piston gripping means are motionally coupled to the piston actuator. Accordingly, following engagement behind the flange of the piston, the piston can be moved relative to the cylinder, by means of the piston actuator, for the purpose of taking up and/or dispensing volumes of fluid.

For the purpose of releasing the piston-cylinder unit from the known dispenser, the first and the second fastening means are manually actuated in such a manner that the cylinder gripping levers and the piston gripping levers are forced radially outward, until the cylinder and the piston are no longer held by positive engagement on the dispenser. The piston-cylinder unit can then be separated from the dispenser.

SUMMARY OF THE INVENTION

It is essential for the present invention that the piston-cylinder units can be mounted on the dispenser by means of a movement at least substantially in an axial direction of the dispenser. This allows the corresponding system to be operated in a simple, user-friendly and ergonomically advantageous manner, and with a lesser susceptibility to error. The expression “axial direction of the dispenser” in this case denotes an orientation coinciding with or parallel to the longitudinal axis of the dispenser.

The present invention focuses on piston-cylinder units that operate according to the direct displacement principle, and on motor-operated, electronic multiple dispensers. In the case of such dispensers, the actuation of one or more pushbuttons activates a taking up, or aspiration, mechanism, or a dispensing mechanism. The piston of a piston-cylinder unit mounted on the dispenser is moved by means of a motor, the volume dispensing being controlled by a microprocessor. The piston tightly strips the inner wall of the cylinder of the piston-cylinder unit, such that exactly reproducible volume results are achieved.

For the systems that are relevant here, the mounting of a piston-cylinder unit on the dispenser and the releasing of this piston-cylinder unit from the dispenser are central aspects of the use of the dispenser. A further aspect are piston-cylinder units having information carrier portions, and dispensers having an acquisition device for automatically identifying, by means of the information carrier portions, the type of a piston-cylinder unit attached to the dispenser. The dispensing of volumes of fluid can then be controlled on the basis of the identified type.

An object of the present invention is to improve the known dispenser, or the known system, or the known method, for releasably mounting the piston-cylinder unit on the known dispenser, or the known method for releasing a piston-cylinder unit mounted on the dispenser, in respect of handling and/or stability when the piston-cylinder unit is being mounted and/or released, and/or in respect of accuracy when volumes of fluid are being taken up and dispensed, and/or in respect of the structure, reliability and/or durability.

According to a first aspect of the invention, the previously stated object is achieved by the dispenser as claimed in claim1. Preferred designs of this aspect of the invention are provided by the dependent claims relating thereto.

It goes without saying that designs, embodiments, advantages and the like that, in the following, are cited only in relation to one aspect of the invention, in order to avoid repetitions, apply correspondingly in relation to the other aspects of the invention.

On this basis, the present invention is described in greater detail in the following.

The basis of the first aspect of the invention is a dispenser, for taking up and dispensing volumes of fluid, on which a piston-cylinder unit, having a piston and a cylinder, can be releasably mounted by means of a movement at least substantially in the axial direction of the dispenser. The dispenser has a piston actuator for moving the piston relative to the cylinder. The piston actuator is arranged in a movable manner in the dispenser and driven by means of a drive.

According to the invention, the dispenser has a locking element, which is arranged in a movable manner in the dispenser and driven by means of a drive. The drive of the locking element is separate from the drive of the piston actuator.

Preferably, the locking element is arranged so as to be movable in the axial direction, and can be moved into different positions. Further elements, or means, of the dispenser, explained in the following, can be moved as a result of the locking element being moved. The further elements, or means, in this case are not necessarily moved by the locking element itself. However, moving of the locking element causes the other elements, or means, to be moved. Thus, moving of the locking element may have the effect, for example, that an element that was previously blocked in respect of movement is moved with or following the moving of the locking element, the moving of this element being able to be effected, for example, by the spring force of a spring element. It is preferred, however, if the locking element, as a result of its movement, itself moves a further element, or a further means.

It is advantageous in this case that the elements, or means, do not have to be moved manually, but are moved automatically at the instigation of a user and/or a control means of the dispenser. This provides for convenient handling of the dispenser.

Preferably, the drive of the locking element is an electric stepper motor. Advantageously, the locking element is driven, by means of its drive, via a self-arresting gear unit.

In a preferred design, the dispenser has a housing, a stop element, and a first fastening means for fixing the cylinder to the dispenser. The stop element is movable at least substantially in the axial direction, relative to the housing, and can be pressed relative to the housing, at least partly, in the direction of mounting. This enables the cylinder to be moved further in the direction of mounting, relative to the housing, after the fastening portion of the cylinder abuts on the stop element. Further pressing of the cylinder during mounting of the piston-cylinder unit is thus possible.

The dispenser is realized such that, during mounting of the piston-cylinder unit on the dispenser, a fastening portion of the cylinder can abut on the stop element. The first fastening means can be moved into a fixing position in which the first fastening means blocks a relative movement between the cylinder and the housing, counter to the direction of mounting.

In the case of this design, the locking element can be moved into a locking position in which the locking element blocks a relative movement between the stop element and the housing, in the direction of mounting. The stop element can thus be locked. A relative movement between the stop element and the housing in the axial direction is blocked, on the one hand, by the locking element, and on the other hand by the first fastening means, i.e., is not possible. In this state, when the piston is being displaced in the cylinder, in the direction of mounting, in particular when a viscous or highly viscous liquid is being taken up, the fastening portion is prevented from moving the stop element in the direction of mounting in such a manner that the cylinder slips, or a delay is caused, as a result of which the desired volume of fluid to be taken up differs from the volume of fluid actually taken up. This results in increased accuracy in the taking up and dispensing of volumes of fluid.

In particular, when the locking element is in the locking position, the fastening portion of the cylinder can be clamped between the first fastening means and the stop element, in such a manner that a relative movement between the cylinder and the housing is blocked in the axial direction, and optionally in the radial direction and/or circumferential direction.

Preferably, the dispenser has means for mechanically, electronically, inductively and/or optically detecting the mounting of a piston-cylinder unit on the dispenser. This detection enables further steps to be triggered, e.g., moving of the locking element.

For this purpose, the dispenser may have an optical, electronic, mechanical, magnetoresistive and/or inductive sensor means, by means of which the moving of the stop element in the axial direction can be detected. The sensor means may have, for example, a light barrier, having a light-beam source and a sensor for detecting light beams of the light-beam source, the light barrier being arranged such that moving of the stop element in the axial direction can be detected by the light barrier.

It has proved to be advantageous if the dispenser has a reset means, which exerts a resetting force upon the stop element, at least substantially in the axial direction, counter to the direction of mounting. If the fastening portion of the cylinder abuts on the stop element and the locking element is not in its locking position, moving the cylinder further in the direction of mounting, relative to the housing, must be performed against the resetting force of the reset means. As a result, tolerances of the stop element of the dispenser, or of the fastening portion of the cylinder, are compensated, and damage to the dispenser, or cylinder, or effects of wear thereof, are avoided, or at least reduced.

Preferably, the stop element is mounted in a pivotable, or tiltable, manner on the dispenser, in particular on precisely one bearing. The pivot axis or tilt axis may be oriented such that it is perpendicular and skew in relation to the longitudinal axis of the dispenser. It is preferred if the reset means is arranged, in the radial direction, diametrically opposite the precisely one bearing of the stop element.

In a preferred design, the stop element extends in the circumferential direction and/or has a passage opening for the piston.

Advantageously, the reset means has a spring element, in particular precisely one spring element, the spring force of which acts as a retting force of the reset means upon the stop element. This enables the reset means to be realized in a simple, robust, reliable and inexpensive manner.

It may be provided, moreover, that the reset means has a bolt around which the spring element extends. The pin and/or the spring element may be supported against the housing of the dispenser. The stop element may be arranged on the bolt such that it is guided along the bolt when the stop element is being moved.

It is preferred if the dispenser and its reset means are realized such that a piston-cylinder unit mounted on the dispenser can be separated from the dispenser by means of the reset means. The reset means thus facilitates automatic separation, or ejection, of the piston-cylinder unit from the dispenser after the first fastening means has been moved, out of its fixing position, into a release position in which a relative movement can be executed between the cylinder and the housing, counter to the direction of mounting. In addition, the dispenser is realized such that, when the first fastening means is in the release position, the piston-cylinder unit can be separated, or ejected, in an unimpeded manner from the dispenser.

In a further preferred design, the dispenser has a housing, and a first fastening means for fixing the cylinder to the dispenser. The first fastening means can be moved into a fixing position in which the first fastening means blocks a relative movement between the cylinder and the housing, counter to the direction of mounting.

In the case of this design, as a result of moving of the locking element, in particular in the axial direction, the first fastening means of the dispenser can be moved from its fixing position into a release position in which a relative movement between the cylinder and the housing can be executed, counter to the direction of mounting. When the locking element is in the release position, the movement capability of the stop element is thus uninfluenced by the locking element.

The dispenser according to the invention provides for ease of handling, in particular convenient release and/or separation of a piston-cylinder unit from the dispenser.

Preferably, the first fastening means has at least two pivotably mounted cylinder gripping levers, which, when the first fastening means is in the fixing position, can engage behind the fastening portion of the cylinder.

In a further preferred design, the dispenser has a second fastening means for fixing the piston to the dispenser. The second fastening means can be moved into a fixing position in which the piston is releasably connected to a piston actuator of the dispenser in such a manner that the piston can be moved relative to the cylinder, by means of the piston actuator, for the purpose of taking up and/or dispensing volumes of fluid. For this purpose, the second fastening means may have at least two pivotably mounted piston gripping levers.

In the case of this design, as a result of moving of the locking element, the second fastening means can be moved from its fixing position into a release position and vice versa, wherein the piston is not connected to the piston actuator when the second fastening means is in the release position.

Preferably, the second fastening means is motionally coupled to the piston actuator and, in its fixing position, can be guided, over the entire travel that it can execute during the moving of the piston actuator, by the locking element in such a manner that it remains in its fixing position.

Preferably, the second fastening means has two pivotably mounted piston gripping levers having cutting rollers, wherein the piston can be gripped by means of the piston gripping levers during moving the second fastening means into its fixing position. Each piston gripping lever in this case may have a positioning head, by means of which the respective piston gripping lever can be pivoted. During moving of the locking element and/or of the piston actuator, each positioning head is guided on a guide contour of the locking element. Advantageously, the extent of the guide contour in the axial direction is greater than the stroke that can be executed by the piston actuator. This prevents release of the second fastening means, in particular as a result of turning of the piston-cylinder unit.

In a further preferred design, the dispenser has an acquisition device for automatically identifying the type of a piston-cylinder unit mounted on the dispenser. The acquisition device has a radial information reader, by means of which information of a radially oriented information carrier portion of the piston-cylinder unit can be acquired. Alternatively or additionally, the acquisition device has an axial information reader, by means of which information of an axially oriented information carrier portion of the piston-cylinder unit can be acquired.

In the case of this design, at least a part of the radial information reader and/or at least a part of the axial information reader can be moved as a result of moving of the locking element.

Preferably, as a result of moving of the locking element, at least a part of the radial information reader can be inserted in the radial direction into a recess, extending in the radial direction, on a piston head of the piston-cylinder unit, and/or at least a part of the axial information reader can be inserted in the axial direction into a recess, in particular a groove, extending in the axial direction, in an end face of the piston head of the piston-cylinder unit.

In particular, the axial information reader has an acquisition element that can be inserted in the axial direction, at least partly, into the axially oriented recess. The dispenser has means by which the depth of the recess can be determined. The depth of the recess specifies the type of the piston-cylinder unit, at least partly. The term “type” in this case denotes, for example, a purpose, a state and/or a property of the piston-cylinder unit such as, for example, the maximum fluid volume that can be taken up and/or dispensed.

The expression “axially oriented recess” in this case is to be understood such that this recess is accessible in the axial direction of the piston-cylinder unit and/or the information thereof can be acquired in the axial direction of the piston-cylinder unit. The axially oriented recess has a geometric extent, in the axial direction of the piston-cylinder unit, by means of which the information of the axially oriented recess that can be acquired is coded. Moreover, the axially oriented recess has a geometric extent in the radial direction of the piston-cylinder unit and in the circumferential direction of the piston-cylinder unit.

The term “groove” is to be understood such that the recess extending in the axial direction of the piston-cylinder unit is not completely surrounded by piston material in the radial direction of the piston-cylinder unit, but is partly open in the radial direction, preferably along the entire depth of the recess. Such a design facilitates cleaning of the recess, and offers the possibility of ease of control.

Preferably, the acquisition element is realized in the manner of a plunger and/or in the shape of a pin and/or is spring-loaded, in particular elastically biased against the direction of mounting of the piston-cylinder unit. It is particularly preferred if the acquisition element can be moved into a release position as a result of moving of the locking element, and can be held, or blocked, there. As soon as the locking element no longer blocks the acquisition element, the spring-loaded acquisition element is moved toward the piston, and finally pressed into the recess of the piston that extends in the axial direction.

Preferably, the piston actuator can be moved onto the piston, in particular a piston head of the piston, until a stop of the piston actuator abuts on an end face of the piston. This movement, also referred to as block travel, serves to acquire a piston-side reference point. The piston-side reference point marks, in particular, the starting point of a determination of the depth of the axially oriented recess of the piston.

Preferably, the locking element is driven by means of a first motor, and/or the piston actuator is driven by means of a second motor. In particular, the first motor has a lesser nominal output power than the second motor.

Preferably, the dispenser according to the invention is a fully autonomous hand-held device that, irrespective of location, combines all components in one housing. These include, as usual, a gear unit, which converts the rotary motion of the drive into a longitudinal movement of the piston actuator, and a set of electronics and an electric power supply.

According to a second aspect of the invention, the previously stated object is achieved by a system for taking up and dispensing volumes of fluid.

The system according to the second aspect of the invention has a piston-cylinder unit, realized as a replacement part, and a dispenser as previously described. The piston-cylinder unit can be releasably mounted on the dispenser by means of a movement at least substantially in the axial direction, and has a piston and a cylinder that has a fastening portion.

A further aspect relates to a method for releasably mounting a piston-cylinder unit on a dispenser. The piston-cylinder unit has a piston and a cylinder that has a fastening portion. The dispenser has a housing, a stop element, a first fastening means, for fixing the cylinder to the dispenser, and a locking element. In particular, the dispenser is realized as described further above.

The method comprises the following method steps:a) placing the fastening portion of the cylinder of the piston-cylinder unit against the stop element of the dispenser by means of a movement at least substantially in the axial direction of the dispenser,b) moving the first fastening means of the dispenser into a fixing position, as a result of which the cylinder of the piston-cylinder unit is fixed to the dispenser by means of the first fastening means of the dispenser, such that a relative movement between the cylinder of the piston-cylinder unit and the housing of the dispenser is blocked counter to the direction of mounting, and optionally in the radial direction, andc) moving the locking element by means of a drive.

It may be provided in step a) that the piston is moved through a passage opening of the stop element. In order not to impede further pressing of the piston-cylinder unit, a piston actuator of the dispenser may be moved into a release position before step a).

Preferably, in step b) the first fastening means, in the fixing position, engages behind the fastening portion of the cylinder by means of at least two pivotably mounted cylinder gripping levers.

Preferably, the dispenser has an acquisition device, for automatically identifying a type of a piston-cylinder unit mounted on the dispenser. The acquisition device has a radial information reader, by means of which information of a radially oriented information carrier portion of the piston-cylinder unit can be acquired. Alternatively or additionally, the acquisition device has an axial information reader, by means of which information of an axially oriented information carrier portion of the piston-cylinder unit can be acquired. According to the method, it may now be provided that, in step c), as a result of moving of the locking element, at least a part of the radial information reader can be inserted in the radial direction into a radially oriented recess on a piston head of the piston-cylinder unit, and/or at least a part of the axial information reader can be inserted in the axial direction into an axially oriented recess, in particular a groove, in an end face of the piston head of the piston-cylinder unit.

Preferably, moving of the stop element in the direction of mounting is detected mechanically, electronically, inductively and/or optically, preferably by means of a light barrier.

In the case of a preferred embodiment of the method, in step c) the locking element of the dispenser is moved, preferably in the axial direction, into a locking position in which a relative movement between the stop element and the housing is blocked in the direction of mounting. This step may be performed automatically by the dispenser following a detection of a movement of the stop element in the direction of mounting. When the locking element is in the locking position, the fastening portion of the cylinder is clamped between the first fastening means and the stop element, such that a relative movement between the cylinder and the housing is blocked in the axial direction, and optionally in the radial direction and/or circumferential direction. The cylinder is thus held by positive engagement—between the stop element and the fastening means—on the dispenser.

It may be provided that, for the purpose of fixing the piston to the dispenser, as a result of moving of the locking element a second fastening means of the dispenser is moved into a fixing position in which the piston is releasably connected to a piston actuator of the dispenser in such a manner that, for the purpose of taking up and/or dispensing volumes of fluid, the piston can be moved relative to the cylinder by means of the piston actuator.

Advantageously, the locking element is moved by means of a first motor, and/or the piston actuator is moved by means of a second motor. The movements may be triggered upon an input by a user, or automatically by the dispenser.

For the purpose of taking up or dispensing a volume of fluid, a relative movement between the piston and the cylinder may be generated by means of the piston actuator. In this case, the path travelled by the piston relative to the housing of the dispenser may be determined incrementally, and/or the absolute travel position of a position element of the dispenser, which is motionally coupled to the piston actuator, may be acquired.

In the case of a preferred embodiment of the method, a reference point on the piston is acquired by moving the piston actuator of the dispenser toward the piston until a stop of the piston actuator abuts on an end face of the piston. The distance travelled by the piston actuator can then be determined, in particular by a means for incremental distance measurement.

Preferably, an acquisition element of the dispenser is inserted in the axial direction, at least partly, into an axially oriented recess in an end face of the piston, and the depth of this recess is determined. The determined depth value can be used to identify the type of the piston-cylinder unit.

A further aspect relates to a method for releasing a piston-cylinder unit mounted on a dispenser. The piston-cylinder unit has a piston and a cylinder. The dispenser has a housing, a first fastening means, for fixing the cylinder to the dispenser, and a locking element. In particular, the dispenser is realized as described further above.

The method comprises the following method steps:moving the locking element by means of a drive,moving the first fastening means out of a fixing position, in which the first fastening means blocks a relative movement between the cylinder and the housing, counter to the direction of mounting, into a release position, in which a relative movement between the cylinder and the housing can be executed, counter to the direction of mounting, andmoving the cylinder relative to the housing, counter to the direction of mounting.

Preferably, as a result of the moving of the locking element, a second fastening means of the dispenser is moved out of a fixing position, in which the piston is releasably connected to a piston actuator of the dispenser in such a manner that, for the purpose of taking up and/or dispensing volumes of fluid, the piston can be moved relative to the cylinder by means of the piston actuator, into a release position, in which the piston is not connected to the piston actuator.

Preferably, the piston-cylinder unit is separated from the dispenser by the resetting force of a reset means of the dispenser upon a stop element of the dispenser.

The invention is explained in greater detail in the following on the basis of the description of preferred exemplary embodiments, in part with reference to the drawing. The features described above and/or in the description that follows may be combined with each other as may be required, but may also be realized independently of each other, even if this is not expressly described in detail.

DETAILED DESCRIPTION OF THE INVENTION

Shown schematically inFIG.1is a perspective view of a preferred embodiment of a dispenser1according to the invention for taking up and dispensing volumes of fluid. The dispenser1has a housing2, an axial direction A and a radial direction R.

A piston-cylinder unit3can be releasably mounted on the dispenser1by means of a movement at least substantially in the axial direction A of the dispenser1. For this purpose, on an underside4the dispenser1has an opening5for receiving a part of the piston-cylinder unit3.

The term “direction of mounting” denotes a direction, at least substantially in the axial direction A of the dispenser1, toward the opening5of the dispenser1, thus from right to left inFIG.1. InFIG.1the direction of mounting F is indicated by an arrow.

Shown schematically inFIG.2is a perspective view of the dispenser1fromFIG.1and of a piston-cylinder unit3, as parts of a preferred embodiment of a system6according to the invention for taking up and dispensing volumes of fluid.

The piston-cylinder unit3is realized as a replacement part. It may be realized in the form of a syringe, and exist in various sizes having differing receiving volumes. It has a sealed piston7, which can be moved in a cylinder8of the piston-cylinder unit3for the purpose of taking up, or aspirating, and dispensing, or ejecting, a fluid to be pipetted or dosed. The cylinder8has a fastening portion9, which here is formed by a flange, thus an annular widening of the cylinder8, and specifically at that end of the cylinder8from which the piston7projects out of the cylinder8. The flange9has a U-shaped profile in longitudinal section, thus being similar to a collar.

FIGS.3and4show differing views of a part of the dispenser1fromFIG.1.FIGS.5to14show various views of the system6fromFIG.2in differing states. InFIGS.3to14, the dispenser1is represented only partially. This is becauseFIGS.3to14are limited to the representation of those components that in each case are necessary for explaining the present invention. In the case of the vertical longitudinal sections, the system fromFIG.2is cut along a plane that intersects the plane of the drawing in a vertical straight line (in a state other than the initial state). In the case of the horizontal longitudinal sections, the system fromFIG.2is cut along a plane that intersects the plane of the drawing in a horizontal straight line (in a state other than the initial state).

The dispenser1has a piston actuator10for moving the piston7relative to the cylinder8. The piston actuator10is arranged in a movable manner in the dispenser1and is driven by means of a first drive11, namely a motor11.

The dispenser has a locking element12, which is arranged in a movable manner in the dispenser1and is driven by means of a second drive13. The second drive13of the locking element12is separate from the first drive11of the piston actuator10.

In the case of the preferred exemplary embodiment represented here, the second drive13of the locking element12is an electric stepper motor. The locking element12is driven, by means of its drive13, via a self-arresting gear unit G. Here, the motor13has a lesser nominal output power than the motor11of the piston actuator10. This enables less expensive realization.

In the case of the preferred exemplary embodiment represented here, the locking element12is arranged so as to be movable in the axial direction A, and can be moved into different positions.FIG.3shows the locking element12in its initial position.

In the case of the preferred exemplary embodiment represented here, the dispenser1has a stop element14, having a passage opening15for the piston7, and a first fastening means16for fixing the cylinder8to the dispenser1. The stop element14is movable relative to the housing2, at least substantially in the axial direction A, and can be pressed relative to the housing2, at least partly, in the direction of mounting F.

Here, the dispenser1is realized such that, during mounting of the piston-cylinder unit3on the dispenser1, the fastening portion9of the cylinder8, specifically an abutment surface of this fastening portion9, can abut on the stop element14.

The first fastening means16can be moved into a fixing position in which the first fastening means16blocks a relative movement between the cylinder8and the housing2, counter to the direction of mounting F.

The locking element12in this case can be moved into a locking position in which the locking element12blocks a relative movement between the stop element14and the housing2, in the direction of mounting F. The stop element14can thus be locked. In this state, a relative movement of the cylinder8in the axial direction A is blocked, on the one hand, by the locking element12(in the direction of mounting F) and, on the other hand, by the first fastening means16(counter to the direction of mounting F).

When the locking element12is in the locking position, the fastening portion9of the cylinder8can be clamped between the first fastening means16and the stop element14in such a manner that a relative movement between the cylinder8and the housing2is blocked in the axial direction A and in the radial direction R and in the circumferential direction. The cylinder8is thus held by positive engagement—between the stop element14and the fastening means16—on the dispenser1.

In the case of the preferred exemplary embodiment represented here, the stop element14is pivotably mounted on the dispenser1, specifically on a bearing17. The pivot axis is oriented such that it is perpendicular to the longitudinal axis of the dispenser1. If the abutment surface of the fastening portion9of the cylinder8is taken as a notional annulus, then the pivot axis extends as a passant radially outside of the annulus, parallel to the annulus and in the direction of mounting F above the annulus, and perpendicular to the axial direction A. InFIG.4, the pivot axis is perpendicular to the plane of the drawing.

In the case of the preferred exemplary embodiment presented here, the dispenser1additionally has a reset means18, which exerts a resetting force upon the stop element14, at least substantially in the axial direction A, counter to the direction of mounting F. The reset means18is arranged, in the radial direction R, diametrically opposite the bearing17of the stop element14. Here, the reset means18has precisely one spring element19, the spring force of which acts as a resetting force upon the stop element14.

For this purpose, the reset means18has a bolt20as a guide for the spring element19. The bolt20extends in the axial direction A. The stop element14is arranged on the bolt20such that, during moving of the stop element14, it is guided along the bolt20. For this purpose, the stop element14has a lateral extension21that has a recess22for the bolt20. The spring element19is supported on the extension21and against the housing2.

Specifically, the stop element14can be moved, by application of force in the direction of mounting F—e.g., by a user who places a piston-cylinder unit3onto the stop element14and then presses further in the direction of mounting F—in this same direction, and counter to the resetting force. If the application of force ceases—e.g., because the user is no longer pressing further—the reset means18resets the stop element14, counter to the direction of mounting F, in particular by means of the spring force of the spring element19. This movement, however, is blocked by the fastening portion9of the cylinder8, held by the first fastening means16in its fixing position.

In the case of the preferred exemplary embodiment represented here, the first fastening means16can be moved from its fixing position into a release position for the fastening portion9by moving of the locking element12in the direction of mounting F. In this release position, a relative movement, between the cylinder8and the housing2, can be executed, counter to the direction of mounting F. If the locking element12is not in its locking position, it releases the movement capability of the stop element14. This is an important function for releasing a piston-cylinder unit3from the dispenser1. This release position of the first fastening means16(seventh state) is represented inFIG.11, the longitudinal section inFIG.11extending through the locking element12.

In the case of the preferred exemplary embodiment represented here, the first fastening means16has two pivotably mounted cylinder gripping levers23that, when the first fastening means16is in the fixing position, can engage behind the fastening portion9of the cylinder8. The cylinder gripping levers23are each of a two-arm design, having a gripping arm23aand an actuating arm23b, and are pivotably mounted in the connection region of the gripping arm23aand the actuating arm23b. Spring elements24act upon the cylinder gripping levers23in such a manner that, in the absence of a counteracting force, the gripping arms23aare pivoted radially inward, in particular toward each other. The cylinder gripping levers23are arranged and mounted in such a manner that, during mounting of a piston-cylinder unit3, the gripping arms23acan be forced radially outward by the fastening portion9of the cylinder8(first state, as shown inFIG.5), and then automatically engage behind the fastening portion9when the fastening portion has been moved far enough in the direction of mounting F. This second state is shown inFIG.6. The fixing position of the first fastening means16can be seen inFIGS.6to14.

Here, the gripping arms23aare arranged such that they are not visible in the vertical longitudinal sections represented. Moreover, the gripping arms23aare curved in cross section, such that, inFIG.5, in the case of the upper gripping arm23athat is not represented in section, it appears that this upper gripping arm23ais not forced far enough radially outward. In fact, here in each case an inner side of the respective gripping arm23aextends along the outer side of the fastening portion9, there being no need for the inner side of the respective gripping arm23ato completely abut on the outer side of the fastening portion9.

For the purpose of moving the first fastening means16from its fixing position into its release position by moving the locking element12in the direction of mounting F, the actuating arms23bof the cylinder gripping levers23of the first fastening means16each have a guide contour, in or on which in each case a cam26of the locking element12can engage when the locking element12is moved, in the direction of mounting F, into the release position. The guide contours25are realized and arranged such that, during moving of the locking element12in the direction of mounting F, the actuating arms23bare moved radially inward by means of the cams26. The gripping arms23aare thereby moved radially outward.

To facilitate automatic release and/or separation of a piston-cylinder unit3, the dispenser1and its reset means18are realized such that a piston-cylinder unit3mounted on the dispenser1can be separated from the dispenser1, by means of the reset means18, after the first fastening means16has been moved out of its fixing position and into its release position, and the piston-cylinder unit3has been released. For this purpose, the dispenser1and its reset means18are realized such that the spring element19can decompress when the fastening means16is in the release position, and separation of the piston-cylinder unit3from the dispenser1is not prevented.

In the case of the preferred exemplary embodiment represented here, the dispenser1has a second fastening means27, which serves to fix the piston7to the dispenser1. The second fastening means27can be moved into a fixing position in which the piston7is releasably connected to the piston actuator10of the dispenser1in such a manner that, for the purpose of taking up and/or dispensing volumes of fluid, the piston7can be moved relative to the cylinder8, between a retracted position and an extended position, by means of the piston actuator10. This fixing position of the second fastening means27is represented inFIGS.9,10,12and13.

For this purpose, the second fastening means27has two pivotably mounted piston gripping levers28, by means of which the piston7can be gripped during moving of the second fastening means27into its fixing position. Each piston gripping lever28here has a cutting roller, having five cutting elements formed on the cutting roller which, when the piston gripping lever28is moved into the fixing position, grip on the piston and partly penetrate the piston7.

In the case of the preferred exemplary embodiment represented here, as a result of the locking element12being moved in the axial direction A, the second fastening means27can be moved from its fixing position into a release position and vice versa, the piston7not being connected to the piston actuator10when the second fastening means27is in the release position. For this purpose, each piston gripping lever28has a positioning head28, and the locking element12has a matching guide contour30and an axial extension31. The piston gripping levers28can be pivoted by means of the positioning heads29. During moving of the locking element12and/or of the piston actuator10, each positioning head29is guided on the guide contour30of the locking element12.

When the second fastening means27is in the fixing position, both positioning heads29are guided in the guide contour30, in particular each in a separate portion between two walls of the guide contour30. In the release position, both positioning heads29abut on the axial extension31and the housing2, and are further apart from each other than in the fixing position.

If the second fastening means27is in its release position (FIG.8) and the locking element12is then moved, counter to the direction of mounting F, from its initial position into a second intermediate position, the positioning heads29are guided along the axial extension31and the housing2into the guide contour30, specifically each positioning head29being guided into its own portion of the guide contour30. The positioning heads29in this case are moved toward each other. As a result, the piston gripping levers28are moved onto the piston7until they grip, or fix, the piston7, in particular by their cutting rollers. The second fastening means27is then in its fixing position (FIG.9).

In the case of the preferred exemplary embodiment represented here, the second fastening means27is motionally coupled to the piston actuator10, and in its fixing position can be guided, over the entire travel that it can execute during moving of the piston actuator10, by the locking element12in such a manner that it remains in its fixing position. In particular, the extent of the guide contour30in the axial direction A is greater than the stroke that can be executed by the piston actuator10.

If the piston7is in its retracted position and the second fastening means27is in its fixing position, and if the locking element12is then moved, in the direction of mounting F, from the second position into a first intermediate position, the positioning heads29are guided along the guide contour30and finally out of the latter, such that the positioning heads29are guided between the axial extension31and the housing2. The positioning heads29in this case are moved apart from each other, or at a distance from each other. As a result, the piston gripping levers28are moved away from the piston7, such that the piston7is no longer fixed. The second fastening means27is then in its release position.

The axial extension31fulfills a further purpose, namely, it delimits the travel of the locking element12when the latter is moved, counter to the direction of mounting F, into its locking position without there being a piston-cylinder unit mounted on the dispenser1. In this case, owing to the absence of the cylinder8, the stop element14has no counter-stop. In order to prevent damage and ensure operational reliability, the axial extension31is realized and arranged such that, when the locking element12comes against the stop element14, it comes against a stop of the housing2, as a result of which the locking element12, and thus the stop element14, cannot be moved further counter to the direction of mounting F.

In the case of the preferred exemplary embodiment represented here, the dispenser1has means for optically sensing the mounting of a piston-cylinder unit3on the dispenser1. These means comprise a light barrier32having a light-beam source and a sensor for detecting light beams of the light-beam source, the light beam32being arranged such that moving of the stop element14in the axial direction A can be detected by the light barrier32. For this purpose, the stop element14has a web33, which is moved synchronously with the stop element14. When the stop element14is moved, or pressed, far enough in the direction of mounting F, the web33interrupts the light barrier32. Without force being applied to the stop element14, in the direction of mounting F, the stop element14is in its initial position, in which the light barrier32is not interrupted by the web33. The dispenser1can thus ascertain whether or not a piston-cylinder unit3has been mounted on the dispenser1. This sensing enables further steps to be triggered, e.g., moving of the locking element12.

In the case of the preferred embodiment represented, for the purpose of acquiring a piston-side reference point, the piston actuator10can be moved onto the piston7, until a stop34of the piston actuator10abuts on an end face of the piston7. This third state is shown inFIG.7. The absolute position of this piston-side reference point can be determined by means of a position determining means.

In the case of the preferred embodiment represented, the dispenser1has an acquisition device for automatically identifying the type of a piston-cylinder unit3mounted on the dispenser1. The acquisition device has a radial information reader, by means of which information of a radially oriented information carrier portion35of the piston-cylinder unit3can be acquired. In addition, the acquisition device has an axial information reader, by means of which information of an axially oriented information carrier portion36of the piston-cylinder unit3can be acquired.

The radially oriented information carrier portion35is realized hear as a radially oriented recess in the piston7, and the axially oriented information carrier portion36is realized as an axially oriented recess in an end face of the piston7.

As a result of the locking element12moving out of the first intermediate position and into the second intermediate position, at least a part of the radial information reader, namely a projection37, can be inserted into the radially oriented recess35, in the radial direction R. As a result of the locking element12moving out of its initial position and into the first intermediate position, at least a part of the axial information reader can be inserted into the axially oriented recess36, in the axial direction A. In particular, the axial information reader has an acquisition element38that can be inserted, at least partly, into the axially oriented recess36, in the axial direction A. The depth of the axially oriented recess36can be determined by the position determining means. The type of the piston-cylinder unit3can be identified, at least partly, on the basis of the thus determined depth of the recess36.

The previously determined piston-side reference point marks the starting point of a determination of the depth of the axially oriented recess36.

Here, the acquisition element38is elastically biased, by means of a spring39, counter to the direction of mounting F. By means of the locking element12, moved from the first intermediate position into its initial position, the acquisition element38can be moved into a release position, and held there. The locking element12holds the acquisition element38in its release position in that a driver40of the locking element12, on an extension41of the acquisition element38, counteracts the force of the spring39and blocks a movement of the acquisition element38in the direction of the spring force (thus, counter to the direction of mounting F).

As a result of the locking element12being displaced, counter to the direction of mounting F, from its initial position into the first intermediate position, a movement of the acquisition element38is no longer blocked, such that the acquisition element38is pressed by the spring39onto the piston7, and then into the axially oriented recess36, until the acquisition element38comes to the end of the axially oriented recess36, and is blocked there. This fourth state is shown inFIG.8.

Here, the axially oriented recess36is open upwardly in the axial direction A. The recess36is realized here in the form of a groove. It is thus not a cylindrical hole enclosed in the radial direction R. Instead, in the radial direction R the recess36is partly open outwardly, specifically along the entire depth of the recess36.

The dispenser1has further means, including an electronic control means, a gear unit, an electric power supply means, an indicating means and an input means.

Described in the following is a preferred sequence of a method for releasably mounting a piston-cylinder unit3on the dispenser1.

At the start of the method, the locking element12is in its initial position.

Firstly, the fastening portion9of the cylinder8of the piston-cylinder unit3is placed against the stop element14of the dispenser1, by means of a movement at least substantially in the axial direction A, typically manually by a user. The piston7is thereby moved through the passage opening15of the stop element14. In addition, the gripping arms23aof the cylinder gripping levers23are forced radially outward by the fastening portion9, such that the gripping arms23aslide along the fastening portion9. This first state is shown inFIG.5.

In order not to impede further pressing of the piston-cylinder unit3, before placement of the latter the piston actuator10was moved into a release position.

Following placement, the cylinder8is moved further relative to the housing2, in the direction of mounting F. The stop element14is thereby forced counter to the resetting force of the reset means18, in the direction of mounting F. The spring element19of the reset means18is thereby compressed.

When the cylinder8has been moved far enough in the direction of mounting F, the gripping arms23aengage behind the fastening portion9, whereby the first fastening means16is moved into its fixing position, as a result of which the cylinder8is fixed to the dispenser1, such that a relative movement between the cylinder8and the housing2is blocked counter to the direction of mounting F and in the radial direction R. This second state is shown inFIG.6.

The moving of the stop element14in the direction of mounting F is detected optically by means of the light barrier32. The piston actuator10is thereupon moved, counter to the direction of mounting F, onto the piston7, until the stop34of the piston actuator10abuts on an end face of the piston7. This third state is shown inFIG.7. The distance travelled by the piston actuator10is determined. A reference point on the piston is thereby acquired, which represents, as it were, a distance calibration that renders the method at least largely non-dependent on differences in the dimensional tolerances of the parts of the piston-cylinder unit3.

The locking element12is then moved automatically, counter to the direction of mounting F, into the first intermediate position. As a result, the acquisition element38is no longer blocked by the locking element12, and is inserted, at least partly into the axially oriented recess36in the axial direction A. This fourth state is shown inFIG.8. The depths of this recess36is determined, and the determined depth value is used to identify the type of the piston-cylinder unit3.

The locking element12is then automatically moved further, counter to the direction of mounting F, into the second intermediate position. As a result, the second fastening means27is moved with its piston gripping levers28into its fixing position, in which the piston7is releasably connected to the piston actuator10in such a manner that the piston7can be moved relative to the cylinder8, by means of the piston actuator10, for the purpose of taking up and dispensing volumes of fluid. This fifth state is shown inFIG.9. At the same time, the projection37of the radial information reader is inserted into the radially oriented recess35.

The locking element12is then automatically moved further counter to the direction of mounting F, into its locking position. This sixth state is shown inFIG.10. In this case, the fastening portion9of the cylinder8is clamped between the cylinder gripping levers23and the stop element14, such that a relative movement between the cylinder8and housing2is blocked in the axial direction A and in the radial direction R and in the circumferential direction.

A relative movement between the piston7and the cylinder8can now be effected, by means of the piston actuator10, for the purpose of taking up or dispensing a volume of fluid.

To release the piston-cylinder unit3mounted on the dispenser1, the piston actuator10is moved such that the piston7is in its retracted position. The locking element12is then moved, in the direction of mounting F, out of its locking position and, via the second intermediate position and the first intermediate position, into its initial position. As a result, the second fastening means27is moved out of its fixing position and into its release position. The piston7is now no longer connected to the piston actuator10. In addition, the projection37of the radial information reader is moved out of the radially oriented recess35, and the acquisition element38is moved out of the axially oriented recess36.

The locking element12is automatically moved further, in the direction of mounting F, into the release position. As a result, the first fastening means16is moved out of its fixing position and into its release position. This seventh state is shown inFIG.11. The relative movement between the cylinder8and the housing2can now be executed unimpeded, counter to the direction of mounting F.

The resetting force of the reset means18upon the stop element14, in particular the decompressing of the spring element19, causes the piston-cylinder unit3to be separated from the dispenser1. The movement of the stop element14initiated by the spring element19, in the axial direction A, is detected by the light barrier32.

The locking element12is moved automatically into its initial position, and the piston actuator10is moved into its initial position, such that the described sequence can recommence with the mounting of a piston-cylinder unit3.