EP3164214A1

EP3164214A1 - Pipette for activating a syringe

Info

Publication number: EP3164214A1
Application number: EP15732592.9A
Authority: EP
Inventors: Burkhardt Reichmuth; Jörg SATTLER; Marc Wilth
Original assignee: Eppendorf SE
Current assignee: Eppendorf SE
Priority date: 2014-07-04
Filing date: 2015-06-23
Publication date: 2017-05-10
Anticipated expiration: 2035-06-23
Also published as: PL3164214T3; WO2016001010A1; CN106470760B; US20170151556A1; CN106470760A; US10507463B2; JP6595518B2; JP2017523029A; EP3164214B1; DE102014109345A1

Abstract

Pipette for activating a syringe comprising – a rod-shaped housing, – a first receptacle with a first opening at the lower end of the housing for inserting a first fastening section at the upper edge of a cylinder of the syringe, – a receiving body with a second receptacle and a second opening at the lower end in the housing for inserting a second fastening section at a piston of the syringe, – first means for detachably holding the first fastening section in the first receptacle, – second means for detachably holding the second fastening section in the second receptacle, – first means for displacing the receiving body in the housing away from the first receptacle, – second means for displacing the receiving body toward the first receptacle in steps with a step size corresponding to the volume of liquid to be discharged from the syringe during the steps, – an actuatable operating element outside of the housing for carrying out individual steps, – a toothed rack with a toothing, arranged in the housing and connected to the receiving body, – a pawl, pivotably mounted on the operating element in the housing, which engages with the toothing of the toothed rack during downward displacement of the operating element and carries the same along, and which disengages with the toothing during upward displacement of the operating element, – an adjustable adjusting element outside of the housing for adjusting the step size of the steps, – a cover arranged displaceably on the toothed rack on the side of the pawl and comprising a detaining surface facing the pawl for preventing the pawl from engaging in the toothing and comprising a catching edge on the lower end, beneath which catching edge the toothing is uncovered for engagement by the pawl, – a coupling element arranged on the cover and coupled to the adjusting element in order to transmit an adjustment of the adjusting element to the cover, – wherein the cover has a first cover part made of plastic which comprises the coupling element and a longitudinal slot, and a second cover part made of sheet metal, held on the lower cover part, and which comprises a bend arranged in the longitudinal slot and a spring finger connected to the bend, – the catching edge is formed on the first cover part, – the toothed rack has a protruding notch on the side facing away from the cover which notch meets the bend in the longitudinal slot at the end of the displacement of the receiving body toward the first receptacle, by which means the spring finger is deflected and the pawl is prevented by the spring finger from a further engagement in the toothing of the toothed rack, and – the second cover part, with the exception of a section comprising at least the bend and spring finger, is overmoulded by the plastic of the first cover part in a defined position of the bend with respect to the coupling element, and by this means the first cover part and the second cover part are fixedly connected to each other.

Description

Pipette for actuating a syringe

The invention relates to a pipette for actuating a syringe.

The pipettes used here for actuating a syringe serve to dispense liquid received in the syringe in several steps. They are also referred to as dispensers or repeating pipettes. These pipettes have at the lower end of a rod-shaped housing a receptacle for a flange of a cylinder of the syringe and in the housing a displaceable receiving body with a piston receptacle for the upper end portion of a piston rod of a piston of the syringe. The syringe can be used with the flange and the end portion of the piston rod through axially directed openings of the receptacles. The flange and the end portion are held in the receptacles by means for detachable holding, which are designed, for example, as spring-loaded gripping levers. Furthermore, the pipette comprises means for displacing the receiving body, which allow a partial withdrawal of the piston from the cylinder for the suction of liquid into the syringe and a stepwise depression of the piston into the cylinder for the stepwise discharge of liquid.

DE 29 26 691 C2 and US 4,406,170 A describe means for displacing the receiving body in the housing. These include an elevator lever connected to the receiving body and projecting out of the housing through a straight-line slot for drawing fluid into the syringe by displacing the receiving body away from the receptacle. In addition, they include a rack-pawl means for stepwise piston advance by a reciprocating metering lever. At the metering a pivoting pawl is mounted. The rack is connected to the receiving body and arranged in the pivoting range of the pawl. An adjustable sliding cover covers the row of teeth on the rack more or less to limit the engagement of the pawl in the rack when pivoting the metering lever. The sliding cover is displaceable by means of a rotary knob, which is arranged on the pipette housing. The knob is designed with an eccentric guide curve in which engages a guide pin of the sliding cover. Further, the rack is designed with a lofty approach and the cover has an obliquely downwardly directed offset, which engages with the approach at far advanced piston, whereby the cover of the rack is displaced away, so that it prevents the pawl from to intervene in the uncovered teeth of the rack. This Resthubsperre prevents that a residual amount is discharged from the syringe, which is smaller than the dispensed at each dosing dose (dispensing volume).

The manual pipette "Multipette®" Eppendorf AG is designed according to the above patent.

Further developments of the means for releasably holding the syringe are described in EP 0 656 229 B1 and US Pat. No. 5,620,660 A. EP 1 724 020 Bl and US Pat. No. 7,731,908 describe a further development of the holding devices, which makes it possible to release the syringe from the pipette by one-hand operation.

EP 0 657 216 B1 and US Pat. No. 5 620 661 A describe such a pipette with a sensor for scanning elevations and depressions on the syringe flange of the syringes and correspondingly configured syringes. The sensor is used to determine the size of the syringe used. Based on the set increment, electronics determines the amount of fluid dispensed at each dispensing step. This is displayed on a display. Further developments of the means for displacing the receiving body are described in DE 44 37 716 C2, EP 0 679 439 B1 and US Pat. No. 5,591,408. According to EP 0 679 439 B1 and US Pat. No. 5,591,408 A, a repeating pipette has a constant stepping device which sets the width of the first step for displacing the receiving body for the actuating section of the syringe plunger to the cylinder receptacle for the syringe cylinder to a constant value which is independent of the setting of the following Is increments. By this constant reversal stroke when moving the receiving body back to the cylinder holder after the liquid is drawn up, a dosing accuracy impairing game between the pipette and syringe is overcome.

In the case of the Eppendorf AG manual pipette "Multipette® Plus", the cover has an elongated plastic sleeve in which a threaded rod is displaceably arranged, a metal sleeve is glued into the lower end of the plastic sleeve and the metal sleeve protrudes from the lower end of the plastic sleeve At a dosing step, the pawl first slides over the metal sleeve, which keeps the pawl from interfering with the threads of the threaded rod As it passes through the thread, it is pressed against the metal sleeve and the thread by means of a spring.Thanks to manufacturing tolerances, it can happen that the pawl under the incidence edge does not fall exactly into the thread root of the thread but onto a flank or on a crest of the thread the pawl meets a flank or the apex of the thread, which is located above the thread root, the metering lever must be a little further down, until engages the pawl in the thread root and advances the threaded rod and thus the piston of the syringe. This leads to a Dosierfehler, because it is delivered too little liquid. If the pawl meets a flank or the apex of the thread, which is arranged below the thread root, too little part of the pivoting movement of the metering lever is used for the displacement of the threaded rod and thus of the piston. Also in this case too little liquid is dispensed. It may even happen that the pawl slips off the flank or the apex of the thread and falls further down into the thread root or several times slipped over the thread, which leads to an increased dosing error or no liquid is discharged. The dosing error can be overcome by adjusting the threaded rod. For this purpose, the threaded rod is screwed into a setting thread in the receiving body for the upper end of the piston rod and provided with a transverse bore. By means of a pin inserted into the transverse bore, the threaded rod in another axial position with respect to the receiving body can be screwed. As a result, the position of the threaded rod is changed when the latch. This adjustment to the assembled pipette is complicated. If the metal sleeve is glued too deep into the plastic sleeve, too much liquid will be dispensed and the indicated number of dosing steps can not be achieved. This error must be corrected by replacing the cover.

In the case of the "Multipette®Plus", a sheet metal strip is fixed on the sleeve made of plastic, which has a protruding bend and a spring tongue running parallel to the rack.The sheet metal strip is held on plastic domes, the ends of which have been ultrasonically melted and reshaped. The rack has a cam at the end, the position of which is adjustable in the axial direction of the rack Piston meets the cam on the bend, whereby the deflectable portion of the metal strip deflected and the pawl is prevented from further engagement with the rack. As a result, the Resthubsperre is realized. In order for the residual lift lock to take effect precisely when there is insufficient dosing quantity available, the cam must be adjusted after adjusting the threaded rod. The production of the cover and the adjustments are complex. In addition, all adjustments must be made anew when replacing components of the piston drive.

DE 10 2012 011 938 AI describes a pipette, wherein the cover has a first cover part made of plastic, on which the guide pin is formed. On the first cover part, a second cover part is arranged in the form of a metal strip on which the incidence edge is formed and which has the angled portion and the spring tongue of Resthubsperre. The relative position of the first and the second cover part to each other in the longitudinal direction of the rack is adjustable by means of an eccentric of the cover. As a result, the distance from the incidence edge and guide pin is exactly adjusted to ensure despite manufacturing tolerances or wear or repair that the pawl always exactly falls into the rack. When adjusting the incidence edge, the residual stroke lock is also adjusted, so that then an adjustment of the Resthubsperre by adjusting the axial position of the cam on the rack is required. Even with this cover the cost of manufacturing and assembly is high, as always two adjustments must be made. When replacing components of the piston drive, the adjustments must be repeated. Another disadvantage is that the cam on the rack is first guided on a smooth inner surface of the cover member until it enters a longitudinal slot of the first cover member by striking the bend. When crossing the cam in the Longitudinal slot may cause a small lateral movement of the rack, which prevents a correct incidence of the pawl in the rack, if the adjustments are not made sufficiently accurate.

The "Handy-Step-S" manual pipette from Brand also adjusts the volume of liquid to be dispensed at each step with a rotary knob The other part of the rotary knob has the guide cam which is engaged by the pin protruding from the cover, turning the knob moves the cover along the rack. By adjusting the angular position of the two rotary knob parts, the position of the incidence edge can be adjusted so that the latch falls into a valley of the toothing.This pipette is disadvantageous because of the high constructional effort and the high outlay for the adjustment that has to be made with the pipette assembled.

The above pipette is essentially described in DE 20 2010 010 942 Ul.

Based on this, the present invention seeks to provide a pipette in which an optimal collapse of the pawl can be achieved in the rack with further reduced effort for manufacture and assembly.

The object is achieved by a pipette having the features of claim 1.

Advantageous embodiments of the pipette are specified in subclaims.

The pipette according to the invention for actuating a syringe has a rod-shaped housing,

a first receptacle having a first opening at the lower end of the housing for inserting a first attachment portion at the upper edge of a cylinder of the syringe,

a receiving body having a second receptacle and a second opening at the lower end in the housing for inserting a second attachment portion on a piston of the syringe,

first means for releasably holding the first attachment portion in the first receptacle,

second means for releasably holding the second attachment portion in the second receptacle,

first means for displacing the receiving body in the housing away from the receptacle,

second means for displacing the receiving body toward the first receptacle in steps of one increment corresponding to the volume of fluid to be expelled from the syringe during the steps,

an actuatable outside the housing actuator for performing individual steps,

one connected to the receiving body, arranged in the housing rack with a toothing,

a in the housing on the actuating element pivotally mounted pawl, which comes with displacement of the actuating element downwards with the teeth of the rack engages and this entrains and dislocation of the actuator comes up out of engagement with the teeth, an adjustable outside of the housing adjustment for adjusting the Increment of steps, A cover displaceably arranged on the rack on the side of the pawl, with a pawl facing the pawl for disengaging the pawl from engagement with the toothing and an incipient edge at the lower end below which the toothing is exposed for engagement by the pawl;

A coupling element arranged on the cover, which is coupled to the setting element in order to transmit an adjustment of the setting element to the cover,

Wherein the cover comprises a first cover part made of plastic, which comprises the coupling element and a longitudinal slot, and a second cover part, which is held on the first cover part and comprises a bend arranged in the longitudinal slot and a spring tongue connected thereto,

The incidence edge is formed on the first cover part,

• The rack on the side facing the cover has a protruding cam, the slit at the end of the displacement of the receiving body for receiving in the longitudinal direction meets the bend, whereby the spring tongue deflected and the pawl of the spring tongue at a further engagement in the teeth Rack is held, and

• The second cover member except for at least angled section and spring tongue comprehensive portion of the plastic of the first cover member in a defined position of the bend with respect to the coupling element and thereby the first cover part and the second cover part are firmly connected.

In the previous pipettes it was assumed that an optimal collapse of the pawl in the toothing of the rack and an effect of the Resthubsperre upon actuation of the actuator, in which no more complete dosing is possible, requires two adjustments. The invention is based on the finding that for the optimal engagement of the pawl and the correct triggering of Resthubsperre compliance with defined distances of coupling element and incident edge and incident edge and angling and accurate positioning of the cam with respect to the toothing on the rack are relevant. Furthermore, the invention is based on the finding that the production methods used hitherto (sheet metal processing and injection molding) and joining methods (gluing, forming of retaining domes and screwing) do not allow sufficient manufacturing tolerances for this purpose. Surprisingly, it was found with the invention that by partially encapsulating the second cover part in a defined position of the bend with the plastic of the first cover part sufficiently accurate distances between coupling element and incidence edge and incidence edge and angling can be achieved. During encapsulation of the second cover part, the entire first cover part and thus also the coupling element and the incidence edge are injection-molded. By encapsulating the first and second cover part are firmly connected. Coupling element, incidence edge and angling have defined distances from each other due to the high accuracy of the injection molding process and the exact positioning of the bend during injection molding. The combination of injection molding and accurate positioning of the bend a sufficiently dimensionally stable coverage is achieved. Tolerances in the production of the second cover member made of sheet metal do not affect the dimensional accuracy of the cover, because in injection molding, the bend occupies a defined position and coupling element and incidence edge are generated at defined intervals of the bend. In the production of the cover, the second cover part is first inserted into an injection mold, wherein the bend is supported on a contact surface of the injection molding and then encapsulated with the mold partially closed with the plastic of the first cover part. The rack is preferably molded in one piece with the plastic cam. Alternatively, the rack is provided with an adjustable cam to compensate for remaining inaccuracies.

In the case of the pipette according to the invention, production and assembly costs are reduced and, nevertheless, the desired accuracy of the metering and the residual stroke lock is ensured. Subsequent readjustments have proven to be fundamentally unnecessary, so the lack of adjustment possibilities is not a disadvantage. Also, when replacing components of the piston drive no readjustment is required, since equally accurate components can be used.

According to an embodiment of the pipette, a head portion of the second cover member adjacent to an upper slot portion of the longitudinal slot on the rack side facing the edge of the plastic of the first cover member encapsulated and the head portion is connected at the lower end with the bend, in a lower slot portion of Longitudinal slot is arranged next to the second cover member is not molded with the plastic of the first cover member, so that the cam in the longitudinal slot can slide along the head portion before he meets the bend. This embodiment avoids a lateral deflection of the cam when entering the slot and thereby avoids dosing errors caused thereby.

According to a further embodiment, the second cover part has a first strip-shaped connected to the lower end of the head portion Section which is connected at the lower end with the bend and arranged in the lower slot portion. The first strip-shaped section forms a spiral spring, which facilitates the deflection of the bend by the cam.

According to a further embodiment, the second cover part has a third strip-shaped section connected to the lower end of the bend, which is arranged in the lower slot section and on which the cam can slide after passing through the bend. As a result, the displacement of the cam is facilitated by the bend over upwards.

According to a further embodiment, a connecting portion is connected to a longitudinal edge of the first or second strip-shaped portion, extends through a recess in the top of the first cover member to the longitudinal edge of the first cover member and extending over a deflection parallel to the longitudinal side of the first cover member down connected to the spring tongue. This is advantageous for the production and favors a wide deflection of the spring tongue.

According to a preferred embodiment, the second cover part is resilient.

According to a further embodiment, the second cover part is made in one piece from sheet metal, ie from a flat, thin-walled metal sheet. The wall thickness of the sheet is a maximum of 0.5 mm, preferably 0.4 mm. For the production of the second cover part, one or more of the following sheet-metal processing methods are preferably used: stamping, laser cutting, etching, bending, wire EDM, water jet cutting. According to a preferred embodiment, the adjusting element is a dial. According to a further embodiment, the guide curve is spiral.

According to one embodiment, the second cover part is covered on the side facing away from the rack side of the first cover part of transverse to the rack extending webs of the first cover part. The webs bridge the longitudinal slot on the side facing away from the rack and keep the first cover part together at the top to save material.

According to a further embodiment, a web carries the coupling element.

According to a further embodiment, the coupling element is a protruding from the first cover part pin and the adjusting element has a guide curve on the underside, in which engages the pin, so that upon adjustment of the adjusting element, the guide cam moves the pin in the axial direction of the rack.

According to a preferred embodiment, the lower end of the first cover part on the incidence edge. This allows a particularly accurate positioning of the incidence edge with respect to the coupling element.

According to a further embodiment, the first cover part has a wall thickness gradually decreasing towards the lower end. As a result, the incidence edge has a particularly short distance from the rack, which promotes that the pawl always coincides with their teeth exactly in the toothing of the rack. Due to the greater wall thickness of the first cover part above the incidence edge, a sufficient breaking strength can be achieved. According to a preferred embodiment, the first cover part at the engagement edge has a wall thickness of at most 0.5 mm, preferably from 0.2 to 0.4 mm.

According to a further embodiment, the first cover part on the side facing the rack on a flat contact surface on which the rack can create and in which the longitudinal slot is arranged. As a result, an accurate and low-friction guidance of the rack is achieved in the cover part.

According to a further embodiment, the first cover part with the planar contact surface on the side facing away from the rack side to the lower end to a chamfer. As a result, a particularly small distance of the incidence edge is achieved by the rack.

According to a further embodiment, the first cover part has the shape of an elongated hollow body with two parallel, strip-shaped side parts and a base defining a channel, wherein the longitudinal slot is formed in the base and the second cover part is encapsulated in the base of the plastic of the first cover part , In the channel, the rack can be accurately guided.

According to a further embodiment, the first cover part on the two longitudinal sides laterally projecting wings. The wings can be used for precise guidance of the cover part in the housing.

According to a preferred embodiment, the rack with the cam is integrally molded from plastic. According to a further preferred embodiment, the first cover part and / or the rack made of PEEK or of another plastic with similar mechanical properties.

According to a preferred embodiment, the pawl on a plurality of ratchet teeth, which engage in the toothing of the rack after passing the incidence edge. However, the invention also includes embodiments in which the pawl has only a single pawl tooth.

According to a further embodiment, the cam is arranged einjustierbar on the rack in the axial direction. According to another embodiment, the cam on the side of the Abhalteelements protrudes through a slot of the rack and has an axial bore, an adjusting screw is screwed through the bore into a Einstellgewinde at the upper end of the rack and is a spring element between the upper end of the Rack and arranged the cam. This configuration allows adjustment of the axial position of the cam on the rack. As a result, the position of the rack is affected, in which the cam meets the second cover part and the Resthubsperre is effective.

According to a further embodiment, the first cover part made of plastic and / or the second cover part is made of a metal sheet. The first cover part is preferably made by injection molding and / or the second cover part by etching and / or punching and / or laser and / or wire EDM and / or water jet cutting and / or bending a sheet or other manufacturing processes. The means for releasably holding the first fastening portion in the first receptacle and the second fastening portion in the second receptacle are preferably formed as in EP 0 656 229 B1 and US Pat. No. 5,620,660 A or in EP 1 724 120 B1 and US Pat 7,731,908 B2, the content of which is hereby incorporated into the present application.

The first means for displacing the receiving body in the housing are preferably designed as elevator levers, as described in DE 29 26 691 C2 and US Pat. No. 4,406,170A or the publications cited in the preceding paragraph, the contents of which are hereby incorporated into the present application.

According to one embodiment, the pipette has a sensor for scanning elevations and depressions on the syringe flange of the syringes, as described in EP 0 657 216 Bl and US Pat. No. 5,620,661 whose contents are hereby incorporated into the present application.

In the present application, the term "toothed rack" is used to refer both to a toothed rack in the true sense, ie a rod with a series of teeth arranged thereon, and to a threaded rod, ie a rod with at least one thread arranged thereon provided with a rack in the true sense.

In the present application, the terms "top" and "bottom", "high" and "deep" and derived terms refer to the orientation of the pipette in which the bar-shaped housing is vertically aligned and the receptacle for the syringe is located below. The invention is described below with reference to the accompanying drawings

Embodiment explained in more detail. In the drawings show:

1 a pipette according to the invention with a syringe held therein in a

Perspective view from the side;

FIG. 2 shows the same pipette in a longitudinal section; FIG.

Fig. 3 the same pipette with removed front housing half in one

Perspective view obliquely from the front and from the side;

4 shows an upper frame part with components of the same arranged therein

Pipette with removed housing in an enlarged perspective view;

Fig. 5 shows the same arrangement in a longitudinal section;

Fig. 6 rack with actuator, latch and cover the same pipette in a further enlarged perspective view; Fig. 7 shows the cover in a perspective view;

8 shows a second cover part in an enlarged perspective view;

9 shows the dial in a view from the bottom;

10 shows the pipette on actuation of the actuating element before the engagement of the pawl in the toothing in a longitudinal section;

11 shows the pipette in the same situation in an enlarged detail view;

12 shows the pipette during optimal engagement of the pawl in the toothing in a longitudinal section;

13 shows the pipette in the same situation in an enlarged detail view;

Fig. 14 shows an alternative rack in an upper frame part with

Actuator, pawl and cover in a longitudinal section.

1, a pipette 1 has a rod-shaped housing 2 in which a syringe 3 is held at the bottom. From a side wall of the housing 2 is above a straight line slot 4 an elevator lever 5 of the housing 2 in front. From the same side wall of the housing 2 is about two further slots 6, 7, a control knob 8 of a rack-pawl control before. In addition, a display device in the form of a display 9 is embedded in the same side wall of the housing 2. From openings in the adjacent side wall are segments of a dial 10 out.

According to FIG. 2, the syringe 3 has a cylinder 11 and a piston 12 arranged displaceably therein. The cylinder 11 has at the bottom a conical portion 13 with a hole 14 for the passage of liquids and above a cylindrical portion 15 in which the piston 12 is displaceable. At the top, the cylinder 11 has a first mounting portion 16 with a peripheral flange 17. From the piston 12 is upwardly a piston rod 18 which has a second mounting portion 19 with a plurality of circumferential beads.

The syringe 3 is arranged with the flange 17 in a first receptacle 20 at the lower end of the housing 2, which at the lower end of the housing 2 has an axially directed first opening 21 for insertion and removal of the syringe 3. The syringe 3 presses with its upper side against a pressure-sensitive ring sensor 22, which scans projections on the upper edge of the flange 17. The indicated on the flange 17 code denotes the size of the respective syringe 3. The flange 17 is held in this position by means of first means for releasably holding in the form of first gripping levers 23 in the housing 2.

The second attachment portion 19 of the piston 12 is arranged in a second receptacle 24 in a hollow cylindrical receiving body 25. This has for insertion of the second attachment portion 19 on an axially directed second opening 26. The second attachment portion 19 is by means of second means for releasably holding held in the form of second gripping levers 27 which engage between the beads of the second mounting portion 19 or pinch this.

The receiving body 25 is fixedly connected to a rack 28 with a toothing 29 which extends below the slot 4 in the longitudinal direction of the housing 2.

An elevator shebelhalterung 30 is fixed to the receiving body 25 and to a lower part of the rack 28.

Further, an elevator lever carrier 31 is present, which abuts with a sliding plate 32 at the bottom of the edges of the slot 4. The elevator lever carrier 31 has an upwardly projecting post 33, which passes through the slot 4. On the post 33, the elevator lever 5 is fixed outside the housing 2.

At the end of the displacement of the receiving body 25 to the first receptacle 20 towards the plate 32 meets the lower edge of the slot 4, whereby a lower stop is given.

In the upper half of the housing 2, an actuating element in the form of a metering lever 36 is pivotably mounted in a swivel bearing 34 in a bulge 35 of the slot 4 opposite side wall of the housing 2. The metering lever 36 has shown in FIGS. 3 to 6, two spaced apart legs 37, 38 which protrude on the opposite side wall of the housing 2 from the two slots 6, 7. There, the control knob 8 is fixed to the protruding ends of the legs 37, 38. At the end of the displacement of the receiving body 25 from the first receptacle 20 away upwards, the elevator lever carrier 31 strikes a fixedly arranged in the housing 2 bearing body in which the pivot bearing 34 is formed for the metering lever 36. As a result, the upper stop for the displacement of the receiving body 25 is given.

Between the two legs 37, 38 of the metering lever 36, a pawl 39 is pivotally mounted. The pawl 39 is arranged with a plurality of ratchet teeth 40 (three in the example) above the toothing 29 of the rack 28. The metering lever 36 is pressed by a spring device in the position of Fig. 2. Contrary to the action of the spring device of the metering lever 36 by pressing the control knob 8 is pivoted downwards. The pawl 39 is pressed by means of a further spring means to the toothing 29 of the rack 28. As a result, the rack 28 is pushed down.

Between the pawl 39 and the rack 28, a sliding cover 41 is arranged. The cover 41 is displaceable by turning the laterally projecting out of the housing 2 dial 10 so that it covers the teeth 29 of the rack 28 more or less. The pawl is first pressed against the cover 41 upon actuation of the control knob 8 and falls under it into the toothing 29 a. Therefore, the amount of displacement of the rack bar 28 when pivoting the metering lever 36 downward depends on the position of the cover 41 with respect to the toothing 29.

The cover 41 consists, according to FIG. 7, of a first cover part 42 made of plastic and a second cover part 43 made of a thin sheet metal, which is partially embedded in the plastic of the first covering part 42 by encapsulation. 8, the second cover part 43 has a head portion 44, which in the example has the shape of a wide strip. The head portion 44 has at the bottom on the two longitudinal sides opposing notches 45, 46, which serve the anchorage in the plastic of the first cover part 42. Below this, the head portion 44 has a taper 47.

The lower end of the taper 47 is connected to a first strip-shaped portion 48. The first strip-shaped section 48 is connected via a counter-angled bend 49 with a second strip-shaped section 50. The head portion 44, the first strip-shaped portion 48 and the second strip-shaped portion 50 have a common longitudinal axis.

The second strip-shaped portion 50 is connected in the upper part on one longitudinal side with a strip-shaped connecting portion 51 which protrudes perpendicularly from the second strip-shaped portion 50. The connecting portion 51 is connected via a deflection 52 with a spring tongue 53.

The second cover part 43 is made in one piece from a thin sheet metal. This is preferably a resilient material, in particular a spring steel.

As shown in FIG. 7, the first cover member 42 is generally in the form of an elongated hollow body having a U-shaped cross section. It has two parallel strip-shaped side parts 54, 55 and a base 56 bridging these. The side parts 54, 55 and the base 56 have inside planar contact surfaces for guiding the rack 28. The side members 54, 55 and base 56 define a channel 57.

An upper base part 58 has a greater wall thickness than a lower base part 59 of the base 56. Upper and lower base parts 58, 59 are connected to one another via a ramp 60, so that a smooth transition exists between the outer sides.

A longitudinal slot 61 extends centrally in the base 56. The longitudinal slot 61 extends over the entire upper base part 57 and ends shortly before the lower end of the lower base part 59.

In the region of the upper base part 58, an upper slot section 62 of the longitudinal slot 61 is covered laterally by the head section 44.

A lower slot portion 63 of the longitudinal slot 61 extends in the lower base part 59 and is wider than the first and second strip-shaped portions 48, 50 and the angled portion 49, which are disposed within or slightly in front of the slot portion 63. Thus, a gap exists on both sides of the first and second strip-shaped section 48, 50 and the bend 49 and the lower slot section 63.

The head portion 44 is encapsulated within the upper base part at the edge with the plastic of the first cover part 42. On the side facing away from the rack 28 side, the width of the edge-facing plastic enclosure is less than on the side of the head portion 44, which faces the rack 28, where the edge-side enclosure defines the upper slot portion 62 In the upper base portion 58 are the notches 45, 46 anchored. As a result, the second cover part 43 is fixed to the first cover part 42. The portions of the second cover part 43 below the head portion 44 are not encapsulated and therefore rebuttable with respect to the first cover part 42. For this purpose, the taper 47 or the first strip-shaped section 48 emerges from the ramp 60.

On the outside of the head portion is bridged by webs 64 to 67, which cut perpendicular to the head 44 extend.

From the web 65 projects a coupling element 68 in the form of a pin, which is injection-molded in one piece with the first cover part 42.

The first cover part 42 has in the outer side a recess 69 which extends from the lower slot portion 63 to the lateral edge of the side part 54. Through this recess 69, the connecting portion 51 extends to the side, so that the spring tongue 53 extends at a small distance from the first cover part 42.

The first cover part 42 has an incident edge 70 at the lower end. This is formed at the lower end of the lower base part 59. There, the lower base part 59 has a wall thickness of at most 5 mm, preferably 4 mm or even lower.

The outer side surface of the lower base portion 59 is a detent surface 71 for the pawl 39. The lower base portion has a chamfer 72 at the bottom on the outside. At the upper end of the chamfer 72, the lower base portion 59 has a wall thickness of 5 mm or more.

The incidence edge 70 is interrupted by a short, slit-like axial space 73 extending in the axial direction. Perpendicular to the outer sides of the side parts 54, 55 are strip-shaped wings 74, 75 before.

The cover 41 is produced, in which the second cover part 43 is inserted into an injection mold, so that the bend 49 rests against a certain contact surface. Thereafter, the tool is closed and the first cover member 42 injection molded. The finished cover is characterized in that the bend 49, pin 68 and incidence edge 70 with sufficient tolerances occupy predetermined positions.

According to Fig. 2 to 7, the rack 28 extends through the channel 57 of the first cover 42. The pawl 39 is threaded with a guide slot 76 at the lower end to the spring tongue 53 of the second cover 43. On the wings 74, 75, the cover 41 is slidably guided in the housing 2 in the longitudinal direction.

By turning the dial 10, the cover 41 is displaceable in the longitudinal direction. 9 has a central bearing hole 77 and a helical guide cam 78. The dial 10 is rotatably mounted on the bearing hole 77 on an axis on the housing 2 and the pin 68 of the cover 41 engages the guide cam 78 a. As a result, upon rotation of the dial 10, the cover 41 is displaced along its guide in the housing 2.

The dial 10 is associated with a further sensor 79 which detects the rotational position of the dial 10.

According to FIG. 5, a cam 80 is firmly molded onto the upper end of the rack 28 at a defined position. Upon a downward displacement of the rack 28, the cam 80 is moved through the longitudinal slot 61 of the cover 41 and enters from the upper slot portion 62 in the lower slot portion 63 a. Finally, the cam 80 meets the protruding bend 49 and presses it together with the spring tongue 53 forward (in Fig. 5 to the top). As a result, the guided on the spring tongue 53 pawl 39 is excavated from the toothing 29 and realized a Resthubsperre.

In addition to the rack 28, a transfer member 81 is arranged for controlling a Umkehrhubes in the housing of the pipette. The transmission member 81 has a strip-shaped transmission section 82, which is guided parallel to the rack 28 in the housing 2 of the pipette and displaced.

The strip-shaped transfer section 82 has a lower transfer member end 83, which is located in a displacement of the transfer member 82 down in the displacement region of a side of the rack 28 protruding lower stop 84.

To the upper end of the strip-shaped transfer section 82, two control arms 85, 86 are connected, which are arranged parallel to each other in a plane perpendicular to the plane of the drawing.

The transmission member 81 is displaceable so that the control arms 85, 86 reach with their upper ends in the displacement region of beveled stop edges on the legs 37, 38 (see Fig. 2).

The transmission member 81 and the cooperating components are preferably formed as in European Patent Application 120 02 849.3-2113 and in US 13 / 867,800, the contents of which are hereby incorporated by reference in the present application.

Further, in the upper half of the housing 2, a printed circuit board 87 is arranged with an electronics 88. There is also an electrical power supply in the form of at least one battery 89 (eg button cell) or a battery 89. The electronics 88 is wired to the ring sensor 22, the further sensor 79 for detecting the rotational position of the dial 10 and the display 9 , Further, the electronics 88 is connected to the battery 89.

The electronics 88 determined from the measurement signals supplied by the ring sensor 22, the respective syringe size and the setting of the dial 10, the respective step size. From this it calculates the set dispensing volume and brings it to display 9 for display.

In the application of the pipette 1, a syringe 3 is first connected with a user-selected syringe size releasably connected to the pipette 1 by being inserted with the first mounting portion 16 in the receptacle 20 and with the second mounting portion 19 in the receptacle 24, so that the Flange 17 of the first gripping levers 23 and the attachment portion 19 is gripped by the second gripping levers 27. This situation is shown in FIG.

The ring sensor 22 scans the coding on the flange 17 of the syringe 3. The electronics 88 determines from the signals supplied by the ring sensor 22 that a syringe 3 is inserted and turns on the display 9. The electronics 88 determines based on the signals supplied by the ring sensor 22 and the further sensor 79, the set Dispensiervolumen and brings this on the display 9 for display. Optionally, the user changes by means of the dial 10 the Setting the Dispensiervolumens and the changed Dosiervolumen is displayed by the display 9.

To draw liquid through the hole 14 of the syringe 3, the elevator lever 5 is pushed upwards from the position of FIG.

At the end of the elevator movement of the lower stop 84 takes the transmission member 81 with.

Before the set dosing volume can be dispensed step by step, a reverse stroke must be carried out. This is done by pressing the control knob 8. Here meet the legs 37, 38 on the control arms 85, 86 and shift the transmission member 81 down. The transmission member 81 takes over the lower stop 84 with the rack 28. This reverse stroke removes the lots from the system.

Thereafter, the absorbed liquid amount can be delivered in small steps by the control knob 8 is pressed repeatedly against the action of the spring device down. Here, the further spring device pushes the pawl 39 with the ratchet teeth 40 against the retention surface 71 of the cover 41 until the ratchet teeth 40 reach the lower end of the retention surface 71. This situation is shown in FIGS. 10 and 11.

After exceeding the incidence edge 70, the pawl 39 falls with the ratchet teeth 40 in the toothing 29 of the rack 28 and takes the rack 28 during further pivoting of the metering lever 36 down with a piece. This situation is shown in FIGS. 12 and 13. Due to the precise positioning of pin 68 and incidence edge 70, the ratchet teeth 40 fall in exactly the toothing 29 a. The displacement of the rack 28 with each pivoting of the metering lever 36 until reaching a lower stop depends on a set by means of the dial 10 position of the cover 41 from. After relieving the control knob 8 he is pushed by the spring device up and another dosing can be performed.

The dispensing without NachbefüUen the syringe 3 is possible until the residual amount of liquid remaining in the syringe 3 is smaller than the set Dosiermenge. Then the Resthubsperre ensures that the ratchet teeth 40 can not enter the toothing 29 by the cam 80, the spring tongue 53 is actuated, which pivots the pawl 39 of the rack 28.

Due to the exact positioning of the cam 80 on the rack 28, the pawl 39 is prevented from engaging the rack 28 when a full dosing step is no longer possible.

Residual liquid in the syringe 3 can be discharged by displacing the elevator lever 5 down. Thereafter, the syringe 3 can be separated from the pipette 1. For this purpose, the user actuates the first gripping levers 23 which act on the second gripping levers 27 via projections on the inside, as described in EP 0 656 229 B1 and US Pat. No. 5,620,660 A.

Preferably, a pipette according to the invention instead of directly manually operable gripping levers 23, 27 first and second means for releasably holding the syringe, which are formed as described in EP 2 033 712 AI and US 2009/139351 AI, the content hereby in the this application is incorporated. In the pipette according to the two aforementioned publications, the syringe after emptying by a further actuation of the metering lever detached from the pipette. For this purpose, the pipette on a transmission which is controlled by the metering lever and acts on the first and second means for holding the syringe to release the syringe from the pipette. According to an embodiment of this pipette, the first and second releasably holding means are designed as gripping levers which are integrated into the housing and can not be actuated directly from the outside.

Referring to Figs. 12 and 13, the pawl 39 optimally engages the teeth, i. each ratchet tooth 40 engages exactly in a valley between two teeth of the toothing 29 a.

FIG. 14 shows a pipette with an alternatively formed rack 28.

In this rack 28, the cam 80 projects from a further longitudinal slot 90 of the rack 28 to the outside. Under the further longitudinal slot 90, the cam 80 has an axial bore 91. An adjusting screw 92 is screwed through the axial bore 91 into a Einstellgewinde 93 at the upper end of the rack 28. A coil spring 94 is guided on the adjusting screw 92 and is supported at one end on the screw head of the adjusting screw 92 and the other end at the upper end of the rack 28 to hold the cam 80 in contact with the screw head.

By turning the adjusting screw 92, the position of the cam 80 in the longitudinal direction of the rack 28 is variable. This allows adjustment of the Resthubsperre, if this - for whatever reason - should be required. LIST OF REFERENCE NUMBERS

1 pipette

2 housings

3 syringe

4 slot

5 elevator shebel

6 slot

7 slot

8 control knob

9 display

10 dial

11 cylinders

12 pistons

13 conical section

14 holes

15 cylindrical section

16 first attachment section

17 flange

18 piston rod

19 second attachment portion

20 first shot

21 first opening

22 ring sensor

23 first gripping lever

24 second shot

25 receiving body

26 second opening

27 second gripping lever

28 rack

29 teeth

30 elevator shebelhaltemng

31 elevator lever carrier

32 sliding plate

33 posts

34 pivot bearings

35 bulge

36 dosing lever

37 thighs

38 thighs

39 pawl

40 ratchet teeth cover

first cover part

second cover part

Head cut off

notch

rejuvenation

first strip-shaped section

angling

second strip-shaped section strip-shaped connection sab section

redirection

spring tongue

side panel

Base

channel

upper base part

lower base part

ramp

longitudinal slot

upper slot section

lower slot section

web

Coupling selement

deepening

incidence edge

withholding surface

bevel

free space

wing

Guide s slot

bearing hole

guide curve

Another sensor

cam

transmission member

transmission section 83 lower transfer member end

84 lower stop

85 control arm

86 control arm

87 circuit board

88 electronics

89 battery

90 additional longitudinal slot

91 axial bore

92 adjusting screw

93 one adjusting thread

94 screw fields

Claims

Claims:

1. Pipette for actuating a syringe with

a rod-shaped housing (2),

- A first receptacle (20) having a first opening (21) at the lower end of the housing (2) for insertion of a first attachment portion (16) at the upper edge of a cylinder (11) of the syringe (3),

- A receiving body with a second receptacle (24) and a second

Opening (26) at the lower end in the housing (2) for insertion of a second attachment portion (19) on a piston (12) of the syringe (3),

- First means for releasably holding (23) of the first attachment portion

(16) in the first receptacle (20),

- Second means for releasably holding (27) of the second

Fixing portion (19) in the second receptacle (24),

- First means for displacing (5) of the receiving body (25) in the housing (2) of the first receptacle (20) away,

second means for displacing (28, 36, 39) the receiving body (25) towards the first receptacle (20) in steps of a step size corresponding to the volume of liquid to be ejected from the syringe (3) during the steps,

- an actuatable outside the housing (2) actuating element (36) for

Performing individual steps,

- one with the receiving body (25) connected in the housing (2) arranged rack (28) with a toothing (29),

- One in the housing (2) on the actuating element (36) pivotally mounted

Pawl (39) which, upon displacement of the actuating element (36) downwards with the toothing (29) of the rack (28) engages and this entrains and upon displacement of the actuating element (36) up out of engagement with the toothing (29) comes,

- An outside of the housing (2) adjustable adjustment (10) for

Setting the step size of the steps,

- One on the rack (28) on the side of the pawl (29) displaceably arranged cover (41) with a pawl (39) facing Abhaltefläche (71) for holding the pawl (39) of an engagement in the toothing (29) and having a lower edge of incidence (70) below which the toothing (29) is exposed for engagement by the pawl (39),

a coupling element (68) arranged on the cover (41), which is coupled to the adjusting element (10) in order to transmit an adjustment of the adjusting element (10) to the cover (41),

wherein the cover comprises a first cover part (42) made of plastic, which comprises the coupling element (68) and a longitudinal slot (61), and a second cover part (43) made of sheet metal held on the lower cover part (42) and one in the longitudinal slot (43). 61) arranged angled portion (49) and a spring tongue (53) connected thereto,

the incidence edge (70) is formed on the first cover part (42), the rack on the side facing from the cover has a projecting cam (80) which at the end of the displacement of the

Receiving body (25) to the first receptacle (20) out in the longitudinal slot (61) meets the bend (49), whereby the spring tongue (53) deflected and the pawl (39) of the spring tongue (53) on a further engagement in the

Teeth (29) of the rack (28) is held, and

the second cover part (43) with the exception of at least angling

(49) and spring tongue (53) comprising, section of the plastic of the first cover part (42) in a defined position of the bend (49) with respect to the coupling element (68) encapsulated and thereby the first cover part (42) and the second cover part (43) are firmly connected to each other.

2. A pipette according to claim 1, wherein a head portion (44) of the second cover part (43) adjacent to an upper slot portion (62) of the longitudinal slot (61) on the rack (28) side facing edge of the plastic of the first cover part ( 42) is overmolded and the head portion (44) is connected at the lower end to the bend (49) disposed in a lower slot portion (63) of the longitudinal slot (61) adjacent to which the second cover portion (43) is out of plastic the first cover part (42) is encapsulated, so that the cam (80) in the longitudinal slot (61) on the head portion (44) can slide along before it meets the bend (49).

3. A pipette according to claim 2, wherein the second cover part (43) has a with the lower end of the head portion (44) connected to the first strip-shaped portion (48) connected at the lower end with the bend (49) and in the lower slot portion (63) is arranged.

4. A pipette according to claim 2 or 3, wherein the second cover part (43) has a with the lower end of the bend (49) connected second strip-shaped portion (50) which is arranged in the lower slot portion (63) and on which Cam (80) after passing the bend (49) can slide along.

5. A pipette according to any one of claims 1 to 4, wherein a connecting portion (51) having a longitudinal edge of the first or second strip-shaped Section (48, 50) is connected, through a recess (69) in the top of the first cover part (42) therethrough to the longitudinal edge of the first cover part (42) and via a deflection (52) with the parallel to the longitudinal side of the first cover part (42) downwardly extending spring tongue (53) is connected.

6. Pipette according to one of claims 1 to 5, wherein the second cover part (43) is made in one piece from sheet metal.

7. Pipette according to one of claims 1 to 6, wherein the second cover part (43) on the side facing away from the rack (28) side of the first cover part (42) of transversely to the rack (28) extending webs (64 - 67) the first cover part (42) is covered.

8. A pipette according to claim 7, wherein a web (65) carries the coupling element (68).

9. A pipette according to any one of claims 1 to 8, wherein the lower end of the first cover part (42) has the incidence edge (70).

10. A pipette according to claim 9, wherein the first cover part (42) has a towards the lower end gradually decreasing wall thickness.

11. Pipette according to one of claims 1 to 10, wherein the first cover part (42) at the engagement edge has a wall thickness of at most 0.5 mm, preferably from 0.4 to 0.2 mm.

12. Pipette according to one of claims 1 to 11, wherein the first cover part (42) on the rack (28) side facing a flat contact surface, to which the rack (28) can create and in which the longitudinal slot (61 ) is arranged.

13. The pipette of claim 9 and 12, wherein the first cover part (42) on the side facing away from the rack (28) side to the lower end has a chamfer (72).

14. A pipette according to any one of claims 1 to 13, wherein the first cover member (42) in the form of an elongated hollow body with two parallel, strip-shaped side parts (54, 55) and a base (56) defining a channel (57) wherein the longitudinal slot (61) is formed in the base (56) and the second cover part (43) in the base (56) is overmolded by the plastic of the first cover part (42).

15. A pipette according to any one of claims 1 to 14, wherein the first cover part (42) on the two longitudinal sides laterally projecting wings (74, 75).

16. A pipette according to any one of claims 1 to 15, wherein the rack (28) with the cam (80) is integrally molded from plastic.

17. A pipette according to any one of claims 1 to 15, wherein the cam (80) in the axial direction einjustierbar on the rack (28) is arranged.